Best Practices

IMO people don’t understand how VOLUME1 works so they don’t use it. It’s generally used far too rarely! In short VOLUME means two things: Whatever is left in directory marked as VOLUME, stays there and can’t be changed in later layers (actually it can be changed but changes won’t be persistent). Volumes are not part of layered image FS. They’re mounted as anonymous volumes located on standard file system. This means they’re working much faster....

People often complain, that building Docker image takes a long time. “I just added a single jar package” they say… Really? They often don’t remember that whole “build context”1 is uploaded to Docker daemon during build, which often means they’re not only adding “single jar”, but also all sources, test results and whatever they have in working directory. Solution is simple - to use .dockerignore file2. Syntax is similar to ....

I’ve been thinking for a long time about writing set of articles on the topic of: “Dockerfile writing best practices”. As it’s often my daily job to prepare best in class containers, that are later used by thousands of company’s applications, I have quite good insights on the topic. Some experience and knowledge gathered is often against intuition and building it took me a while. I want to share it, with a hope that feedback I get will allow me to excel on the topic even further....