feat(client): enable gzip encoding (#44)

If client enables gzip via env var client.gzip.enabled (string representing bool)
then gzip will be enabled by default in all GRPC calls via DialOptions. Servers
created via grpc.NewServer() will have gzip compressor by default if imported
as per:

https://github.com/grpc/grpc-go/blob/master/examples/features/compression/server/main.go#L33

client/client.go

@@ -10,15 +10,17 @@ package client
 import (
 	"context"
 	"fmt"
+	"strings"
+	"sync"
+	"time"
+
 	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
 	"github.com/opentracing/opentracing-go"
 	"github.com/topfreegames/eventsgateway/v4/metrics"
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"go.opentelemetry.io/otel"
+	"google.golang.org/grpc/encoding/gzip"
 	"google.golang.org/grpc/keepalive"
-	"strings"
-	"sync"
-	"time"
 
 	uuid "github.com/satori/go.uuid"
 	"github.com/sirupsen/logrus"
@@ -101,6 +103,11 @@ func New(
 		opts...,
 	)
 
+	gzipEnabled := c.config.GetBool(fmt.Sprintf("%sclient.gzip.enabled", configPrefix))
+	if gzipEnabled {
+		dialOpts = append(dialOpts, grpc.WithDefaultCallOptions(grpc.UseCompressor(gzip.Name)))
+	}
+
 	c.logger = c.logger.WithFields(map[string]interface{}{
 		"serverAddress": c.serverAddress,
 		"async":         async,

config/local.yaml

@@ -19,6 +19,8 @@ client:
     time: 60s
     timeout: 15s
     permitwithoutstreams: true
+  gzip:
+    enabled: false
   grpc:
     serverAddress: eventsgateway-api:5000 #eventsgateway-api:5000
     timeout: 500ms

config/test.yaml

@@ -11,6 +11,8 @@ client:
   maxRetries: 3
   numRoutines: 1
   retryInterval: 1s
+  gzip:
+    enabled: false
   grpc:
     serverAddress: eventsgateway-api:5000
     timeoutms: 500ms

server/app/app.go

@@ -39,6 +39,10 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
 	"go.opentelemetry.io/otel/propagation"
 
+	// Installing the gzip encoding registers it as an available compressor.
+	// gRPC will automatically negotiate and use gzip if the client supports it.
+	_ "google.golang.org/grpc/encoding/gzip"
+
 	goMetrics "github.com/rcrowley/go-metrics"
 	"github.com/topfreegames/eventsgateway/v4/server/logger"
 	"github.com/topfreegames/eventsgateway/v4/server/metrics"