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What is set Dockerfile?
Sets the working directory for any RUN , CMD , ENTRYPOINT , COPY , and ADD instructions that follow it. It can be used multiple times in the one Dockerfile.
What does from do in Dockerfile?
The FROM instruction initializes a new build stage and sets the Base Image for subsequent instructions. As such, a valid Dockerfile must start with a FROM instruction. The image can be any valid image – it is especially easy to start by pulling an image from the Public Repositories.
What is $@ In Dockerfile?
exec “$@” is typically used to make the entrypoint a pass through that then runs the docker command. It will replace the current running shell with the command that “$@” is pointing to. By default, that variable points to the command line arguments.
Can there be multiple CMD in Dockerfile?
Docker will always run a single command, not more. So at the end of your Dockerfile, you can specify one command to run. Not more.
How does the entry point work in Docker?
Introduction of Docker ENTRYPOINT. Docker entrypoint is a Dockerfile directive or instruction that is used to specify the executable which should run when a container is started from a Docker image. It has two forms, the first one is the ‘exec’ form and the second one is the ‘shell’ form. If there is no entrypoint or CMD specified in
What does set-E and exec “$ @ ” do for Docker?
The intention is basically “Do everything in this .sh script, then in the same shell run the command the user passes in on the command line”. set -e sets a shell option to immediately exit if any command being run exits with a non-zero exit code.
Where does the dockerfile go when issuing a command?
When you issue a docker build command, the current working directory is called the build context. By default, the Dockerfile is assumed to be located here, but you can specify a different location with the file flag ( -f ).
What does EXEC shell do for Docker entrypoint scripts?
If you have an image with an entrypoint pointing to entrypoint.sh, and you run your container as docker run my_image server start, that will translate to running entrypoint.sh server start in the container. At the exec line entrypoint.sh, the shell running as pid 1 will replace itself with the command server start.