logging: panic in resource dection for Cloud Functions

[someone1]

Client

Logging

Environment

Go 1.13 on Cloud Functions

Updating only the dependency in our project resulted in this panic for our Cloud Function

panic: runtime error: slice bounds out of range [:-1]

goroutine 1 [running]:
functions/vendor/cloud.google.com/go/logging.regionFromZone(...)
	/workspace/src/functions/vendor/cloud.google.com/go/logging/logging.go:407
functions/vendor/cloud.google.com/go/logging.detectCloudFunction(0x1379001)
	/workspace/src/functions/vendor/cloud.google.com/go/logging/logging.go:360 +0x2db
functions/vendor/cloud.google.com/go/logging.detectResource.func1()
	/workspace/src/functions/vendor/cloud.google.com/go/logging/logging.go:374 +0x6a
sync.(*Once).doSlow(0x214d888, 0x13c8d80)
	/usr/local/go/src/sync/once.go:66 +0xe3
sync.(*Once).Do(...)
	/usr/local/go/src/sync/once.go:57
functions/vendor/cloud.google.com/go/logging.detectResource(0x120)
	/workspace/src/functions/vendor/cloud.google.com/go/logging/logging.go:367 +0x59
functions/vendor/cloud.google.com/go/logging.(*Client).Logger(0xc00008ef00, 0x1379ef4, 0x7, 0xc000933cb8, 0x2, 0x2, 0xc00027c000)
	/workspace/src/functions/vendor/cloud.google.com/go/logging/logging.go:523 +0x34

Related to #3909

[someone1]

cc @nicoleczhu

[0xSage]

PR to fix this is in, thanks for reporting @someone1 !

Out of curiosity, was your zone a nil value or just didn't contain -'s? I'm curious under what circumstances the zone returned could be a different format than -

[someone1]

Code:

package testenv

import (
	"net/http"
	"net/http/httputil"
	"os"
	"strings"

	"cloud.google.com/go/compute/metadata"
)

func DumpEnv(w http.ResponseWriter, r *http.Request) {
	_, _ = w.Write([]byte(strings.Join(os.Environ(), "\n")))

	b, _ := httputil.DumpRequest(r, false)
	_, _ = w.Write(b)

	zone, _ := metadata.Zone()
	_, _ = w.Write([]byte("zone=" + zone))
}

Command:

$ go version
go version go1.14.15 linux/amd64
$ go mod init example.com/testenv
$ go mod edit -go=1.13
$ go get cloud.google.com/go/compute/metadata
$ go mod tidy
$ go mod vendor
$ gcloud functions deploy DumpEnv --runtime go113 --trigger-http --project=$PROJECT_ID --allow-unauthenticated

Response:

PATH=/layers/google.go.build/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
K_SERVICE=DumpEnv
DEBIAN_FRONTEND=noninteractive
GCF_BLOCK_RUNTIME_go112=410
S2A_ACCESS_TOKEN=<REMOVED>
PORT=8080
K_REVISION=7
GOROOT=/usr/local/go/
HOME=/root
CGO_ENABLED=1
FUNCTION_SIGNATURE_TYPE=http
GAE_RUNTIME=go113
FUNCTION_TARGET=DumpEnv
PWD=/workspace
GCF_BLOCK_RUNTIME_nodejs6=410

GET / HTTP/1.1
Host: us-central1-$PROJECT_ID.cloudfunctions.net
Connection: close
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Connection: close
Forwarded: for="<REMOVED>";proto=https
Function-Execution-Id: mwn7qym1cgwj
Sec-Ch-Ua: " Not A;Brand";v="99", "Chromium";v="90", "Google Chrome";v="90"
Sec-Ch-Ua-Mobile: ?0
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: cross-site
Sec-Fetch-User: ?1
Traceparent: 00-c8634ec7c009f52002c327dc316067c4-5c08e8e6651c53ff-01
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36
X-Appengine-City: <REMOVED>
X-Appengine-Citylatlong: <REMOVED>
X-Appengine-Country: US
X-Appengine-Default-Version-Hostname: <REMOVED>
X-Appengine-Https: on
X-Appengine-Region: <REMOVED>
X-Appengine-Request-Log-Id: 60832c7d00ff0e935ebf6315950001737e79386334303232633538343635353835382d7470000135383463643435656330336537626462663130316466386532386233323835353a37000100
X-Appengine-Timeout-Ms: 599999
X-Appengine-User-Ip: <REMOVED>
X-Cloud-Trace-Context: c8634ec7c009f52002c327dc316067c4/6631806527539532799;o=1
X-Forwarded-For: <REMOVED>
X-Forwarded-Proto: https

zone=us6

[someone1]

@nicoleczhu - did that provide the answer you were looking for? It seems that the assumption Cloud Functions would return a location/zone in the format documented is not the case in this environment (e.g. us6 vs us-central1)

[dylanmpeck]

Experiencing this same issue in a Qwiklab. Calling logger := client.Logger(logName).StandardLogger(logging.Info) in a Cloud Function with Go 1.13 is giving the exact same panic error that someone1 reported.

Downgrading the logging module to v1.3.0 removed the error.

@nicoleczhu - will that PR be merged/in effect relatively soon?

[0xSage]

Hi @dylanmpeck @someone1 , thanks for the context. I'm back from a 1 week vacation. Plan to get this in asap.