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Docker

Installing Docker-CE on Ubuntu Linux 18.04​

(Should be the same for most current versions)

# Update the apt package list.
sudo apt-get update -y

# Install Docker's package dependencies.
sudo apt-get install -y \
    apt-transport-https \
    ca-certificates \
    curl \
    software-properties-common

# Download and add Docker's official public PGP key.
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

# Verify the fingerprint.
sudo apt-key fingerprint 0EBFCD88

# Add the `stable` channel's Docker upstream repository.
sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

# Update the apt package list (for the new apt repo).
sudo apt-get update -y

# Install the latest version of Docker CE.
sudo apt-get install -y docker-ce

# Allow your user to access the Docker CLI without needing root access.
# You need to log out and log back in so that your group membership is re-evaluated
sudo usermod -aG docker $USER

Clean unused data​

Removes all:

  • Stoped containers
  • Unused networks
  • Dangling images
  • Dangling build cache
docker system prune

Clear docker logs​

Finds all .log files in /var/lib/docker/containers/ and truncates their size to 0.

sudo find /var/lib/docker/containers/ -name "*.log*" -exec truncate -s 0 {} \;

Get IP Address of a container​

Remember to change the container name or id

docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' container_name_or_id

Docker Cheatsheet​

Docker build​

// simple build

docker build .

// good practice

docker build -t <tag name> .

// please note, for these command to work you need to have a dockerfile present.

Docker images​


// list all images on disk

docker images

// search a particular image
docker images --filter=reference="centos"  //will give all locally present images of centos

// remove a certain image

docker image rm <image hash> //only first 3 characters of hash code is enough for docker daemon to distinguish the image.

Docker containers​

// list all containers online/offline
docker ps -a
docker container ls -a

// remove/stop/kill a certain container
docker kill rm <container hash>

//coming out of container without exiting it
ctrl+P+Q

//searching docker image on docker hub
docker search <<image_name>>

//tagging local image with another name
docker tag <<old_image_name>> <<new_image_name>>

//"SSH" into a running container
docker exec -it <<container_name>> /bin/bash

//Execute arbitrary command in container
docker exec -it <<container_name>> <<command>>

Remove all dangling images​

docker rmi $(docker images | grep "^<none>" | awk "{print $3}")

or

docker rmi -f $(docker images -f "dangling=true" -q)

Remove all exited containers​

docker ps -a | grep Exit | cut -d ' ' -f 1 | xargs docker rm