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 - `mkdir -p /var/docker/data`
  18 - Clone this project from github into `/var/docker`
  19 - `cp samples/standalone.yml containers/app.yml`
  20 - **Edit** app.yml with your environment specific information, including binds and volumes
  21 - `sudo ./launcher bootstrap app`
  22 - `sudo ./launcher start app`
  23 - Ensure you setup iptables or some other firewall to protect various ports (like postgres/redis in multi image setups)
  24
  25 Note: you can add yourself to the docker group if you wish to avoid `sudo` with `usermod -a -G docker your-user-name`.
  26
  27 ### Directory Structure
  28
  29 - cids
  30
  31 Contains container ids for currently running Docker containers. cids are Docker's "equivalent" of pids. Each container will have a unique git like hash.
  32
  33 - containers
  34
  35 This directory is to contain container definitions for your various Discourse containers. You are in charge of this directory, it ships empty.
  36
  37 - samples
  38
  39 Sample container definitions you may use to bootstrap your environment. You can copy and amend templates here into the containers directory.
  40
  41 - shared
  42
  43 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.
  44
  45 - templates
  46
  47 [pups](https://github.com/samsaffron/pups) managed pups templates you may use to bootstrap your environment.
  48
  49 - image
  50
  51 Dockerfile for both the base image `samsaffron/discoruse_base` and discourse image `samsaffron/discourse`.
  52
  53 `samsaffron/discourse_base` contains all the OS dependencies including sshd, runit, postgres, nginx, ruby.
  54
  55 `samsaffron/discourse` builds on the base image and configures a discourse user and `/var/www/discourse` directory for the Discourse source.
  56
  57 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.
  58
  59 ###launcher
  60
  61 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.
  62
  63 ```
  64 Usage: launcher COMMAND CONFIG
  65 Commands:
  66     start:      Start/initialize a container
  67     stop:       Stop a running container
  68     restart:    Restart a container
  69     destroy:    Stop and remove a container
  70     ssh:        Start a bash shell in a running container
  71     logs:       Docker logs for container
  72     bootstrap:  Bootstrap a container for the config based on a template
  73 ```
  74
  75
  76 ###About the container configuration
  77
  78 The beggining of the container definition will contain 3 "special" sections:
  79
  80 - templates:
  81
  82 ```
  83 templates:
  84   - "templates/cron.template.yml"
  85   - "templates/postgres.template.yml"
  86 ```
  87
  88 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.
  89
  90 - expose:
  91
  92 ```
  93 expose:
  94   - "2222:22"
  95 ```
  96
  97 Expose port 22 inside the container on port 2222 on ALL local host interfaces.
  98
  99
 100 - volumes:
 101
 102 ```
 103 volumes:
 104   - volume:
 105       host: /var/docker/data
 106       guest: /shared
 107
 108 ```
 109
 110 Expose a directory inside the host inside the container.
 111
 112 ###Upgrading discourse
 113
 114 The docker setup gives you multiple upgrade options:
 115
 116 1. You can use the front end at http://yoursite.com/admin/docker to upgrade an already running image.
 117
 118 2. You can create a new base image by running:
 119   - `./launcher bootstrap my_image`
 120   - `./launcher destroy my_image`
 121   - `./launcher start my_image`
 122
 123 ###Multi image vs Single image setups
 124
 125 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.
 126
 127 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.
 128
 129 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.
 130
 131 ###Email setup
 132
 133 For a Discourse instance to function properly Email must be setup. You can use an after_code hook in your template to setup mail, for example this will setup email integration with mandrill (which offer free smtp services).
 134
 135 ```
 136     - replace:
 137         filename: /var/www/discourse/config/environments/production.rb
 138         from: /end/
 139         direction: reverse
 140         to: |
 141           config.action_mailer.delivery_method = :smtp
 142           config.action_mailer.smtp_settings = {
 143             :address              => 'smtp.mandrillapp.com',
 144             :port                 => 587,
 145             :domain               => 'mydomain.com',
 146             :user_name            => 'user@example.com',
 147             :password             => 'some_password',
 148             :authentication       => 'login',
 149             :enable_starttls_auto => true
 150           }
 151           end
 152
 153 ```
 154
 155 The docker image does not contain postfix, exim or another mta, it was omitted cause it is very tricky to setup perfectly.
 156
 157 ###Troubleshooting
 158
 159 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:
 160
 161 1. Run a terminal as root
 162 2. cd `~/.ssh`
 163 3. `ssh-key-gen`
 164 4. paste the contents of `id_rsa.pub` into your templates (see placeholder in samples)
 165 5. bootstrap and run your container
 166 6. `./launcher ssh my_container`
 167
 168 ###Security
 169
 170 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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