Docker is an open source project to pack, ship and run any Linux application in a lighter weight, faster container than a traditional virtual machine.
The templates and base image configure Discourse with the Discourse team's recommended optimal defaults.
The simplest way to get started is via the standalone template, which can be installed in 30 minutes or less. For detailed install instructions, see
Contains container ids for currently running Docker containers. cids are Docker's "equivalent" of pids. Each container will have a unique git like hash.
This directory is for container definitions for your various Discourse containers. You are in charge of this directory, it ships empty.
Sample container definitions you may use to bootstrap your environment. You can copy templates from here into the containers directory.
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.
pups managed pups templates you may use to bootstrap your environment.
Dockerfile for both the base image
/discourse_base and discourse image
/discourse_basecontains all the OS dependencies including sshd, runit, postgres, nginx, ruby.
/discoursebuilds on the base image and configures a discourse user and
/var/www/discoursedirectory for the Discourse source.
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.
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.
Usage: launcher COMMAND CONFIG [--skip-prereqs] Commands: start: Start/initialize a container stop: Stop a running container restart: Restart a container destroy: Stop and remove a container enter: Use nsenter to enter a container ssh: Start a bash shell in a running container logs: Docker logs for container bootstrap: Bootstrap a container for the config based on a template rebuild: Rebuild a container (destroy old, bootstrap, start new)
If the environment variable "SUPERVISED" is set to true, the container won't be detached, allowing a process monitoring tool to manage the restart behaviour of the container.
The beginning of the container definition can contain the following "special" sections:
templates: - "templates/cron.template.yml" - "templates/postgres.template.yml"
This template is "composed" out of all these child templates, this allows for a very flexible configuration structure. Furthermore you may add specific hooks that extend the templates you reference.
expose: - "2222:22" - "127.0.0.1:20080:80"
Expose port 22 inside the container on port 2222 on ALL local host interfaces. In order to bind to only one interface, you may specify the host's IP address as
([<host_interface>:[host_port]])|(<host_port>):<container_port>[/udp] as defined in the docker port binding documentation
volumes: - volume: host: /var/discourse/shared guest: /shared
Expose a directory inside the host to the container.
links: - link: name: postgres alias: postgres
Links another container to the current container. This will add
to the options when running the container.
The Docker setup gives you multiple upgrade options:
Use the front end at http://yoursite.com/admin/upgrade to upgrade an already running image.
Create a new base image manually by running:
./launcher rebuild my_image
Single Container vs. Multiple Container
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.
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:
- 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.
- Scale your forum to multiple servers.
- Add servers for redundancy.
- Have some required services (e.g. the database) run on beefier hardware.
If you want a multiple container setup, see the
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.
WARNING: In a multiple container configuration, make sure you setup iptables or some other firewall to protect various ports (for postgres/redis).
On Ubuntu, install the
iptables-persistent package to manage firewall rules.
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.
View the container logs:
./launcher logs my_container
You can ssh into your container using
./launcher ssh my_container, we will automatically set up ssh access during bootstrap.
Spawn a shell inside your container using
./launcher enter my_container. This is the most foolproof method if you have host root access.
If you see network errors trying to retrieve code from
rubygems.org try again - sometimes there are temporary interruptions and a retry is all it takes.
Behind a proxy network with no direct access to the Internet? Add proxy information to the container environment by adding to the existing
env block in the
env: …existing entries… HTTP_PROXY: http://proxyserver:port/ http_proxy: http://proxyserver:port/ HTTPS_PROXY: http://proxyserver:port/ https_proxy: http://proxyserver:port/
Directory permissions in Linux are UID/GID based, if your numeric IDs on the
host do not match the IDs in the guest, permissions will mismatch. On clean
installs you can ensure they are in sync by looking at
/etc/group, the Discourse account will have UID 1000.
- Setting up SSL with Discourse Docker
- Multisite configuration with Docker
- Linking containers for a multiple container setup
- Replace rubygems.org with taobao mirror to resolve network error in China