backend: refactor: refreshAndCacheNewToken in headlamp.go

[Faakhir30]

Fixes #1848
The refreshAndCacheNewToken function in backend/cmd/headlamp.go is currently too long and complex, requiring a //nolint:funlen directive to bypass linter warnings. This makes the code harder to maintain and understand.

Refactored the function by:

• Breaking it down into smaller, more focused functions
• Improving readability and maintainability
• Removing the need for the funlen linter bypass

Testing

• Ran make backend-test to ensure all tests pass
• Verified with make backend-lint that code passes linting without exceptions

[knrt10]

Thanks you for the PR @Faakhir30. Some suggestions

[knrt10]

@Faakhir30 you can try running make backend-lint command to see the errors locally. Would help before pushing.

[Faakhir30]

@Faakhir30 you can try running make backend-lint command to see the errors locally. Would help before pushing.

Yeah, did try that a lot, but for some reason it is not working for me locally, did asked in #headlamp CNCF slack channel also.
Did implement other changes, however lint failing.

couldnt find much about this error. most probably its some packages version conflict, but im not sure:
@knrt10 Is there any preffered go version? mine is go version go1.23.5 linux/amd64
also tried modifying versions of golang-lint in Makefile to [email protected]
and [email protected] , both giving same following output:

f@f:~/w/oss/headlamp$ make backend-lint 
GOBIN=`pwd`/backend/tools go install github.com/golangci/golangci-lint/cmd/[email protected]
cd backend && ./tools/golangci-lint run
WARN [runner] The linter 'golint' is deprecated (since v1.41.0) due to: The repository of the linter has been archived by the owner. Replaced by revive. 
WARN [runner] The linter 'interfacer' is deprecated (since v1.38.0) due to: The repository of the linter has been archived by the owner.  
ERRO [linters_context/goanalysis] buildir: panic during analysis: Cannot range over: func(yield func(K, V) bool), goroutine 10688 [running]:
runtime/debug.Stack()
        /snap/go/10818/src/runtime/debug/stack.go:26 +0x5e
github.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*action).analyzeSafe.func1()
        /home/f/go/pkg/mod/github.com/golangci/[email protected]/pkg/golinters/goanalysis/runner_action.go:105 +0x5a
panic({0x160ef80?, 0xc00199bb90?})
        /snap/go/10818/src/runtime/panic.go:785 +0x132
honnef.co/go/tools/go/ir.(*builder).rangeStmt(0xc005425968, 0xc00547c500, 0xc00542c120, 0x0, {0x1a9b488, 0xc00542c120})
        /home/f/go/pkg/mod/honnef.co/go/[email protected]/go/ir/builder.go:2214 +0x894
honnef.co/go/tools/go/ir.(*builder).stmt(0xc005425968, 0xc00547c500, {0x1aa0570?, 0xc00542c120?})
        /home/f/go/pkg/mod/honnef.co/go/[email protected]/go/ir/builder.go:2427 +0x20a
.............
        /home/f/go/pkg/mod/github.com/golangci/[email protected]/pkg/golinters/goanalysis/runner_loadingpackage.go:75 +0x1e9 
WARN [runner] Can't run linter goanalysis_metalinter: goanalysis_metalinter: buildir: package "slices" (isInitialPkg: false, needAnalyzeSource: true): Cannot range over: func(yield func(E) bool) 
ERRO Running error: 1 error occurred:
        * can't run linter goanalysis_metalinter: goanalysis_metalinter: buildir: package "slices" (isInitialPkg: false, needAnalyzeSource: true): Cannot range over: func(yield func(E) bool) 
 
make: *** [Makefile:35: backend-lint] Error 3
f@f:~/w/oss/headlamp$ 

[knrt10]

You need Go version 1.22.* for current project setup. You can easily change it is gvm. Mine currently is

❯ go version
go version go1.22.1 darwin/amd64

Also, you can always check our actions workfows for the passing CI

headlamp/.github/workflows/backend-test.yml

Lines 31 to 55 in 4f110c1

	- uses: actions/setup-go@41dfa10bad2bb2ae585af6ee5bb4d7d973ad74ed # v5.1.0
	with:
	go-version: '1.22.*'
	- name: Install dependencies
	run: |
	cd backend
	go mod download
	- name: Start cluster
	uses: medyagh/setup-minikube@d8c0eb871f6f455542491d86a574477bd3894533 # latest
	- name: Check cluster status and enable headlamp addon
	run: |
	minikube status
	minikube addons enable headlamp
	kubectl wait deployment -n headlamp headlamp --for condition=Available=True --timeout=30s
	- name: setup and run golangci-lint
	uses: golangci/golangci-lint-action@d6238b002a20823d52840fda27e2d4891c5952dc # v4.0.1
	with:
	version: v1.54
	working-directory: backend
	skip-cache: true
	args: --timeout 3m

[Faakhir30]

Changes implemented, lint errors fixed, rebased with main, ready for review. @knrt10 thanks

[knrt10]

Awesome. Thanks again for PR, appreciate it

[illume]

🎉 great work, thanks!