Images & Containers

Building and tagging images, and running/inspecting/cleaning up containers — the day-to-day loop of local container development.

Building images#

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docker build -t myapp:latest .
docker build -t myapp:v1.2.0 -f Dockerfile.prod .
docker build --no-cache -t myapp:latest .           # ignore layer cache, force a full rebuild
docker build --build-arg NODE_ENV=production -t myapp:latest .

docker build is now backed by BuildKit (docker buildx build under the hood) — --no-cache invalidates every layer, while a targeted fix is usually cheaper: touching the file that changed and letting the layer cache do its job from that point forward.

Tagging and pushing images#

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docker tag myapp:latest myregistry.io/myteam/myapp:v1.2.0
docker push myregistry.io/myteam/myapp:v1.2.0
docker pull myregistry.io/myteam/myapp:v1.2.0
docker images                                        # list local images
docker rmi myapp:latest                              # remove a local image

Running containers#

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docker run -d --name my-app -p 8080:80 myapp:latest
docker run -d --name my-app -e LOG_LEVEL=info -v ./data:/app/data myapp:latest
docker run --rm -it myapp:latest /bin/bash            # interactive, auto-removed on exit
docker run -d --restart unless-stopped myapp:latest

-p 8080:80 maps host:container — the host port comes first. Getting this backwards is a common cause of "it works when I exec in but not from the browser."

Listing and inspecting containers#

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docker ps                                            # running containers only
docker ps -a                                         # include stopped containers
docker ps --filter status=exited
docker inspect my-app                                # full container config as JSON
docker stats                                          # live CPU/memory/network usage

Logs and exec#

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docker logs my-app
docker logs -f my-app                                # follow/stream
docker logs --tail 100 --since 1h my-app
docker exec -it my-app /bin/bash                      # interactive shell in a running container
docker exec my-app env                                 # one-off command, no shell

Stopping and removing containers#

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docker stop my-app
docker rm my-app
docker rm -f my-app                                   # stop and remove in one step
docker container prune                                 # remove all stopped containers