ssh-agent does not persist over sessions in WSL2 with current openSUSE Linux and other common distributions. Linux native bashrc solutions don’t work here. Let’s use keychain instead
zypper in keychain
Then let’s add some snippet to .bashrc and remove any eval ssh-agent lines
# Once per key to load by default
/usr/bin/keychain -q --nogui $HOME/.ssh/id_rsa
/usr/bin/keychain -q --nogui $HOME/.ssh/id_host_www.ralf-lang.de
# Only once
Then open a new window. It will ask you to enter your passphrase once. Enter any additional windows, it won’t ask you
My 2023 started in a bad way. I did not attend to any non-work twitter, email or other communication and FOSS work to deal with that. Don’t worry, I will catch up soon. Sorry for any delays and inconveniences.
Satis is the lightweight, static repository generator for the composer package manager. It enables admins to provide PHP software packages inside airgapped CIs, OS packaging environments and restricted data centers.
Back in August I added a plugin mode to satis to make it work as a regular composer plugin. While working on it, I also fixed some preexisting issues found by static analysis and made it compatible with the recent composer versions 2.3 and 2.4.
This week, the upstream maintainers merged my contribution. I feel a bit satis-fied 😉
Why make it a plugin?
When looking under the hood, it is easy to see that satis always has been some awkward kind of plugin or extension. It literally sits on top of an internal copy of composer. It hooks into its internals in not quite transparent ways, it uses its class and interface organs for its own vital functions. You might call it a parasite that attaches to composer’s body for its own needs. There are downsides to this approach. The first is that you need a private copy of composer. The second is that any refactoring of composer internals likely breaks satis compatibility. That happened some time ago when composer 2.3 and 2.4 were released and not for the first time. Composer has a maturing plugin API with nice, well-defined integration points. It provides some means to overload or amend core functionality but it also provides messaging between core and plugins. I only did the bare minimum work to make satis hook into the plugin API and not break the standalone mode. When installed as a dependency, package resolution will ensure that the API versions used by satis matches the API versions provided by the underlying composer.
I don’t quite understand… What is the benefit?
By itself, this change provides little benefit. It is a feature enabling feature.
Satis can be further refactored to make compatibility bread less often
Satis can send and receive events from composer or other composer plugins. This enables running satis as part off a custom command. Think passing unit and integration tests of a project and then conditionally updating the staging or canary package repository.
Satis’ schema could be amended to make a project’s root package also function as an instruction to build a repository of all dependencies with almost zero configuration. Add this to a workflow or add a collaborator plugin that handles the necessary push/release and you have a powerful tool for CI and developer laptop alike.
But as I went along, I also re-aligned satis with the latest breaking changes inside composer 2.3/2.4. This will benefit users who do not care about the whole plugin story.
With satis 3.0-dev merging this initial change, the next steps are obvious, but not urgent. Making the new plugin mode play nice with the latest composer was already easier than fixing the standalone mode. Satis still has an internal, now updated dependency copy of composer which is only run in standalone mode.
Standalone mode should be refactored to be just a thin wrapper around composer calling into its satis plugin. Keeping intrusion into composer internals to the bare minimum to hide the builtin commands and re-brand it as satis, this would make breakage on upcoming updates much less likely. Eventually, we can maybe stop carrying around a source code copy of composer at all.
Finally, there is reaping the benefits. I want to leverage composer/satis functionality inside the horde/components tool. Rolling out new versions of horde stuff could be so much easier.
The way we write dates is very different among cultures and technologies. Even countries of the same language family might have totally different notions where to put the year, where to put the month, where to put the day when writing down a date in numbers. Apart from the order, we might use hyphen -, dot . or slash / to mark the sections. Leading zero yes or no. It gets much worse when writing out a date, like “Vlad was born on the 13th of June” or “Monday, October 10 I will have a barbecue”. Mix in different languages and different ways to abbreviate Monday as “Mo”, “Mon”, “M”. The PHP-native ways to deal with date math and date formatting are a little quirky and best wrapped in some code that hides away the nasty details but exposes useful capabilities.
The horde/date library has been around for ages and it does its job. Due to changes in the PHP 8.1+ engine, it requires some internal re-engineering. As it is also due for a conversion to namespaces and PSR-4, I decided to think about the interface a little more. These are rough ideas and I am still figuring what will be fun and safe to work it and what is possibly over-thinking it.
It’s DateTime all right.
PHP provides internal data types to store and manipulate a date: DateTime and DateTimeImmutable. Horde_Date behaves similar to DateTimeImmutable but implements a lot of intricate math on its own. Still, it uses DateTime for some conversions. It makes sense to delegate most mutation math to the DateTimeImmutable class and make it also hold most state. No need to manually manage minutes, hours, days of weeks etc in most cases. Preferring Immutable safes us some clone magic.
