Frequently Asked Questions

This document is an attempt to explain concepts you’ll face when deploying and managing applications using tsuru. To request additional explanations you can open an issue on our issue tracker, talk to us at #tsuru @ freenode.net or open a thread on our mailing list.

How do environment variables work?

All configurations in tsuru are handled by the use of environment variables. If you need to connect with a third party service, e.g. twitter’s API, you are probably going to need some extra configurations, like client_id. In tsuru, you can export those as environment variables, visible only by your application’s processes.

When you bind your application into a service, most likely you’ll need to communicate with that service in some way. Services can export environment variables by telling tsuru what they need, so whenever you bind your application with a service, its API can return environment variables for tsuru to export on your application’s units.

How does the quota system work?

Quotas are handled per application and user. Every user has a quota number for applications. For example, users may have a default quota of 2 applications, so whenever a user tries to create more than two applications, he/she will receive a quota exceeded error. There are also per applications quota. This one limits the maximum number of units that an application may have.

How does routing work?

tsuru has a router interface, which makes it extremely easy to change the way routing works with any provisioner. There are two ready-to-go routers: one using hipache and another with galeb.

Note

as of 0.10.0 version tsuru supports more than one router. You can have a default router, configured by “docker:router” and you can define a custom router by plan

How are Git repositories managed?

tsuru uses Gandalf to manage git repositories. Every time you create an application, tsuru will ask Gandalf to create a related git bare repository for you to push in.

This is the remote tsuru gives you when you create a new app. Everytime you perform a git push, Gandalf intercepts it, check if you have the required authorization to write into the application’s repository, and then lets the push proceeds or returns an error message.