#81 template traceparent into exec command args

CHANGELOG.md

@@ -1,3 +1,11 @@
+## [0.4.3] - 2024-02-23
+
+Add injection of `{{traceparent}}` to `otel-cli exec`.
+
+### Added
+
+- `otel-cli exec echo {{traceparent}}` is now supported to pass traceparent to child process
+
 ## [0.4.2] - 2023-12-01
 
 The Docker container now builds off `alpine:latest` instead of `scratch`. This

README.md

@@ -70,6 +70,11 @@ otel-cli exec --kind producer "otel-cli exec --kind consumer sleep 1"
 # used by span and exec. use --tp-ignore-env to ignore it even when present
 export TRACEPARENT=00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01
 
+# you can pass the traceparent to a child via arguments as well
+# {{traceparent}} in any of the command's arguments will be replaced with the traceparent string
+otel-cli exec --name "curl api" -- \
+   curl -H 'traceparent: {{traceparent}}' https://myapi.com/v1/coolstuff
+
 # create a span with a custom start/end time using either RFC3339,
 # same with the nanosecond extension, or Unix epoch, with/without nanos
 otel-cli span --start 2021-03-24T07:28:05.12345Z --end 2021-03-24T07:30:08.0001Z

otelcli/exec.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/equinix-labs/otel-cli/otlpclient"
+	"github.com/equinix-labs/otel-cli/w3c/traceparent"
 	"github.com/spf13/cobra"
 	tracev1 "go.opentelemetry.io/proto/otlp/trace/v1"
 )
@@ -53,27 +54,52 @@ otel-cli exec -s "outer span" 'otel-cli exec -s "inner span" sleep 1'`,
 func doExec(cmd *cobra.Command, args []string) {
 	ctx := cmd.Context()
 	config := getConfig(ctx)
+	span := config.NewProtobufSpan()
 
 	// put the command in the attributes, before creating the span so it gets picked up
 	config.Attributes["command"] = args[0]
 	config.Attributes["arguments"] = ""
 
 	// no deadline if there is no command timeout set
 	cancelCtxDeadline := func() {}
+	// fork the context for the command so its deadline doesn't impact the otlpclient ctx
 	cmdCtx := ctx
 	cmdTimeout := config.ParseExecCommandTimeout()
 	if cmdTimeout > 0 {
 		cmdCtx, cancelCtxDeadline = context.WithDeadline(ctx, time.Now().Add(cmdTimeout))
 	}
 
+	// pass the existing env but add the latest TRACEPARENT carrier so e.g.
+	// otel-cli exec 'otel-cli exec sleep 1' will relate the spans automatically
+	childEnv := []string{}
+
+	// set the traceparent to the current span to be available to the child process
+	var tp traceparent.Traceparent
+	if config.GetIsRecording() {
+		tp = otlpclient.TraceparentFromProtobufSpan(span, config.GetIsRecording())
+		childEnv = append(childEnv, fmt.Sprintf("TRACEPARENT=%s", tp.Encode()))
+		// when not recording, and a traceparent is available, pass it through
+	} else if !config.TraceparentIgnoreEnv {
+		tp := config.LoadTraceparent()
+		if tp.Initialized {
+			childEnv = append(childEnv, fmt.Sprintf("TRACEPARENT=%s", tp.Encode()))
+		}
+	}
+
 	var child *exec.Cmd
 	if len(args) > 1 {
+		tpArgs := make([]string, len(args)-1)
+		// loop over the args replacing {{traceparent}} with the current tp
+		for i, arg := range args[1:] {
+			tpArgs[i] = strings.Replace(arg, "{{traceparent}}", tp.Encode(), -1)
+		}
+
 		// CSV-join the arguments to send as an attribute
 		buf := bytes.NewBuffer([]byte{})
-		csv.NewWriter(buf).WriteAll([][]string{args[1:]})
+		csv.NewWriter(buf).WriteAll([][]string{tpArgs})
 		config.Attributes["arguments"] = buf.String()
 
-		child = exec.CommandContext(cmdCtx, args[0], args[1:]...)
+		child = exec.CommandContext(cmdCtx, args[0], tpArgs...)
 	} else {
 		child = exec.CommandContext(cmdCtx, args[0])
 	}
@@ -83,30 +109,13 @@ func doExec(cmd *cobra.Command, args []string) {
 	child.Stdout = os.Stdout
 	child.Stderr = os.Stderr
 
-	// pass the existing env but add the latest TRACEPARENT carrier so e.g.
-	// otel-cli exec 'otel-cli exec sleep 1' will relate the spans automatically
-	child.Env = []string{}
-
 	// grab everything BUT the TRACEPARENT envvar
 	for _, env := range os.Environ() {
 		if !strings.HasPrefix(env, "TRACEPARENT=") {
-			child.Env = append(child.Env, env)
-		}
-	}
-
-	span := config.NewProtobufSpan()
-
-	// set the traceparent to the current span to be available to the child process
-	if config.GetIsRecording() {
-		tp := otlpclient.TraceparentFromProtobufSpan(span, config.GetIsRecording())
-		child.Env = append(child.Env, fmt.Sprintf("TRACEPARENT=%s", tp.Encode()))
-		// when not recording, and a traceparent is available, pass it through
-	} else if !config.TraceparentIgnoreEnv {
-		tp := config.LoadTraceparent()
-		if tp.Initialized {
-			child.Env = append(child.Env, fmt.Sprintf("TRACEPARENT=%s", tp.Encode()))
+			childEnv = append(childEnv, env)
 		}
 	}
+	child.Env = childEnv
 
 	// ctrl-c (sigint) is forwarded to the child process
 	signals := make(chan os.Signal, 10)
@@ -119,6 +128,7 @@ func doExec(cmd *cobra.Command, args []string) {
 		close(signalsDone)
 	}()
 
+	span.StartTimeUnixNano = uint64(time.Now().UnixNano())
 	if err := child.Run(); err != nil {
 		span.Status = &tracev1.Status{
 			Message: fmt.Sprintf("exec command failed: %s", err),