docker

Posted 2020-11-08 anyu686

in DockerFile 

ockerfile contains instructions on how the image should be built. Here are some of the most common instructions that you can meet in a Dockerfile:

• FROM is used to specify a base image for this build. It‘s similar to the builder configuration which we defined in a Packer template, but in this case instead of describing characteristics of a VM, we simply specify a name of a container image used for build. This should be the first instruction in the Dockerfile.
• ADD and COPY are used to copy a file/directory to the container. See the difference between the two.
  • ADD allows <src> to be an URL
  • If the <src> parameter of ADD is an archive in a recognised compression format, it will be unpacked 
• RUN is used to run a command inside the image. Mostly used for installing packages.
• ENV sets an environment variable available within the container.
• WORKDIR changes the working directory of the container to a specified path. It basically works like a cdcommand on Linux.
• CMD sets a default command, which will be executed when a container starts. This should be a command to start your application.
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