This guide helps you to deploy a Ruby service in a Docker container using the D2C platform. It might be helpful for beginners as well as for advanced developers.
A container image is a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it: code, runtime, system tools, system libraries, settings. Containers isolate software from its surroundings, for example, differences between development and staging environments and help reduce conflicts between teams running different software on the same infrastructure.
Please, check out the original Docker post about containers for a better understanding of all the benefits of the technology.
Creating Ruby service
At first, you need to open or create any project and click “+Create service“. You will see a list of services which can be deployed with D2C:
Let’s go ahead and click on the Ruby bar.
Creating Ruby service. Service settings
The name should start with a letter and contain up to 16 characters (Latin letters, numbers, hyphen).
Each service has its unique name. Services can communicate with each other by container names (e.g.
finn-1) or alias-names (e.g.
finn). Moreover, we use them to create public domains like: [servicename]-[www].[accountID].[at].d2c.io for your services which are served by NGINX or HAProxy. We will talk about edge services in the next articles.
You can choose a version for your application from a list:
If your application requires node.js or its modules (e.g. for building) you can choose what you need to install into a container
In this field, you can specify commands for installing global dependencies and modifying Docker image of your service. For modifying source code use Local dependencies.
npm install -g
Creating Ruby service. Application source
You can choose what to use for getting application sources. The most recommended is Git. If you use a private repository you should add an SSH key to your account. Here are manuals about adding SSH keys into your GitHub, BitBucket, GitLab accounts. Another way is to use Login/Password, but the best practice is to use SSH keys.
Another method is to specify a link to sources.
Protocols: http, https, ftp (for closed ftp you should specify login/password).
File formats: .tar.bz2, .tar.gz, .tar, .zip
Moreover, you can upload from your machine.
File formats: .tar.bz2, .tar.gz, .tar, .zip
Maximum size: 50MB
Creating Ruby service. Ports
This is an important part.
By default, application containers are started inside a private network and have dynamically assigned local IP addresses. Apps can reference each other by service name. It does not matter on which host the app is running – all private network intercommunication is transparent for all services in your account.
Access from the Internet is disabled by default (except edge services). You can enable access from the Internet while creating or editing service. For example, if you publish your application on port 3000, you can access it at ip_address_of_a_host:3000.
Creating a Ruby service. Application source
Local dependencies and code’s preparation
bower install, etc. or do some for preparation:
grunt build, etc.
Start command for your application
sleep 1d. After that, you can connect to a container via the terminal and check what went wrong.
Commands which are executed only once on the first container after the first deploying a service. You can use it for populate database or migration.
You can specify environment variables for your application. They can be edited after creating a service.
Creating Ruby service. Advanced settings. Persistent data volumes
Click “Show advanced settings”.
The first block in this area is Persistent data volumes.
D2C separates the application itself from its data. Docker volumes are used to store persistent data. Data is stored locally on the hosts. Any data which is generated by an application should be added to Persistent data volumes. All modifications outside of these directories will be deleted after restart/rebuild/redeploy of a container/service (Docker restores the original state of a container).
When you have several containers and want to synchronise data between them you should mark “Sync” checkbox. We use Lsync for synchronisation.
However, we recommend storing user generated content in a cloud storage like Amazon S3 or CDN.
Creating Ruby service. Advanced settings. Configs
You can add your additional config files. These files do not change after restart/rebuild/redeploy of your applications.
Click “+Add custom config” and specify a full path where it should be stored.
After that, fill it in.
Generating new config button, in this case, erase all content.
Creating Ruby service. Select hosts
You can choose one or several hosts where the similar containers will be deployed. It’s not necessary at the start, and you can scale your services after deployment. Also, at this step you can create other hosts and choose them even they are not online yet (creating/setting up status). The containers will be deployed when they are ready.
After succesful deployment your project should look like: