= Jenkins Update Center Generator

This project is primarily used to generate the jenkins.io update center layout.

With a few modifications it could easily be used to generate your corporate update center as well.

[IMPORTANT] This tool is optimized for use by the Jenkins project in Jenkins project infrastructure. Expect incompatible changes, like options not used by the Jenkins project being dropped. Additionally, this documentation is focused on how the tool is used by the Jenkins project, rather than the customizations necessary to create private update sites.

== Output

See link:site/LAYOUT.md[site layout] for more detailed documentation on site structure.

== Information Sources

The generator pulls information from:

• Artifactory artifact repository (see ArtifactoryRepositoryImpl.java)
  • Artifactory API for listing artifacts
  • downloading artifact files
  • downloading individual files in archives such as MANIFEST.MF
• GitHub (see GitHubSource.java)
  • determine source code repository that actually exists (sometimes metadata is wrong)
  • plugin labels from repositories topics
• Jenkins usage statistics (see Popularities.java)
  • latest plugin installation numbers for popularity entries in update center JSON
• link:resources/[Local resource files in this repository]
  • GitHub topic whitelist (resources/allowed-github-topics.properties)
  • Artifact ignore list (resources/artifact-ignores.properties)
  • Deprecations (resources/deprecations.properties)
  • Label assignments (resources/label-definitions.properties)
  • Security warnings (resources/warnings.json)
  • Plugin URL overrides (resources/wiki-overrides.properties)

== Features Controlled Through Resource Files

=== Categorizing plugins

Plugin labels are shown to users:

• as categories in Jenkins before 2.224 and on the link:https://plugins.jenkins.io/[plugins site]
• as tags in Jenkins from 2.224 and also on the plugins site.

See https://github.com/jenkinsci/jenkins/blob/master/core/src/main/resources/hudson/model/Messages.properties[this Jenkins resource file] (look for UpdateCenter.PluginCategory) for the localization overrides applied to labels by Jenkins. Other labels are categorized into general Misc (custom-label-here) categories (Jenkins before 2.224) or displayed as is.

Two ways can be used to define these labels:

==== GitHub

Add https://help.github.com/en/github/administering-a-repository/classifying-your-repository-with-topics[topics] to your GitHub repository. For a list of supported topics, see the link:src/main/resources/allowed-github-topics.properties[whitelist file] that contains all topics that can be set on GitHub repositories that will be reflected in update sites. Topics can be set with or without the prefix jenkins-. If a topics has that prefix, it is removed first: To add the label matrix for your plugin, you would add either matrix or jenkins-matrix on your repository.

==== Resource File

As an alternative to the above, plugin labels can be defined in the file https://github.com/jenkins-infra/update-center2/edit/master/src/main/resources/label-definitions.properties[`resources/label-definitions.properties`] in this repository.

This is the preferable approach when a plugin isn't in the jenkinsci GitHub organization, or a GitHub repository contains multiple plugins whose labels should be different.

=== Plugin URL Override

Plugins are generally expected to provide a <url> to their documentation in their POM. Historically, these URLs have been pages on the Jenkins wiki, but can point anywhere.

This requirement no longer exists, but it may still be useful to define a documentation URL for plugins that do not specify the correct URL. //Due to update center tiers that can result in older releases of a plugin being distributed, it might not be enough to have a URL in the latest release. // TODO This is probably obsolete since we always look at the latest release now?

The file resources/wiki-overrides.properties defines these wiki page overrides.

=== Deprecations

// TODO Once https://github.com/jenkinsci/jenkins/pull/4073 is merged, specify which version is the first one. Plugins are considered deprecated by Jenkins when either the update site metadata does one or both of the following:

• Uses the label deprecated for the plugin. This can be done via GitHub repository topics, or the resources/label-definitions.properties described above. Jenkins will use the plugin URL as the reference URL for the deprecation notice.
• Lists an entry with the plugin ID as key in the top-level deprecations map in update-center.json. This can be done through entries in the https://github.com/jenkins-infra/update-center2/edit/master/src/main/resources/deprecations.properties[`resources/deprecations.properties`] file. The value from the properties file will be used as the URL for the deprecation notice in Jenkins. This entry and URL take precedence over a deprecated label, i.e. when both are set, the URL from the top-level element shall be used.

