Prefix URLs in templates with AtlantisURL

[jml]

Resolves #213

Allows users to run Atlantis behind a shared reverse proxy, which is a fairly common use case.

make test passes for me, but make test-all does not, both on this branch and an unchanged master.

[codecov]

Codecov Report

Merging #314 into master will increase coverage by 0.03%.
The diff coverage is 80.95%.

@@            Coverage Diff            @@
##           master    #314      +/-   ##
=========================================
+ Coverage   70.67%   70.7%   +0.03%     
=========================================
  Files          61      62       +1     
  Lines        3655    3673      +18     
=========================================
+ Hits         2583    2597      +14     
- Misses        893     895       +2     
- Partials      179     181       +2

Impacted Files	Coverage Δ
cmd/server.go	79.02% <ø> (ø)	⬆️
server/url.go	100% <100%> (ø)
server/locks_controller.go	92.42% <100%> (+0.11%)	⬆️
server/router.go	100% <100%> (ø)	⬆️
server/server.go	62.2% <63.63%> (-0.25%)	⬇️

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[lkysow]

Thanks for the PR!

A couple thoughts:

1. Ideally we'd use a function like linkify but the template is compiled as a var so it would require a refactor to get the AtlantisURL into a FuncMap before the template is compiled. Thus for now I think this is an okay way to do it.
2. We need to add some validation into cmd/server.go to ensure that users don't pass in an atlantis-url with a trailing /
3. The docs for --atlantis-url should be updated to point out that a URL prefix is supported:

   URL that Atlantis can be reached at. Defaults to
   http://$(hostname):$port where $port is from --port.
   Supports a base path, ex. https://example.com/basepath.
   

[lkysow]

Looks like things got messed up here (snscript, </hea)

[lkysow]

Shouldn't need the / at the end here for <a title="atlantis" href="{{ .AtlantisURL }}/">

[lkysow]

Are you sure .LockURL doesn't start with /?

[jml]

In fact, it always starts with a / (unless it starts with "https://..."!). Have adjusted accordingly.

[lkysow]

again, don't need the / here.

[jml]

Thanks! All good comments, I'll get to them as soon as I can.

We need to add some validation into cmd/server.go to ensure that users don't pass in an atlantis-url with a trailing /

Good point. I think what I'd like to do is:

• parse the --atlantis-url value into a url.URL as soon as we can
• ensure it doesn't have a trailing slash
• pass that around everywhere

I think if a user passes one with a trailing slash, we should silently remove it.

[lkysow]

Okay that sounds good. Just note that url.Parse is super lenient and will not error out on a lot of URLs so you have to inspect the result and ensure that things aren't blank.
ex. url.Parse("hi") will succeed

[jml]

I've addressed all the comments. I want to do some more local testing to ensure this doesn't mess up the routing.

[jml]

Also, congratulations on your recent acquisition!

[lkysow]

@jml the site is pretty broken at the moment. Can you squash your changes into one commit and then I can do the remaining fixes.

[jml]

Done. Thanks.

[lkysow]

For future reference here is how I've been testing this.

docker-compose.yaml

version: '2'

services:
  reverseproxy:
    image: mynginx
    ports:
    - 8080:8080
    restart: always

  atlantis:
    ports:
    - 4141:4141
    depends_on:
    - reverseproxy
    image: reverse-proxy
    restart: "no"
    command: [server, --gh-user, atlantisbot, --gh-token, ****, --log-level, debug, --repo-whitelist, "github.com/*", --atlantis-url, "https://f80439fb.ngrok.io/basepath"]

Building my nginx proxy image

FROM nginx:alpine

COPY nginx.conf /etc/nginx/nginx.conf

worker_processes 1;

events { worker_connections 1024; }

http {

    sendfile on;

    upstream docker-atlantis {
        server atlantis:4141;
    }

    server {
        listen 8080;

        location = /basepath {
            return 302 /basepath/;
        }

        location /basepath/ {
            proxy_pass         http://docker-atlantis/;
            proxy_redirect     off;
            proxy_set_header   Host $host;
            proxy_set_header   X-Real-IP $remote_addr;
            proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header   X-Forwarded-Host $server_name;
        }
    }
}