Wrap it up or extend it?
There are two possible approaches to dealing with the builtin type: Either extend it or hide it in a wrapper. The third option would be to implement the interface but this is not possible. Extending any of the two DateTime types would be handy as it is the lingua franca between different library ecosystems. We could simply inject our Horde Date type into any library that uses it. There are down sides to this approach though. While DateTimeInterface is reasonably small and mostly useful, DateTime and DateTimeImmutable expose a lot of functionality. Some of it is awkwardly named. Some of it would have to be wrapped in extending to avoid inconsistencies in our own object. Some of it possibly clashes with own naming schemes and blocks us from using preferred signatures. Some of it might not fit into our own notion of what belongs where. There is also a risk of exposing different functionality based on PHP versions. This is undesirable. Extending is not the way to go. Hiding away the DateTimeImmutable object and exposing it explicitly might seem a little verbose. It offers some interesting applications.
Clock Date – Now is the right time.
A clock date type always emits now. Asking it again at a later point will yield a later time without having to manipulate the object. This is useful for tracing duration of processes or for emitting status messages. We can also make this clock the second element of a time span. Its duration will automatically expand. We can add a Stop method to the clock which will return a regular, fixed date for further processing.
No Date – When it’s not right for you.
Sometimes we cannot rely on a date being present in the input. It might be optional. It might be required by the current data model but used to be optional or malformed. Traditional options would be expressing the non-date as null value, throwing an exception or silently assuming no date means now. These are appropriate, good solutions in many cases. Sometimes you may prefer to have the “no date” information behave a little like a date – until it reaches a point where it cannot. For example, a “not a date” can be formatted many ways. It can be serialized to the backend, provided the backend can deal with it. It can however not be calculated, mutated or cast to a DateTimeImmutable. I am not yet sure how to handle this. Maybe it should be confined to Formatters and Readers.
In The Zone.
PHP provides an own finite list of Time Zone identifiers. Wrapping PHP’s timezone objects allow dealing with well known but unsupported timezone names. We can map them to known names. We can safe the originally provided name for later usage. We might not carry a PHP timezone at all but signal the other parts of the library that some custom code must be applied.
In Good Format.
There are a plethora of ways to express a given date. There are three builtin date renderers in PHP, IntlDateFormatter (not always installed), strftrime (deprecated) and DateTimeInterface::format (English only). You might add your own. Each has its own dependencies, arguments, requirements. It is much simpler if there is a Formatter type. Implementations can just configure it and load it with a date. Consumers have a simple interface to work with them regardless of how they are implemented.This also allows to keep the dependency footprint of the core date library low and makes adding more output formats very easy. The same is true for reading data. Reading values from various formats should not be the Date object’s concern. Another object should turn arbitrary string, integer or other data into dates – including legacy Horde_Date objects.
If you ever read a github pull request or similar extension proposal, you will likely have seen side by side comparisons of the original and the changed file. You may also have seen some text format that highlights only differences and a little context but hides the unchanged rest of the file. Both of these formats are called Diff, named after the popular diff and patch utilities dating back to ancient Unix times. The git diff command does something very similar. The horde/text_diff library and its ancestor, the pear/text_diff library, are tools to generate and format such difference information for different usage scenarios.
Apart from Horde’s internal usage in its repository viewer, horde/chora, and its wiki software, horde/wicked, the tool is also used by external parties. WebSVN maintainer Michael O. approached me because he wanted to use a PHP 8.2 ready version of horde/text_diff to substitute an older component which did not do the job. Michael has been very helpful in getting me started, pointing me to some issues to solve and also providing his own solutions in some parts. The result is a conservative update of horde/text_diff that will run in the upcoming versions of PHP without causing any trouble. But this is only where I started.
Breaking bad habits
A closer look at the internal structure of the library showed that it deserved a major overhaul. The solution was to refrain from a verbatim upgrade to namespaces and the likes but to actually change some things. This meant breaking backwards compatibility. I go to great lengths to keep a conservative drop-in version of everything I touch in the lib/ folder. Sometimes it is just an interface or wrapper, sometimes the new and old code do not really share a lot.
I began with adding type hints to most methods. Targetting PHP 8.1+ for the src/ path allows to use union types and intersection types. A lot of knowledge hidden in phpdoc comments is moved into actual code and makes it more robust.
Exploring the code for base classes and interfaces, I noticed that some things I did not like.
Method signatures did not add up
Some method signatures did not add up. Depending on the type of Diff Engine, the diff() method would take different types of arguments. The interface was mixing the specifics of how the diff engine is set up with the command to create a list of operations objects. Loading the engine is now separated from running it. The running method is now always called in the same way.
