Add --tf-download-url configuration option

[cullenmcdermott]

This fixes #614

I'm new to Go so I'm sure I'll need plenty of changes before this can be merged. The main thing I'm unsure about is how I implemented the downloadUrl. I feel as though the modifications I made would fit better as part of Downloader however I'm not entirely sure the best way to go about modifying that.

I don't currently have access to an internal mirror of releases.hashicorp.com so I haven't had a chance to fully test this functionality myself. I'm hoping to have the time to do that later this week.

[codecov]

Codecov Report

Merging #787 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #787      +/-   ##
==========================================
+ Coverage   71.83%   71.86%   +0.02%     
==========================================
  Files          65       65              
  Lines        5213     5217       +4     
==========================================
+ Hits         3745     3749       +4     
  Misses       1183     1183              
  Partials      285      285

Impacted Files	Coverage Δ
server/user_config.go	100% <ø> (ø)	⬆️
server/server.go	63.69% <100%> (+0.11%)	⬆️
cmd/server.go	78.97% <100%> (+0.19%)	⬆️
server/events/terraform/terraform_client.go	78.04% <100%> (+0.1%)	⬆️

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[lkysow]

Looks great! Almost there. I don't think it makes sense to be in Downloader actually, I like where you put it. Downloader is just used as a shim during testing.

[lkysow]

maybe set this to https://my-mirror.releases.mycompany.com in this test to make it clear it's being tested

[cullenmcdermott]

I think I adjusted this to match what you are asking, can you double check?

[lkysow]

yes this looks good

[cullenmcdermott]

I just tried to test this with atlantis testdrive and it looks like there's an issue with the version verification now.

Error: creating atlantis server: timeout, logs:
2019/11/03 17:37:01-0700 [WARN] cmd: No GitHub webhook secret set. This could allow attackers to spoof requests from GitHub
2019/11/03 17:37:01-0700 [WARN] cmd: No Azure DevOps webhook user and password set. This could allow attackers to spoof requests from Azure DevOps.
Error: initializing server: initializing terraform: Malformed version: https://releases.hashicorp.com

[lkysow]

initializing terraform

Atlantis runs terraform version. What's the output when you run that.