mirror of
https://github.com/docker/docker-agent.git
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David Gageot
2f002b4eb8
Both call sites had a context in scope but used the non-contextual slog.Warn/slog.Debug, which the SlogContextual linter flags because handlers (e.g. OpenTelemetry) cannot read trace context from them.
70 lines
2.6 KiB
Go
70 lines
2.6 KiB
Go
package profiling
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import (
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"context"
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"errors"
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"fmt"
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"log/slog"
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"net"
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"net/http"
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"net/http/pprof"
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"time"
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)
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// StartPprofServer starts an HTTP server exposing Go runtime profiling endpoints
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// at /debug/pprof/ on the given addr. It binds the listener synchronously and
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// returns an error if the address is unavailable. The server runs in a background
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// goroutine and shuts down when ctx is cancelled.
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// addr must be a TCP host:port address (e.g. "127.0.0.1:6060"); unix://, npipe://,
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// and fd:// schemes are not supported. Prefer a loopback address over a bare port
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// (":6060") — the latter binds all interfaces, exposing process memory and arguments
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// to the network.
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func StartPprofServer(ctx context.Context, addr string) error {
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mux := http.NewServeMux()
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mux.HandleFunc("/debug/pprof/", pprof.Index)
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mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
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mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
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mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
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mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
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ln, err := (&net.ListenConfig{}).Listen(ctx, "tcp", addr)
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if err != nil {
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return fmt.Errorf("pprof: listen on %s: %w", addr, err)
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}
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// ReadHeaderTimeout guards against slow-loris connections on the debug port.
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// WriteTimeout is intentionally omitted: profile/trace captures legitimately
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// run for tens of seconds and would be truncated by a short write deadline.
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srv := &http.Server{Handler: mux, ReadHeaderTimeout: 10 * time.Second}
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slog.InfoContext(ctx, "pprof server listening", "addr", ln.Addr().String())
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if tcpAddr, ok := ln.Addr().(*net.TCPAddr); ok && !tcpAddr.IP.IsLoopback() {
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slog.WarnContext(ctx, "pprof server is listening on a non-loopback address — "+
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"/debug/pprof/cmdline and heap profiles are network-reachable without authentication",
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"addr", tcpAddr.String())
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}
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go func() {
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if err := srv.Serve(ln); err != nil && !errors.Is(err, http.ErrServerClosed) {
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slog.WarnContext(ctx, "pprof server error", "error", err)
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}
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}()
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go func() {
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<-ctx.Done()
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// 5s grace: favors prompt process exit over draining in-flight profile
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// captures. CPU/trace profiles run up to 30s by default; callers should
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// cancel their requests before the process exits rather than relying on
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// this timeout to drain them.
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// context.WithoutCancel preserves ctx values (e.g. trace IDs) without
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// inheriting the cancellation, so the shutdown timeout is not pre-expired.
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shutdownCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 5*time.Second)
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defer cancel()
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if err := srv.Shutdown(shutdownCtx); err != nil {
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slog.WarnContext(shutdownCtx, "pprof server shutdown error", "error", err)
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}
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}()
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return nil
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}
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