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Can Development Life Exist Without Docker Desktop?
Java microservices without Docker Desktop on macOS
If you haven’t heard by now, Docker Desktop will charge a subscription fee for companies with more than 250 employees or more than 10 million dollars in revenue. It’s not a huge fee, and if your company is already using Docker Hub private repositories, I believe you’re covered. But it does beg the question, can we live without Docker Desktop on development computers? I believe the answer is yes, and I will demonstrate how.
There are two distinct aspects of Docker that need to be replaced: building images and running images. For building images, there are a number of non-Docker solutions but I’m going to choose Google Jib. For running images, I’m going to use MicroK8s. Both solutions will work with most Java microservices with only minor changes.
To demonstrate what is needed for these solutions, I’m going to convert my blockchain microservices from Docker Compose to MicroK8s based Kubernetes. These services already use Google Jib, as most of my Java services do, but I will go over what you will need to do to switch over your services. Read my article about blockchain microservices for more information on the code involved.
One trick to building Docker images is that the build needs to happen inside the VM if there are any platform-specific operations that need to happen. This is where Java’s write-once-run-anywhere facet comes in handy, there are no platform-specific operations needed for most builds. So Jib adds three layers to a basic JRE image; dependent jars, class files from your build, and resource files from your build. That way if you only change a resource file, it only needs to rebuild a small layer. Only if you change your dependencies does it need to build all three layers.
To use Jib, you simply need to add the Maven plugin to your pom.xml file for all projects that produce an image. You don’t need a Dockerfile because the instructions for building the image are very similar for all Java applications. The only differences are finding the main class to run on image startup, and how it starts up. Jib does a good job finding a unique main class, but it will need help if you have more than one main class or your main class is in a dependent jar…