Internal dependency creation
The Diff, Threeway Diff and Mapped Diff utilities all created their diff engine internally. To do this, they needed a very flexible constructor that allowed passing whatever is needed to set up the actual engine. That was bad enough but they also did it in different ways. The Differs’ constructor now only accepted a pre-constructed engine. For convenience, I created a factory which would take over the responsibilities originally assigned to the differs’ constructor: Building a differ from input and if no specific differ was chosen, selecting one by some priority logic. In the end it turned out that the Differ does not need the engine at all but rather needs the product of the Engine: A set of operations to transform document A to document B. Born is the OperationList class. I did not want to just pass an array. I added a small static method as a named constructor. It frees the actual constructor of too many responsibilities and allows to keep the interface clean and strict.
More explicit type juggling
Creation if diffs contains some interesting math. The algorithms use a lot of short variable names and operations that make sense if you know the underlying theory but otherwise look like garbage. I added some explicit conversions between string and integer and made some changes to ensure a number zero or an empty string is not mistaken for a “false” or “null” value which would have another meaning. Overall it is now much easier for static analyzers to spot any issues.
Dual stacks have a price tag
Essentially maintaining two different sets of the library comes with some cost. One must ensure that unit tests targeted at the newer platform are not run when testing for compatibility with the older platform. The conservative lib/ is ready to run PHP 7.4 code but the modern version in src/ must be transpiled to be run in PHP 7.4 – I do that on release but still it is another aspect that needs minding. As I also use automated tools for some upgrade tasks, I need to ensure I do not upgrade the lib/ path. The price is worth it as I cannot convert the code base at once and I want to provide a good development experience to all who are caught in between maintaining an older release or creating new code. I am in that spot myself. Essentially it allows me to run two conflicting major versions of some critical libraries and pick the right one for different sub systems. The need will go away as code is gradually migrating towards the newer implementations. At some point a next major version will drop the conservative path. Anybody interested is free to maintain the older major version and keep using it.
I consider the external interface of the newer horde/text_diff implementation fairly stable by now. Internally, however, there is a lot of room for improvement. Some functionality should move out of the base classes and into separate traits – which the base classes will use. Some getters should be added and used, preparing to move some public variables to internal state in a next major release. The new OperationList gets unloaded to plain arrays in several places – It needs to learn some tricks without degrading into a glorified array. None of this should stop early adopters from using the new code base. None of this is supposed to break any user code.
Out of scope for now
There are some items which I decided to postpone for now. One thing which bothers me is the amount of dependencies. While a dependency on horde/exception makes sense, it pulls in horde/translation for no good reason. Horde\Util is pulled in but really only used in two places: A horde/string call which could be reduced to a direct call to an internal function and one call to a helper for handling temporary files. That helper should maybe live in its own library, nicely decoupled from unrelated utilities. There was a reason why they were packed together but it is no longer relevant.
Also, some functionality is missing in the Xdiff-based engine. Most distributions do not even offer php-xdiff, including my own development platform. I will add that feature once I get it into CI and into the development setup. I do not want to delay other items to do that right now. Patches welcome 🙂
Code generators have been invented and forgotten at least four times in software history. They have an appeal to developers like the sun to Daedalus’ son. Let’s not be Icarus, let’s keep them generators at a distance and watch them carefully.
Whenever a language, framework or paradigm forces developers to do the same thing over and over and over and over again they will try to get rid of that repetition. One approach is to automate writing code. It is not pretty but it saves time to concentrate on more interesting and useful things. Seasoned and reasonable software developers have resorted to that solution and many inexperienced have followed. Outside very narrow use cases I think generated code should better not exist at all.
Valid use case
Generated code and other kinds of boilerplate code are valid where avoiding them is not practical. This is often true for entry points. Depending on language, it might not be trivial for a the first piece of running code to find
its collaborators, base classes, dependencies
useful data from previous runs
I have written a long, long piece on two-stage autoloaders and other two-stage bootstrapping topics and I keep rewriting it, breaking out separate topics. It is still unreleased for a reason. Any two-stage process that splits automated detection or definition of artifacts from the production run that uses them is essentially code generation. Avoiding it might be possible but impractical. Some level of repetition cannot be avoided at all and is best automated.
Another valid use case is generating code from code or transpiling. Nothing is wrong with that.
