hero: Gollum - A recipe for your own git-based wiki

# Gollum

Gollum is a simple wiki system built on top of Git. A Gollum Wiki is simply a git repository (_either bare or regular_) of a specific nature:

* A Gollum repository's contents are human-editable, unless the repository is bare.
* Pages are unique text files which may be organized into directories any way you choose.
* Other content can also be included, for example images, PDFs and headers/footers for your pages.

Gollum pages:

* May be written in a variety of markups.
* Can be edited with your favourite system editor or IDE (_changes will be visible after committing_) or with the built-in web interface.
* Can be displayed in all versions (_commits_).


![Gollum Screenshot](../images/gollum.png)

As you'll note in the (_real world_) screenshot above, my requirements for a personal wiki are:

* Portable across my devices
* Supports images
* Full-text search
* Supports inter-note links
* Revision control

Gollum meets all these requirements, and as an added bonus, is extremely fast and lightweight.

    Since Gollum itself offers no user authentication, this design secures gollum behind an [oauth2 proxy](https://geek-cookbook.funkypenguin.co.nz/reference/oauth_proxy/), so that in order to gain access to the Gollum UI at all, oauth2 authentication (_to GitHub, GitLab, Google, etc_) must have already occurred.


## Ingredients

    Existing:

    1. [X] [Docker swarm cluster](https://geek-cookbook.funkypenguin.co.nz/ha-docker-swarm/design/) with [persistent shared storage](https://geek-cookbook.funkypenguin.co.nz/ha-docker-swarm/shared-storage-ceph.md)
    2. [X] [Traefik](https://geek-cookbook.funkypenguin.co.nz/ha-docker-swarm/traefik_public) configured per design
    3. [X] DNS entry for the hostname you intend to use, pointed to your [keepalived](ha-docker-swarm/keepalived/) IP

## Preparation

### Setup data locations

We'll need an empty git repository in /var/data/gollum for our data:

```
mkdir /var/data/gollum
cd /var/data/gollum
git init
```

### Prepare environment

1. Choose an oauth provider, and obtain a client ID and secret
2. Create gollum.env, and populate with the following variables (_you can make the cookie secret whatever you like_)

```
OAUTH2_PROXY_CLIENT_ID=
OAUTH2_PROXY_CLIENT_SECRET=
OAUTH2_PROXY_COOKIE_SECRET=
```

### Setup Docker Swarm

Create a docker swarm config file in docker-compose syntax (v3), something like this:

        I share (_with my [patreon patrons](https://www.patreon.com/funkypenguin)_) a private "_premix_" git repository, which includes necessary docker-compose and env files for all published recipes. This means that patrons can launch any recipe with just a ```git pull``` and a ```docker stack deploy``` 
```
version: '3'

services:
  app:
    image: dakue/gollum
    volumes:
     - /var/data/gollum:/gollum
    networks:
    - internal
    command: |
      --allow-uploads
      --emoji
      --user-icons gravatar

  proxy:
    image: a5huynh/oauth2_proxy
    env_file : /var/data/config/gollum/gollum.env
    networks:
      - internal
      - traefik_public
    deploy:
      labels:
        - traefik.frontend.rule=Host:gollum.example.com
        - traefik.docker.network=traefik_public
        - traefik.port=4180
    volumes:
      - /var/data/config/gollum/authenticated-emails.txt:/authenticated-emails.txt
    command: |
      -cookie-secure=false
      -upstream=http://app:4567
      -redirect-url=https://gollum.example.com
      -http-address=http://0.0.0.0:4180
      -email-domain=example.com
      -provider=github
      -authenticated-emails-file=/authenticated-emails.txt

networks:
  traefik_public:
    external: true
  internal:
    driver: overlay
    ipam:
      config:
        - subnet: 172.16.9.0/24
```

    Setup unique static subnets for every stack you deploy. This avoids IP/gateway conflicts which can otherwise occur when you're creating/removing stacks a lot. See [my list](https://geek-cookbook.funkypenguin.co.nz/reference/networks/) here.



## Serving

### Launch Gollum stack

Launch the Gollum stack by running ```docker stack deploy gollum -c <path-to-docker-compose.yml>```

Authenticate against your OAuth provider, and then start editing your wiki!

## Chef's Notes 

1. In the current implementation, Gollum is a "single user" tool only. The contents of the wiki are saved as markdown files under /var/data/gollum, and all the git commits are currently "Anonymous"