docker best practices

docker

best practices

config default data directory

  • default data directory /var/lib/docker

  • change default directory

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    # step1
    vim /etc/docker/daemon.json

    {
      "data-root": "/path/to/directory"
    }

    # step2
    systemctl restart docker 

    # check modify available
    docker info | grep "Docker Root Dir"

non-root user manage docker

  1. Create the docker group.

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    $ sudo groupadd docker

  2. Add your user to the docker group.

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    $ sudo usermod -aG docker $USER

  3. Log out and log back in so that your group membership is re-evaluated.

    If testing on a virtual machine, it may be necessary to restart the virtual machine for changes to take effect.

    On a desktop Linux environment such as X Windows, log out of your session completely and then log back in.

    On Linux, you can also run the following command to activate the changes to groups:

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    $ newgrp docker

  4. Verify that you can run docker commands without sudo.

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    $ docker run hello-world

migration

reference

5 ways to move Docker container to another host

Build a Docker Image with MySQL Database

Plan A

  • Step1 create an Image From a Container

Create a new image from a container’s changes

commit command

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sudo docker commit [OPTIONS] CONTAINER [REPOSITORY[:TAG]]

options

Name, shorthand Default Description
--author , -a Author (e.g., “will brook”)
--change , -c Apply Dockerfile instruction to the created image
--message , -m Commit message
--pause , -p true Pause container during commit
  • Step 2 export the image to a file 
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sudo docker save -o /path/to/your_image.tar your_image_name
  • Step 3 load the Docker image file
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sudo docker load -i your_image.tar

Plan B

  • Step 1

First save the new image by finding the container ID (using docker container ls) and then committing it to a new image name. Note that only a-z0-9-_. are allowed when naming images:

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# create image from container
docker container commit c16378f943fe rhel-httpd:latest
  • Step 2

tag the image with the host name or IP address, and the port of the registry:

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# re-tag repository:tag info about image
docker image tag rhel-httpd:latest registry-host:5000/myadmin/rhel-httpd:latest
or
docker tag 0e5574283393 registry-host:5000/myadmin/rhel-httpd:latest
  • Step 3

log in from Docker client:

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docker login <harbor_address>
  • Step 4

push the image to the registry using the image ID.

In this example the registry is on host named registry-host and listening on port 5000. (harbor默认配置端口80，详见harbor.yml)

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# push repository:tag,
docker image push registry-host:5000/myadmin/rhel-httpd:latest
or
docker push registry-host:5000/myname/myimage

Pull Image from Harbor

Connecting to Harbor via HTTP

  • Step 1

add the option --insecure-registry to your client’s Docker daemon. By default, the daemon file is located at /etc/docker/daemon.json.

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{
"insecure-registries" : ["ip:port", "0.0.0.0"] #如果port为80，则可省略
}

Restart Docker Engine.

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systemctl restart docker
  • Step 2
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docker pull hostAddress/library/REPOSITORY:TAG

troubleshoot

  • Failed to load listeners: no sockets found via socket activation: make sure the service was started by systemd
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edit the docker’s systemd unit file and change the ExecStart:
sudo systemctl edit docker.service

edite The value ExecStart, change fd:// to unix://:
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H unix://
  • Error creating default “bridge” network: cannot create network (docker0): conflicts with network (docker0): networks have same bridge name
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sudo rm -rf /var/lib/docker/network
sudo systemctl start docker
  • accident delete /var/run/docker.sock
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sudo systemctl stop docker
sudo systemctl restart docker.socket
sudo systemctl start docker