Unfortunate Use Cases
There are other use cases that should be avoided. Your framework follows convention over configuration so making magic work requires having some artifacts in the right places. Even if they have no natural place in your specific solution they are needed for technical reasons so you copy/paste or auto-generate the minimum sufficient implementation and make it fit. This is something to look for. Often there are ways around it. Another case is limits of the underlying language. You evolved from using magic properties and methods to implementing type safe, explicit equivalents but now you have to re-invent the type specific list or container type and you automate it. Bonus points if your ORM tool requires it. If your language does not support generics or another templating method, you are stuck between repetitive, explicit code and weakly typed magic. You end up using a code generator. Hopefully at one point somebody is annoyed enough and ventures to bring generics into your language. That would be the better solution but it is likely out of scope for your day to day work.
Stinking unnecessary use cases
Beyond that you are likely in the land of fluff where things just happen while they can and lines of code are generated just because it is customary. This is a foolish thing best avoided. Granted, automating code is better than hand-writing it. It does however not mean the code should exist at all. If you have no specific reason to repeat code, it is likely a design smell. This is not new, the Cunningham wiki had this thought a decade or more ago. Likely they were not even the first to recognize it. Refactoring, abstraction, configuring the specifics can help reduce the necessity for repetitive code.
My programming tools were full of wizards. Little dialog boxes waiting for me to click “Next” and “Next” and “Finish.” Click and drag and shazzam! — thousands of lines of working code. No need to get into the “hassle” of remembering the language. No need to even learn it. It is a powerful siren-song lure: You can make your program do all these wonderful and complicated things, and you don’t really need to understand.
Let us take the input to a code generator and make it the input to abstracted, ready to run code instead. We will know when it is not practical, not performant or not possible. Then code generation is a blessed thing. Otherwise it is a sin.
Developers sometimes choose not to use the latest available language features that would be appropriate to tackle a problem for fear of alienating users and collaborators. This is a bad habit and we should stop doing that. Part of the solution are transpilers. What are transpilers, where are they used and what is the benefit? Why should we consider transpiling all our code?
I cut this piece from an upcoming article that is way too long anyway. I made this new article by reusing and reshaping existing text for a new audience and frame. You are reading a new text that first was built as a part of another text. – Yes. This was transpiling: Rephrasing an input, including externally supplied, derivative or implicit facts about it to an output that generally expresses the same. Excuse me, what? Let me go into some details.
Transpiling: Saying the same but different
In software, transpilers are also known as source to source compilers. They take in a program written in one language and write out a roughly equivalent program for another language. The other language may be another version or dialect of the input language or something entirely different. Don’t be too critical about the words: transpilers are just like all other compilers. Source code is machine-intelligible, otherwise it could not be compiled. Machine code is intelligible by humans, at least in principle.
Preprocessors are transpilers
A preprocessor is essentially a transpiler even if it does not interpret the program itself. The C language preprocessor is a mighty tool. It allows you to write placeholders that will be exchanged for code before the actual C compiler touches it. These placeholders may even have parameters or make the program include more code only if needed. Concatenating many source files into one and minifying these by stripping unnecessary whitespace can also be seen as a primitive form of transpiling.
Coding Style Fixers are transpilers
Automatic tools that edit your source code are transpilers. They might only exchange tabs for four space characters or make sure your curly braces are always in the same place or they may do much more involved stuff. For example php-cs-fixer transforms your technically correct code written in plain PHP into technically correct code in standards-conforming plain PHP. One such standard is PSR-2, later deprecated in favor of PSR-12 and PER-1 – these are all maintained by the PHP FIG. Software projects may define their own standards and configure tools to transpile existing code to conform to their evolving standards.
Compilers are transpilers
A compiler is a transpiler. It takes in the source code and builds a machine-executable artifact, the binary code. It might also build a byte code for some execution platform like Java’s JVM. It might build code for a relatively primitive intermediate language like CIL or a machine specific Assembly Language. Another compiler or an interpreter will be able to work with that to either run the software or turn it into a further optimized format. These transformations are potentially lossy.
Decompilers are transpilers
Earlier in life I used tools like SoftICE that would translate back from binary machine instructions to Assembly Language so that I could understand what exactly the machine is doing and make it do some unorthodox things. Compiling back from Machine Code to the machine-specific Assembly Language is technically possible and lossless but the result is not pretty.
Lost in translation
When humans rewrite a text for another target audience, they will remove remarks that are unintelligible or irrelevant to the new audience. They may also add things that were previously understood without saying or generally known in the former audience. Transpilers do the same. When they transpile for machine consumption, they remove what the machine has no interest in: Whitespace, comments, etc. They can also replace higher concept expressions by detailed instructions in lower concepts. Imagine I compiled a program from assembly language into binary machine code and then decompiled back to assembly language. Is it still the same program? Yes and no. It is still able to compile back into the same machine program. It does not look like the program I originally wrote. Any macro with a meaninful name was replaced by the equivalent step by step instructions without any guidance what their intention is. Any comments I wrote to help me or others navigate and reason about the code are lost in translation. The same is true anytime when we translate from a more expressive higher concept to a lower concept. Any implicit defaults I did not express now show up as deliberate and explicit artifacts or the other way around, depending on tool settings.
