Panic handling and stack trace don't work when GOPATH includes /go/ in it

[ralfthewise]

In a typical setup of go with docker containers (using the official images at https://hub.docker.com/_/golang/) the GOPATH is setup to be /go. The first frame in a panic stack trace is almost always:

/usr/local/go/src/runtime/debug/stack.go:24

The panic handling function findRelevantStackFrame (https://github.com/revel/revel/blob/master/errors.go#L128) has logic to find the first frame in the source path that isn't robust enough and ends up thinking /usr/local/go/src/runtime/debug/stack.go is the first item because it contains /go/src. This results in an actual panic in revel itself, no helpful stacktrace returned to the browser, and output like this:

app server.go:2848: http: panic serving 127.0.0.1:34942: open /go/src/runtime/debug/stack.go: no such file or directory
goroutine 50 [running]:
net/http.(*conn).serve.func1(0xc4203fc000)
	/usr/local/go/src/net/http/server.go:1697 +0xd0
panic(0x895fe0, 0xc42039c060)
	/usr/local/go/src/runtime/panic.go:491 +0x283
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.MustReadLines(0xc42037605a, 0x1e, 0xc42013aad0, 0x1, 0x1)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/util.go:55 +0x83
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.NewErrorFromPanic(0x8b3bc0, 0xc4203fea58, 0x42ab28)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/errors.go:68 +0x4e3
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.handleInvocationPanic(0xc42023c9c0, 0x8b3bc0, 0xc4203fea58)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/panic.go:26 +0x39
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.PanicFilter.func1(0xc42023c9c0)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/panic.go:17 +0x4d
panic(0x8b3bc0, 0xc4203fea58)
	/usr/local/go/src/runtime/panic.go:491 +0x283
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.InterceptorFilter.func1(0xc42023c9c0)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/intercept.go:98 +0x7d
panic(0x8b3bc0, 0xc4203fea58)
	/usr/local/go/src/runtime/panic.go:491 +0x283
github.com/radartools/account-management/backend/app/controllers.Organizations.Index(0xc42023c9c0, 0x20, 0xc420341350)
	/go/src/github.com/radartools/account-management/backend/app/controllers/organizations.go:31 +0x1a6
github.com/radartools/account-management/backend/app/controllers.(*Organizations).Index(0xc42000fa40, 0x0, 0x0)
	<autogenerated>:1 +0x3c
reflect.Value.call(0x913be0, 0xc42000fa40, 0xe13, 0x92665e, 0x4, 0x0, 0x0, 0x0, 0x8725c0, 0x3, ...)
	/usr/local/go/src/reflect/value.go:434 +0x905
reflect.Value.Call(0x913be0, 0xc42000fa40, 0xe13, 0x0, 0x0, 0x0, 0xc42000fa40, 0xe13, 0x10)
	/usr/local/go/src/reflect/value.go:302 +0xa4
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.ActionInvoker(0xc42023c9c0, 0xc4202f6d18, 0x0, 0x1)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/invoker.go:45 +0x5b8
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.CompressFilter(0xc42023c9c0, 0xc4202f6d10, 0x1, 0x2)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/compress.go:84 +0x9c
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.InterceptorFilter(0xc42023c9c0, 0xc4202f6d08, 0x2, 0x3)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/intercept.go:108 +0xee
github.com/radartools/account-management/backend/app.glob..func1(0xc42023c9c0, 0xc4202f6d00, 0x3, 0x4)
	/go/src/github.com/radartools/account-management/backend/app/init.go:54 +0x13f
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.I18nFilter(0xc42023c9c0, 0xc4202f6cf8, 0x4, 0x5)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/i18n.go:212 +0xa1
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.ValidationFilter(0xc42023c9c0, 0xc4202f6cf0, 0x5, 0x6)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/validation.go:269 +0x19b
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.FlashFilter(0xc42023c9c0, 0xc4202f6ce8, 0x6, 0x7)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/flash.go:50 +0x13c
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.SessionFilter(0xc42023c9c0, 0xc4202f6ce0, 0x7, 0x8)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/session.go:158 +0x117
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.ParamsFilter(0xc42023c9c0, 0xc4202f6cd8, 0x8, 0x9)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/params.go:179 +0xb1
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.FilterConfiguringFilter(0xc42023c9c0, 0xc4202f6cd0, 0x9, 0xa)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/filterconfig.go:211 +0x126
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.RouterFilter(0xc42023c9c0, 0xc4202f6cc8, 0xa, 0xb)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/router.go:789 +0x414
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.PanicFilter(0xc42023c9c0, 0xc4202f6cc0, 0xb, 0xc)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/panic.go:20 +0x93
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.glob..func32(0xc42023c9c0, 0xc4202f6cb8, 0xc, 0xd)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/watcher.go:222 +0x7d
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.handleInternal(0xbac0e0, 0xc42024c740)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/server-engine.go:145 +0x3cd
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.(*GoHttpServer).Handle(0xc4202421b0, 0xbaf420, 0xc420416000, 0xc420406000)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/server_adapter_go.go:101 +0x39e
github.com/radartools/account-management/backend/vendor/github.com/revel/revel.(*GoHttpServer).Init.func3(0xbaf420, 0xc420416000, 0xc420406000)
	/go/src/github.com/radartools/account-management/backend/vendor/github.com/revel/revel/server_adapter_go.go:43 +0x48
net/http.HandlerFunc.ServeHTTP(0xc42022f3b0, 0xbaf420, 0xc420416000, 0xc420406000)
	/usr/local/go/src/net/http/server.go:1918 +0x44
net/http.serverHandler.ServeHTTP(0xc42023c1a0, 0xbaf420, 0xc420416000, 0xc420406000)
	/usr/local/go/src/net/http/server.go:2619 +0xb4
net/http.(*conn).serve(0xc4203fc000, 0xbafde0, 0xc420398180)
	/usr/local/go/src/net/http/server.go:1801 +0x71d
created by net/http.(*Server).Serve
	/usr/local/go/src/net/http/server.go:2720 +0x288  section=system

Somewhat related to #1266

[notzippy]

Thanks, will look into this

[djtm]

Hi,

as a hotfix I've tried:

• using /golang as gopath with a symlink (ENV GOPATH=/golang)
• using /lang as gopath with a symlink (ENV GOPATH=/lang)
• adding the path so that /go/src/runtime/debug/stack.go is actually present.

To my surprise, both didn't help. Any further ideas at least for a hotfix?

[ralfthewise]

@djtm we were able to work around it with Dockerfiles starting off as such:

FROM golang:1.9.2                                                                                                                                                                                              
MAINTAINER radar <radar@radartools.net>
     
ENV PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/go/bin:/gopath/bin
RUN mkdir /gopath
ENV GOPATH=/gopath
     
ADD backend /gopath/src/github.com/foo/bar/backend
...

[djtm]

@ralfthewise: Thanks a lot! Did you get it to work with minimal images?

FROM golang:1.9-alpine AS builder
...
FROM alpine
COPY --from=builder /gopath/...backend/ /gopath/...backend/
COPY --from=builder /usr/local/go/ /go/
RUN mkdir -p /usr/local && ln -s /go /usr/local/go

Still getting the same error however...

[notzippy]

Hi guys, sorry this fell through the cracks - is this still an issue in the later builds ?