# Dockerfile

## Dockerfile

* dockerfile manuals:
    * https://takacsmark.com/dockerfile-tutorial-by-example-dockerfile-best-practices-2018/
* best practice:
	* https://docs.docker.com/develop/develop-images/dockerfile_best-practices/


### key instructions

* `FROM` - base image
* `ENV variable=test`
	* environment variable
    * can be used with bash syntax `$variable`
* `VOLUME [ "/var/test" ]`
	* used to expose some storage
* `CMD`
    * what command should be run in the image
    * `CMD [“executable”, “param1”, “param2”, ...]`
    * Its possible to override the command on starting up a container `docker run myImage:latest _command_`
    * Only last `CMD` will be used (so specifiy only one).
    * Its a good practice to specify at leaset  a shell command here.
* `ENTRYPOINT`
    * Used to specify the 'main executable' of the image
    * If `ENTRYPOINT` is specified, `CMD` paramas will be added to the `ENTRYPOINT`
    * ```
      ENTRYPOINT ["git"]
      CMD ["--help"]
      ```
      
      
      
### building

[Docker CLI](https://bookstack.draab.at/link/29#bkmrk-build-dockerfile)