docker commands

Command	Syntax	Description	Usage
FROM	FROM <image>:<tag>	Sets the base image for building your container.	Define a starting image, e.g., FROM python:3.9
RUN	RUN <command>	Executes commands during the build process, creating a new layer.	Install dependencies, e.g., RUN apt-get update && apt-get install -y curl
COPY	COPY <src> <dest>	Copies files or directories from the local filesystem into the container.	Add local files, e.g., COPY . /app
ADD	ADD <src> <dest>	Copies files and supports additional features like URL downloads and auto-extracting archives.	Use for archives or URLs, e.g., ADD archive.tar.gz /app/extracted
WORKDIR	WORKDIR <path>	Sets the working directory for subsequent commands.	Define a working directory, e.g., WORKDIR /app
ENV	ENV <key>=<value>	Sets environment variables in the container.	Add environment variables, e.g., ENV PORT=8000
EXPOSE	EXPOSE <port>	Declares the network ports the container listens on.	Inform Docker of port, e.g., EXPOSE 8000
CMD	CMD ["executable", "param1", "param2"]	Specifies the default command to run when the container starts.	Set default process, e.g., CMD ["python", "app.py"]
ENTRYPOINT	ENTRYPOINT ["executable", "param1"]	Configures the container to run as an executable with fixed command.	Define entry command, e.g., ENTRYPOINT ["uvicorn"]
VOLUME	VOLUME ["<path>"]	Creates a mount point and marks it as holding externally mounted volumes.	Use for data persistence, e.g., VOLUME ["/data"]
USER	USER <username or UID>	Sets the user for executing subsequent commands.	Run as non-root, e.g., USER appuser
ARG	ARG <name>=<default>	Defines variables that users can pass at build-time with --build-arg.	Set build args, e.g., ARG ENV=production
ONBUILD	ONBUILD <Dockerfile command>	Adds a trigger that executes when the image is used as a base for another image.	Use for parent images, e.g., ONBUILD RUN apt-get install build-essential
STOPSIGNAL	STOPSIGNAL <signal>	Sets a system call signal to stop the container.	Define stop signal, e.g., STOPSIGNAL SIGTERM
HEALTHCHECK	HEALTHCHECK CMD <command>	Checks the container's health by running a command at intervals.	Set up health checks, e.g., `HEALTHCHECK --interval=30s CMD curl -f http://localhost/
LABEL	LABEL <key>=<value>	Adds metadata to the image, such as version or description.	Organize image info, e.g., LABEL version="1.0" description="FastAPI app"