Lost in Translation but with Humans
You may know that from machine translated text. Put any non trivial text into a machine translator, translate it from English to Russian to Chinese to German and then back to English. In the best case, it still expresses the core concept. In the worst case it is complete garbage and misleading.
Another such thing are Controlled Languages like Simple English, Français fondamental, Leichte Sprache, etc. They use a reduced syntax with less options and variations and a smaller selection of words. Some like Aviation English or Seaspeak also try to reduce chance for fatal ambiguity or mishearing.
These reduced languages are supposedly helpful for those who cannot read very well, are still learning the language or have a learning disability. They may also enable speakers of a closely related foreign language to understand a text and they generally cater to machine translation. For those who easily navigate the full blown syntax and vocabulary and can cope with ambiguity and pun, simplified language can be repetitive, boring and an unnecessary burden to actual communication. Choosing a phrase or well known roughly fitting word over a less used but more precise word is an intellectual effort. Reading a known specific word can be easier on the brain than constructing a meaning from a group of more common words. Speaking to an expert in a language deliberately evading technical terms may have an unintended subtext. Speaking to a layman in lawyerese or technobabble might not only make it hard for them to understand you but also hard for them to like you. Readers will leave if I make this section any longer.
Now that everybody is bored enough, let’s see why it is useful and how good it is.
Upgrading Code to newer language versions
You can use a transpiler to upgrade code to a newer version of the language. Why would you want that? Languages evolve. New features are added that allow you to write less and mean the same. Old expressions become ambiguous by new syntax and features. Keywords can be reserved that previously weren’t. Old features become deprecated and will finally stop working in later versions. A transpiler can rewrite your code in a way that it will run in the current and next version of a language. It can also move meta information from comments or annotations into actual language code.
* @access private
* @var FluffProviderInterface Tool that adds bovine output
* Constructs an example
* @access public
* @param IllustrableTopicInterface A topic to explain by example
* @param bool $padWithFluff Whether to make it longer than needed
* @param int $targetLength How long to make the article
* @return string The Article
function constructExample($topic, $padWithFluff=true, $targetLength=3000)
Now that’s what I call a contrived example. Code might look like this if it was originally written in PHP 4 and later enhanced over the years, only using new expressiveness where needed. While it technically runs, it is not how we would possibly write it today.
* @var FluffProviderInterface Tool that adds bovine output
private readonly FluffProviderInterface $fluffProvider;
* Constructs an example
* @param IllustrableTopicInterface A topic to explain by example
* @param bool $padWithFluff Whether to make it longer than needed
* @param int $targetLength How long to make the article
* @return string The Article
public function constructExample(
That could be the output of a transpiler. It takes meta information from controlled language in the comments and uses the advanced grammar of the improved PHP language to express them. In other words, the upgraded code has turned instructions for the human or for external tools into instructions that the language can actually enforce at runtime. Before it helped you understand what to put in and what to expect out. Now it forbids you from putting in the wrong things and errors if the code tries to give back anything but text.
It may drop comments that are already expressed in the actual code. Some project standards suggest to drop @param and @return altogether to make the code more consise to read. I am a little conservative on this topic. A documentation block may be removed if it does not contain any guidance beyond the code. There is no need to rephrase “this is the constructor” or “The parameter of type integer with name $targetLength tells you how long it should be”. But sometimes things deserve explaining and sometimes the type annotations exceed what actual the language expresses. Intersection types are PHP 8.1+. PHP 8.2 can express “return this class or false but not true” while before the language only allowed “This class or a boolean (either true or false)”. Annotations can be read by tools to work with your code. As demonstrated, a transpiler can use them to rewrite your code to a more robust form. Static analyzers can detect type mismatch that can lead to all sorts of bugs and misbehaviours. Documentation generators can strip away the actual code and transform the comments and structural information into something you can easily navigate and reason about. Code including high concept and documentation is first and foremost for humans. Adapting it for machines often means dumbing it down.
Downgrading to an older platform or language version
Imagine we create a book for small children. We will first create a compelling story, lovely characters and possibly some educational tangent using our words and our thoughts, the level of abstraction we are fluent in and the tools we can handle. We finally take care to adapt wording, level of detail and difficult concepts to fit the desired product. We don’t write to the agent, the publisher or the printing house in baby english. So why should we use anything less than our own development environment supports? It is not healthy. Outside very special situations or for the joy of it, we generally don’t work with one hand tied to the back, using antiquated tools and following outmoded standards.
