A Docker / Docker Compose Cheat Sheet

DockerCheatSheet.md

Docker / Docker Compose Cheat Sheet

Docker

Add this to Dockerfile to add aliases of your choice (works for images that have /bin/bash)

# Add alias to user profile
RUN echo "alias ll='ls -la'" >> /root/.bashrc

Docker Compose

Running arbitrary commands on a Docker containter managed with Docker Compose

Execute the Docker Compose run command, from the same directory that contains your docker-compose.yml file.

# Simple form
docker compose run -it SERVICE-NAME-IN-COMPOSE-YML "COMMAND" "ARGS-TO-COMMAND"

# Simple form, to get a shell
docker compose run -it SERVICE-NAME-IN-COMPOSE-YML "/bin/bash"

# If you need to override the entrypoint
docker compose run -it --entrypoint /bin/bash SERVICE-NAME-IN-COMPOSE-YML "COMMAND" "ARGS-TO-COMMAND"

run will ALWAYS start a new instance of a container!

In contrast, exec will operate on a running container (and won't create a new instance)!

Note: On some platforms, use docker-compose instead of docker compose.

Force Emulation on Docker Images that don't have an ARM build (on an Apple Silicon Mac):

The Docker for Mac app comes packed with QEMU, a popular OSS emulator. Therefore, Docker can run both arm64 and amd64 images on Macs with Apple Silicon.

Read more here: (scroll to “Using Docker”) https://earthly.dev/blog/using-apple-silicon-m1-as-a-cloud-engineer-two-months-in/

If you have an Apple Silicon Mac and you need to run a Docker image that does not have an ARM build, then you can force Docker to download an amd64 image and emulate.

Some ways to do this: (there’s probably others, like docker pull etc.)

• If you’re using Docker Compose with no Dockerfile to build from, for the particular service, just include platform: linux/amd64.
• If you’re using a Dockerfile, use the --platform switch in the FROM. For example FROM --platform=linux/amd64 centos .

References:

• Docker Desktop for Apple silicon

License

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