Entrypoint instruction
The ENTRYPOINT instruction is a Dockerfile directive that specifies the executable or command run when a container starts.
Learn Docker in a Month of Lunches, Second Edition
The ENTRYPOINT instruction specifies the executable or command that a container runs when started from an image.
- How it is used
- Defines the application Docker launches when a container starts from an image.
- How deep it goes
- Explains the startup role and shows executable, arguments, and JAR path, while treating CMD only as an alternative.
- Examples
- Uses a Java Dockerfile and a docker container run command to launch a REST API from a packaged JAR.
- What you can do after
- Operate/configure a Docker image to launch a Java application automatically when its container starts.
Read how Learn Docker in a Month of Lunches, Second Edition explains entrypoint instruction →
Kubernetes in Action, Second Edition
The ENTRYPOINT instruction specifies the executable command that runs when a container starts.
- How it is used
- Defines the executable that launches a containerized application and establishes its image-level startup behavior.
- How deep it goes
- Explains executable selection, CMD arguments, image layers, and Kubernetes overrides without detailing pod manifest syntax.
- Examples
- Uses Node.js Dockerfiles, the Kiada application, docker build output, and docker history output.
- What you can do after
- Apply it via a Dockerfile to make a container launch a chosen application with default command-line arguments.
Read how Kubernetes in Action, Second Edition explains entrypoint instruction →
Podman in Action: Secure, rootless containers for Kubernetes, microservices, and more
A container image build directive that specifies the executable or command behavior used when a container starts.
- How it is used
- Configures executable behavior recorded for a container image when users launch it with Podman.
- How deep it goes
- Distinguishes ENTRYPOINT from CMD and RUN, and specifies argument handling without detailing implementation internals.
- Examples
- Uses ENTRYPOINT "/bin/sh -c" and podman run <image> -d to demonstrate argument passing.
- What you can do after
- Operate/configure images by setting an executable entrypoint and passing launch arguments with podman run.
Related concepts
- cmd directivealternative to · The Dockerfile CMD instruction specifies the default command or arguments executed when a container starts, unless overridden at runtime.
- Dockerfilepart of · A Dockerfile is a text file containing declarative instructions for building a container image and specifying its contents and runtime metadata.
- WebAssembly moduleconfigures · A WebAssembly module is a compiled, self-contained unit of WebAssembly code and associated definitions that a compatible host can instantiate and execute.
- entry pointconfigures · An entry point is a designated starting location or interface through which a program, component, process, or interaction begins.
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