Docker Cookbook

Useful apps

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Useful commands

  1. docker ps — Lists running containers. Some useful flags include: -a / -all for all containers (default shows just running) and —-quiet /-q to list just their ids (useful for when you want to get all the containers).
  2. docker pull — Most of your images will be created on top of a base image from the Docker Hub registry. Docker Hub contains many pre-built images that you can pull and try without needing to define and configure your own. To download a particular image, or set of images (i.e., a repository), use docker pull.
  3. docker build — The docker build command builds Docker images from a Dockerfile and a “context”. A build’s context is the set of files located in the specified PATH or URL. Use the -t flag to label the image, for example docker build -t my_container . with the . at the end signalling to build using the currently directory.
  4. docker run — Run a docker container based on an image, you can follow this on with other commands, such as -it bash to then run bash from within the container. Also see Top 10 options for docker run — a quick reference guide for the CLI commanddocker run my_image -it bash
  5. docker logs — Use this command to display the logs of a container, you must specify a container and can use flags, such as --follow to follow the output in the logs of using the program. docker logs --follow my_container
  6. docker volume ls — This lists the volumes, which are the preferred mechanism for persisting data generated by and used by Docker containers.
  7. docker rm — Removes one or more containers. docker rm my_container
  8. docker rmi — Removes one or more images. docker rmi my_image
  9. docker stop — Stops one or more containers. docker stop my_containerstops one container, while docker stop $(docker ps -a -q) stops all running containers. A more direct way is to use docker kill my_container, which does not attempt to shut down the process gracefully first.
  10. Use them together, for example to clean up all your docker images and containers:
  • kill all running containers with docker kill $(docker ps -q)
  • delete all stopped containers with docker rm $(docker ps -a -q)
  • delete all images with docker rmi $(docker images -q)

Create new container

Start a new docker image with a given name

You can start a new container by using the run command and specify the desired image 

$ docker run -it --name playground ubuntu:17.10 /bin/bash
....
root@c106fbb48b20:/# exit

As a result, you are in the container at the bash command line

Reconnect to image
$ docker attach playground
Commit changes in container
$ docker start playground
$ docker attach playground
root@c106fbb48b20:/# echo 1.0 >VERSION
root@c106fbb48b20:/# exit
$ docker commit playground playground:1.0
$ docker tag playground:1.0 playground:latest
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
playground 1.0 01703597322b Less than a second ago 94.6MB
playground latest 01703597322b Less than a second ago 94.6MB

Add tools and utilities

Python

$ apt-get update 
$ apt-get upgrade 
$ apt-get install python3 python3-pip

Java

$ apt-get install default-jre

Manage File Shares

File shares with Docker Desktop on Mac OS

Configuration is stored under

~/Library/Group\ Containers/group.com.docker/settings.json

Monitor Docker Logs

Logs with Docker Desktop on Mac OS

pred='process matches ".*(ocker|vpnkit).*" || (process in {"taskgated-helper", "launchservicesd", "kernel"} && eventMessage contains[c] "docker")'
/usr/bin/log stream --style syslog --level=debug --color=always --predicate "$pred"

Alternative you can run

/usr/bin/log show --style syslog --debug --info --last 1d --predicate "$pred" >/tmp/logs.txt

Install local apps in a docker container

Install Atom Editor

Start docker image

$ docker run -it --name docker-atom -v /Dockerfiles/HOME:/home -e DISPLAY=192.168.99.1:0 ubuntu /bin/bash

Install Atom

# apt-get update
# apt-get install curl
# curl -sL https://deb.nodesource.com/setup_7.x | bash -
# apt-get install nodejs
# node -v
v7.4.0
# apt-get -y install git
# apt-get -y install software-properties-common
# add-apt-repository -y ppa:webupd8team/atom
# apt-get update
# apt-get -y install atom
# apt-get install libxss1

Commit changes  and build a image

# docker commit -a "Docker Tutorial 1.0.0" -m ionic d378e8647af9 atom:1.0.0
# docker tag atom:1.0.0 atom:latest

Links and Resources

Docker quick reference guides

Docker in more depth

Working with networks

I’ve got a lot of inspiration from wsargent/docker-cheat-sheet.

Goal

We will setup to applications, each in his one container, running on the smae network, so they can communication together.

Setup

Starting with the default configuration, you will see 4 networks

$ docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
6742a11bff1e        bridge              bridge              local
3af0a1c9eaac        host                host                local
e60f68aad9d6        none                null                local

Create a bridged network for running two apps inside: web and database

$ docker network create -d bridge playground_bridge
c97a80b449d9b6b28ddffa0a7bd4a7938e0b8261773080ab33ae4b7ab08826b1
$ docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
6742a11bff1e        bridge              bridge              local
3af0a1c9eaac        host                host                local
e60f68aad9d6        none                null                local
c97a80b449d9        playground_bridge   bridge              local

