The purpose of a CMD instruction is to provide defaults for an executing container. You can think of the CMD instruction as a starting point of your image, when the container is being run later on. This can be an executable, or, if you specify the ENTRYPOINT instruction (we are going to explain it next), you can omit the executable and provide the default parameters only. The CMD instruction syntax can have two forms:
- CMD ["executable","parameter1","parameter2"]: This is a so called exec form. It's also the preferred and recommended form. The parameters are JSON array, and they need to be enclosed in square brackets. The important note is that the exec form does not invoke a command shell when the container is run. It just runs the executable ...
