138 lines
3.2 KiB
Go
138 lines
3.2 KiB
Go
// This template contains a simple
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// app with OTEL bootstrap that will create an
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// HTTP server configured by environment that exports
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// spans and metrics to an OTEL collector if configured
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// to do so. Will also stand up a prometheus metrics
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// endpoint.
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//
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// Configuration and logger stored in context
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// Reference implementation of the provided packages
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package main
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import (
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"context"
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"net/http"
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"os"
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"os/signal"
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"sync"
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"time"
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"github.com/rs/zerolog"
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"go.opentelemetry.io/otel/codes"
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"go.opentelemetry.io/otel/trace"
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"golang.org/x/sys/unix"
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"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/config"
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"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/logging"
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"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/otel"
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"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/srv"
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)
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var (
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cfg *config.AppConfig
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l *zerolog.Logger
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tracer trace.Tracer
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)
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func main() {
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ctx, cncl := signal.NotifyContext(context.Background(), os.Interrupt, unix.SIGTERM)
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defer cncl()
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shutdownFuncs := make([]func(context.Context) error, 0)
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// Load configuration and setup logging
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ctx = setupConfigAndLogging(ctx)
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// Set up OTEL
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ctx, otelShutdown := otel.Init(ctx)
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shutdownFuncs = append(shutdownFuncs, otelShutdown)
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tracer = otel.MustTracerFromCtx(ctx)
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// Start App
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ctx, initSpan := tracer.Start(ctx, "init")
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// Start HTTP Server
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dummyFuncs := []srv.HTTPFunc{
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{
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Path: "/dummy",
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HandlerFunc: func(w http.ResponseWriter, r *http.Request) {
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w.Write([]byte("hello world"))
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},
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},
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}
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httpShutdown, httpDone := srv.MustInitHTTPServer(ctx, dummyFuncs...)
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shutdownFuncs = append(shutdownFuncs, httpShutdown)
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// Startup Complete
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l.Info().
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Str("name", cfg.Name).
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Str("version", cfg.Version).
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Str("logLevel", cfg.Logging.Level).
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Msg("app initialized")
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initSpan.SetStatus(codes.Ok, "")
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initSpan.End()
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// Wait for signal
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select {
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case <-httpDone:
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l.Warn().Msg("shutting down early on http server done")
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case <-ctx.Done():
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l.Warn().Str("reason", ctx.Err().Error()).
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Msg("shutting down on context done")
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}
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shutdown(shutdownFuncs...)
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}
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func shutdown(shutdownFuncs ...func(context.Context) error) {
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now := time.Now()
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doneCtx, cncl := context.WithTimeout(context.Background(), 15*time.Second)
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defer func() {
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if doneCtx.Err() == context.DeadlineExceeded {
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l.Err(doneCtx.Err()).
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Dur("shutdownTime", time.Since(now)).
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Msg("app shutdown aborted")
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} else {
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l.Info().
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Int("shutdownFuncsCalled", len(shutdownFuncs)).
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Dur("shutdownTime", time.Since(now)).
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Msg("app shutdown normally")
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}
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cncl()
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}()
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doneCtx, span := tracer.Start(doneCtx, "shutdown")
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defer span.End()
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var wg sync.WaitGroup
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wg.Add(len(shutdownFuncs))
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for _, f := range shutdownFuncs {
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go func() {
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defer wg.Done()
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err := f(doneCtx)
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if err != nil {
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span.SetStatus(codes.Error, "shutdown failed")
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span.RecordError(err)
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l.Err(err).Send()
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}
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}()
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}
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wg.Wait()
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}
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func setupConfigAndLogging(ctx context.Context) context.Context {
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ctx, err := config.LoadConfig(ctx)
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if err != nil {
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panic(err)
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}
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cfg = config.MustFromCtx(ctx)
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ctx = logging.MustInitLogging(ctx)
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l = zerolog.Ctx(ctx)
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l.Trace().Any("config", *cfg).Send()
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return ctx
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}
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