Start the database application using the bridges network

$ docker run -d --net=playground_bridge --name playground_db training/postgres
88abb9d018c628ed1abe7da0466289846a8342a28b2cbef3305ea5313c46d647
$ docker inspect --format='{{json .NetworkSettings.Networks}}' playground_db| python -m json.tool
{
    "playground_bridge": {
        "Aliases": [
            "88abb9d018c6"
        ],
        "DriverOpts": null,
        "EndpointID": "9fdfe9baf5b159471a39601779ee451aa555a9a9be72be4472e56bd3fcfd1350",
        "Gateway": "172.18.0.1",
        "GlobalIPv6Address": "",
        "GlobalIPv6PrefixLen": 0,
        "IPAMConfig": null,
        "IPAddress": "172.18.0.2",
        "IPPrefixLen": 16,
        "IPv6Gateway": "",
        "Links": null,
        "MacAddress": "02:42:ac:12:00:02",
        "NetworkID": "c97a80b449d9b6b28ddffa0a7bd4a7938e0b8261773080ab33ae4b7ab08826b1"
    }
}

Now, start the web application with the default network (not the playground_bridge used by the database)

$ docker run -d --name playground_web training/webapp python app.py
2f31761168d75d10c2f1bffc805fb8963a18529e17c2592c2b279afd9e364e7b

They cannot communication, because they are running in different networks:

$ docker exec -it playground_db ifconfig | grep inet
         inet addr:172.18.0.2 Bcast:0.0.0.0 Mask:255.255.0.0
         inet addr:127.0.0.1 Mask:255.0.0.0
$ docker exec -it playground_web ifconfig | grep inet
         inet addr:172.17.0.2 Bcast:0.0.0.0 Mask:255.255.0.0
         inet addr:127.0.0.1 Mask:255.0.0.0

Now check the connectivity. The Web application can reach itself:

$ docker exec -it playground_web ping -c 5 172.17.0.2
PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.027 ms
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.033 ms
64 bytes from 172.17.0.2: icmp_seq=3 ttl=64 time=0.036 ms
64 bytes from 172.17.0.2: icmp_seq=4 ttl=64 time=0.031 ms
64 bytes from 172.17.0.2: icmp_seq=5 ttl=64 time=0.029 ms

But could not reach the database application (because of the different network):

$ docker exec -it playground_web ping -c 5 172.18.0.2
PING 172.18.0.2 (172.18.0.2) 56(84) bytes of data.

--- 172.18.0.2 ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4126ms

To connect both apps together, put them in the same network:

Before, they use different networks:

$ docker inspect --format='{{json .NetworkSettings.Networks}}' playground_web | python -m json.tool|grep NetworkID
        "NetworkID": "6742a11bff1ebcdeaee9151f146a74b1c3d77db95d4931e4e79f48f7d7f491f7"
$ docker inspect --format='{{json .NetworkSettings.Networks}}' playground_db | python -m json.tool|grep NetworkID
        "NetworkID": "c97a80b449d9b6b28ddffa0a7bd4a7938e0b8261773080ab33ae4b7ab08826b1"

Connect Web Application to network playground_bridge:

$ docker network connect playground_bridge playground_web

 Now, they use the same network:

$ docker inspect --format='{{json .NetworkSettings.Networks}}' playground_web | python -m json.tool|grep NetworkID
        "NetworkID": "6742a11bff1ebcdeaee9151f146a74b1c3d77db95d4931e4e79f48f7d7f491f7"
        "NetworkID": "c97a80b449d9b6b28ddffa0a7bd4a7938e0b8261773080ab33ae4b7ab08826b1"
$ docker inspect --format='{{json .NetworkSettings.Networks}}' playground_db | python -m json.tool|grep NetworkID
        "NetworkID": "c97a80b449d9b6b28ddffa0a7bd4a7938e0b8261773080ab33ae4b7ab08826b1"

And they can communication

$ docker exec -it playground_web ping -c 5 172.17.0.2
PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.044 ms
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.032 ms
64 bytes from 172.17.0.2: icmp_seq=3 ttl=64 time=0.033 ms
64 bytes from 172.17.0.2: icmp_seq=4 ttl=64 time=0.032 ms
64 bytes from 172.17.0.2: icmp_seq=5 ttl=64 time=0.033 ms

--- 172.17.0.2 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4144ms
rtt min/avg/max/mdev = 0.032/0.034/0.044/0.008 ms

$ docker exec -it playground_web ping -c 5 172.18.0.2
PING 172.18.0.2 (172.18.0.2) 56(84) bytes of data.
64 bytes from 172.18.0.2: icmp_seq=1 ttl=64 time=0.134 ms
64 bytes from 172.18.0.2: icmp_seq=2 ttl=64 time=0.052 ms
64 bytes from 172.18.0.2: icmp_seq=3 ttl=64 time=0.056 ms
64 bytes from 172.18.0.2: icmp_seq=4 ttl=64 time=0.052 ms
64 bytes from 172.18.0.2: icmp_seq=5 ttl=64 time=0.053 ms

--- 172.18.0.2 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4156ms
rtt min/avg/max/mdev = 0.052/0.069/0.134/0.033 ms