Git (or bzr etc). based deployment of user application
Notes about missing parts for revision control based deployment of user applications.
Blueprint information
- Status:
- Complete
- Approver:
- None
- Priority:
- Undefined
- Drafter:
- Marius B. Kotsbak
- Direction:
- Needs approval
- Assignee:
- None
- Definition:
- Obsolete
- Series goal:
- None
- Implementation:
-
Unknown
- Milestone target:
- None
- Started by
- Completed by
- Curtis Hovey
Sprints
Whiteboard
Current state (AFAIK):
* There are basic charm wrappers for popular development platforms like
Node: http://
Rails: http://
They support cloning a git repository once at deploy time
* Problems:
* No support for authentication to the repository (e.g. by SSH key). Documentation uses public github hosting, while in reality it will often be a protected repository
- A workaround for Github is to generate Oauth login key to be used or make a machine dummy user at Github to use.
- For accessing a git repository in the same cloud, how would that work? Does nodes have ssh client keys that could be used to authencitate them?
* No support for updating the application. Setting the branch is no workaround, as unchanged configuration items are not triggering the hooks. LP: #1130092.
- Proposal: add a config parameter "revid" that the user can set to a revision ID or tag to change the deployment to. Maybe we can just use the "app_branch" option and let the user enter any revision (SHA1/tags) to deploy.
* No support for auto updating application to the latest branch content automatically (using github or other repository)
* The problem above causes another one; you risk nodes running different version of the application, as the code is only fetched at installation of the nodes.
* It should be possible to clone the repository once in the cloud and distribute from there to all nodes. Currently all application nodes clones from a potential remote location (incurring delay and possibly extra cost of data transfer)
* No restart functionality (?)
Proposed new charms:
Github-gateway
-------
* Has a relation to all of the app charm wrappers
* Caches the content of a remote Github repository.
* Handles authentication to Github (use machine key?)
* Listen for commit notifications using https:/
Extending Gitolite charm (http://
-------
* Add a relation from the app charm wrappers to Gitolite
* Add notification from git receive hooks to the app charms to let them know that they might want to update to the latest version (should maybe be configurable)
Notification issue
-------
The most obvious would be to use "relation-set" from github-gateway (http hook) or gotolite-charm (git hook) to signal something like "master:[SHA1]". It seems that it is not possible, since it happens outside any hooks:
https:/
A workaround would be to make a new notification protocol that is set up during the establishing of the relation and use that one to communicate new revisions.
