Monthly Archives: January 2015

Publish an Eclipse p2 repository on Sourceforge with rsync

This can be seen as a follow-up post of my previous post on building Eclipse p2 composite repositories. In this blog post I’ll show an automatic way for publishing an Eclipse p2 (composite) repository (a.k.a. update site) on Sourceforge, using rsync for synchronization. You may find online many posts about publishing update sites on Github pages and recently on bintray. (as a reminder, rsync is a one-way synchronization tool, and we assume that the master replica is the one on sourceforge; rysnc, being a synchronization tool, will only transfer the changed files during synchronization).

I prefer sourceforge for some reasons:

  • you have full and complete access to the files upload system either with a shell or, most importantly for the technique I’ll describe here, with rsync. From what I understand, instead, bintray will manage the binary artifacts for you;
  • in order to create and update a p2 composite site you must have access to the current file system layout of the p2 update site, which I seem to understand is not possible with bintray;
  • you have download statistics and your artifacts will automatically mirrored in sourceforge’s mirrors.

By the way: you can store your git repository anywhere you want, and publish the binaries on sourceforge. (see this page and this other page).

I’ll reuse the same example of the previous post, the repository found here https://github.com/LorenzoBettini/p2composite-example, where you find all the mechanisms for creating and updating a p2 composite repository.

The steps of the technique I’ll describe here can be summarized as follows: when it comes to release a new child in the p2 composite update site (possibly already published on Sourceforge), the following steps are performed during the Maven/Tycho build

  1. Use rsync to get an update local version of the published p2 composite repository somewhere in your file system (this includes the case when you never released a version, so you’ll get a local empty directory)
  2. Build the p2 repository with Tycho
  3. Add the above created p2 repository as a new child in the local p2 composite repository (this includes the case where you create a new composite repository, since that’s your first release)
  4. Use rsync to commit the changes back to the remote p2 composite repository

Since we use rsync, we have many opportunities:

  • we’re allowed to manually modify (i.e., from outside the build infrastructure) the p2 composite repository, for instance by removing a child repository containing a wrong release, and commit the changes back;
  • we can release from any machine, notably from Jenkins or Hudson, since we always make sure to have a synchronized local version of the released p2 composite repository.

Prepare the directory on Sourceforge

This assumes that you have an account on Sourceforge, that you have registered a project. You need to create the directory that will host your p2 composite repository in the “Files” section.

For this example I created a new project eclipseexampleshttps://sourceforge.net/projects/eclipseexamples/, and I plan to store the p2 composite in the sourceforge file system on this path: p2composite.example/updates.

So I’ll create the directory structure accordingly (using the “Add Folder” button:

sourceforge create folder structure 1 sourceforge create folder structure 2 sourceforge create folder structure 3

Ant script for rsync

I’m using an ant script since it’s easy to call that from Maven, and also manually from the command line. This assumes that you have already rsync installed on your machine (or in the CI server from where you plan to perform releases).

This ant file is meant to be completely reusable.

Here’s the ant file

We have a macro for invoking rsync with the desired options (have a look at rsync documentation for understanding their meaning, but it should be straightforward to get an idea).

In particular, the transfer will be done with ssh, so you must have an ssh key pair, and you must have put the public key on your account on sourceforge. Either you created the key pair without a passphrase (e.g., for releasing from a CI server of your own), or you must make sure you have already unlocked the key pair on your local machine (e.g., with an ssh-agent, or with a keyring, depending on your OS).

The arguments source and dest will depend on whether we’re doing an update or a commit (see the two ant targets). If you define the property dryrun as -n then you can simulate the synchronization (both for update and commit); this is important at the beginning to make sure that you synchronize what you really mean to synchronize. Recall that when you perform an update, specifying the wrong local directory might lead to a complete deletion of that directory (the same holds for commit and the remote directory). Moreover, source and destinations URLs in rsync have a different semantics depending on whether they terminate with a slash or not, so make sure you understand them if you need to customize this ant file or to pass special URLs.

The properties rsync.remote.dir and rsync.local.dir will be passed from the Tycho build (or from the command line if you call the ant script directly). Once again, please use the dryrun property until you’re sure that you’re synchronizing the right paths (both local and remote).

Releasing during the Tycho build

Now we just need to call this ant’s targets appropriately from the Tycho build; I’ll do that in the pom.xml of the project that builds and updates the composite p2 repository.

Since I don’t want to push a new release on the remote site on each build, I’ll configure the plugins inside a profile (it’s up to you to decide when to release): here’s the new part:

Now the URL to access a remote path on sourceforge with ssh has the following shape

<username>,<project>@frs.sourceforge.net:/home/frs/project/<project>/<path>

So in my case I specified (again, the final / is crucial for what we want to synchronize with rsync, see the note above):

lbettini,eclipseexamples@frs.sourceforge.net:/home/frs/project/eclipseexamples/p2composite.example/updates/

The local URL specifies where the local p2 composite site is stored (see the previous post), in this example it defaults to

${user.home}/p2.repositories/updates/

Again, the final / is crucial.

