Docker for Rails Developers

Sharing Images

Up until now, during development, we’ve been building our custom images on our local machine. Initially, we did this with this command:

$ docker build [OPTIONS] .

We quickly progressed to using Compose to build images for us—for example:

$ docker-compose build web

However, we have a problem. We’re going to need to run those same images we’ve been building locally on different machines as our app progresses through our build pipeline environments (such as testing, integration, staging, and production). How will we get our images onto the different machines?

One possibility is to rebuild the image on each machine that needs it, but this is wasteful and time-consuming. Images are more than just a convenient ...