doc/md/docker/docker-101.md

   1 ## Basics
   2 Install [Docker](https://www.docker.com/), by following the instructions relevant
   3 to your OS / distribution, and start the service.
   4
   5 ### Search an image on [DockerHub](https://hub.docker.com/)
   6
   7 ```bash
   8 $ docker search debian
   9
  10 NAME            DESCRIPTION                                     STARS   OFFICIAL   AUTOMATED
  11 ubuntu          Ubuntu is a Debian-based Linux operating s...   2065    [OK]
  12 debian          Debian is a Linux distribution that's comp...   603     [OK]
  13 google/debian                                                   47                 [OK]
  14 ```
  15
  16 ### Show available tags for a repository
  17 ```bash
  18 $ curl https://index.docker.io/v1/repositories/debian/tags | python -m json.tool
  19
  20 % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
  21 Dload  Upload   Total   Spent    Left  Speed
  22 100  1283    0  1283    0     0    433      0 --:--:--  0:00:02 --:--:--   433
  23 ```
  24
  25 Sample output:
  26 ```json
  27 [
  28     {
  29         "layer": "85a02782",
  30         "name": "stretch"
  31     },
  32     {
  33         "layer": "59abecbc",
  34         "name": "testing"
  35     },
  36     {
  37         "layer": "bf0fd686",
  38         "name": "unstable"
  39     },
  40     {
  41         "layer": "60c52dbe",
  42         "name": "wheezy"
  43     },
  44     {
  45         "layer": "c5b806fe",
  46         "name": "wheezy-backports"
  47     }
  48 ]
  49
  50 ```
  51
  52 ### Pull an image from DockerHub
  53 ```bash
  54 $ docker pull repository[:tag]
  55
  56 $ docker pull debian:wheezy
  57 wheezy: Pulling from debian
  58 4c8cbfd2973e: Pull complete
  59 60c52dbe9d91: Pull complete
  60 Digest: sha256:c584131da2ac1948aa3e66468a4424b6aea2f33acba7cec0b631bdb56254c4fe
  61 Status: Downloaded newer image for debian:wheezy
  62 ```
  63
  64 Docker re-uses layers already downloaded. Iow. if you have images based only Alpine or some Ubuntu version for example, those can share disk space.
  65
  66 ### Start a container
  67 A container is an instance created from an image, that can be run and that keeps running until its main process exits. Or until the user stops the container.
  68
  69 The simplest way to start a container from image is ``docker run``. It also pulls the image for you if it is not locally available. For more advanced use, refer to ``docker create``.
  70
  71 Note that stopped containers are not destroyed, unless you specify ``--rm``. To view all created, running and stopped containers, enter:
  72 ```bash
  73 $ docker ps -a
  74 ```
  75
  76 Some containers may be designed or configured to be restarted, others are not. Note that both network ports and volumes of a container are created on start, and not editable later.
  77
  78 ### Access a running container
  79 A running container is accessible using ``docker exec``, or ``docker copy``. You can use ``exec`` to start a root shell in the Shaarli container:
  80 ```bash
  81 $ docker exec -ti <container-name-or-id> bash
  82 ```
  83 Note the names and ID's of containers are list in ``docker ps``. You an even type only one or two letters of the ID, given they are unique.
  84
  85 Access can also be through one or more network ports, or disk volumes. Both are specified on and fixed on ``docker create`` or ``run``.
  86
  87 ### Docker disk use
  88 Trying out different images can fill some gigabytes of disk quickly. Besides images, the docker volumes usually take up most disk space.
  89
  90 If you care only about trying out docker and not about what is running or saved, the following commands should help you out quickly:
  91
  92 ```bash
  93 $ docker rmi -f $(docker images -aq) # remove or mark all images for disposal
  94 $ docker volume rm $(docker volume ls -q) # remove all volumes
  95 ```