roachtest: grafana link does not have cluster name

[annrpom]

Currently (as of 07/28/23), in a roachtest failure on 23.2 (like #107862), the generated Grafana link in the "Help" section redirects you to cockroachlabs.com - instead of testeng Grafana.

Looking at the issue linked above as an example, we see the following vanity link for Grafana: https://go.crdb.dev/p/roachfana//1690711427218/1690713270780

Instead, we should be seeing the following:
https://go.crdb.dev/p/roachfana/teamcity-11114747-1690696061-26-n5cpu4/1690711427218/1690713270780

The cluster name seems to be empty - clusterName in generateHelpCommand.

Jira issue: CRDB-30247

[blathers-crl]

cc @cockroachdb/test-eng

[renatolabs]

generateHelpCommand is called by (*githubIssues).createPostRequest:

cockroach/pkg/cmd/roachtest/github.go

Line 221 in 509f8c8

HelpCommand: generateHelpCommand(clusterName, start, end),

The clusterName variable passed to it is the variable associated with the --cluster roachtest command line flag:

cockroach/pkg/cmd/roachtest/main.go

Lines 184 to 189 in 509f8c8

	rootCmd.PersistentFlags().StringVarP(
	&clusterName, "cluster", "c", "",
	"Comma-separated list of names existing cluster to use for running tests. "+
	"If fewer than --parallelism names are specified, then the parallelism "+
	"is capped to the number of clusters specified. When a cluster does not exist "+
	"yet, it is created according to the spec.")

That variable will only be set if the roachtest call was passed the --cluster argument, which is not the case in TeamCity nightly builds (in that case, clusters are created by the test runner as tests run).

Luckily, the githubIssues struct already includes a handle to the cluster used in the run, so we can change the generateHelpCommand call to pass g.cluster.Name() instead.

@annrpom do you have the time to make that change? Let me know if the above is not clear.

[annrpom]

@renatolabs it is clear - thank you for the insight! my reasoning for why i thought clusterName was not being populated was ultimately incorrect (sob sob), but i do have a draft PR up: #107984

if/when you have the time, would you be able to address my comment/question about the guard i put for when a cluster creation fails (where i made the behavior == no grafana link) :>

thank you for taking your time to explain this to me/look over things!