Mastering Docker: Complete Guide to Working with Commands

Docker is a platform that enables running applications in isolated containers and is widely adopted in modern software development. Docker containers are used to rapidly and reliably run, deploy, and manage applications. Containers leverage the same operating system kernel while providing isolated environments for application execution.

This guide covers the most commonly used commands when working with Docker — managing images, controlling containers, configuring networks and volumes, Docker Compose, working with registries, and cleaning up system resources. Understanding these commands will help you work efficiently and effectively with Docker.

Essential Docker Commands

docker version

This command is used to check the installed version of Docker. It displays version information for both the Docker Client and the Server (Docker daemon).

docker version

The output includes the following information:

• Client and Server version numbers
• API version
• Git commit hash
• Go version
• Build date and OS (operating system)

docker info

This command provides detailed information about the Docker daemon.

docker info

The output includes the following information:

• Docker version
• Number of available containers and images
• Docker Engine operational status and memory limits
• Information about networks, volumes, and storage drivers

docker --help

This command is used to obtain help information for any Docker command. If you want to learn all the parameters and options for a specific command, this will provide the additional details you need.

docker --help
 
# Help for a specific command
docker run --help
docker build --help

Working with Images

docker images

This command displays a list of all Docker images available on the current system.

docker images

The output shows the following columns for each image:

• REPOSITORY — image name
• TAG — version tag
• IMAGE ID — unique identifier of the image
• CREATED — creation time
• SIZE — image size

# Show only image IDs
docker images -q
 
# All images (including intermediate layers)
docker images -a
 
# With filter
docker images --filter "dangling=true"

docker pull

This command is used to download an image from Docker Hub or another registry. If no tag is specified, Docker automatically pulls the image with the latest tag.

docker pull image-name:tag

The output shows:

• Information about the download progress of each image layer
• A confirmation message upon successful download

docker search

This command is used to search for images on Docker Hub.

# Search for an image
docker search nginx
 
# Official images only
docker search --filter is-official=true nginx
 
# Filter by star count
docker search --filter stars=100 nginx

docker build

This command is used to build an image based on a Dockerfile. It points to the directory containing the Dockerfile and creates a new image from it.

docker build -t image-name:tag .

If the Dockerfile is not in the current working directory, specify its path using the -f flag:

docker build -f /path/to/Dockerfile -t image-name:tag .

The output shows:

• Reading the Dockerfile and the execution status for each layer
• Image creation success and its identifier (sha256)

Useful flags:

# Build without cache
docker build --no-cache -t image-name:tag .
 
# Pass a build argument
docker build --build-arg VERSION=1.0 -t image-name:tag .
 
# Target stage (multi-stage build)
docker build --target builder -t image-name:tag .

docker tag

This command is used to assign a new name and tag to an image. It does not clone the image; it simply creates a new reference (alias).

docker tag image-name new-image-name

# Tag for a registry
docker tag myapp:latest registry.example.com/myapp:v1.0

docker rmi

This command is used to remove an image from the system. If the image is currently in use by a container, it cannot be removed.

docker rmi image-name:tag

# Force removal
docker rmi -f image-name:tag
 
# Remove multiple images
docker rmi image1:tag image2:tag
 
# Remove all images
docker rmi $(docker images -q)

docker save and docker load

docker save — used to export an image as a .tar archive file.

docker save -o image-file.tar image-name:tag

This command is commonly used to transfer images as .tar archives to air-gapped servers that lack internet connectivity.

docker load — used to import a previously saved .tar file back as a Docker image.

docker load -i image-file.tar

# Can also be used via pipe
docker save myapp:latest | gzip > myapp.tar.gz
gunzip -c myapp.tar.gz | docker load

docker history

This command allows you to view the history of layers used to build an image. Each layer corresponds to a single instruction in the Dockerfile.

docker history image-name:tag

# View full commands (without truncation)
docker history --no-trunc image-name:tag

docker inspect

This command is used to obtain detailed technical information about an image or container. The result is returned in JSON format.

docker inspect image-name:tag

# Retrieve specific information (Go template)
docker inspect --format='{{.Config.ExposedPorts}}' image-name
 
# View image size
docker inspect --format='{{.Size}}' image-name

Working with Containers

docker ps

This command displays a list of currently running containers.

docker ps

The output shows the following columns for each container: ID, IMAGE, COMMAND, CREATED, STATUS, PORTS, and NAMES.

To display all containers (both running and stopped), use the -a flag:

docker ps -a

The output now also includes stopped containers. In this case, redis is a stopped container.

