[META] Go 1.16

[Adirio]

This issue aims to tracks all the changes that need to/can be done once moving to go 1.16. This is obviously gated by dependencies.

• [cleanup] Go 1.16 sets GO111MODULES to on by default instead of auto. There are several remanents of this env variable that we should remove throughout the codebase.
• [enhancement] Go 1.16 includes a new embed package that allows to embed files into the binary using //go:...-style comments. This allows to split the files template from their logic offering way better support by IDEs (templates will no longer be a string, so they will be styled, auto-completed, and all the goodness of IDEs).

If there is any other feature enabled/required by go 1.16 that you will like to see in this list, please comment and I will update the list.

[camilamacedo86]

We also need before that just to clarify, have the same bump in controller-runtime, declarative-kb and k8s-api before we are able to address that here.

[kuritka]

The go install command can install go programs without affecting mod file dependencies. For example, executing go install github.com/dummy/myapp@v0.1.2 is enough. Will you plan to update Makefile ?
something like this :

# would work in GO1.16
generate: 
	## Download controller-gen locally if necessary.
	go install sigs.k8s.io/controller-tools/cmd/controller-gen@v0.4.1
	## Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
	controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."

or you plan to support older GO versions (stay with go get... / go-get-tool),
like this:

# without GO1.16
generate: controller-gen ## Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
	$(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..."

CONTROLLER_GEN = $(shell pwd)/bin/controller-gen
controller-gen: ## Download controller-gen locally if necessary.
	$(call go-get-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen@v0.4.1)

# go-get-tool will 'go get' any package $2 and install it to $1.
PROJECT_DIR := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))
define go-get-tool
@[ -f $(1) ] || { \
set -e ;\
TMP_DIR=$$(mktemp -d) ;\
cd $$TMP_DIR ;\
go mod init tmp ;\
echo "Downloading $(2)" ;\
GOBIN=$(PROJECT_DIR)/bin go get $(2) ;\
rm -rf $$TMP_DIR ;\
}
endef

[DirectXMan12]

@kuritka AFAIK, go install-ing something is still global, so while we could potentially switch to using go install instead of go mod init; go get, we'd still have to have the GOBIN trick to avoid clobbering the user's existing configuration, unfortunately

[estroz]

1.16 is backwards compatible, so are there really any blockers here? Removing GO111MODULES should be done prior to switching, embed is just a nice-to-have so not necessary, and the current way bins are installed is fine and imo a feature request.

[estroz]

I believe I found a blocker: our test matrix. I think some bug fixes (features?) in go 1.16 made module installation more strict (see https://github.com/kubernetes-sigs/kubebuilder/pull/2182/checks?check_run_id=2614771863#step:6:520), which results in errors in go/v2 tests. For full backwards-compatibility, we'll likely want to start running all tests in golang:{x}.{y} containers like in prow.

Edit: adding go mod tidy to the testdata test script effectively fixes the module-related command changes in go 1.16 and should unblock update PRs for now. The test matrix upgrade suggestion still stands.

[k8s-triage-robot]

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This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
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You can:

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[sonnysideup]

I'm slightly confused. Is this still an issue now that 3.1.0 is out? It seems like #2182 updates kubebuilder to Go 1.16 but perhaps that's related to building the CLI vs what the CLI supports?

[estroz]

Both the kubebuilder binary and projects created by the binary use go 1.16, so I'm going to close this.

/close

[k8s-ci-robot]

@estroz: Closing this issue.

In response to this:

Both the kubebuilder binary and projects created by the binary use go 1.16, so I'm going to close this.

/close

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