chore: use the same tag in Makefile as in code when installing Gateway API CRDs

[pmalek]

What this PR does / why we need it:

In order to use the same version of Gateway API CRDs when installing them via Makefile as in the Go code.

This PR adds a make target generate.gateway-api-crds-url that generates test/consts/gateway.go (from test/internal/cmd/generate-gateway-api-crds-url/gateway_consts.tmpl) using ./test/internal/cmd/generate-gateway-api-crds-url/main.go.

If one would like to override the version then it's as simple as adding GATEWAY_API_VERSION to the make target invocation like so:

GATEWAY_API_VERSION=v0.4.1 make generate.gateway-api-crds-url

---

Related PR that fixed it in Go code: #2551

[mflendrich]

Bitrot alert. go.mod today references v0.4.1-0.20220306235253-71fee1c2808f and it's guaranteed that discrepancies between the version in go.mod, in the makefile and in the test as changed in #2551 will keep reappearing.

Can we do something to have a single source of truth for the gateway api version?
Maybe, rather than referring to a specific release from github, we can kustomize build the kustomization already downloaded to $(go env GOPATH)/pkg/mod/sigs.k8s.io/[email protected] ? Or somehow else ensure that the version in go.mod is authoritative.

Maybe that's an excess of form over content, just wanted to bring this up for your consideration.

[pmalek]

sigs.k8s.io/gateway-api

Agreed, and that's actually a great idea. PTAL at what's proposed in https:/Kong/kubernetes-ingress-controller/pull/2567/files#diff-76ed074a9305c04054cdebb9e9aad2d818052b07091de1f20cad0bbac34ffb52

[shaneutt]

How would you feel about changing the code in internal/util/test/crds.go from the previous PR to accept the version from the environment, so that we don't have to update that going forward?

[pmalek]

How would you feel about changing the code in internal/util/test/crds.go from the previous PR to accept the version from the environment, so that we don't have to update that going forward?

Do you have an environment variable in mind or something else? What we could do is to make a separate file for that URL and add a go generate clause which would pull the same info as in the Makefile (go list -m -f ...) and put it in the const. WDYT?

[shaneutt]

How would you feel about changing the code in internal/util/test/crds.go from the previous PR to accept the version from the environment, so that we don't have to update that going forward?

Do you have an environment variable in mind or something else? What we could do is to make a separate file for that URL and add a go generate clause which would pull the same info as in the Makefile (go list -m -f ...) and put it in the const. WDYT?

I'm not opposed to making it a generated var, however this does preclude the notion that someone could seed the value with an environment variable, so maybe just do a combination of both?

[shaneutt]

I would just like to see us put the link to the TODO follow up into the Makefile and then lgtm