Dockerfile instructions
| Instruction | Description |
|---|---|
FROM <image> |
Set the base image |
FROM <image> AS <name> |
Set the base image and name the build stage |
RUN <command> |
Execute a command |
RUN ["exec", "param1", "param2"] |
Execute a command |
CMD ["exec", "param1", "param2"] |
Execute a command when the container starts |
ENTRYPOINT ["exec", "param1"] |
Configure the container to run as an executable |
ENV <key>=<value> |
Set an environment variable |
EXPOSE <port> |
Expose a port |
COPY <src> <dest> |
Copy files from source to destination |
COPY --from=<name> <src> <dest> |
Copy files from a build stage to destination |
WORKDIR <path> |
Set the working directory |
VOLUME <path> |
Create a mount point |
USER <user> |
Set the user |
ARG <name> |
Define a build argument |
ARG <name>=<default> |
Define a build argument with a default value |
LABEL <key>=<value> |
Set a metadata label |
HEALTHCHECK <command> |
Set a healthcheck command |
Best practices
- Use the official base images from https://hub.docker.com/
- Use the COPY instruction instead of ADD unless you need to extract a tar file
- Use the COPY –chown instruction to set the owner of copied files
Build
In the directory with Dockerfile:
docker build .