Docker - Command Line Quick Reference

Complete Docker CLI reference — image builds, container lifecycle, volumes, networking, Compose, and cleanup commands for daily container work.

Docker — Command Line Quick Reference

Images

Build, tag, and manage the artifacts your containers run from.

BASH

docker build -t razorpay/orders-api:v2.3.1 .
docker images                          ## list local images
docker tag razorpay/orders-api:v2.3.1 razorpay/orders-api:latest
docker rmi razorpay/orders-api:v2.3.0   ## remove an image
docker history razorpay/orders-api:v2.3.1   ## inspect layer-by-layer size
docker pull postgres:16
docker push razorpay/orders-api:v2.3.1

Parameter Breakdown:

-t: Tags the image during build — always use name:version, never rely on latest in production
history: Shows the size each layer added — first stop when an image is too large
tag: Creates a second reference to the same image, does not duplicate storage

Containers — Lifecycle

Run, stop, and remove containers.

BASH

docker run -d --name orders-api \
  -p 8080:8080 \
  -e DB_HOST=db.internal.razorpay.net \
  razorpay/orders-api:v2.3.1
docker ps                              ## running containers
docker ps -a                           ## all containers, including stopped
docker stop orders-api
docker start orders-api
docker restart orders-api
docker rm orders-api                   ## remove a stopped container
docker rm -f orders-api                ## force remove a running container

Command Parameter Table:

Flag	Description
`-d`	Run detached, in the background
`-p`	Map host port to container port, `host:container`
`-e`	Inject an environment variable into the container

Inspecting and Logs

Debug a running or recently exited container.

BASH

docker logs orders-api                 ## current logs
docker logs -f orders-api              ## stream live
docker logs --tail 100 orders-api      ## last 100 lines only
docker inspect orders-api              ## full JSON config and state
docker exec -it orders-api bash        ## interactive shell
docker top orders-api                  ## processes running inside
docker stats orders-api                ## live CPU/memory usage

Parameter Breakdown:

exec -it: Opens an interactive shell inside an already-running container
inspect: Returns full JSON — pipe through --format or jq to extract one field
stats: Live resource usage, similar to top but container-scoped

Volumes

Persist data outside the container's writable layer.

BASH

docker volume create orders-db-data
docker volume ls
docker volume inspect orders-db-data
docker run -d --name orders-db \
  -v orders-db-data:/var/lib/postgresql/data \
  postgres:16
docker run -d --name orders-api \
  -v $(pwd)/config:/app/config:ro \
  razorpay/orders-api:v2.3.1
docker volume rm orders-db-data

Parameter Breakdown:

-v name:path: Named volume — Docker manages the storage location
-v $(pwd)/dir:path: Bind mount — maps a host directory directly
:ro: Mounts the volume read-only inside the container

Networking

Connect containers to each other and the outside world.

BASH

docker network ls
docker network create payments-net
docker network inspect payments-net
docker run -d --name orders-api \
  --network payments-net \
  razorpay/orders-api:v2.3.1
docker network connect payments-net orders-db
docker network disconnect payments-net orders-db

Parameter Breakdown:

--network: Containers on the same custom network resolve each other by container name
Default bridge network does not support name-based DNS — always create a custom network
network inspect: Shows every container currently attached, with their IPs

Docker Compose

Run multi-container applications from one file.

BASH

docker compose up -d                   ## start all services, detached
docker compose down                    ## stop and remove containers + network
docker compose down -v                 ## also remove named volumes
docker compose ps                      ## status of services in this project
docker compose logs -f orders-api      ## stream logs for one service
docker compose exec orders-api bash    ## shell into a running service
docker compose build --no-cache        ## force a clean rebuild
docker compose restart orders-api

Parameter Breakdown:

up -d: Starts every service defined in docker-compose.yml in the background
down -v: Use with caution — this deletes named volumes and their data
--no-cache: Ignores Docker's build cache, useful when a base image silently changed

Build Optimization

Keep images small and builds fast.

BASH

## Multi-stage build pattern (Dockerfile excerpt)
## FROM golang:1.22 AS builder
## WORKDIR /app
## COPY . .
## RUN go build -o orders-api
##
## FROM alpine:3.19
## COPY --from=builder /app/orders-api /usr/local/bin/
## ENTRYPOINT ["orders-api"]

docker build --no-cache -t orders-api:debug .
docker build --build-arg ENV=staging -t orders-api:staging .
docker buildx build --platform linux/amd64,linux/arm64 \
  -t razorpay/orders-api:v2.3.1 --push .

Parameter Breakdown:

Multi-stage builds: Only the final stage ships — build tools never reach production
--build-arg: Passes a build-time variable into the Dockerfile
buildx --platform: Builds and pushes multi-architecture images in one command

Cleanup and Pruning

Reclaim disk space on build servers and laptops.

BASH

docker system df                       ## see space used by images/containers/volumes
docker container prune                 ## remove all stopped containers
docker image prune                     ## remove dangling (untagged) images
docker image prune -a                  ## remove all unused images
docker volume prune                    ## remove unused volumes
docker system prune -a --volumes       ## remove everything unused, including volumes

Command Parameter Table:

Flag	Description
`image prune`	Removes only dangling images by default
`image prune -a`	Removes every image not used by a running container
`system prune -a --volumes`	Most aggressive cleanup — confirm before running on shared hosts

Troubleshooting

Common failures and the first command to run for each.

BASH

## "port is already allocated"
docker ps --filter "publish=8080"      ## find what's using the port

## "no space left on device"
docker system df                       ## check usage
docker system prune -a                 ## reclaim space

## Container exits immediately
docker logs orders-api                 ## check the actual error
docker inspect orders-api \
  --format='{{.State.ExitCode}}'       ## get the exact exit code

## Permission denied inside container
docker exec -it orders-api whoami      ## confirm running user

Notes:

Exit code 137 almost always means the container was OOM-killed — check memory limits
Exit code 1 is a generic application error — the real reason is in docker logs

Useful Aliases and One-Liners

Shortcuts worth adding to your dotfiles.

BASH

alias dps='docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"'
alias dlog='docker logs -f'
alias dex='docker exec -it'

## Stop and remove every running container
docker stop $(docker ps -q) && docker rm $(docker ps -aq)

## Remove all images not associated with a container
docker image prune -a -f

## Follow logs of every Compose service at once
docker compose logs -f