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Docker

Docker Commands
Verify commands are current/up to date and execute (&& is used to run multiple commands in sequence, if the first command fails, the second command will not run):
sudo apt-get update &&
sudo apt-get install -y apt-transport-https ca-certificates curl software-properties-common &&
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add - &&
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" &&
sudo apt-get update &&
sudo apt-get install -y docker-ce
Start the Docker service: 
sudo systemctl start docker
Enable Docker to start on boot: 
sudo systemctl enable docker
Verify the Docker installation: 
docker --version
Add standard user to Docker group: 
sudo usermod -aG docker $USER
Pull a Docker image from a registry: 
docker pull image_name
Pull a specific version. Without specifying tag, latest is pulled: 
docker pull image_name:tag
Pull an image from a private registry: 
docker pull registry_url/image_name
Common Images: 
docker pull ubuntu
docker pull alpine
docker pull centos
docker pull python
docker pull nginx
docker pull mysql
docker pull node
Run a Docker container in detached mode: 
docker run -d image_name
Run a Docker container with a specific name: 
docker run --name container_name image_name
Run a Docker container with a specific port: 
docker run -p host_port:container_port image_name
Run a Docker container with a specific volume: 
docker run -v host_path:container_path image_name
Run a Docker container with environment variables: 
docker run -e key=value image_name

docker run --env-file env_file image_name
Test a Docker container --rm will remove the container after it stops: 
docker run --rm image_name
Inspect a Docker container: 
docker inspect <container_id>
Provides detailed information about the container, including its configuration, network settings, and more. 
docker inspect --format='{{.State.Status}}' <container_id>
Inspect a container's IP address: 
docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <container_id>
Inspect an image: 
docker inspect <image_id>
Inspect a network: 
docker inspect <network_id>
View logs, add -f to follow the logs: 
docker logs -f <container_id>
View logs for a specific number of lines: 
docker logs --tail 100 <container_id>
View logs with timestamps, the --details flag shows extra details: 
docker logs --details --timestamps <container_id>
Add --since and --until to view logs within a specific time range: 
docker logs --since 2021-01-01T12:00:00 --until 2021-01-02T12:00:00 <container_id>
Add regex to filter logs, 2>&1 redirects stderr to stdout: 
docker logs --details --timestamps <container_id> 2>&1 | grep "pattern"
Add -E to search for multiple patterns, -i to ignore case: 
docker logs --details --timestamps <container_id> 2>&1 | grep -Ei "error|exception"

Execute Commands against a Container

Copy files from a container to the host: 
docker cp <container_id>:/path/to/file /host/path
Copy files from the host to a container: 
docker cp /host/path <container_id>:/path/to/file
Copy files between containers: 
docker cp <source_container_id>:/path/to/file <destination_container_id>:/path/to/file
Enter a shell of a running container: 
docker exec -it <container_id> /bin/bash

docker exec -it <container_id> sh

docker exec -it <container_id> /bin/sh
Stop a container: 
docker stop <container_id>
Start a container: 
docker start <container_id>
Restart a container: 
docker restart <container_id>
Pause a container: 
docker pause <container_id>
Unpause a container: 
docker unpause <container_id>
View all containers: 
docker ps -a
View all images: 
docker images
Remove a container, -f to force removal: 
docker rm -f <container_id>
Remove all containers: 
docker rm $(docker ps -a -q)
Remove an image, -f to force removal: 
docker rmi -f <image_id>
Remove all images: 
docker rmi $(docker images -q)
Docker prune removes all stopped containers, dangling images, and unused networks: 
docker system prune
Create a network: 
docker network create network_name
List all networks: 
docker network ls
Inspect a network: 
docker network inspect network_name
Connect a container to a network: 
docker network connect network_name container_name
Disconnect a container from a network: 
docker network disconnect network_name container_name
Create a volume: 
docker volume create volume_name
List all volumes: 
docker volume ls
Inspect a volume: 
docker volume inspect volume_name
Remove a volume: 
docker volume rm volume_name
Docker Builds
Create a simple Dockerfile in your current directory - e.g. vim Dockerfile: 
FROM alpine
Build an image, -t to tag the image, . to build from the current directory, from file named Dockerfile: 
docker build -t image_name .
Build an image from a specific Dockerfile: 
docker build -t image_name -f Dockerfile_name .
Build an image with a specific build argument: 
docker build --build-arg key=value -t image_name .
For example, this would be used to specify the version of the application, which can be accessed in the Dockerfile: 
docker build --build-arg APP_VERSION=1.0 -t image_name .
To see this, define APP_VERSION in the Dockerfile. ARG is the same as ENV, but only available during the build process: 
ARG APP_VERSION
RUN echo $APP_VERSION
Build File Example

Build with ENVs, Entry Point, Copy files, Switch User and CMD 

FROM alpine
ENV APP_VERSION=1.0
WORKDIR /app
COPY . .
RUN chown -R 1000:1000 /app
USER 1000
ENTRYPOINT ["sh", "entrypoint.sh"]
CMD ["sh", "cmd.sh"]

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Build Docker Image

Build an image, -t to tag the image, . to build from the current directory, from file named Dockerfile: 
docker build -t image_name .
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Build Docker Image

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Build Docker Image