When does the helper function run?

[YoonSungHyun-Git]

Hello,

I want to install helper functions such as get_psutil_cpu, get_load_average, etc. on the collection target server.

So I'm looking for the part in the pgwatch2.go source where the helper function is executed.

TryCreateMetricsFetchingHelpers seem to play that role. But I want to know the conditions at the time this is executed.

			_, connectFailedSoFar := failedInitialConnectHosts[db_unique]

			if connectFailedSoFar { // idea is not to spwan any runners before we've successfully pinged the DB
				var err error
				var ver DBVersionMapEntry

				if connectFailedSoFar {
					log.Infof("retrying to connect to uninitialized DB \"%s\"...", db_unique)
				} else {
					log.Infof("new host \"%s\" found, checking connectivity...", db_unique)
				}

				ver, err = DBGetPGVersion(db_unique, db_type, true)
				if err != nil {
					log.Errorf("could not start metric gathering for DB \"%s\" due to connection problem: %s", db_unique, err)
					if opts.AdHocConnString != "" {
						log.Errorf("will retry in %ds...", opts.ServersRefreshLoopSeconds)
					}
					failedInitialConnectHosts[db_unique] = true
					continue
				} else {
					log.Infof("Connect OK. [%s] is on version %s (in recovery: %v)", db_unique, ver.VersionStr, ver.IsInRecovery)
					if connectFailedSoFar {
						delete(failedInitialConnectHosts, db_unique)
					}
					if ver.IsInRecovery && host.OnlyIfMaster {
						log.Infof("[%s] not added to monitoring due to 'master only' property", db_unique)
						continue
					}
					metric_config = host.Metrics
					hostLastKnownStatusInRecovery[db_unique] = ver.IsInRecovery
					if ver.IsInRecovery && len(host.MetricsStandby) > 0 {
						metric_config = host.MetricsStandby
					}
				}

				if !opts.Ping && (host.IsSuperuser || (adHocMode && StringToBoolOrFail(opts.AdHocCreateHelpers, "--adhoc-create-helpers"))) && IsPostgresDBType(db_type) && !ver.IsInRecovery {
					if noHelperFunctions {
						log.Infof("[%s] Skipping rollout out helper functions due to the --no-helper-functions flag ...", db_unique)
					} else {
						log.Infof("Trying to create helper functions if missing for \"%s\"...", db_unique)
						_ = TryCreateMetricsFetchingHelpers(db_unique)
					}
				}

				if !(opts.Ping || (opts.Datastore == DATASTORE_PROMETHEUS && !promAsyncMode)) {
					time.Sleep(time.Millisecond * 100) // not to cause a huge load spike when starting the daemon with 100+ monitored DBs
				}
			}

What conditions make the connectFailedSoFar variable true?

[pashagolub]

Hello,

helper functions are executed during metrics fetching. They are helping to gather metric information and called from SQL. You won't find it in .go files. Check the metrics definition.

[YoonSungHyun-Git]

Hello,

Helper functions are not created automatically.

check List ::
md_is_superuser : true

I checked the metric definitions. However, I don't know what part causes failedInitialConnectHosts to be set to true.
Can you elaborate a little bit on what you need to check in metric definitions?
I want to know how and when the failedInitialConnectHosts value changes.