We configured the maven-antrun-plugin with two executions:

  1. before updating the p2 composite update site (phase prepare-package) we make sure we have a synchronized local version of the repository
  2. after updating the p2 composite update site (phase verify) we commit the changes to the remote repository
  3. That’s all 🙂

Let’s try it

Of course, if you want to try it, you need a project on sourceforge and a directory on that project’s Files section (and you’ll have to change the URLs accordingly in the pom file).

To perform a release we need to call the build enabling the profile release-composite, and specify at least verify as goal:

Let’s say we still haven’t released anything.

Since the remote directory is empty, in our local file system we’ll simply have the directory created. In the end of the build, the composite site is created and the remote directory will be synchronized with our local contents:

Let’s have a look at the remote directory, it will contain the create p2 composite site

sourceforge uploaded artifacts 1

sourceforge uploaded artifacts 2

Let’s perform another release; Our local copy is up-to-date so we won’t receive anything during the update phase, but then we’ll commit another release

Let’s have a look at sourceforge and see the new release

sourceforge uploaded artifacts 3

Let’s remove our local copy and try to perform another release, this time the update phase will make sure our local composite repository is synchronized with the remote site (we’ll get the whole composite site we had already released), so that when we add another composite child we’ll update our local composite repository; then we’ll commit the changes to the server (again, by uploading only the modified files, i.e., the compositeArtifacts.xml and compositeContent.xml and the new directory with the new child repository:

Again, the remote site is correctly updated

sourceforge uploaded artifacts 4

Providing the URL of your p2 repository

Now that you have your p2 repository on sourceforge, you only need to give your users the URL to use for installing your features in Eclipse.

You have two forms for the URL

  • This will use the mirror infrastructure of sourceforge: http://sourceforge.net/projects/<project>/files/<path>
  • This will bypass mirrors: http://master.dl.sourceforge.net/project/<project>/<path>

If you use the mirror form, when installing in Eclipse (or provisioning a target platform) you’ll see warnings on the console of the shape

But it’s safe to ignore them.

For our example the URL can be one of the following:

  • With mirrors: http://sourceforge.net/projects/eclipseexamples/files/p2composite.example/updates/
  • Main site: http://master.dl.sourceforge.net/project/eclipseexamples/p2composite.example/updates/

You may want to try them both in Eclipse.

Please keep in mind that you may hit some unavailability errors now and then, if sourceforge sites are down for maintenance or unreachable for any reason… but that’s not much different when you hit a bad Eclipse mirror, or the main Eclipse download site is down… I guess no hosting site is perfect anyway 😉

I hope you find this blog post useful, Happy releasing! 🙂

 

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Creating p2 composite repositories during the build

I like to build p2 composite repositories for all my Eclipse projects, to keep all the versions available for consumption.

Quoting from https://wiki.eclipse.org/Equinox/p2/Composite_Repositories_(new)

The goal of composite repositories is to make this task easier by allowing you to have a parent repository which refers to multiple children. Users are then able to reference the parent repository and the children’s content will transparently be available to them.

The nice thing of composite repositories is that they can be nested at any level. Thus, I like to have nested composite repositories according to the major.minor, major.minor.service.qualifier.

Thus the layout of the p2 composite repository should be similar to the following screenshot

p2composite1

Note that the name of the directories that contain a standard p2 repository have the same name of the contained feature.

The key points of a p2 composite repository are the two files compositeArtifacts.xml and compositeContent.xml. Their structure is simple, e.g.,

Note that a child location is intended relative to the path of these files; you can also specify absolute paths, not to mention http urls to other remote p2 sites.

The structure is not that complex, so you can also create it by hand; but keeping it up to date might not be that trivial. With that respect, p2 provides some ant tasks for managing composite repositories (creating, adding an entry, removing an entry), and that’s my favorite way to deal with composite repositories. I’ll detail what I usually do in this blog post, in particular, how to create (or update) a p2 composite repository with a new entry during the build.

The ant file is completely reusable and customizable by passing properties; you can reuse it as it is, after you setup your pom.xml as detailed below.

In this blog post I’ll show how to do that with Maven/Tycho, but the same procedure can be done in a Buckminster build (as I’ll hint at the end).

I’ll use a simple example, https://github.com/LorenzoBettini/p2composite-example, consisting of a plug-in project, a feature project, a project for the site, and a releng project (a Maven/Tycho parent project). The plug-in and feature project are not interesting in this context: the most interesting one is the site project (a Tycho eclipse-repository packaging type).

