Promtail: no need for GCP promtail_instance label now that loki suppo…

…rts out-of-order writes (#4556)

Closes #4474

clients/pkg/promtail/targets/gcplog/formatter.go

@@ -6,7 +6,6 @@ import (
 	"time"
 
 	"cloud.google.com/go/pubsub"
-	"github.com/gofrs/uuid"
 	json "github.com/json-iterator/go"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/pkg/labels"
@@ -18,16 +17,6 @@ import (
 	"github.com/grafana/loki/pkg/util"
 )
 
-var instanceID uuid.UUID
-
-func init() {
-	id, err := uuid.NewV4()
-	if err != nil {
-		panic(err)
-	}
-	instanceID = id
-}
-
 // LogEntry that will be written to the pubsub topic.
 // According to the following spec.
 // https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry
@@ -66,14 +55,6 @@ func format(
 	lbs := labels.NewBuilder(nil)
 	lbs.Set("resource_type", ge.Resource.Type)
 
-	// `promtail_instance` uniquely identifies each promtail instance trying
-	// to scrape gcplog(from single subscription_id).
-	//
-	// We need this unique identifier to avoid out-of-order errors from Loki servers.
-	// Because say two promtail instances rewrite timestamp of log entries(with same labelset)
-	// at the same time may reach Loki servers at different times can cause Loki servers to reject it.
-	lbs.Set("promtail_instance", instanceID.String())
-
 	// labels from gcp log entry. Add it as internal labels
 	for k, v := range ge.Resource.Labels {
 		lbs.Set("__"+util.SnakeCase(k), v)

clients/pkg/promtail/targets/gcplog/formatter_test.go

@@ -57,7 +57,6 @@ func TestFormat(t *testing.T) {
 					"resource_type":        "gcs",
 					"backend_service_name": "http-loki",
 					"bucket_name":          "loki-bucket",
-					"promtail_instance":    model.LabelValue(instanceID.String()),
 				},
 				Entry: logproto.Entry{
 					Timestamp: mustTime(t, "2020-12-22T15:01:23.045123456Z"),
@@ -76,9 +75,8 @@ func TestFormat(t *testing.T) {
 			useIncomingTimestamp: true,
 			expected: api.Entry{
 				Labels: model.LabelSet{
-					"jobname":           "pubsub-test",
-					"resource_type":     "gcs",
-					"promtail_instance": model.LabelValue(instanceID.String()),
+					"jobname":       "pubsub-test",
+					"resource_type": "gcs",
 				},
 				Entry: logproto.Entry{
 					Timestamp: mustTime(t, "2020-12-22T15:01:23.045123456Z"),
@@ -96,9 +94,8 @@ func TestFormat(t *testing.T) {
 			},
 			expected: api.Entry{
 				Labels: model.LabelSet{
-					"jobname":           "pubsub-test",
-					"resource_type":     "gcs",
-					"promtail_instance": model.LabelValue(instanceID.String()),
+					"jobname":       "pubsub-test",
+					"resource_type": "gcs",
 				},
 				Entry: logproto.Entry{
 					Timestamp: time.Now(),

docs/sources/clients/promtail/scraping.md

@@ -211,10 +211,6 @@ It also support `relabeling` and `pipeline` stages just like other targets.
 
 When Promtail receives GCP logs the labels that are set on the GCP resources are available as internal labels. Like in the example above, the `__project_id` label from a GCP resource was transformed into a label called `project` through `relabel_configs`. See [Relabeling](#relabeling) for more information.
 
-Log entries scraped by `gcplog` will add an additional label called `promtail_instance`. This label uniquely identifies each Promtail instance trying to scrape gcplog (from a single `subscription_id`).
-We need this unique identifier to avoid out-of-order errors from Loki servers when Loki is not configured to [accept out-of-order writes](../../../configuration/#accept-out-of-order-writes).
-If two Promtail instances rewrite the timestamp of log entries (with same labelset) at the same time, the log entries may reach Loki servers at different times. This can cause Loki servers to reject the out-of-order log entry.
-
 ## Syslog Receiver
 
 Promtail supports receiving [IETF Syslog (RFC5424)](https://tools.ietf.org/html/rfc5424)

go.mod

@@ -36,7 +36,6 @@ require (
 	github.com/go-logfmt/logfmt v0.5.1
 	github.com/go-redis/redis/v8 v8.11.4
 	github.com/gocql/gocql v0.0.0-20200526081602-cd04bd7f22a7
-	github.com/gofrs/uuid v4.0.0+incompatible
 	github.com/gogo/protobuf v1.3.2 // remember to update loki-build-image/Dockerfile too
 	github.com/golang/protobuf v1.5.2
 	github.com/golang/snappy v0.0.4
@@ -162,6 +161,7 @@ require (
 	github.com/go-stack/stack v1.8.0 // indirect
 	github.com/go-zookeeper/zk v1.0.2 // indirect
 	github.com/gofrs/flock v0.7.1 // indirect
+	github.com/gofrs/uuid v4.0.0+incompatible // indirect
 	github.com/gogo/googleapis v1.4.0 // indirect
 	github.com/gogo/status v1.1.0 // indirect
 	github.com/golang-jwt/jwt/v4 v4.0.0 // indirect