docker-basics

Docker containers are made of layers

• if the layers of image are same, then not all layers will be downloaded
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Docker create creates the container while docker run is combination of creating and starting container. Docker run creates a new container while docker start starts the existing one.

• -d runs the container in the background
  By default docker run attach to the running container and it’s not interactive.
  To build a image, use docker build -t the-image-name:tag . and . is the folder where the Dockerfile is.
  To access a terminal from running container use docker exec -it name bash to interactively access the terminal.
  During docker volume bind mount, docker will default to creating a directory in bind mount, this is true if bind mounting a file that does not exist on the host
  docker tag command rename docker images, when pushing to dockerhub, if user says latest, it will default to the newest version

Docker Logs
Moved to docker-logs

Use docker inspect | jq .[].Keys to parse the json data of a given container

• .[].HostConfig general configuration of container
• .[].HostConfig.Binds to check volume bindings
• .[].Mounts shows all the volumes
• .[].NetworkSettings check the network settings for example port map
• .[].NetworkSettings.Ports shows the exposed ports
• .[].Config.Env shows all the environment variables
• .[].State.Status get the status of running container eg. exited running
  Docker ps
• -q will only show the ID of a image which is useful to pipe into xargs
• --filter can filter based on conditions, such as names, status=exited
• expose=1000-2000/tcp filter shows all the containers with port 1000-2000 exposed
• -s get the size a container takes on disk

Docker Stats
- docker stats give the CPU usage statistics
- docker top give list of running processes of a given container

Docker Exec

• -i makes the session interactive
• -t TTY terminal from container in this host
• this is similar to docker attach, which attach to the running process of the docker container

Pushing to DockerHub

• login to dockerhub first
• use docker tag to rename the image with docker username
• vttc08/my-image:0.0.0
• docker push