Add support for basic Netlify redirects

Add support for basic Netlify redirects

• Fix #24 (closed)
• Supports basic 301, 302 Netlify style redirects using plain text style _redirects
  • https://docs.netlify.com/routing/redirects/
  • The other more advanced options are not supported: https://docs.netlify.com/routing/redirects/redirect-options/
• The _redirects file is not publicly accessible but when you visit /_redirects, it will show validation messages per line of _redirects file
• Documentation MR: gitlab!42011 (merged)

Benchmarks

Need to look into the numbers to see if actually acceptable:

Previous

$ go test ./internal/redirects -bench=.
goos: darwin
goarch: amd64
pkg: gitlab.com/gitlab-org/gitlab-pages/internal/redirects
BenchmarkRedirectsRewrite/10_redirects-8         	  158222	      7207 ns/op
BenchmarkRedirectsRewrite/100_redirects-8        	   98227	     12031 ns/op
BenchmarkRedirectsRewrite/1000_redirects-8       	   19407	     61143 ns/op
BenchmarkRedirectsParseRedirects/10_redirects-8  	    6319	    173126 ns/op
BenchmarkRedirectsParseRedirects/100_redirects-8 	    5889	    198681 ns/op
BenchmarkRedirectsParseRedirects/1000_redirects-8         	    2431	    499812 ns/op
PASS
ok  	gitlab.com/gitlab-org/gitlab-pages/internal/redirects	8.119s

Latest:

• Parse 1000 redirects takes 0.296 ms (296043 ns)
• Rewrite URL matching the last rule in 1000 takes 0.058475 ms (58475 ns)

$ go test ./internal/redirects -bench=.
goos: darwin
goarch: amd64
pkg: gitlab.com/gitlab-org/gitlab-pages/internal/redirects
BenchmarkRedirectsRewrite/10_redirects-8         	  294306	      3864 ns/op
BenchmarkRedirectsRewrite/100_redirects-8        	  128731	      8844 ns/op
BenchmarkRedirectsRewrite/1000_redirects-8       	   20427	     58361 ns/op
BenchmarkRedirectsParseRedirects/10_redirects-8  	   29253	     41024 ns/op
BenchmarkRedirectsParseRedirects/100_redirects-8 	   18249	     65300 ns/op
BenchmarkRedirectsParseRedirects/1000_redirects-8         	    3867	    297138 ns/op
PASS
ok  	gitlab.com/gitlab-org/gitlab-pages/internal/redirects	9.209s

Dev notes

• http://group.redirects.pages.gdk.test:8090/project-redirects/redirect-portal.html
• http://group.redirects.pages.gdk.test:8090/project-redirects/magic-land.html

$ make
$ ./gitlab-pages -listen-http ":8090" -pages-root shared/pages -pages-domain pages.gdk.test -log-verbose

make test

go test ./internal/serving/disk/
go test ./internal/serving/disk/ -run TestDisk_ServeFileHTTP

make setup

make lint

Running benchmarks:

go test ./internal/redirects -bench=.

Running acceptance tests:

go test ./ -run TestStatusPage

go test ./ -run TestRedirectStatusPage -test.v
go test ./ -run TestRedirect -test.v

go test ./ -list=Test

Todo

• Blocked by !325 (merged)
• Acceptance tests
• Benchmarks
  • https://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go
  • https://golang.org/pkg/testing/#B.Error
• Feature flag
• Docs -> gitlab!42011 (merged)
• Add feature flag to https://ops.gitlab.net/gitlab-cookbooks/chef-repo
  • https://docs.gitlab.com/ee/development/feature_flags/
  • https://ops.gitlab.net/gitlab-cookbooks/chef-repo/-/merge_requests/4246
• Try out Netlify behavior of file overriding redirect, !336 (comment 403520570)

---

Fix #24 (closed)