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feat: Add support for pprof in coder agent #1985

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Jun 6, 2022
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17 changes: 16 additions & 1 deletion cli/agent.go
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package cli
import (
"context"
"net/http"
_ "net/http/pprof" //nolint: gosec
"net/url"
"os"
"path/filepath"
Expand All @@ -25,7 +26,9 @@ import (

func workspaceAgent() *cobra.Command {
var (
auth string
auth string
pprofEnabled bool
pprofAddress string
)
cmd := &cobra.Command{
Use: "agent",
Expand All @@ -49,6 +52,16 @@ func workspaceAgent() *cobra.Command {
logger := slog.Make(sloghuman.Sink(cmd.ErrOrStderr()), sloghuman.Sink(logWriter)).Leveled(slog.LevelDebug)
client := codersdk.New(coderURL)

if pprofEnabled {
srvClose := serveHandler(cmd.Context(), logger, nil, pprofAddress, "pprof")
defer srvClose()
} else {
// If pprof wasn't enabled at startup, allow a
// `kill -USR1 $agent_pid` to start it (on Unix).
srvClose := agentStartPPROFOnUSR1(cmd.Context(), logger, pprofAddress)
defer srvClose()
}

// exchangeToken returns a session token.
// This is abstracted to allow for the same looping condition
// regardless of instance identity auth type.
Expand Down Expand Up @@ -139,5 +152,7 @@ func workspaceAgent() *cobra.Command {
}

cliflag.StringVarP(cmd.Flags(), &auth, "auth", "", "CODER_AGENT_AUTH", "token", "Specify the authentication type to use for the agent")
cliflag.BoolVarP(cmd.Flags(), &pprofEnabled, "pprof-enable", "", "CODER_AGENT_PPROF_ENABLE", false, "Enable serving pprof metrics on the address defined by --pprof-address.")
cliflag.StringVarP(cmd.Flags(), &pprofAddress, "pprof-address", "", "CODER_AGENT_PPROF_ADDRESS", "127.0.0.1:6060", "The address to serve pprof.")
return cmd
}
38 changes: 38 additions & 0 deletions cli/agent_unix.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
//go:build !windows

package cli

import (
"context"
"os"
"os/signal"
"syscall"

"cdr.dev/slog"
)

func agentStartPPROFOnUSR1(ctx context.Context, logger slog.Logger, pprofAddress string) (srvClose func()) {
ctx, cancel := context.WithCancel(ctx)

usr1 := make(chan os.Signal, 1)
signal.Notify(usr1, syscall.SIGUSR1)
go func() {
defer close(usr1)
defer signal.Stop(usr1)

select {
case <-usr1:
signal.Stop(usr1)
srvClose := serveHandler(ctx, logger, nil, pprofAddress, "pprof")
defer srvClose()
case <-ctx.Done():
return
}
<-ctx.Done() // Prevent defer close until done.
}()

return func() {
cancel()
<-usr1 // Wait until usr1 is closed, ensures srvClose was run.
}
}
12 changes: 12 additions & 0 deletions cli/agent_windows.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
package cli

import (
"context"

"cdr.dev/slog"
)

// agentStartPPROFOnUSR1 is no-op on Windows (no SIGUSR1 signal).
func agentStartPPROFOnUSR1(ctx context.Context, logger slog.Logger, pprofAddress string) (srvClose func()) {
return func() {}
}