services: create a way to tsuru api run extra commands

[andrewsmedina]

A service can has a plugin () to add extra commands to tsuru cli. There is no way to get the info passed to a service by tsuru to be used by the extra commands.

By example, if I have a mysql service and want to create a command to make a backup. On service-add and service-bind tsuru pass the info about user, and the instances. In my plugin I dont have any info about the user that makes impossible to verify if this user has permission to do a backup, and know how instances the user has access.

A way to make it possible is create a resource in tsuru api to be a proxy between the plugin and the service. This resource should receive the user token, process it and execute a url to the service custom url as callback.

By example:

POST /service/proxy/myservice?callback=/backup

[fsouza]

What's myservice. The service instance or the service itself?

Also, the callback would be just a path? Do we want to support query string in this path?

[andrewsmedina]

@fsouza myservice is a service instance. The callback is a path. I don't know if we want to support querystrings.

[fsouza]

Good. I think it makes sense.