Of course, in order to run such ant tasks, you must run them using the org.eclipse.ant.core.antRunner application. Buckminster, as an Eclipse product, already contains that application. With Tycho, you can use the tycho-eclipserun-plugin, to run an Eclipse application from Maven.

We use this technique for releasing a new version of our EMF-Parsley Eclipse project. We do that directly from our Hudson HIPP instance; the idea is that the location of the final main composite site is the one that will be served through HTTP from the download.eclipse.org. We have a dedicated Hudson job that will release a new version and put it in the composite repository.

The ant file

The internal details of this ant files are not necessary to reuse it, so you can skip the first part of this section (you only need to know the main properties to pass). Of course, if you read it and you have suggestions for improve it, I’d be very grateful 🙂

The ant file consists of some targets and macro definitions.

The main macro definition is the one invoking the p2 ant task:

Note that we’ll also create a p2.index file. I prefer not to compress the compositeArtifacts.xml and compositeContent.xml files for easier inspection or manual modification, but you can compress them setting the “compressed” to “true” property above.

This macro will be called twice in the main task

First of all, this task will copy the p2 repository created during the build in the correct place inside the nested p2 composite repository.

Then, it will create or update the composite site for the nested repository major.minor, and then it will create or update the composite site for the main site (the one storing all the versions). The good thing about these ant tasks is that if you add a child location that already exists they won’t complain (though you can set a property to make them fail in such situations); this is crucial for updating the main repository, since most of the time you will not release a new major.minor.

This target calls (i.e., depends on) another target to compute the properties to pass to the macrodef, according to the information passed from the pom.xml

Default properties (that can be modified by passing a value from the pom.xml file):

  • software.download.area: the absolute path of the parent folder for the composite p2 site (default is “p2.repositories” in your home directory)
  • updates.dir: the relative path of the composite p2 site (default is “updates”); this is relative to software.download.area

Thus, by default, the main p2 composite update site will end in ${user.home}/p2.repositories/updates. As hinted in the beginning, this can be any absolute local file system path; in EMF-Parsley Eclipse, since we release from Hudson, it will be the path served by the Eclipse we server download.eclipse.org. So we specify the two above properties accordingly.

These are the properties that must be passed from the pom.xml file

  • site.label: the main label that will appear in the composite site (and that will be recorded in the “Eclipse available sites”). The final label will be “${site.label} All Versions” for the main site and “${site.label} <major.minor>” for the nested composite sites.
  • project.build.directory: the location of the p2 repository created during the build (usually of the shape <project.id>/target/repository)
  • unqualifiedVersion: the version without qualifier (e.g., 1.1.0)
  • buildQualifier: the replaced qualifier in the built version

Note that except for the first property, the other ones have exactly the same name as the ones in Tycho (and are set by Tycho directly during the build, so we’ll reuse them).

The ant file will use an additional target (not shown here, but you’ll find it in the sources of the example) to extract the major.minor part of the passed version.

Calling the ant task from pom.xml

Now, we only need to execute the above ant task from the pom.xml file of the eclipse-repository project,

ATTENTION: in the following snipped, for the sake of readability, I split the <appArgLine> into several lines, but in your pom.xml it must be exactly in one (long) line.

As I said, you should pass site.label as you see fit (for the other properties you can use the default).

You may want to put this plugin specification inside a Maven profile, that you activate only when you are actually doing a release (see, e.g., what we do in this pom.xml, taken from our EMF-Parsley Eclipse project).

Try the example

Let’s simulate some releases:

To see what you get, just clone the repository found here https://github.com/LorenzoBettini/p2composite-example, cd to p2composite.example.tycho and run

After Maven finished downloading all the dependencies you should see something like

And here’s the directory layout of your ${user.home}/p2.repositories

p2composite2Run the command again, and you’ll get another child in the nested composite repository 1.0 (the qualifier has been replaced automatically with the new timestamp):

p2composite3Let’s increase the service number, i.e., 1.0.1, (using the tycho-versions-plugin) and rebuild:

and the new child will still be in 1.0 folder:

p2composite4Let’s increase the minor number, i.e., 1.1.0 and rebuild

and you’ll get another major.minor child repository

p2composite5Let’s increase the major number, i.e., 2.0.0

and you’ll get another major.minorp2composite6and so on 🙂

With Buckminster

As I hinted before, with Buckminster you can directly call the p2 ant tasks, since they are included in the Buckminster headless product. You will only need to add custom actions in the .cspec (or in the .cspex if you’re inside a plugin or feature project) that call the ant task passing the right properties. An example can be found here. This refers to a slightly different ant file from the one shown in this blog post, but the idea is still the same.

Possible Improvements

You may want to add another nesting level, e.g., major -> major.minor etc… This should be straightforward: you just need to call the macrodef another time, and compute the main update site directory differently.

Hope this helps.

 

 

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