README.md

   1 ### About
   2
   3 - [Docker](https://www.docker.io/) is an open source project to pack, ship and run any Linux application in a lighter weight, faster container than a traditional virtual machine.
   4
   5 - Docker makes it much easier to deploy [a Discourse forum](https://github.com/discourse/discourse) on your servers and keep it updated. For background, see [Sam's blog post](http://samsaffron.com/archive/2013/11/07/discourse-in-a-docker-container).
   6
   7 - The templates and base image configure Discourse with the Discourse team's recommended optimal defaults.
   8
   9
  10 ### IMPORTANT: Before You Start
  11
  12 1. Run docker and launcher as root.
  13 2. Use [Ubuntu 12.04 LTS](http://releases.ubuntu.com/precise/) or [Ubuntu 13.04](http://releases.ubuntu.com/13.04/) or [Ubuntu 13.10](http://releases.ubuntu.com/13.10/). Device mapper support in docker is still rough.
  14 3. Upgrade to the [latest version of Docker](http://docs.docker.io/en/latest/installation/ubuntulinux/).
  15 4. Install Discourse docker into `/var/docker`
  16
  17 ### Getting Started
  18
  19 The simplest way to get started is the  **standalone** template:
  20
  21 1. **Clone** this project from github: `git clone https://github.com/SamSaffron/discourse_docker.git /var/docker`
  22 2. **Copy** the standalone sample into the containers directory: `cp samples/standalone.yml containers/app.yml`
  23 3. **Edit** `containers/app.yml` with your environment specific information
  24   - [bindings](#expose)
  25   - [volumes](#volumes) (make sure you create the appropriate directories on the host)
  26 4. **Bootstrap** the image: `sudo ./launcher bootstrap app`
  27 5. **Start** the image: `sudo ./launcher start app`
  28
  29 Note: you can add yourself to the Docker group if you wish to avoid `sudo` with `usermod -aG docker <your-user-name>`.
  30
  31 ### Directory Structure
  32
  33 #### `/cids`
  34
  35 Contains container ids for currently running Docker containers. cids are Docker's "equivalent" of pids. Each container will have a unique git like hash.
  36
  37 #### `/containers`
  38
  39 This directory is for container definitions for your various Discourse containers. You are in charge of this directory, it ships empty.
  40
  41 #### `/samples`
  42
  43 Sample container definitions you may use to bootstrap your environment. You can copy and amend templates here into the containers directory.
  44
  45 #### `/shared`
  46
  47 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.
  48
  49 #### `/templates`
  50
  51 [pups](https://github.com/samsaffron/pups) managed pups templates you may use to bootstrap your environment.
  52
  53 #### `/image`
  54
  55 Dockerfile for both the base image `samsaffron/discoruse_base` and discourse image `samsaffron/discourse`.
  56
  57 - `samsaffron/discourse_base` contains all the OS dependencies including sshd, runit, postgres, nginx, ruby.
  58
  59 - `samsaffron/discourse` builds on the base image and configures a discourse user and `/var/www/discourse` directory for the Discourse source.
  60
  61 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.
  62
  63 ### Launcher
  64
  65 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.
  66
  67 ```
  68 Usage: launcher COMMAND CONFIG
  69 Commands:
  70     start:      Start/initialize a container
  71     stop:       Stop a running container
  72     restart:    Restart a container
  73     destroy:    Stop and remove a container
  74     ssh:        Start a bash shell in a running container
  75     logs:       Docker logs for container
  76     bootstrap:  Bootstrap a container for the config based on a template
  77 ```
  78
  79
  80 ### Container Configuration
  81
  82 The beginning of the container definition will contain 3 "special" sections:
  83
  84 #### templates:
  85
  86 ```
  87 templates:
  88   - "templates/cron.template.yml"
  89   - "templates/postgres.template.yml"
  90 ```
  91
  92 This template is "composed" out of all these child templates, this allows for a very flexible configuration struture. Furthermore you may add specific hooks that extend the templates you reference.
  93
  94 #### expose:
  95
  96 ```
  97 expose:
  98   - "2222:22"
  99 ```
 100
 101 Expose port 22 inside the container on port 2222 on ALL local host interfaces.
 102
 103
 104 #### volumes:
 105
 106 ```
 107 volumes:
 108   - volume:
 109       host: /var/docker/data
 110       guest: /shared
 111
 112 ```
 113
 114 Expose a directory inside the host inside the container.
 115
 116 ### Upgrading Discourse
 117
 118 The Docker setup gives you multiple upgrade options:
 119
 120 1. Use the front end at http://yoursite.com/admin/docker to upgrade an already running image.
 121
 122 2. Create a new base image by running:
 123   - `./launcher bootstrap my_image`
 124   - `./launcher destroy my_image`
 125   - `./launcher start my_image`
 126
 127 ### Single Container vs. Multiple Container
 128
 129 The samples directory contains a standalone template. This template bundles all of the software required to run Discourse into a single container. The advantage is that it is easy.
 130
 131 The multiple container configuration setup is far more flexible and robust, however it is also more complicated to set up. A multiple container setup allows you to:
 132
 133 - Minimize downtime when upgrading to new versions of Discourse. You can bootstrap new web processes while your site is running and only after it is built, switch the new image in.
 134 - Scale your forum to multiple servers.
 135 - Add servers for redundancy.
 136 - Have some required services (e.g. the database) run on beefier hardware.
 137
 138 If you want a multiple container 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.
 139
 140 WARNING: In a multiple container configuration, *make sure* you setup iptables or some other firewall to protect various ports (for postgres/redis).
 141
 142 ### Email
 143
 144 For a Discourse instance to function properly Email must be set up. Use the `SMTP_URL` env var to set your SMTP address, see sample templates for an example. The Docker image does not contain postfix, exim or another MTA, it was omitted because it is very tricky to set up correctly.
 145
 146 ### Troubleshooting
 147
 148 We strongly recommend you have ssh access to your running containers, this allows you very easily take a sneak peek at internals. The simplest way to gain access is:
 149
 150 1. Run a terminal as root
 151 2. cd `~/.ssh`
 152 3. `ssh-key-gen`
 153 4. paste the contents of `id_rsa.pub` into your templates (see placeholder in samples)
 154 5. bootstrap and run your container
 155 6. `./launcher ssh my_container`
 156
 157 ### Security
 158
 159 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.