README.md

   1 ##Discourse Docker
   2
   3 A toolkit for building and managing Docker images for Discourse.
   4
   5 ### About
   6
   7 The Discourse docker templates were designed by Sam Saffron. See the following introduction: http://samsaffron.com/archive/2013/11/07/discourse-in-a-docker-container
   8
   9 These templates are agnostic, you may run Discourse in multiple containers or a single container.
  10
  11 The templates and base image take care of configuring Discourse with best practices in mind. The latest version of Ruby 2.0 is included as is fairly extensive memory and GC tuning. The web template uses unicorn which helps cut down on overall memory usage making this very suitable for VPS type installs.
  12
  13 ###Getting started
  14
  15 The simplest (though slightly more fragile) way of getting started is using the standalone template.
  16
  17 - `cp samples/standalone.yml containers/app.yml`
  18 - **Edit** app.yml with your environment specific information, including binds and volumes
  19 - `sudo ./launcher bootstrap app`
  20 - `sudo ./launcher start app`
  21 - Ensure you setup iptables or some other firewall to protect various ports (like postgres/redis in multi image setups)
  22
  23 Note: you can add yourself to the docker group if you wish to avoid `sudo` with `usermod -a -G docker your-user-name`.
  24
  25 ### Directory Structure
  26
  27 - cids
  28
  29 Contains container ids for currently running Docker containers. cids are Docker's "equivalent" of pids. Each container will have a unique git like hash.
  30
  31 - containers
  32
  33 This directory is to contain container definitions for your various Discourse containers. You are in charge of this directory, it ships empty.
  34
  35 - samples
  36
  37 Sample container definitions you may use to bootstrap your environment. You can copy and amend templates here into the containers directory.
  38
  39 - shared
  40
  41 Placeholder spot for shared volumes with various Discourse containers. You may elect to store certain persistent information outside of a container, in our case we keep various logfiles and upload directory outside. This allows you to rebuild containers easily without losing important information. Keeping uploads outside of the container allows you to share them between multiple web instances.
  42
  43 - templates
  44
  45 [pups](https://github.com/samsaffron/pups) managed pups templates you may use to bootstrap your environment.
  46
  47 - image
  48
  49 Dockerfile for both the base image `samsaffron/discoruse_base` and discourse image `samsaffron/discourse`.
  50
  51 `samsaffron/discourse_base` contains all the OS dependencies including sshd, runit, postgres, nginx, ruby.
  52
  53 `samsaffron/discourse` builds on the base image and configures a discourse user and `/var/www/discourse` directory for the Discourse source.
  54
  55 The Docker repository will always contain the latest built version at: https://index.docker.io/u/samsaffron/discourse/ , you should not need to build the base image.
  56
  57 ###launcher
  58
  59 The base directory contains a single bash script which is used to manage containers. You can use it to "bootstrap" a new container, ssh in, start, stop and destroy a container.
  60
  61 ```
  62 Usage: launcher COMMAND CONFIG
  63 Commands:
  64     start:      Start/initialize a container
  65     stop:       Stop a running container
  66     restart:    Restart a container
  67     destroy:    Stop and remove a container
  68     ssh:        Start a bash shell in a running container
  69     logs:       Docker logs for container
  70     bootstrap:  Bootstrap a container for the config based on a template
  71 ```
  72
  73
  74 ###About the container configuration
  75
  76 The beggining of the container definition will contain 3 "special" sections:
  77
  78 - templates:
  79
  80 ```
  81 templates:
  82   - "templates/cron.template.yml"
  83   - "templates/postgres.template.yml"
  84 ```
  85
  86 This template is "composed" out of all these child templates, this allows for a very flexible configuration struture. Further more you may add specific hooks that extend the templates you reference.
  87
  88 - expose:
  89
  90 ```
  91 expose:
  92   - "2222:22"
  93 ```
  94
  95 Expose port 22 inside the container on port 2222 on ALL local host interfaces.
  96
  97
  98 - volumes:
  99
 100 ```
 101 volumes:
 102   - volume:
 103       host: /var/docker/data
 104       guest: /shared
 105
 106 ```
 107
 108 Expose a directory inside the host inside the container.
 109
 110 ###Upgrading discourse
 111
 112 The docker setup gives you multiple upgrade options:
 113
 114 1. You can use the front end at http://yoursite.com/admin/docker to upgrade an already running image.
 115
 116 2. You can create a new base image by running:
 117   - `./launcher bootstrap my_image`
 118   - `./launcher destroy my_image`
 119   - `./launcher start my_image`
 120
 121 ###Multi image vs Single image setups
 122
 123 The samples directory conains a standalone template. This template will bundle all of the programs required to run discourse into a single image. The advantage is that it is very easy to get started as you do not need to wire up comms between containers.
 124
 125 However, the disadvantage is that the bootstrapping process will launch a new postgres instance, having 2 postgres instances running against a single directory can lead to unexpected results. Due to that, if you are ever to bootstrap the `standalone` template again you should first stop the existing container.
 126
 127 A multi image setup allows you to bootstrap new web processes while your site is running and only after it is built, switch the new image in. The setup is far more flexible and robust, however is a bit more complicated to setup. See the `data.yml` and `web_only.yml` templates in the samples directory. To ease this process, `launcher` will inject an env var called `DISCOURSE_HOST_IP` which will be available inside the image.
 128
 129 ###Troubleshooting
 130
 131 It is strongly recommended you have ssh access to your running containers, this allows you very easily take sneak peak of the internals. Simplest way to gain access is:
 132
 133 1. Run a terminal as root
 134 2. cd `~/.ssh`
 135 3. `ssh-key-gen`
 136 4. paste the contents of `id_rsa.pub` into your templates (see placeholder in samples)
 137 5. bootstrap and run your container
 138 6. `./launcher ssh my_container`
 139
 140 ###Security
 141
 142 Directory permissions in Linux are sid based, if your sids on the host do not match the sids in the guest, permissions will mismatch. On clean installs you can ensure they are in sync by looking at `/etc/passwd` and `/etc/group`, the discourse account will have the sid 1000.
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