If we cater to the lowest assumable set of capabilities at development time, we limit ourselves in a costly way. We cannot benefit from the latest and most convenient, i.e. effortless and reliable set of tools. We are slower than we could be, we will make more mistakes and it will exhaust us more than needed.
Provided our production pipeline from the development laptop or container to the CI are able to work with the latest tools, we can use them.
Deliver using a transpiler
The source branch should always target your development baseline, tools as modern as you can come by. Delivery artifacts, i.e. released versions, should deviate from the source distribution anyway:
Why should you ship build time dependencies with a release?
Why should you ship CI recipes or linter configurations with a release?
Depending on circumstances, shipping the unit tests might be useful or waste.
You would not normally ship your .git directory, would you?
Adding a transpiler step is just another item, just another reason. Transpiling to your lowest supported baseline is not really different from zipping a file, editing a version string or running a test suite to abort faulty builds before they ship. But still, it is not perfect. The shipped code will run on the oldest supported environment but it will miss many runtime benefits of newer versions. This is especially true if your library is a build time dependency of another project. In the best scenario, a build for a fairly recent but reasonable platform expectation exists and another build for an well-chosen older target exists. Both need to run through the test suite and ideally the older build will pass the test suite both when actually run on the old platform and when run on an upgraded platform. There are some details, edge cases and precautions needed to make this feasible and reliable. This will be detailed in an upcoming article which just shrank by a good portion.
tl;dr – I packaged horde/components as a single file for easy inclusion in build pipelines.
The horde/components commandline app is an important development tool. It lets you generate a composer.json file from the .horde.yml definition, helps with managing the changelog yml and provides a simple workflow utility which I use for release pipeline. Last year I added some capabilities for managing git branches and tags. It is very opinionated and I often think about generalizing some functionality to make it more useful beyond horde development.
But the tool is unwieldy. It installs 69 horde dependencies, 5 pear libraries and several more stuff, including a complete distribution of sabre/dav. This is an issue that will eventually get solved by slowly redesigning the dependency graphs. For now we have to live with it. But how? You don’t want to require-dev that beast into your working tree. Chances are it would blur what is really needed for the unit worked on and what is only needed to support the tool. It could also lead to library version conflicts.
So move it out of tree and run it as a separate root project, then symlink the commandline program to some path like /usr/local/bin? Yes, that did work but still two or three steps when there ought to be only one. I wished for a single file that I could easily install. The solution in php is a phar file, similar to a jar in java.
The documentation of phar consists of only a few pages detailing all the possible calls into phar, all the capabilities of the extension – but it left me completely in the dark how to actually use it. Looking at some CI pipelines of popular tools distributed via phar.io / phive gave some ideas but also did not bring the wanted outcome. The evening dragged on and on. Finally I found an old article by Matthew Weier O’Phinney. Back in 2015 he advised to use a helper (box-project/box) to build a phar. He pointed out what I already learned in a painful way: The official documentation won’t get me where I want fast.
His article also included some bits on distribution and signing which I will consider at a later stage and some bits specifically linked to Travis CI, back then the natural champion for CI needs in Github. Today Github promotes Github Actions as the preferred CI tool so I will have a look into this.
horde/components not only contains some internal workflows, it also used to have functionality to set up a jenkins CI environment. I haven’t used it in years and it is likely broken. I think I should rather implement functionality to call into a Github or Gitlab Hook, read metadata from the API, create artifacts like packages and release notes. Having the components tool in one ready to run file also makes it easy to get it into a CI. But we are not yet there.
My preliminary build is available via https://horde-satis.maintaina.com/horde-components – there are no versions yet, there is no nightly update and there is no signing yet. I am still figuring out which parts work as expected and which need further improvements. This build is based on the maintaina-com repository and differs in functionality from the official horde.org code base. I think this deviation is inevitable for the moment though I don’t like it much.
If you want to build and distribute your own phar component, read the original article by MWOP. I am very glad I found it – saved this evening’s success.
TL;DR – horde/horde-installer-plugin will now install apps to vendor dir and then link to web dir
Apps in the web dir
Until today, the composer plugin for installing horde apps installed apps directly into the web dir and linked configs from outside the webdir into the apps. That had several drawbacks. Developers could not just traverse the vendor dir to jump between libraries and app plugins. That is a deviation from composer standards which install everything besides the root package into a two-level structure below /vendor directory.
