Problem you have encountered:

Cloud Functions lags (particulary) Go releases.

The platform recommends Go 1.16 (Feb'21) while Go 1.18 is imminent.

One of the major Golang APIs (Kubernetes) now prefers Go 1.17(.5)

Kubernetes v1.23.1 CHANGELOG: "Kubernetes is now built with Golang 1.17.5"

Customers wishing to use Cloud Functions must remain on earlier versions of these APIs to avoid breaking changes.

Remaining on earlier versions of the API because of a platform dependency is:

frustrating
can make code more complex (supporting older versions for Cloud Functions and newer versions everywhere else)
involves the tedium of encountering breaking changes, diagnosing them, reverting them
commenting code to not upgrade because of them.

What you expect(ed) to happen:

I expect Google to remain current on Cloud Functions runtimes (especially for its own runtimes, e.g. Go) and even if the runtimes were provided on a "developer beware" basis.

Truthfully, it's remarkable that there is such latency on the availability of these runtimes. It would be helpful if Google were willing to consider providing a roadmap for future runtime availability (and even better some insight into why currency is challenging).

Steps to reproduce:

I'm using the (otherwise excellent) Google Cloud Firestore Triggers. On a change event in a Firestore database, the code creates a Kubernetes client and mutates the equivalent Custom Resource in Kubernetes.

package f

import (
	"encoding/json"
	"net/http"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// Example is a struct that leverages Kubernetes' API machinery
type Example struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`
}

// Handler is a function that implements a simple Cloud Function using Example
func Handler(w http.ResponseWriter, _ *http.Request) {
	k := &Example{
		ObjectMeta: metav1.ObjectMeta{
			Name: "test",
		},
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(k)
}

With go.mod:

module github.com/some-repo

// Must remain at 1.16 for Cloud Functions runtime dependency
go 1.16

// Corresponds to Kubernetes v1.23.1 which depends on Go 1.17.5
require k8s.io/apimachinery v0.23.1

And:

gcloud functions deploy ${NAME} \
--trigger-http \
--entry-point=Handler \
--max-instances=1 \
--runtime=go116 \
--memory=256MB \
--region=${REGION} \
--project=${PROJECT}

Yields:

Deploying function (may take a while - up to 2 minutes)...⠛                                                                                                                                                                                                                                                                                                                                                                  
For Cloud Build Logs, visit: https://console.cloud.google.com/cloud-build/builds;region=us-west1/9a0dc6b7-fea0-4ae5-bf7b-75c96743e7b2?project=272595850285
Deploying function (may take a while - up to 2 minutes)...failed.                                                                                                                                                                                                                                                                                                                                                            
ERROR: (gcloud.functions.deploy) OperationError: code=3, message=Build failed: # sigs.k8s.io/json/internal/golang/encoding/json
/layers/google.go.functions-framework/gopath/pkg/mod/sigs.k8s.io/json@v0.0.0-20211020170558-c049b76a60c6/internal/golang/encoding/json/encode.go:1249:12: sf.IsExported undefined (type reflect.StructField has no field or method IsExported)
/layers/google.go.functions-framework/gopath/pkg/mod/sigs.k8s.io/json@v0.0.0-20211020170558-c049b76a60c6/internal/golang/encoding/json/encode.go:1255:18: sf.IsExported undefined (type reflect.StructField has no field or method IsExported); Error ID: 975560ac

And this is because, in the standard library in 1.16(.12), the reflect package's StructField type does not have the method:

https://pkg.go.dev/reflect@go1.16.12#StructField

Whereas it does since 1.17.1:

https://pkg.go.dev/reflect@go1.17.1#StructField.IsExported

Downgrading k8s.io/apimachinery` to v0.22.5 succeeds:

go.mod:

module github.com/some-repo

// Must remain at 1.16 for Cloud Functions runtime dependency
go 1.16

require k8s.io/apimachinery v0.22.5

And:

gcloud functions call test \
--region=${REGION} \
--project=${PROJECT}

executionId: 9yse45zkls1f
result: |
  {"metadata":{"name":"test","creationTimestamp":null}}

Other information (workarounds you have tried, documentation consulted, etc):

Issue 212457467

Mentioned issues (1)

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