# Show only container IDs
docker ps -q
 
# Last created container
docker ps -l
 
# With filter
docker ps --filter "status=exited"
docker ps --filter "name=redis"
 
# Custom format
docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"

docker run

This command is used to create and start a new container from an image. If the image is not available locally, it is automatically pulled from Docker Hub via docker pull by default.

docker run image-name:tag

The container is created and attached to your terminal.

Detached mode (-d)

To run a container in the background (detached), use the -d flag — the container runs without being attached to the terminal.

docker run -d image-name:tag

The container starts in the background and its ID is displayed in the terminal. You can verify it is running using docker ps.

Interactive mode (-it)

Launches the container in interactive mode and attaches the terminal to it. A console session is opened inside the container.

docker run -it image-name /bin/bash
# or
docker run -it image-name /bin/sh

An interactive session is opened inside the container, allowing you to execute commands directly within it.

Port mapping (-p)

Map a host port to a container port:

# host_port:container_port
docker run -d -p 8080:80 nginx
 
# Multiple ports
docker run -d -p 8080:80 -p 8443:443 nginx
 
# Bind to localhost only
docker run -d -p 127.0.0.1:8080:80 nginx
 
# Random host port
docker run -d -p 80 nginx

Volume mount (-v)

Attach a volume to a container:

docker run -v volume:/path image-name

Environment variables (-e)

Set environment variables when starting a container:

docker run --name mysql-server -e MYSQL_ROOT_PASSWORD=FL20315dl2w132 -d mysql:latest

-e MYSQL_ROOT_PASSWORD=FL20315dl2w132 — sets the password for the MySQL root user.

# Multiple environment variables
docker run -e DB_HOST=localhost -e DB_PORT=5432 image-name
 
# Load environment variables from a file
docker run --env-file .env image-name

Name (--name)

Assign a name to a container:

docker run -d --name my-redis redis:latest

Restart policy (--restart)

Defines the behavior when a container stops:

docker run -d --restart always image-name

Auto-remove (--rm)

Automatically removes the container when it stops — very useful for testing and temporary tasks:

docker run --rm -it ubuntu:24.04 /bin/bash

Resource limits

Set CPU and memory limits for a container:

docker run -d --cpus 2 --memory 512m --memory-swap 1g image-name

Advanced docker run examples

sudo docker run -d -p 3000:3000 --name devops-journey --restart always devopsjourneyuz/devops-journey-uz:latest

This command utilizes several parameters:

• -d — runs the container in the background
• -p 3000:3000 — maps port 3000 on the local machine to port 3000 in the container
• --name devops-journey — assigns the name "devops-journey" to the container
• --restart always — automatically restarts the container if it stops
• devopsjourneyuz/devops-journey-uz:latest — pulls and runs the devops-journey-uz:latest image from Docker Hub

Advanced example with a volume:

This command utilizes several parameters:

• -d (detach mode) — runs the container in the background
• -p 8081:8081 — maps port 8081 on the local host to port 8081 inside the container. This allows you to access the container's web interface at http://localhost:8081 on your host system
• --name nexus — assigns the name nexus to the container
• -v /mnt/nexus-data:/nexus-data — mounts the /mnt/nexus-data directory on the host system to the /nexus-data directory inside the container. This ensures persistent storage — data is preserved even when the container is removed
• sonatype/nexus3 — the image for version 3 of Nexus Repository Manager

docker stop / docker start / docker restart

docker stop — used to gracefully stop a running container. A SIGTERM signal is sent to the container, allowing it to perform a graceful shutdown.

docker stop container-name

# With timeout (default is 10 seconds)
docker stop -t 30 container-name
 
# Stop multiple containers
docker stop container1 container2 container3
 
# Stop all running containers
docker stop $(docker ps -q)

docker start — used to restart a stopped container.

docker start container-name

The container resumes running in an active state.

docker restart — used to restart a container (stop + start).

docker restart container-name

The container is stopped and immediately restarted.

docker kill

Used to forcefully and immediately stop a container. This command sends a SIGKILL signal — the container is terminated without a graceful shutdown.

docker kill container-name

docker rm

Used to remove a stopped container from the system. A running container cannot be removed — it must first be stopped using docker stop or docker kill.

docker rm container-name

# Force removal (even if running)
docker rm -f container-name
 
# Remove all stopped containers
docker rm $(docker ps -aq --filter "status=exited")

docker exec

Allows you to enter a running container and execute commands inside it. If bash is not available in the container, use sh instead.

docker exec -it container-name /bin/bash
# or
docker exec -it container-name /bin/sh

An interactive terminal session is opened inside the container.