Handle equal things equal
Move setup to post installation
Recently, a new composer command horde:reconfigure was added to trigger the reconfiguration mechanisms on demand. The latest changes prepare a next step, reusing the linking and post installation procedures in tools that don’t run as composer plugins. At one point, the plugin can become a useful but optional component. Without the plugin, composer only adds, removes or updates software and kills any modifications to vendor dir. In this case it is up to the administrator to run another tool that re-applies the necessary configurations. The ultimate goal is to require less and less such modifications in the vendor dir and also less fiddling with the web dir.
Side effect: Added security
The applications are now symlinked to the web dir, but selectively. Documentation, bindir, admin scripts and unit tests are no longer available in the web dir, as well as some non-runtime files from the root dir. This reduces the surface for attacks in case filtering mechanisms like htaccess files fail.
Unsolved: Deinstallation case
At the moment the installer does not properly tackle deinstallation of apps. It leaves a directory containing broken symlinks. This is to be solved before a tagged release of this new change can happen.
Backward Compatibility Implications
It is intended to be mostly backward compatible. Users are encouraged to call into vendor/bin instead of calling into the application directories directly – be it in their old or new locations. The components CLI application, mostly used by developers and Continuous Integration jobs, will no longer show up in the web dir at all. You SHOULD configure it through var/config like other apps and then run the CLI through vendor/bin or wherever your bindir is located. This was the preferred approach before. The components app only showed up in the web dir because it is classified as a horde-app.
Back in the old days when rock musicians took the same drugs as your grandfather, authorisation and authentication might have been very simple. You had a user name, you had a password. Most likely you had one and the same password for each and everything. Congrats if you were smarter back then. Maybe your application had a notion of a super user flag or user levels. The more advanced had a permission system but who would ever need that? Well, there will only ever be the need for 5 computers, some researchers argued back in the old days, referring to an even older, albeit questioned, quote.
Today, authentication and authorization are much more complicated. People might still log into a system by user name and password. They might need a second factor like a One Time Password right away or later to perform advanced operations like committing orders. There might be elaborate permission or role-based systems restricting what the user can do on which resources. Users might not have a local password at all but a shadow identity linked to an authentication provider like Google or Github – who are the party assuring to the app that you are in fact the person you claim to be. In an enterprise context, devices might identify their users by SSL Certificates or bearer tokens. Finally the app might have long-lived remember-me cookies separate from their short-lived session tokens/session cookies. These might be bound to specific clients. Changing browsers may put you into a situation where login by user name and password will result in a more elaborate, email-based password.
And on a completely different level you might want to to authorize REST API access to entities either linked to a specific user account or to a specific outside service. Things got elaborate, things got complicated.
Basic Definition: Authentication
Authentication is the process of identifying who is dealing with the application. This generally involves two orthogonal questions:
How is the authentication communicated?
This is usually achieved by presenting some evidence of authentication to the resource. Showing your passport, you might say. In a stateless API, the evidence is presented with each request. In classic HTTP Basic Authentication, the user first accesses a resource and the resource answers, “Authentication required”. Then the user agent (browser) presents the user a form to enter user name and password. The request against the resource is sent again, along with an authentication header containing the user and password in a transport-friendly envelope (BASE64 encoding) which provides no security by itself. The server will check this information and if it matches, grant access to the resource. The latter is actually authorization – see below. As far as authentication goes, presenting evidence and accepting it is the whole thing. More advanced systems may send a derivative of the actual authentication information. Digest Authentication sends a value computed from user name and password which the server knows or can check against something it knows. The server or any intruder can not deduce from that value what the actual password was. Another derivative mechanism is cookie or bearer token authentication. A new authentication credential is created, for example by sending user name and password to the server (or to a third party) only once. The credential is now sent along with each request to verify it’s you. You might need your passport or driver’s license to acquire a key to your hotel room but once you have it, the key is all you need to get in.
How authentication information is checked
The other major aspect is how the server side keeps the necessary information to verify authentication data. More simply put: How does the server know if your user name and password are legit? User name and password might be stored in a file. The password might better not be stored in the file but a derivative value like a computed hash. This way, if somebody steals the file, he will only know the users but cannot know the passwords. The password (or its hash) might be stored in a database or in an LDAP server. The credentials might be sent to an authentication API. In some cases, the server does not have to store any authentication data. This is true when the authentication data contains means to verify that it has been created by a trusted third party, is time-limited and has not been tampered with. Finally, the server might not care at all. A traditional chat service may receive your user name and create a session key. This key is used to understand who sent or asked for what. As long as you are logged in and keep communicating, no new session for this user can be created. Once you are out for long enough, the session expires and anybody can use the same name again. Having to deal with passwords may be an unwanted complexity. Authentication is identifying you by any (sufficient) means.
