plugin store

# GoCD Plugin Store

Installing plugin on GoCD Server has never been as easy task. 
With GoCD Plugins store, installing and upgrading and deleting plugins and addons will be a one click operation.

## Current issues with plugin installation on GoCD Server:
    * Manually need to copy plugin jar (Requires access to the machine :/)
    * Needs a server restart
        - in the cloud word, discovery and restart of server process running in cloud is very difficult. (on `docker swarm`, `DC/OS`, `Kubernetes` platforms)
    * No automatic way to check Plugin compatibility with server
    * No way to upgrade/downgrade bundled Plugin
    * Not cleaning up unloaded plugin jars
        - when two versions of same plugin is available, GoCD will load the firstly detected plugin jar and will ignore the other
    * `plugin-descriptor.xsd` is not sufficient to make some decisions like which endpoint plugin is implementing(and which version).

## Plugin Store helps to:
    - Easily `Install`, `Uninstall`, `Upgrade` or `Downgrade` a plugin with just one click
        - No need to manually copy plugin jar
        - No Server restart required
    - List all the available GoCD plugins at one place on your Go Server!
    - List plugins for current Go Server Version (No need to worry about compatibility anymore)
    - Notification if new version of the installed plugin is available
    - Download count of plugins
    - Allows developer to easily upload or link their plugin on GoCD plugin store

## Capabilities of plugins' store:
    - Standalone App which exposes endpoint to browse, list or download plugins.
    - Understands multiple plugin storage providers. Can fetch a plugin from:
        - Github Tags/Releases
        - Gitlab Tags
        - Maven Repository
        - jcenter


At an abstract level, this is what @ketan, @bhupendra and I have discussed about the plugin store. Just want to share our understanding.

A POC of the same is available here
https://github.com/GaneshSPatil/gocd-plugin-store-poc
https://github.com/GaneshSPatil/gocd/tree/plugin-store-poc


Thanks,
Bhupendra/Ketan/Ganesh