# Execute a single command (non-interactive)
docker exec container-name ls -la /app
 
# Enter as root
docker exec -u root -it container-name /bin/bash
 
# With an environment variable
docker exec -e MY_VAR=hello container-name env
 
# Set working directory
docker exec -w /app container-name pwd

docker logs

Allows you to view the logs of a container. This command is essential when an application stops working or when debugging is required.

docker logs container-name

The image shows the logs for the redis container.

# Follow logs in real-time
docker logs -f container-name
 
# Last N lines
docker logs --tail 100 container-name
 
# Filter by time
docker logs --since 2h container-name
docker logs --since "2024-01-01T00:00:00" container-name
 
# With timestamps
docker logs -t container-name
 
# Follow + tail combination
docker logs -f --tail 50 container-name

docker port

Used to view the port mappings of a container:

docker port container-name

The output shows which container ports are mapped to which host ports.

Working with Volumes

Volumes provide persistent storage for Docker containers. Volumes preserve data even when containers are removed or restarted.

docker volume ls

Displays a list of all volumes created on the system.

docker volume ls

docker volume create

Used to create a new volume.

docker volume create volume-name

docker volume rm

Used to remove an existing volume from the system. If the volume is currently in use by a container, it cannot be removed.

docker volume rm volume-name

docker volume prune

Removes unused volumes. If a volume is not being used by any container, it is removed from the system.

docker volume prune

To remove all volumes:

docker volume rm $(docker volume ls -q)

docker volume inspect

Displays technical information about a volume, including its location and mountpoints.

docker volume inspect volume-name

Mounting a Volume to a Container

Named volume

Creating a named volume and mounting it to a container — the recommended approach:

docker run -v volume-name:/data busybox

In this example, the mysql-volume volume is mounted to the /var/lib/mysql directory inside the container, and all data within the container is persisted in the volume.

Bind mount (Host Path)

A bind mount is used to mount a directory on the host to a directory inside the container:

docker run -v /host/path:/container/path image-name

In this case, the /mnt/nexus-data directory on the host system is mounted to the /nexus-data directory inside the container. Using bind mounts, you can establish real-time data exchange between the container and the host system.

Working with Docker Networks

Docker networks are used to facilitate communication between containers and to run applications in isolated environments.

Docker network drivers

docker network ls

Displays a list of all networks available on the system.

docker network ls

The output shows each network's NETWORK ID, name (NAME), type (DRIVER), and scope.

docker network create

Used to create a new network.

docker network create network-name

# Create with a subnet
docker network create --subnet=172.20.0.0/16 network-name
 
# Specify a driver
docker network create --driver overlay network-name

docker network inspect

Provides detailed technical information about a network — including the list of connected containers and network configuration.

docker network inspect network-name

The output displays the Docker network's technical details in JSON format, including connected containers and other configuration specifics.

docker network connect / disconnect

Connect a container to an existing network:

docker network connect network-name container-name

As a result, the redis container is connected to the redis-network network. You can verify this using docker network inspect network-name.

Disconnect a container from a network:

docker network disconnect network-name container-name

As a result, the redis container is disconnected from the redis-network network.

docker network rm

Used to remove an unused network from the system.

docker network rm network-name

Starting a Container with a Network

# Start a container on a specific network
docker run -d --name redis --network my-network redis:latest
 
# Assign a static IP to a container
docker run -d --name redis --network my-network --ip 172.20.0.10 redis:latest

Working with Docker Compose

Docker Compose is used to manage multiple services simultaneously. With Docker Compose, you can orchestrate all components of your application (e.g., web, database, cache) from a single configuration.

docker compose up

Starts all services defined in the docker-compose.yml file. Images are built and containers are launched. This command must be executed in the directory containing the docker-compose.yml file.

docker compose up
 
# Start in the background
docker compose up -d

The output confirms that the services defined in your docker-compose.yml are up and running.

