Docker flashcards, generated for you.

Docker containerizes applications by packaging code, runtime, dependencies, and config into isolated, portable containers that run consistently across environments.

An image is a read-only blueprint/template; a container is a running instance of that image. One image can spawn many containers.

A Dockerfile is a text file with instructions (FROM, RUN, COPY, EXPOSE, CMD, etc.) that define how to build a Docker image layer-by-layer.

`docker run` creates and starts a container in one step; `docker create` only creates it without starting. `docker start` then launches a created container.

Use the `-p` flag: `docker run -p 8080:3000 image_name` maps host port 8080 to container port 3000. Traffic on host:8080 forwards to container:3000.

A volume is persistent storage outside the container filesystem. Use volumes to persist data, share files between host/container, or enable data to survive container deletion.

`docker-compose` orchestrates multi-container apps using a `docker-compose.yml` file. It defines services, networks, volumes, and environment in one declarative file, then runs `docker-compose up` to start everything.

`docker run` creates and starts a new container; `docker exec` runs a command inside an already-running container. Use `docker exec -it <container> bash` to open a shell in a live container.

`docker ps` lists running containers; `docker ps -a` shows all containers (running and stopped). Both display container ID, image, status, ports, and names.

A Docker network connects containers so they can communicate by name. Create a custom network (e.g., `docker network create mynet`) to enable service-to-service communication and isolation without relying on --link (deprecated).