You know it’s drivin’ me wild – Confusion
Traditional systems have mixed emotions about their guardian angel. As said above, they may mix up knowing who asks (authentication) with knowing if they deserve to receive (authorization). They may also have a notion of an “authentication driver” which might emphasize one aspect over the other, assuming that it is either well-established or irrelevant how the password arrives at the server. New systems should have a clear understanding of both aspects and may link multiple combinations of both receiving and checking credentials to the same identity or user account.
Basic Definition: Authorization
Authorization is the process of deciding if a requester (who could be authenticated or anonymous) is authorized to interact with a resource or system. A concert hall or a renaissance faire may check your authorization to enter by a ticket, a stamp on the hand or ribbon, wrist band. They may not give an elaborate thought about who you are. Why should they care? At its core, a username/password authentication system is just checking by a password if you are authorized to identify as a certain user. It may be beneficial to tie a password to an identity. This identity may have permissions and other attached data which it will keep even when it changes its password. Other systems assign authorization to the token itself which is both the password and the identity. In this case, when the token expires, the identity will expire, too.
DAC: Discretionary Access Control and Permissions
Any system that discerns access by the identity of a user can be considered a DAC system. Permissions may be assigned to a user identity directly or to a named group. The users’ being part of the group can be verified through his identity, hence his access level. This can include special pseudy-groups like “all authenticated users” and “guests” or non-authenticated users. Most systems need to expose at least the means of authentication to a yet unauthenticated client. The horde/perms and horde/share libraries implement such a DAC system. Most DAC systems are cumulative: By being member of more groups, a user can only gain more privileges but not lose them. In practice, it might be easier to define a privilage and allow access if a user does NOT have it (and maybe have some other) rather than trying to work out how to allow negative privileges within the actual system. In a wider sense, countable limits like allowing to upload ten pictures or reading 5 articles per day can also be expressed in a DAC system.
MAC: Mandatory Access Control
Mandatory access control is an evolution from DAC in which acess is defined by policies. These allow or prevent a user from sharing a resource with a defined audience. There is little provision for individual exceptions.
RBAC: Role-Based Access Control
Role-Based Access Control systems combine previous concepts. Multiple permissions on resources are assigned to a role and subjects or identities are authorized for these roles. Who grants this authorization is not defined by the system – usually it is is the person with the role of “approver” on the specific “role” resource. A system may define that a user role is needed to even apply for further roles or application is not possible at all and roles are centrally assigned. Extended RBAC systems can model composed roles out of other roles. They may also define policies for mutually exclusive roles – A person may not apply for a role for which he is the approver or a person may not approve his own application for a role, even if he is allowed to apply for the role and has the authority to approve. A ticket system may ask a user if he is in the requester role or in the processor role and may access to different queues and commands based on that decision. In sports, you might be a player in one game or league and a referee in another but you are not allowed to combine both roles’ permissions during a game. This prevents undesirable situations. A system may ask the top administrator to choose if he is currently acting as the administrator or as a regular user and prevent him from mixing both types of access at once.
Two Factor Authentication and Weak Authentication
Many modern systems combine a primary authentication mechanism like username/password with additional aspects. A user may need to solve a captcha to gain the authority to enter his password. A user may temporarily lose access to the login mechanism if the same IP address has tried to authenticate too many times within a time span. A user may be authenticated by a certificate or long living device cookie but needs to add password authentication or email verification before he has access to some functions, even if his user rank, role, permission, group membership or whatever is otherwise sufficient. One API call may be used in a UI scenario through a short lived session token and in an integration scenario using a separately scoped access token but not through a user / password combination. Finally there are One Time Password mechanisms which are only practical if they are limited either to specific requests like transferring money or are required periodically – like once every 24 hours. Keeping mechanisms nicely separated and combining requirements on a more abstract level is crucial. Trying to make a single mechanism powerful and flexible enough can end up making it overly complex and impractical to use. If you think of PSR-7 middlewares handling a HTTP request in PHP, a middleware’s job may be limited to fetching a credential from a header and calling into a backend or multiplexer. The result is stored back into the request as an extra attribute, leaving it to another middleware further down the line to process the result and implement consequences like an error message, a redirect to a login screen or determining which set of roles or permissions is whitelisted for this login type. By enabling or disabling middlewares for a specific request, complexity increases or decreases.
Challenging backend services
There is an obvious issue with scenarios in which multiple types of credentials may identify and authorize a user to access the system: In each case the system must be able to access its backend resources. This can be trivial for a global resource like a database accessed through a system wide application credential. It can be more tricky if you try to access a user-specific IMAP backend or an LDAP directory which has its own, completely separate notion of access control. There are several ways to tackle this but I will leave this to another article.