copkg Maven Assembly Descriptor
copkg is a simple package format for packaging software for use in a cloud computing environment. The basic idea is that the package contains everything the software needs to run and comes with a defined way to start and stop the software.
When a copkg is unpacked, the resulting directory structure is meant to be immutable. Meaning that when the software is started any runtime state will need to live in a runtime directory. The main motivation for this is to keep software management simple.
In order to use the
copkg assembly descriptor you need to make sure
that you have added the appropriate directories under
src/main/copkg/ (see further down) in your project and you add the
following to your
<plugin> <artifactId>maven-assembly-plugin</artifactId> <dependencies> <dependency> <groupId>org.cloudname</groupId> <artifactId>copkg-assembly</artifactId> <version>1.0.0</version> </dependency> </dependencies> <executions> <execution> <id>assemble</id> <phase>package</phase> <goals> <goal>single</goal> </goals> <configuration> <descriptorRefs> <descriptorRef>copkg</descriptorRef> </descriptorRefs> <includeEmptyDirs>true</includeEmptyDirs> </configuration> </execution> </executions> </plugin>
Structure of a copkg package
A valid copkg package has the following directory structure.
This directory will contain the binaries. Some projects have a single binary while other projects require multiple binaries. The binaries may be anything from Java binaries, Python scripts, ELF binaries. At this point we do not suggest or impose any platform support.
Any static configuration goes into this directory. Static configuration is the sort of configuration that will not vary between multiple instances of the same software running on the same machine.
Anything that does not fit in
etc/ should go into lib.
This directory will contain the scripts for starting and stopping the
software. Currently a valid
copkg package requires two scripts:
copkg borrows its naming scheme from Maven, meaning that packages
are given coordinates that follow the model used in Maven. This
means that a package is identified by three pieces of information:
Usually these are expressed as colon-separated (:) fields like so:
org.cloudname:timber:1.2.3. Two packages with the same groupId,
artifactId and version must be bit-for-bit identical.
Packages are distributed using a web server that serves a filesystem with package files. The download URL for a package can be calculated given the coordinate:
The package coordinate
org.cloudname:timber:1.2.3 thus becomes: