richardjennings/prose repository overview

⁠Dockerfile for github.com/prose/prose⁠

⁠Why

I found the Prose⁠ project interesting and wanted to run it locally. I suspected that I would be able to use Nginx as a proxy rather than the mechanism suggested in the docs⁠ and so had some fun writing this Dockerfile.

⁠About

This Dockerfile provides a "hybrid" Prose⁠ install suitable to run locally. There is no support for SSL currently.

Prose uses Github's OAuth2 API. Requests to http://github.com/login/oauth/access_token⁠ to exchange an authorization code for an access token cannot be made directly by a browser via XHR due to same-origin policy⁠ constraints. The Prose project recommends using prose/gatekeeper⁠ to proxy browser requests for an access token, avoiding same origin issues.

This Dockerfile uses Nginx to serve Prose assets and also provide a proxy to the Github /login/oauth/access_token endpoint.

The proxy functionality can be found in nginx.conf⁠ and looks like (at the time of writing):

        location /authenticate/ {
            rewrite ^/authenticate/(.*)$ /login/oauth/access_token break;
            proxy_method POST;
            proxy_set_body "{\"client_id\":\"%GITHUB_CLIENT_ID%\",\"client_secret\":\"%GITHUB_CLIENT_SECRET%\", \"code\":\"$1\"}";
            proxy_set_header Content-Type "application/json";
            proxy_set_header Accept 'application/json';
            proxy_set_header Accept-Encoding "";
            proxy_set_header HOST "github.com";
            sub_filter_types "*";
            sub_filter '"access_token"' '"token"';
            sub_filter_once on;
            proxy_pass https://github.com/;
        }

One objective was to make the Nginx proxying compatible with Prose without any code changes needed. To do this:

• A POST request to Github is created when a GET request to /authenticate/mycode is made.
• A rewrite rule pulls the code out of the url. This code is then added to a crafted JSON POST body.
• The Nginx http sub module⁠ is used to change "access_token" to "token" in the response body.

⁠Running

To run the build image, 2 environment variables need to be specified. These are:

• GITHUB_CLIENT_ID - the client id of your Github application
• GITHUB_CLIENT_SECRET - the client secret of your Github application

An example running locally on port 8080:

$ docker run -d -p 8080:80 --env "GITHUB_CLIENT_ID=YOUR_ID" --env "GITHUB_CLIENT_SECRET=YOUR_SECRET" --name prose richardjennings/prose 

The Dockerfile uses an entrypoint.sh script which uses sed to replace tokens in code & configuration files with the values provided when the container is run, allowing the runtime specification of Github application details.