feat: add user-agent with lambda extension version and propagate apm agent info (#404)

* feat: add user-agent with lambda extension version and propagate apm agent info

* changelog: add entry

Author: kruskall

CHANGELOG.asciidoc

@@ -26,6 +26,10 @@ https://github.com/elastic/apm-aws-lambda/compare/v1.4.0...main[View commits]
 ===== Bug fixes
 - Log a warning, instead of failing a Lambda function, if auth retrieval from AWS Secrets Manager fails. Reporting APM data will not work, but the Lambda function invocations will proceed. {lambda-pull}401[401]
 
+[float]
+===== Features
+- Use User-Agent header with Lambda extension version and propagate info from apm agents {lambda-pull}404[404]
+
 [float]
 [[lambda-1.4.0]]
 === 1.4.0 - 2023/05/03

accumulator/apmdata.go

@@ -23,4 +23,5 @@ package accumulator
 type APMData struct {
 	Data            []byte
 	ContentEncoding string
+	AgentInfo       string
 }

apmproxy/apmserver.go

@@ -31,6 +31,7 @@ import (
 	"time"
 
 	"github.com/elastic/apm-aws-lambda/accumulator"
+	"github.com/elastic/apm-aws-lambda/version"
 	"go.uber.org/zap"
 )
 
@@ -130,6 +131,7 @@ func (c *Client) PostToApmServer(ctx context.Context, apmData accumulator.APMDat
 
 	endpointURI := "intake/v2/events"
 	encoding := apmData.ContentEncoding
+	agentInfo := apmData.AgentInfo
 
 	var r io.Reader
 	if apmData.ContentEncoding != "" {
@@ -160,6 +162,7 @@ func (c *Client) PostToApmServer(ctx context.Context, apmData accumulator.APMDat
 	}
 	req.Header.Add("Content-Encoding", encoding)
 	req.Header.Add("Content-Type", "application/x-ndjson")
+	req.Header.Set("User-Agent", version.UserAgent+" "+agentInfo)
 	if c.ServerAPIKey != "" {
 		req.Header.Add("Authorization", "ApiKey "+c.ServerAPIKey)
 	} else if c.ServerSecretToken != "" {

apmproxy/receiver.go

@@ -29,6 +29,7 @@ import (
 	"time"
 
 	"github.com/elastic/apm-aws-lambda/accumulator"
+	"github.com/elastic/apm-aws-lambda/version"
 )
 
 const txnRegistrationContentType = "application/vnd.elastic.apm.transaction+ndjson"
@@ -105,6 +106,8 @@ func (c *Client) handleInfoRequest() (func(w http.ResponseWriter, r *http.Reques
 		r.URL.Host = parsedApmServerURL.Host
 		r.URL.Scheme = parsedApmServerURL.Scheme
 		r.Header.Set("X-Forwarded-Host", r.Header.Get("Host"))
+		reqAgent := r.UserAgent()
+		r.Header.Set("User-Agent", version.UserAgent+" "+reqAgent)
 		r.Host = parsedApmServerURL.Host
 
 		// Override authorization header sent by the APM agents
@@ -136,6 +139,7 @@ func (c *Client) handleIntakeV2Events() func(w http.ResponseWriter, r *http.Requ
 		agentData := accumulator.APMData{
 			Data:            rawBytes,
 			ContentEncoding: r.Header.Get("Content-Encoding"),
+			AgentInfo:       r.UserAgent(),
 		}
 
 		if len(agentData.Data) != 0 {

extension/client.go

@@ -25,6 +25,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/elastic/apm-aws-lambda/version"
 	"go.uber.org/zap"
 )
 
@@ -106,6 +107,7 @@ func (e *Client) Register(ctx context.Context, filename string) (*RegisterRespon
 		return nil, fmt.Errorf("failed to create register request: %w", err)
 	}
 	httpReq.Header.Set(extensionNameHeader, filename)
+	httpReq.Header.Set("User-Agent", version.UserAgent)
 	httpRes, err := e.httpClient.Do(httpReq)
 	if err != nil {
 		return nil, fmt.Errorf("extension register request failed: %w", err)
@@ -134,6 +136,7 @@ func (e *Client) NextEvent(ctx context.Context) (*NextEventResponse, error) {
 		return nil, fmt.Errorf("failed to create next event request: %w", err)
 	}
 	httpReq.Header.Set(extensionIdentiferHeader, e.ExtensionID)
+	httpReq.Header.Set("User-Agent", version.UserAgent)
 	httpRes, err := e.httpClient.Do(httpReq)
 	if err != nil {
 		return nil, fmt.Errorf("next event request failed: %w", err)
@@ -161,6 +164,7 @@ func (e *Client) InitError(ctx context.Context, errorType string) (*StatusRespon
 	}
 	httpReq.Header.Set(extensionIdentiferHeader, e.ExtensionID)
 	httpReq.Header.Set(extensionErrorType, errorType)
+	httpReq.Header.Set("User-Agent", version.UserAgent)
 	httpRes, err := e.httpClient.Do(httpReq)
 	if err != nil {
 		return nil, fmt.Errorf("initialization error request failed: %w", err)
@@ -188,6 +192,7 @@ func (e *Client) ExitError(ctx context.Context, errorType string) (*StatusRespon
 	}
 	httpReq.Header.Set(extensionIdentiferHeader, e.ExtensionID)
 	httpReq.Header.Set(extensionErrorType, errorType)
+	httpReq.Header.Set("User-Agent", version.UserAgent)
 	httpRes, err := e.httpClient.Do(httpReq)
 	if err != nil {
 		return nil, fmt.Errorf("exit error request failed: %w", err)

logsapi/subscribe.go

@@ -25,6 +25,8 @@ import (
 	"io"
 	"net"
 	"net/http"
+
+	"github.com/elastic/apm-aws-lambda/version"
 )
 
 // SubscribeRequest is the request body that is sent to Logs API on subscribe
@@ -131,6 +133,7 @@ func (lc *Client) sendRequest(url string, data []byte, extensionID string) (*htt
 
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Lambda-Extension-Identifier", extensionID)
+	req.Header.Set("User-Agent", version.UserAgent)
 
 	resp, err := lc.httpClient.Do(req)
 	if err != nil {

extension/version.go renamed to version/version.go

@@ -15,8 +15,9 @@
 // specific language governing permissions and limitations
 // under the License.
 
-package extension
+package version
 
 const (
-	Version = "1.4.0"
+	Version   = "1.4.0"
+	UserAgent = "apm-aws-lambda/" + Version
 )