cmd/go: cryptic error message when git repository is reachable locally but not reachable from sum.golang.org google SaaS server

What version of Go are you using (go version)?

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

What did you do?

I am trying to go get a module while I'm developing an app to fix my DNS issues, however go get is ignoring the hosts file entry I created to temporarily fix my git server's incorrect domain name. does not work because my git server git.sequentialread.com is not reachable from the sum.golang.org google SaaS server which is tightly integrated into the way the go get command works.

forest@thingpad:~$ nslookup git.sequentialread.com 8.8.8.8
Server:		8.8.8.8
Address:	8.8.8.8#53

Non-authoritative answer:
Name:	git.sequentialread.com
Address: 71.34.16.185


forest@thingpad:~/Desktop/git/gandi-dns-updater$ cat /etc/hosts
127.0.0.1       localhost
127.0.1.1       thingpad

71.34.5.123 pwm.sequentialread.com
71.34.5.123 git.sequentialread.com
71.34.5.123 sequentialread.com

...

forest@thingpad:~/Desktop/git/gandi-dns-updater$ go get git.sequentialread.com/forest/config-lite

What did you expect to see?

I expected the go get software do what I asked, go to my git server and download the module.

However, in the event that go get cannot do that for me, I expected the go get software to tell me in clear, human-readable terms why it cannot do that.

What did you see instead?

forest@thingpad:~/Desktop/git/gandi-dns-updater$ go get git.sequentialread.com/forest/config-lite
go: downloading git.sequentialread.com/forest/config-lite v0.0.0-20220122212408-4941a7aa3dc0
go get: git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0: verifying module: git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0: reading https://sum.golang.org/lookup/git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0: 410 Gone
        server response: not found: git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0: unrecognized import path "git.sequentialread.com/forest/config-lite": https fetch: Get "https://git.sequentialread.com/forest/config-lite?go-get=1": dial tcp 71.34.16.185:443: connect: connection refused

When I 1st saw this error, I was 100% convinced that it was an issue related to golang not parsing /etc/resolv.conf, /etc/nsswitch.conf or /etc/hosts correctly. I quickly realized that it only happened with go get, not with a normal http call to git.sequentialread.com, so I decided to investigate further. However, after following that red herring all day long, I finally got to the point where I had run out of things to check and I could not make sense of what I was seeing, according to delve go get WAS resolving the right IP address 71.34.5.123 not the wrong one 71.34.16.185. It was connecting to 71.34.5.123, not 71.34.16.185. But I was still seeing an error that says dial tcp 71.34.16.185:443: connect: connection refused

Eventually with dumb luck / trying anything after running out of options, I found the answer:

forest@thingpad:~$ curl https://sum.golang.org/lookup/git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0

not found: git.sequentialread.com/forest/config-lite@v0.0.0-20220122212408-4941a7aa3dc0: unrecognized import path "git.sequentialread.com/forest/config-lite": https fetch: Get "https://git.sequentialread.com/forest/config-lite?go-get=1": dial tcp 71.34.16.185:443: connect: connection refused

The error message I was seeing was actually being thrown on google's server, not on my computer.