TheAlanWang

Notes

04.Docker Image and Container Management

6 min read

Overview

This guide covers essential commands for managing Docker images and containers. Learn how to list, inspect, remove, and clean up Docker resources efficiently.

Key Concepts:

  • Image: Template/blueprint for containers (like a class)
  • Container: Running instance of an image (like an object)
  • Containers are built from images

Quick Reference

Images

  • List: docker images
  • Remove: docker rmi <image_id_or_repo:tag>
  • Remove all: docker rmi $(docker images -q)

Containers

  • List running: docker ps
  • List all: docker ps -a
  • Stop: docker stop <id_or_name>
  • Remove: docker rm <id_or_name>
  • Stop and remove: docker rm -f <id_or_name>

Managing Docker Images

List Images

# List all images
docker images
 
# List images with more details
docker images --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}\t{{.CreatedAt}}"
 
# List only image IDs
docker images -q
 
# Filter by repository name
docker images | grep hello-service
 
# Show disk usage
docker system df

Inspect Images

# Show detailed information about an image
docker inspect <image_id_or_repo:tag>
 
# Show image history (layers)
docker history <image_id_or_repo:tag>
 
# Show image size
docker images <image_id_or_repo:tag>

Remove Images

# Remove a specific image
docker rmi <image_id_or_repo:tag>
 
# Remove by image ID
docker rmi <image_id>
 
# Force remove (even if used by containers)
docker rmi -f <image_id_or_repo:tag>
 
# Remove multiple images
docker rmi image1:tag1 image2:tag2
 
# Remove all images
docker rmi $(docker images -q)
 
# Remove dangling images (untagged)
docker image prune
 
# Remove all unused images
docker image prune -a

Build Images

# Build from Dockerfile
docker build -t <image_name>:<tag> .
 
# Build without cache
docker build --no-cache -t <image_name>:<tag> .
 
# Build with specific Dockerfile
docker build -f Dockerfile.prod -t <image_name>:<tag> .

Tag Images

# Tag an image
docker tag <source_image>:<tag> <target_image>:<tag>
 
# Example: Tag for ECR
docker tag hello-service:latest 123456789012.dkr.ecr.us-east-1.amazonaws.com/hello-service:latest

Managing Docker Containers

List Containers

# List running containers
docker ps
 
# List all containers (including stopped)
docker ps -a
 
# List only container IDs
docker ps -q
 
# List with custom format
docker ps --format "table {{.ID}}\t{{.Image}}\t{{.Status}}\t{{.Names}}"
 
# Filter containers
docker ps --filter "name=hello-service"
docker ps --filter "status=running"
docker ps --filter "status=exited"

Inspect Containers

# Show detailed information about a container
docker inspect <container_id_or_name>
 
# Show container logs
docker logs <container_id_or_name>
 
# Follow logs in real-time
docker logs -f <container_id_or_name>
 
# Show last N lines of logs
docker logs --tail 100 <container_id_or_name>
 
# Show container resource usage
docker stats <container_id_or_name>
 
# Show all container stats
docker stats

Start/Stop Containers

# Start a container
docker start <container_id_or_name>
 
# Stop a container
docker stop <container_id_or_name>
 
# Stop container gracefully (SIGTERM, then SIGKILL after timeout)
docker stop <container_id_or_name>
 
# Force stop (SIGKILL immediately)
docker kill <container_id_or_name>
 
# Restart a container
docker restart <container_id_or_name>
 
# Pause a container
docker pause <container_id_or_name>
 
# Unpause a container
docker unpause <container_id_or_name>

Remove Containers

# Remove a stopped container
docker rm <container_id_or_name>
 
# Remove a running container (force)
docker rm -f <container_id_or_name>
 
# Remove multiple containers
docker rm container1 container2 container3
 
# Remove all stopped containers
docker container prune
 
# Remove all containers (stopped and running)
docker rm -f $(docker ps -aq)

Execute Commands in Containers

# Execute a command in a running container
docker exec <container_id_or_name> <command>
 
# Open interactive shell
docker exec -it <container_id_or_name> /bin/sh
docker exec -it <container_id_or_name> /bin/bash
 
# Run command as root
docker exec -u root -it <container_id_or_name> /bin/sh
 
# Example: Check Java version
docker exec hello-service-container java -version

Cleanup Strategies

Remove Unused Resources

# Remove all stopped containers
docker container prune
 
# Remove all unused images
docker image prune -a
 
# Remove all unused volumes
docker volume prune
 
# Remove all unused networks
docker network prune
 
# Remove everything unused (containers, networks, images, build cache)
docker system prune
 
# Remove everything including volumes (more aggressive)
docker system prune -a --volumes

Clean Up by Pattern

# Remove containers matching a pattern
docker ps -a | grep "pattern" | awk '{print $1}' | xargs docker rm
 
# Remove images matching a pattern
docker images | grep "pattern" | awk '{print $3}' | xargs docker rmi
 
# Example: Remove all hello-service containers
docker ps -a | grep hello-service | awk '{print $1}' | xargs docker rm -f

Disk Usage Analysis

# Show disk usage summary
docker system df
 
# Show detailed disk usage
docker system df -v
 
# Show space used by images
docker images --format "{{.Repository}}:{{.Tag}} - {{.Size}}"

Common Workflows

Complete Cleanup

# Stop all running containers
docker stop $(docker ps -q)
 
# Remove all containers
docker rm $(docker ps -aq)
 
# Remove all images
docker rmi $(docker images -q)
 
# Or use system prune (safer)
docker system prune -a --volumes

Remove Specific Application

# 1. Stop containers
docker stop <container_id_or_name>
 
# 2. Remove containers
docker rm <container_id_or_name>
 
# 3. Remove images
docker rmi <image_id_or_repo:tag>
 
# Example:
docker stop hello-service-container
docker rm hello-service-container
docker rmi hello-service:latest

Clean Up After Build Failures

# Remove dangling images (failed builds)
docker image prune
 
# Remove build cache
docker builder prune
 
# Remove all build cache
docker builder prune -a

Best Practices

1. Regular Cleanup

  • Run docker system prune periodically to free up disk space
  • Remove unused images and containers regularly

2. Use Specific Tags

  • Avoid using latest tag in production
  • Use version tags (e.g., v1.0.0, 2024-01-15)

3. Stop Before Remove

  • Always stop containers before removing them
  • Use docker stop for graceful shutdown

4. Check Before Removing

  • Use docker ps -a to see all containers before bulk removal
  • Use docker images to verify images before removal

5. Use Prune Commands

  • Prefer docker system prune over manual removal
  • Safer and more efficient

6. Monitor Disk Usage

  • Regularly check docker system df
  • Set up alerts for disk space

Troubleshooting

Common Issues

IssueSolution
”Cannot remove image: image is being used”Stop/remove containers using the image first
”Cannot remove container: container is running”Stop container first: docker stop <id>
”No space left on device”Run docker system prune -a --volumes
”Image not found”Check with docker images to verify image name/tag
”Container name already in use”Remove existing container or use different name

Force Removal

# Force remove container
docker rm -f <container_id>
 
# Force remove image
docker rmi -f <image_id>
 
# Force remove everything
docker system prune -a --volumes --force

Graph View