These two different approaches to plugin deprecation accomplish complementary goals:

• The label approach is very simple and can easily be done by plugin maintainers themselves via GitHub labels. It is also backward compatible with any earlier version of Jenkins -- it will just show the deprecation as a regular label. Additionally, it doesn't bloat the JSON file size at all, since no special URL is needed.
• The top-level deprecations element allows specifying a URL different from the plugin documentation URL as well as deprecating plugins no longer being distributed. Especially the latter is a common requirement when plugins integrate with services that no longer exist: It makes no sense to continue distributing them, but everyone having them already installed should be informed about it.

=== Removing plugins from distribution

The update center generator allows to specify that certain plugins, or plugin releases, should not be included in the output.

There are various reasons to need to do this, such as:

• A plugin release causes major regressions and a fix is not immediately available.
• A plugin integrates with a service that has been shut down.

Both use cases (entire plugins, or specific versions) are controlled via the file resources/artifact-ignores.properties. See that file for usage examples.

Such plugins typically should get a corresponding deprecation entry in resources/deprecations.properties.

=== Security warnings

Since Jenkins 2.32.2 and 2.40, Jenkins can display security warnings about core and plugins. These warnings are part of the update center metadata downloaded by Jenkins. These warnings are defined in the file resources/warnings.json.

== Usage

=== Invocation

Build (mvn clean verify) the generator and then invoke it as follows:

java -Dfile.encoding=UTF-8 -jar target/update-center2-*-SNAPSHOT-bin/update-center2-*-SNAPSHOT.jar --id default ...

The tool also supports batch mode execution, generating multiple update sites with a single invocation:

java -Dfile.encoding=UTF-8 -jar target/update-center2-*-SNAPSHOT-bin/update-center2-*-SNAPSHOT.jar --arguments-file <filename.txt>

filename.txt is a text file with a list of arguments on each line. Lines that start with # are comments and ignored. Example:

[source]

one update site per line

Minimal update sites for Jenkins <= 2.204 and 2.204.x LTS

--www-dir ./www2/2.204 --limit-plugin-core-dependency 2.204.999 --write-latest-core --www-dir ./www2/stable-2.204 --limit-plugin-core-dependency 2.204.999 --write-latest-core --only-stable-core

Minimal update sites for Jenkins <= 2.222 and 2.222.x LTS

--www-dir ./www2/2.222 --limit-plugin-core-dependency 2.222.999 --write-latest-core --www-dir ./www2/stable-2.222 --limit-plugin-core-dependency 2.222.999 --write-latest-core --only-stable-core

Experimental (alpha/beta) update site, no version caps, collect files for download (including experimental files)

--www-dir ./www2/experimental --with-experimental --downloads-directory ./download

Latest update site for Jenkins > 2.222, with release-history.json, plugin-versions.json, plugin-documentation-urls.json, collect files for download, and generate plugin count

--generate-release-history --generate-plugin-versions --generate-plugin-documentation-urls --write-latest-core --write-plugin-count --www-dir ./www2/current --download-links-directory ./www2/download --downloads-directory ./download --latest-links-directory ./www2/current/latest

For a full list of arguments, invoke the tool as follows:

java -Dfile.encoding=UTF-8 -jar target/update-center2-*-SNAPSHOT-bin/update-center2-*-SNAPSHOT.jar --help

NOTE: --help isn't a real argument, but usage instructions are printed when an invalid argument is provided.

