Add project IDs to error logs

When exporting metrics from multiple projects at once, it's useful to
know which of the projects is generating metrics errors.

collectors/monitoring_collector.go

@@ -235,7 +235,7 @@ func (c *MonitoringCollector) Collect(ch chan<- prometheus.Metric) {
 	if err := c.reportMonitoringMetrics(ch, begun); err != nil {
 		errorMetric = float64(1)
 		c.scrapeErrorsTotalMetric.Inc()
-		level.Error(c.logger).Log("msg", "Error while getting Google Stackdriver Monitoring metrics", "err", err)
+		level.Error(c.logger).Log("msg", "Error while getting Google Stackdriver Monitoring metrics", "err", err, "project_id", c.projectID)
 	}
 	c.scrapeErrorsTotalMetric.Collect(ch)
 
@@ -311,7 +311,7 @@ func (c *MonitoringCollector) reportMonitoringMetrics(ch chan<- prometheus.Metri
 					}
 				}
 
-				level.Debug(c.logger).Log("msg", "retrieving Google Stackdriver Monitoring metrics with filter", "filter", filter)
+				level.Debug(c.logger).Log("msg", "retrieving Google Stackdriver Monitoring metrics with filter", "filter", filter, "project_id", c.projectID)
 
 				timeSeriesListCall := c.monitoringService.Projects.TimeSeries.List(utils.ProjectResource(c.projectID)).
 					Filter(filter).
@@ -322,15 +322,15 @@ func (c *MonitoringCollector) reportMonitoringMetrics(ch chan<- prometheus.Metri
 					c.apiCallsTotalMetric.Inc()
 					page, err := timeSeriesListCall.Do()
 					if err != nil {
-						level.Error(c.logger).Log("msg", "error retrieving Time Series metrics for descriptor", "descriptor", metricDescriptor.Type, "err", err)
+						level.Error(c.logger).Log("msg", "error retrieving Time Series metrics for descriptor", "descriptor", metricDescriptor.Type, "err", err, "project_id", c.projectID)
 						errChannel <- err
 						break
 					}
 					if page == nil {
 						break
 					}
 					if err := c.reportTimeSeriesMetrics(page, metricDescriptor, ch, begun); err != nil {
-						level.Error(c.logger).Log("msg", "error reporting Time Series metrics for descriptor", "descriptor", metricDescriptor.Type, "err", err)
+						level.Error(c.logger).Log("msg", "error reporting Time Series metrics for descriptor", "descriptor", metricDescriptor.Type, "err", err, "project_id", c.projectID)
 						errChannel <- err
 						break
 					}
@@ -416,7 +416,7 @@ func (c *MonitoringCollector) reportTimeSeriesMetrics(
 		c.aggregateDeltas,
 	)
 	if err != nil {
-		return fmt.Errorf("error creating the TimeSeriesMetrics %v", err)
+		return fmt.Errorf("error creating the TimeSeriesMetrics for project %s %v", c.projectID, err)
 	}
 	for _, timeSeries := range page.TimeSeries {
 		newestEndTime := time.Unix(0, 0)