Comments/docs for NO_WINDOWS_SERVICE env var

cmd/otelcol/main_windows.go

@@ -36,6 +36,10 @@ func run(params service.Parameters) error {
 }
 
 func checkUseInteractiveMode() (bool, error) {
+	// If environment variable NO_WINDOWS_SERVICE is set with any value other
+	// than 0, use interactive mode instead of running as a service. This should
+	// be set in case running as a service is not possible or desired even
+	// though the current session is not detected to be interactive
 	if value, present := os.LookupEnv("NO_WINDOWS_SERVICE"); present && value != "0" {
 		return true, nil
 	}

docs/troubleshooting.md

@@ -258,3 +258,11 @@ More often than not, exporting data does not work because of a network
 configuration issue. This could be due to a firewall, DNS, or proxy
 issue. Note that the Collector does have
 [proxy support](https://github.com/open-telemetry/opentelemetry-collector/tree/master/exporter#proxy-support).
+
+### Startup failing in Windows Docker containers
+
+The process may fail to start in a Windows Docker container with the following
+error: `The service process could not connect to the service controller`. In
+this case the `NO_WINDOWS_SERVICE=1` environment variable should be set to force
+the collector to be started as if it were running in an interactive terminal,
+without attempting to run as a Windows service.