A lot of people face problems when they install a rails application server from scratch. Despite the fact that solutions such as Heroku or Engine Yard are available, unfortunately, for various reasons, it’s not always possible to use them.
If we reject «Do It Yourself» options, the obvious solution will be:
- You prepare the server using Puppet, Chef etc. Install the required packages, install and configure services required by the application, create users and so on.
- Describe tasks using Capistrano or Mina tools and initialize deployment.
Unfortunately, this solution has serious disadvantages:
- You essentially have same configuration in 2 different places, which makes it difficult to support and test. Provisioning and deployment tools need to know a lot of information about each other: under which user will run deploy, what passwords and certificates are used, what addresses and ports hanging services.
- There are many ways how to combine deploy and provision tasks such like: provision and deploy only using Puppet/Chef; integration Chef/Puppet into deploy tool and many more.
There is the best solution which, in my opinion, has a great advantage - simplicity.
This is deploy tool which uses a slightly different approach than Capistrano: Mina immediately generates from config/deploy.rb one big bash script, which can be placed to the server and executed as single command. In addition it can simply generate script without execution. This is what you need exactly to combine with Ansible.
This is provision tool. Actually, for the current moment, we use Puppet for our company projects. In general, I have took part in Puppet implementation in our company and I can say that me and my colleagues are satisfied with results. But when I found Ansible it very interested me.
- It doesn’t need a central server. Task running goes from local machine. Perhaps, central server is useful thing, but in our current configuration, as we have several dozen servers, it’s overkill.
- You don’t need any special software on your server, you need just python which is included for almost all OS distributions.
- Ansible is very simple, nevertheless it has enough functionality. You can start working with it right after brew install ansible and quick view examples. Generally Ansible its ideology reminds VIM: within a couple of simple solutions that allow you to do complex things.
- All configuration is described in YAML files, it is declarative and immediately integrated with the documentation.
- It allows you to perform ad hoc tasks on servers. If you need to do it with Puppet, you will need special service Mcollective.
We have highly positive impression after a couple of test implementations of ansible. I guess in our company, together with the planned update of Ubuntu servers 12.04->14.04, will be simultaneous migration from Puppet to Ansible.
Provision & Deploy.
You can deploy with Ansible the right ambience and generate deployment config template for Mina, then run it. Detailed steps look like this:
- Prepare application server, install and configure required packages.
- Install Mina
- Generate deploy.rb from template
- Pass deploy.rb to Mina and it will create up file with deploy commands
- Run up file, which deploys the application
As a result we have all settings in only one place - in Ansible. Ansible executes all necessary moves. Mina just creates one deploy script. It’s very simple and understandable to describe configuration in Ansible.
You can download and run the demo application to see how it works live:
$ git clone https://github.com/dima-exe/demo-deploy-using-ansible-and-mina.git $ brew install ansible $ vagrant up
In this sample we’ll install postgres, nginx and will deploy rails application. Application will be available at http://localhost:8080
Files are used: