x/build: investigate Athens 500 errors

[bradfitz]

The new logging added to the coordinator of non-2xx response codes from our internal Athens instance says:

2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/arm/armasm/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/arm64/arm64asm/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/ppc64/ppc64asm/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/crypto/ssh/terminal/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /github.com/google/pprof/driver/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /github.com/google/pprof/profile/@v/list
2019/04/03 19:02:19 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/x86/x86asm/@v/list
2019/04/03 19:02:20 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/ppc64/@v/list
2019/04/03 19:02:20 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/arm/@v/list
2019/04/03 19:02:20 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/arm64/@v/list
2019/04/03 19:02:20 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/crypto/ssh/@v/list
2019/04/03 19:02:20 modproxy: proxying HTTP 500 Internal Server Error response from backend for builder host-darwin-10_14, GET /golang.org/x/arch/x86/@v/list

What's with that?

/cc @dmitshur

[bradfitz]

$ kubectl logs -f athens-deployment-5f64c6b8dc-qzlvm &

$ curl http://10.200.2.27:3000/golang.org/x/arch/arm/armasm/@v/list
"Internal Server Error"

...
time="2019-04-03T20:31:44Z" level=error msg="exit status 1: go: finding golang.org/x/arch/arm/armasm latest\ngo list -m golang.org/x/arch/arm/armasm: no matching versions for query \"latest\"\n" http-method=GET http-path=/golang.org/x/arch/arm/armasm/@v/list/ http-url=/golang.org/x/arch/arm/armasm/@v/list/ kind="Internal Server Error" module= operation=download.ListHandler ops="[download.ListHandler pool.List protocol.List vcsLister.List]" version=
handler: GET /golang.org/x/arch/arm/armasm/@v/list/ [500]

@bcmills, is this expected?

[bradfitz]

Also, when is cmd/go doing list queries against the module proxy?

[bcmills]

when is cmd/go doing list queries against the module proxy?

I would guess that the Athens server is shelling out to cmd/go, but I don't know why.

[bcmills]

The particular paths in question look like vendored standard-library dependencies — specifically, the dependencies of the cmd module. Perhaps they're being fetched for the vetall builder to resolve x/tools?