Add Prometheus metrics endpoint #222
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,14 @@ | ||
| package adapter | ||
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| import "github.com/prometheus/client_golang/prometheus" | ||
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| var ( | ||
| opCounter = prometheus.NewCounterVec(prometheus.CounterOpts{ | ||
| Name: "elastickv_operations_total", | ||
| Help: "Total number of KV operations", | ||
| }, []string{"op", "client"}) | ||
| ) | ||
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| func init() { | ||
| prometheus.MustRegister(opCounter) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -6,6 +6,7 @@ import ( | |
| "fmt" | ||
| "log" | ||
| "net" | ||
| "net/http" | ||
| "os" | ||
| "path/filepath" | ||
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@@ -17,8 +18,10 @@ import ( | |
| pb "github.com/bootjp/elastickv/proto" | ||
| "github.com/bootjp/elastickv/store" | ||
| "github.com/cockroachdb/errors" | ||
| "github.com/grpc-ecosystem/go-grpc-prometheus" | ||
| "github.com/hashicorp/raft" | ||
| boltdb "github.com/hashicorp/raft-boltdb/v2" | ||
| "github.com/prometheus/client_golang/prometheus/promhttp" | ||
| "golang.org/x/sync/errgroup" | ||
| "google.golang.org/grpc" | ||
| "google.golang.org/grpc/credentials/insecure" | ||
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@@ -31,6 +34,7 @@ var ( | |
| raftId = flag.String("raft_id", "", "Node id used by Raft") | ||
| raftDir = flag.String("raft_data_dir", "data/", "Raft data dir") | ||
| raftBootstrap = flag.Bool("raft_bootstrap", false, "Whether to bootstrap the Raft cluster") | ||
| metricsAddr = flag.String("metrics_address", ":2112", "TCP host+port for Prometheus metrics") | ||
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There was a problem hiding this comment. The test failure you noted ( To fix this, you should configure tests to use a dynamic port. A common technique is to use |
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| ) | ||
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| func main() { | ||
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@@ -62,7 +66,10 @@ func main() { | |
| log.Fatalf("failed to start raft: %v", err) | ||
| } | ||
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| gs := grpc.NewServer( | ||
| grpc.UnaryInterceptor(grpc_prometheus.UnaryServerInterceptor), | ||
| grpc.StreamInterceptor(grpc_prometheus.StreamServerInterceptor), | ||
| ) | ||
| trx := kv.NewTransaction(r) | ||
| coordinate := kv.NewCoordinator(trx, r) | ||
| pb.RegisterRawKVServer(gs, adapter.NewGRPCServer(s, coordinate)) | ||
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@@ -73,19 +80,26 @@ func main() { | |
| leaderhealth.Setup(r, gs, []string{"RawKV", "Example"}) | ||
| raftadmin.Register(gs, r) | ||
| reflection.Register(gs) | ||
| grpc_prometheus.Register(gs) | ||
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| redisL, err := lc.Listen(ctx, "tcp", *redisAddr) | ||
| if err != nil { | ||
| log.Fatalf("failed to listen: %v", err) | ||
| } | ||
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| mux := http.NewServeMux() | ||
| mux.Handle("/metrics", promhttp.Handler()) | ||
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| eg := errgroup.Group{} | ||
| eg.Go(func() error { | ||
| return errors.WithStack(gs.Serve(grpcSock)) | ||
| }) | ||
| eg.Go(func() error { | ||
| return errors.WithStack(adapter.NewRedisServer(redisL, s, coordinate).Run()) | ||
| }) | ||
| eg.Go(func() error { | ||
| return errors.WithStack(http.ListenAndServe(*metricsAddr, mux)) | ||
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There was a problem hiding this comment. 🚫 [golangci] reported by reviewdog 🐶 |
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| }) | ||
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| err = eg.Wait() | ||
| if err != nil { | ||
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While adding metrics is great, manually incrementing the counter in every gRPC method leads to code duplication and is error-prone. If a new method is added, one might forget to add the metrics line.
A better approach is to use a custom gRPC unary interceptor to handle this logic centrally. The interceptor can extract the method name, format it, and increment the counter. This would remove boilerplate from all the service methods and make the code more maintainable.
For example, you could create an interceptor in the
adapterpackage:Then, in
main.go, you would chain this interceptor with the existing one fromgo-grpc-prometheus, for example by using a library likegrpc-middleware.