We're talking about Docker today! As you may know, Docker has a tremendous amount of images on their public registry. But sometimes you may need to pull images from a private Docker registry. Mostly because you can't always publicly publish the images. So, we've added a few environement variables to allow you to fetch these images, let's see how to do it.

In this note post we assume you already have your own Docker registry. If this isn't the case, you can see how to deploy a registry server here.

So, pulling private images is done through the docker build command. To login to a private registry, you need to set a few environment variables:

  • CC_DOCKER_LOGIN_USERNAME: the username to use to login
  • CC_DOCKER_LOGIN_PASSWORD: the password of your username
  • CC_DOCKER_LOGIN_SERVER (optionnal): the server of your private registry. Defaults to Docker's public registry.

This uses the docker login command under the hood.

Build-time variables

You can use the ARG instruction to define build-time environment variables. Every environment variable defined for your application will be passed as a build environment variable using the --build-arg=<ENV> parameter during the docker build.

Source image: Vladimir Malyavko

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By Clément Nivolle

Chief Marketing Officer and co-founder of Clever Cloud. Clement is also in charge of the global user experience.