This document is in alpha state, to suggest improvements check out the related github issue.
Tsuru is an open source PaaS. If you don’t know what a PaaS is and what it does, see wikipedia’s description.
It follows the principles described in the The Twelve-Factor App methodology.
Fast and easy deployment¶
Deploying an app is simple and easy. No special tools needed, just a plain git push. The entire process is very simple, especially from the second deployment, whether your app is big or small.
Tsuru uses git as the means of deploying an application. You don’t need master git in order to deploy an app to Tsuru, although you will need to know the very basic workflow, add/commit/push and remote managing. Git allows really fast deploys, and Tsuru makes the best possible use of it by not cloning the whole repository history of your application, there’s no need to have that information in the application webserver.
Tsuru will also take care of all the applications dependencies in the deployment process. You can specify operating system and language specific dependencies. For example, if you have a Python application, tsuru will search for the requirements.txt file, but first it will search for OS dependencies (a list of deb packages in a file named requirements.apt, in the case of Ubuntu).
Tsuru also has hooks
that can trigger commands before and after some events that happen during the
deployment process, like restart (represented by
Easily create testing, staging, and production versions of your app and deploy to them instantly.
Instantly provision and integrate third party services with one command. Tsuru provides the basic services your application will need, like searching, caching, storage and frontend; you can get all of that in a fashionable and really easy way using Tsuru’s command line.
Per-Environment Config Variables¶
Configuration for an application should be stored in environment variables - and we know that. Tsuru lets you define your environment variables using the command line, so you can have the configuration flexibility your application need.
Tsuru also makes use of environment variables. When you bind a service with your application, Tsuru gives the service the ability to inject environment variables in your application environment. For instance, if you use the default MySQL service, it will inject variables for you to establish a connection with your application database.
Tsuru already has services for you to use, but you don’t need to use them at all if you don’t want to. If you already have, let’s say, a MySQL server running on your infrastructure, all you need to do in order to use it is simply configure environment variables and use them in your application config.
You can also create your own services and make them available for you and others to use it on Tsuru. It’s so easy to do so that you’ll want to sell your own services. Tsuru talks with services using a well defined API, all you have to do is implement four endpoints that knows how to provision instances of your services and bind them to tsuru applications (like creating VMs, authorizing security groups, creating ACLs, etc), and register your service in Tsuru with a really simple yaml manifest.
Logging and Visibility¶
Full visibility into your app’s operations with real-time logging, process
status inspection, and an audit trail of all releases. Tsuru will capture
standard streams (output and error) from your application and expose them via
tsuru log command. You can also filter logs, for example, if you don’t
want to see the logs of developers activity (e.g.: a deploy action), you can
specify the source as “app” and you’ll get only the application webserver logs.
Tsuru manages all processes from an application, so you don’t have to worry about it. But it does not know to start it. You’ll have to teach Tsuru how to start your application using a Procfile. Tsuru reads the Procfile and uses Circus to start and manage the running process. You can even enable a web console for Circus to manage your application process and to watch CPU and memory usage in real-time through a web interface.
Tsuru also allows you to easily restart your application process via command line. Although Tsuru will do all the hard work of managing and fixing eventual problems with your process, you might need to restart your application manually, so we give you an easy way to do it.
Tsuru exposes its features through a solid, stable REST API. You can write clients for this API, or you can use one of the clients maintained by tsuru developers.
Tsuru ships with two API clients: the command line interface (CLI), which is pretty stable and ready for day-to-day usage; and the web interface, which is under development, but is also a great tool to manage, check logs and monitor applications and services resources.
The Juju provisioner allows you to easily add and remove units, enabling one to scale an application painlessly. It will take care of the application code replication, and services binding. There’s nothing required to the developer to do in order to scale an application, just add a new unit and Tsuru will do the trick.
You may also want to scale using the Front end as a Service, powered by Varnish. One single application might have a whole farm of Varnish VMs in front of it handling all the traffic.
Built-in Database Services¶
Tsuru already has a variety of database services available for setup on your cloud. It allows you to easily create a service instance for your application usage and bind them together. The service setup for your application is transparent by the use of environment variables, which are exported in all instances of the application, allowing your configuration to fit several environments (like development, staging, production, etc.)
Extensible Service and Platform Support¶
Tsuru allows you to easily add support for new services and new platforms. For application platforms, it uses Juju Charms, for services, it has an API that it uses to comunicate with them.
Manage sharing and deployment of your application. Tsuru uses teams to control access to resources. A developer may create a team, grant/revoke app access to/from a team or add/remove new users to/from a team. One can be a member of multiple teams and control which applications each team has access to.
Easy Server Deployment¶
Tsuru itself is really easy to deploy and manage, you can get it done by following these simple steps.
Distributed and Extensible¶
Tsuru server is easily extensible, distributed and customizable. It has the
Provisioner: a provisioner is a component that takes care of the
orchestration (VM/container management) and provisioning. By default, it will
deploy applications using the Juju provisioner, but you can easily implement
your own provisioner and use whatever backend you wish.
When you extend Tsuru, you are able to pratically build a new PaaS in terms of behavior of provision and orchestration, making use of the great Tsuru structure. You change the whole Tsuru workflow by implementing a new provisioner.
Tsuru’s components are distributed, it is composed by many pieces of software, each one made to be easily deployable and maintenable. #TODO link architecture overview.
Application Developer Perspective¶
We aim to make developers life easier. #TODO link development workflow.