Ubuntu – Is there a Juju REST API

clientjuju

Is there a REST API for juju or the only possible ways to communicate with it are by juju command-line and juju gui?
A service can communicate with juju main agent and, for instance, add a new unit or start another service? What is the proper way to do this?

Best Answer

The Juju clients (command line and GUI) both use a websocket protocol to communicate with the Juju controller (main agent).

We have plans to provide client libraries that will wrap this API nicely and allow you to develop your own clients that can control Juju.

If you're interested in studying the wire format of the protocol, this document is a good starting point: https://github.com/juju/juju/blob/master/doc/api.txt

There are already some (unofficial) libraries available. More info here: What's the best way to have a charm control Juju?

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Ubuntu – Where does Juju store a log of all commands run and their output for each unit

It appears that each unit stores a log of the commands run in /var/log/juju/unit/unit-service_name-service_number.log. You can access it by taking advantage of Juju's ssh command like so:

juju ssh service_name/service_number

This will drop you into a shell for that unit. You can then use a text editor or even just cat | less to read the log.

Ubuntu – Can juju add-machine be used to prepare a machine for service deployment

If you're using constraints at all, I think you've hit a consequence of this bug -- none of the existing machines will be matched.

You can work around it with the --to parameter to deploy or add-unit:

$ juju deploy mysql --to 3
$ juju add-unit mysql --to 4

Best Answer

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Ubuntu – Where does Juju store a log of all commands run and their output for each unit

Ubuntu – Can juju add-machine be used to prepare a machine for service deployment

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