# Start a specific service only
docker compose up -d redis
 
# Rebuild images and start
docker compose up -d --build
 
# Scale a service
docker compose up -d --scale web=3

docker compose down

Stops all services and removes their containers. Networks are also removed, but volumes are preserved.

docker compose down

# Also remove volumes
docker compose down -v
 
# Also remove images
docker compose down --rmi all

docker compose ps

Displays all active service containers.

docker compose ps

docker compose logs

Allows you to view the logs of all containers.

docker compose logs

# Real-time follow
docker compose logs -f
 
# Logs for a specific service
docker compose logs -f web
 
# Last N lines
docker compose logs --tail 50

docker compose exec

Allows you to enter a specific service container and execute commands inside it.

docker compose exec web /bin/bash

docker compose stop

Used to stop all services. Containers are preserved, but the services are halted.

docker compose stop

docker compose build

Build images for services:

# Build all services
docker compose build
 
# Build a specific service
docker compose build web
 
# Build without cache
docker compose build --no-cache

docker compose pull

Update images from the registry:

docker compose pull

docker compose config

Validate the docker-compose.yml file and view the final resolved configuration:

docker compose config

This command is extremely useful for detecting YAML syntax errors.

Working with Docker Registry

Docker Registry is a system designed for storing, distributing, and consuming Docker images. Docker Hub is the most popular public Docker registry, but you can also set up a private Docker registry — such as Harbor, Nexus, or cloud provider registries (GCR, ECR, ACR).

docker login

Used to authenticate with a Docker registry. You will be prompted for your username and password.

docker login -u user-name

For a private container registry:

docker login registry.example.com -u user-name

docker logout

Used to log out from a Docker registry.

docker logout

docker push

Used to push a Docker image to a registry. The image name must follow the registry/repository:tag format.

docker push registry/repo-name/image-name:tag

The image below demonstrates tagging the redis:latest image as ismoilovdev/redis-test:latest and pushing it to Docker Hub:

Pushing a Docker image to a container registry:

After pushing the Docker image, it should appear in the container registry — in our case, Docker Hub:

docker pull (From Registry)

Used to pull an image from a Docker registry. If no tag is specified, the latest tag is pulled.

docker pull repo-name/image-name:tag

Pulling from Docker Hub:

Pulling from GCR (Google Container Registry) — using the registry-address/repo-name/image-name:tag format:

Docker Cleanup

Docker provides several commands for cleaning up unused or unnecessary resources from the system. These commands are used to optimize the system and free up disk space.

docker system prune

Used to clean up all unnecessary resources from the Docker system — stopped containers, unused images, and networks.

docker system prune

docker container prune

Removes all stopped containers from the system.

docker container prune

docker volume prune

Used to remove unused volumes.

docker volume prune

docker image prune

Removes unused images from the system.

docker image prune

docker network prune

Used to remove unused networks.

docker network prune

docker system prune -af

To perform a complete cleanup of all unnecessary resources — containers, images, volumes, and networks:

• -a (all) — removes all unused images (not just dangling ones, but all unused images)
• -f (force) — executes without a confirmation prompt

docker system prune -af

This command maximizes the amount of freed disk space, but does not affect running containers or their associated resources.

Additional Useful Commands

docker stats

Provides real-time monitoring of container performance metrics — CPU, memory, network, and disk I/O.

docker stats

# Specific container
docker stats container-name
 
# View once (without streaming)
docker stats --no-stream

docker top

Displays the processes running inside a container.

docker top container-name

docker cp

Used to copy files and directories from a container to the host system or from the host to a container.

# From container to host
docker cp container-name:/app/data /home/user/path
 
# From host to container
docker cp /home/user/file.txt container-name:/app/

docker rename

Used to rename a running container.

docker rename old-container-name new-container-name

docker pause / docker unpause

docker pause — temporarily suspends all processes in a container. A SIGSTOP signal is sent to the processes — they remain in memory but cease consuming CPU.

docker pause container-name

docker unpause — resumes a previously paused container. A SIGCONT signal is sent to the processes.

docker unpause container-name

docker update

Used to update resource limits on a running container.

docker update --cpus 2 --memory 2g --memory-swap 3g container-name

# Update restart policy
docker update --restart unless-stopped container-name

docker system df

View the disk space consumed by Docker resources (images, containers, networks, volumes):

docker system df

# Detailed information
docker system df -v

docker diff

Displays files that have changed in a container relative to the host filesystem:

docker diff container-name

The output uses the following indicators:

• A — Added file
• C — Changed file
• D — Deleted file

docker events

Monitor Docker daemon events in real-time:

# Real-time events
docker events
 
# Filter by time
docker events --since 1h
 
# Container events
docker events --filter type=container

docker wait

Waits until a container stops and returns its exit code:

docker wait container-name

This command is useful in CI/CD pipelines or scripts for waiting on container completion.

Additional Resources