feat: make buffer size for agent data configurable

apm-lambda-extension/CHANGELOG.asciidoc

@@ -24,6 +24,7 @@ https://github.com/elastic/apm-aws-lambda/compare/v1.0.2...main[View commits]
 - Added support for Secret Manager {pull}208[208]
 - Added support for Lambda platform metrics {pull}202[202]
 - Migrated to AWS SDK for Go v2 {pull}232[232]
+- Make buffer size for agent data configurable {pull}262[262]
 
 [float]
 ==== Bug fixes

apm-lambda-extension/apmproxy/client.go

@@ -31,6 +31,7 @@ const (
 	defaultDataReceiverTimeout  time.Duration = 15 * time.Second
 	defaultDataForwarderTimeout time.Duration = 3 * time.Second
 	defaultReceiverAddr                       = ":8200"
+	defaultAgentBufferSize      int           = 100
 )
 
 // Client is the client used to communicate with the apm server.
@@ -54,7 +55,7 @@ func NewClient(opts ...Option) (*Client, error) {
 		bufferPool: sync.Pool{New: func() interface{} {
 			return &bytes.Buffer{}
 		}},
-		DataChannel: make(chan AgentData, 100),
+		DataChannel: make(chan AgentData, defaultAgentBufferSize),
 		client: &http.Client{
 			Transport: http.DefaultTransport.(*http.Transport).Clone(),
 		},

apm-lambda-extension/apmproxy/option.go

@@ -65,3 +65,10 @@ func WithReceiverAddress(addr string) Option {
 		c.receiver.Addr = addr
 	}
 }
+
+// WithAgentDataBufferSize sets the agent data buffer size.
+func WithAgentDataBufferSize(size int) Option {
+	return func(c *Client) {
+		c.DataChannel = make(chan AgentData, size)
+	}
+}

apm-lambda-extension/app/app.go

@@ -84,6 +84,15 @@ func New(opts ...configOption) (*App, error) {
 		apmOpts = append(apmOpts, apmproxy.WithReceiverAddress(fmt.Sprintf(":%s", port)))
 	}
 
+	if bufferSize := os.Getenv("ELASTIC_APM_LAMBDA_AGENT_DATA_BUFFER_SIZE"); bufferSize != "" {
+		size, err := strconv.Atoi(bufferSize)
+		if err != nil {
+			return nil, err
+		}
+
+		apmOpts = append(apmOpts, apmproxy.WithAgentDataBufferSize(size))
+	}
+
 	apmOpts = append(apmOpts, apmproxy.WithURL(os.Getenv("ELASTIC_APM_LAMBDA_APM_SERVER")))
 
 	ac, err := apmproxy.NewClient(apmOpts...)

docs/monitoring-aws-lambda.asciidoc

@@ -45,6 +45,9 @@ The following configuration options are particularly relevant for the {apm-lambd
 === `ELASTIC_APM_LAMBDA_APM_SERVER`
 This required config option controls where the {apm-lambda-ext} will ship data. This should be the URL of the final APM Server destination for your telemetry.
 
+=== `ELASTIC_APM_LAMBDA_AGENT_DATA_BUFFER_SIZE`
+The size of the buffer that stores APM agent data to be forwarded to the APM server. The _default_ is `100`.
+
 [[aws-lambda-config-authentication-keys]]
 === `ELASTIC_APM_SECRET_TOKEN` or `ELASTIC_APM_API_KEY`
 One of these (or, alternatively, the corresponding settings for the AWS Secrets Manager IDs) needs to be set as the authentication method that the {apm-lambda-ext} uses when sending data to the URL configured via `ELASTIC_APM_LAMBDA_APM_SERVER`. Alternatively, you can store your APM Server credentials <<aws-lambda-secrets-manager, using the AWS Secrets Manager>> and use the <<aws-lambda-config-secrets-manager-options>> config options, instead. Sending data to the APM Server if none of these options is set is possible, but your APM agent must be allowed to send data to your APM server in https://www.elastic.co/guide/en/apm/guide/current/configuration-anonymous.html[anonymous mode].
@@ -121,4 +124,4 @@ That's it. With the first invocation (cold start) of your Lambda function you sh
 [source, yml]
 ----
 "Using the APM secret token retrieved from Secrets Manager."
-----
+----