Docker Cheat Sheet
Install
From https://www.linuxshelltips.com/install-docker-in-linux-mint/
sudo apt update
sudo apt install apt-transport-https ca-certificates curl gnupg lsb-release -y
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | \
sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
Identify the Ubuntu codename on which my Mint is based:
root@latitude7490:/tmp# cat /etc/os-release |grep -i ubuntu
ID_LIKE="ubuntu debian"
UBUNTU_CODENAME=jammy
In the following replace jammy with the relevant Ubuntu codename:
echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu jammy stable" \
| sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
Finally:
sudo apt update
sudo apt-get install docker-ce docker-ce-cli containerd.io
Verification
Verify the install with docker run:
> docker --version
Docker version 20.10.21, build baeda1f
> sudo docker run hello-world
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
Configuration
The location for client configuration files is determined by DOCKER_CONFIG
environment variable, seems to default to $HOME/.docker. More on docker
environment variables.
Configuration files include:
- config.json
- daemon.json
Networking
Show (standard) networks:
root@suprox:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
6eef1bc6ffc5 bridge bridge local
35dbeb62ddb4 host host local
e023fada21bd none null local
root@suprox:~# docker network inspect host
[
{
"Name": "host",
"Id": "35dbeb62ddb42ebca3f5e2eae576921229b1279b496c387b78ef2c4ced5c70d8",
"Created": "2023-02-10T18:31:29.131467146-08:00",
"Scope": "local",
"Driver": "host",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": []
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {},
"Labels": {}
}
]
Inspect the bridge network to see which containers are connected to it:
root@suprox:~# docker network inspect bridge
[
{
"Name": "bridge",
"Id": "6eef1bc6ffc530537c94652428cc80a295102845a84eb9ab18e40e8b6d666ee2",
"Created": "2023-02-10T18:31:29.14533915-08:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "172.17.0.0/16"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"3dca544da1ce64d8c5a970b38a8ab340e958b86ee36bc2ee4aa0b44035ec21d0": {
"Name": "mjpg-streamer",
"EndpointID": "b1b45b71ba4df575fcbd35650902860691e6f9dbcc82d608e8f4b992322cbe42",
"MacAddress": "02:42:ac:11:00:03",
"IPv4Address": "172.17.0.3/16",
"IPv6Address": ""
},
"bf42b1b5a4f78204a307323c514e22c402950f695e1d51e8c5df0c407dc66f98": {
"Name": "portainer",
"EndpointID": "617ed40e256b0a96dfbb5a74853dad400bc048797c11070735d4bb2b76787987",
"MacAddress": "02:42:ac:11:00:02",
"IPv4Address": "172.17.0.2/16",
"IPv6Address": ""
}
},
"Options": {
"com.docker.network.bridge.default_bridge": "true",
"com.docker.network.bridge.enable_icc": "true",
"com.docker.network.bridge.enable_ip_masquerade": "true",
"com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
"com.docker.network.bridge.name": "docker0",
"com.docker.network.driver.mtu": "1500"
},
"Labels": {}
}
]
List images
docker image ls
better yet:
docker images --digests
More on docker image.
List containers
docker container. List running:
docker container ls
Can also use docker ps.
List all containers, not only running, do not truncate output:
docker container ls -a --no-trunc
List IDs only:
docker container ls -q
1addfea727b3
09c4105cb356
443fc0c41710
b06cfe3053e5
4cf774b9e4a4
Kill all containers
Force delete all containers:
docker container rm -f $(docker container ls -aq)
Inspect the container
Inspecting container produces JSON:
sudo docker inspect _container_id_
Extract container environment and sort it.
sudo docker inspect _container_id_ | jq ".[0].Config.Env|sort[]"
Display the account (username/group) used by the container:
sudo docker inspect _container_id_ | jq ".[].Config.User"
"root:root"
Get a Shell in a Container
docker container exec -it _container_id_or_name_ /bin/bash
Options used:
-i- interactive-t- allocate a pseudo TTY device
Container logs
Default location: /var/lib/docker/containers/<container_id>/<container_id>-json.log.
logging drivers
can change that.
CLI:
docker logs <container_id>
To tail (or to follow) the log:
docker logs <container_id> -f
Observability
root@suprox:~# docker stats mjpg-streamer portainer
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
3dca544da1ce mjpg-streamer 0.11% 1.75MiB / 31.26GiB 0.01% 7.12MB / 1.48GB 0B / 0B 4
bf42b1b5a4f7 portainer 0.00% 12.59MiB / 31.26GiB 0.04% 3.29MB / 8.37MB 0B / 25.4MB 7
^C
Build it
Create Dockerfile. Then use command docker build to build and tag the image:
docker build -t my_stuff .
Run it
Run an image in a container using
docker run.
If you need to provide input for stdin, use -i option:
cat secrets.txt | docker run --pull=always -i my_stuff
| Command | Description |
|---|---|
docker run <image> |
Create and run a new container |
docker run -p 8080:80 <image> |
Publish container port 80 to host port 8080 |
docker run -d <image> |
Run a container in the background |
docker run -v <host>:<container> <image> |
Mount a host directory to a container |
docker ps |
List currently running containers |
docker ps --all |
List all containers (running or stopped) |
docker logs <container_name> |
Fetch the logs of a container |
docker logs -f <container_name> |
Fetch and follow the logs of a container |
docker stop <container_name> |
Stop a running container |
docker start <container_name> |
Start a stopped container |
docker rm <container_name> |
Remove a container |
Executing commands in a container
Command|Description
——-|———–
docker exec <container_name> <command>|Execute a command in a running container
docker exec -it <container_name> bash|Open a shell in a running container
Image commands
Command|Description
——-|———–
docker build -t <image> .|Build a new image from the Dockerfile in the current directory and tag it
docker images|List local images
docker rmi <image>|Remove an image
Container registry commands
| Command | Description |
|---|---|
docker login |
Login to Docker Hub |
docker login <server> |
Login to another container registry |
docker logout |
Logout of Docker Hub |
docker logout <server> |
Logout of another container registry |
docker push <image> |
Upload an image to a registry |
docker pull <image> |
Download an image from a registry |
docker search <image> |
Search Docker Hub for images |
System commands
| Command | Description |
|---|---|
docker system df |
Show Docker disk usage |
docker system prune |
Remove unused data |
docker system prune -a |
Remove all unused dat |