corollary - Your Simple Command Executor

corollary is a simple Python-based command executor. It loads available commands from Python submodules in a specified directory at runtime and executes them one by one as determined by a given YAML file.

It was originally invented to automate version propagation in the release engineering of projects that rely on Maven, OSGi bundles, and/or Gradle as their build management systems. With corollary, version propagation can be automated by using a dead-simple YAML-based syntax to run file manipulation commands line by line.

corollary is invoked from the command-line as follows:
./corollary.py -c $COMMAND_DIR -f $YAML_FILE -t $TARGET_DIR

To get an idea, on how custom corollary commands to be loaded at runtime can be implemented, refer to the lemma.py file in the comands sub-directory. It implements commands such as:

• mvn_tycho_set_version: Use the Tycho Versions Plugin to update the version of a Maven POM.
• osgi_update_bundle_version: Update the Bundle-Version key in an OSGi manifest.
• update_properties_file: Update arbitrary values in a Java properties file.

Moreover, the user can be queried about the version to be used (ask_for_version) and if it's a snapshot release (ask_for_snapshot).

The following YAML file instructs corollary to (i) query the user for version and snapshot information; (ii) update the modules in the "Eclipse Plugins" group via mvn_tycho_set_version (module foo.bar) and osgi_update_bundle_version (module osgi.bundle); and (iii) update the module in the "Gradle Modules" group by directly manipulating its gradle.properties file.

- ask_for_version
- ask_for_snapshot
- ask_for_continuation version
- group "Eclipse Plugins":
  - module foo.bar:
    - mvn_tycho_set_version
  - module osgi.bundle:
    - osgi_update_bundle_version
- group "Gradle Modules":
  - module gradle.project:
    - update_properties_file "gradle.properties" "version" version

corollary makes use of implicit variables to be provided and required by custom commands. For instance, the implicit version variable in the example YAML-based script above is provided by the ask_for_version command and used by all subsequent commands. Moreover, modules are interpreted as directories within the $TARGET_DIR passed to corollary via the command-line.