=== Preparing local execution

Running ./site/generate.sh will first create the batch mode control file ./tmp/args.lst, before actually starting the tool. The following steps are therefore useful when trying to generate output corresponding to the real update sites during development:

1. Implement changes in src/main/.
2. Run ./site/generate.sh until the Java tool is actually launched, then abort. This requires some environment variables to be defined.
3. Edit tmp/args.lst, changing or removing the --key, --certificate, and --root-certificate arguments as necessary.
4. Run +java -Dfile.encoding=UTF-8 -jar target/update-center2-*-SNAPSHOT-bin/update-center2-*-SNAPSHOT.jar --arguments-file tmp/args.lst+

Alternatively, the closest you can get to real executions in local development:

1. Implement changes in src/main/.
2. Deploy a snapshot using mvn deploy. Requires an account in the Jenkins project, see Deploying changes below.
3. Edit site/generate.sh to reference the specific snapshot you deployed (including timestamp) where it is downloaded using wget, see previous build output.
4. Optionally, to speed things up, edit site/generate.sh and remove the arguments --downloads-directory "$DOWNLOAD_ROOT_DIR" from some of the invocations.
5. Run ./site/generate.sh <www-dir> <downloads-dir>. The first argument is the output directory for metadata, the second argument is the output directory for downloads and unused unless the previous step 4 was skipped.

=== Running within an IDE

The project various artifacts to be used on a site hosting a jenkins update center The project produces a jar and a zip file containing all the required dependencies to run the generator.

If you want to run the generator from within your development environment, you can try to use the appassembler plugin as described below. The exec:java plugin won't work.

mvn package appassembler:assemble
sh target/appassembler/bin/app --id default ...

=== Deploying changes

./site/generate.sh downloads and executes a specified version of update-center2. This is different from earlier iterations of this tool that always rebuilt from source. The current iteration requires a (possible snapshot deployment) first, that is then referenced in ./site.generate.sh.

Consequently, merging larger-scale changes to both the tool itself and the wrapper script need to be mindful of this dependency: A new release (or at minimum a snapshot deployment) is needed, which is then referenced in ./site/generate.sh.

NOTE: As of May 2020, everyone can deploy snapshots to Artifactory, so permissions issues shouldn't hinder development.

=== Working with htaccess/mod_rewrite rules

The wrapper script site/generate.sh calls the script site/generate-htaccess.sh with chosen arguments. The latter script will generate the .htaccess file mostly containing mod_rewrite rules to redirect requests to appropriate tiered update sites. To learn more about tiers, see link:site/LAYOUT.md[LAYOUT.md].

To test changes to site/generate-htaccess.sh, run site/test/test.sh. It executes site/generate-htaccess.sh and places it inside an Apache HTTPD Docker container and tests whether redirect rules are correctly applied.

=== Working with certificates

To sign JSON output files, create a development certificate:

openssl genrsa -out resources/certificates/demo.key 4096 openssl req -new -x509 -days 180 -key resources/certificates/demo.key -out resources/certificates/demo.crt -subj "/C=/ST=/L=/O=local-development/OU=local-development/CN=local-development/emailAddress=[email protected]"

Then add these arguments to your tool invocation (or arguments file):

--key resources/certificates/demo.key --certificate resources/certificates/demo.crt --root-certificate resources/certificates/demo.crt

To have your Jenkins instance accept update site JSON signed with this certificate, create a directory update-center-rootCAs/ in the Jenkins home directory, and copy the demo.crt file in there. Once update site JSON files are generated, configure Jenkins to download them in Manage Jenkins » Manage Plugin » Advanced: Either set up a local HTTP server so the URL would be something like +http://localhost:8000/update-center.json+, or specify a file:// URL like +file:///Users/yourname/git/update-center2/www2/update-center.json+

NOTE: For historical reason, the configured URL points to update-center.json, but the file actually downloaded by Jenkins (at least up to 2.235 as of this writing) is update-center.json.html.

=== Filtering Java versions

The --java-version <version> CLI argument can be used to filter plugins based on their minimum Java version requirement. By default such filtering happens based on the Minimum-Java-Version manifest entry provided in Plugin HPIs starting from https://github.com/jenkinsci/maven-hpi-plugin#30-2018-12-05[Maven HPI Plugin 3.0] and https://github.com/jenkinsci/plugin-pom/blob/master/CHANGELOG.md#329[Plugin POM 3.29].

Plugin HPIs without Minimum-Java-Version will be accepted by default. If you want to create an update center for old Java, use the --limit-plugin-core-dependency option to set the filter for core dependencies in plugins.