[receiver/kafkareceiver]: allow tunable fetch sizes (#34431)

**Description:**
This commit adds the ability to tune the minimum, default and maximum
fetch sizes for the Kafka Receiver in the OpenTelemetry configuration
file.

The defaults are kept consistent with the defaults imposed by
[sarama](https://pkg.go.dev/github.com/shopify/sarama#Config)

**Link to tracking Issue:** 
Resolves
#22741

**Testing:**
Built the image with `make docker-otelcontribcol`, uploaded to [Docker
Hub](https://hub.docker.com/r/ckaczynski/otelcontribcol) to pull the
image into our Kubernetes deployment, and hit the cluster with 200k logs
per second with the following settings:
```
        default_fetch_size: 15728640 # 15MB
        max_fetch_size: 31457280 # 30MB
        min_fetch_size: 1048576  # 1MB
```
These limits are absurdly high for no reason other than because I just
wanted to set them higher and see how far I could push it in our
cluster.

No new tests were added, but added to existing configuration tests in
config.go and factory.go

**Documentation:** 
Added the new configuration options to the receiver's README

---------

Co-authored-by: Israel Blancas <iblancasa@gmail.com>
Co-authored-by: Sean Marciniak <30928402+MovieStoreGuy@users.noreply.github.com>

.chloggen/feat_kafkareceiver-fetch-configurable.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: kafkareceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Adds tunable fetch sizes to Kafka Receiver
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [22741, 34431]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Adds the ability to tune the minumum, default and maximum fetch sizes for the Kafka Receiver
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/kafkareceiver/README.md

@@ -45,6 +45,9 @@ The following settings can be optionally configured:
 - `initial_offset` (default = latest): The initial offset to use if no offset was previously committed. Must be `latest` or `earliest`.
 - `session_timeout` (default = `10s`): The request timeout for detecting client failures when using Kafka’s group management facilities.
 - `heartbeat_interval` (default = `3s`): The expected time between heartbeats to the consumer coordinator when using Kafka’s group management facilities.
+- `min_fetch_size` (default = `1`): The minimum number of message bytes to fetch in a request, defaults to 1 byte.
+- `default_fetch_size` (default = `1048576`): The default number of message bytes to fetch in a request, defaults to 1MB.
+- `max_fetch_size` (default = `0`): The maximum number of message bytes to fetch in a request, defaults to unlimited.
 - `auth`
   - `plain_text`
     - `username`: The username to use.

receiver/kafkareceiver/config.go

@@ -78,6 +78,13 @@ type Config struct {
 
 	// Extract headers from kafka records
 	HeaderExtraction HeaderExtraction `mapstructure:"header_extraction"`
+
+	// The minimum bytes per fetch from Kafka (default "1")
+	MinFetchSize int32 `mapstructure:"min_fetch_size"`
+	// The default bytes per fetch from Kafka (default "1048576")
+	DefaultFetchSize int32 `mapstructure:"default_fetch_size"`
+	// The maximum bytes per fetch from Kafka (default "0", no limit)
+	MaxFetchSize int32 `mapstructure:"max_fetch_size"`
 }
 
 const (

receiver/kafkareceiver/config_test.go

@@ -62,6 +62,9 @@ func TestLoadConfig(t *testing.T) {
 					Enable:   true,
 					Interval: 1 * time.Second,
 				},
+				MinFetchSize:     1,
+				DefaultFetchSize: 1048576,
+				MaxFetchSize:     0,
 			},
 		},
 		{
@@ -96,6 +99,9 @@ func TestLoadConfig(t *testing.T) {
 					Enable:   true,
 					Interval: 1 * time.Second,
 				},
+				MinFetchSize:     1,
+				DefaultFetchSize: 1048576,
+				MaxFetchSize:     0,
 			},
 		},
 	}

receiver/kafkareceiver/factory.go

@@ -40,6 +40,13 @@ const (
 	defaultAutoCommitEnable = true
 	// default from sarama.NewConfig()
 	defaultAutoCommitInterval = 1 * time.Second
+
+	// default from sarama.NewConfig()
+	defaultMinFetchSize = int32(1)
+	// default from sarama.NewConfig()
+	defaultDefaultFetchSize = int32(1048576)
+	// default from sarama.NewConfig()
+	defaultMaxFetchSize = int32(0)
 )
 
 var errUnrecognizedEncoding = fmt.Errorf("unrecognized encoding")
@@ -120,6 +127,9 @@ func createDefaultConfig() component.Config {
 		HeaderExtraction: HeaderExtraction{
 			ExtractHeaders: false,
 		},
+		MinFetchSize:     defaultMinFetchSize,
+		DefaultFetchSize: defaultDefaultFetchSize,
+		MaxFetchSize:     defaultMaxFetchSize,
 	}
 }
 

receiver/kafkareceiver/factory_test.go

@@ -28,6 +28,9 @@ func TestCreateDefaultConfig(t *testing.T) {
 	assert.Equal(t, defaultInitialOffset, cfg.InitialOffset)
 	assert.Equal(t, defaultSessionTimeout, cfg.SessionTimeout)
 	assert.Equal(t, defaultHeartbeatInterval, cfg.HeartbeatInterval)
+	assert.Equal(t, defaultMinFetchSize, cfg.MinFetchSize)
+	assert.Equal(t, defaultDefaultFetchSize, cfg.DefaultFetchSize)
+	assert.Equal(t, defaultMaxFetchSize, cfg.MaxFetchSize)
 }
 
 func TestCreateTracesReceiver(t *testing.T) {

receiver/kafkareceiver/kafka_receiver.go

@@ -49,6 +49,9 @@ type kafkaTracesConsumer struct {
 	messageMarking    MessageMarking
 	headerExtraction  bool
 	headers           []string
+	minFetchSize      int32
+	defaultFetchSize  int32
+	maxFetchSize      int32
 }
 
 // kafkaMetricsConsumer uses sarama to consume and handle messages from kafka.
@@ -67,6 +70,9 @@ type kafkaMetricsConsumer struct {
 	messageMarking    MessageMarking
 	headerExtraction  bool
 	headers           []string
+	minFetchSize      int32
+	defaultFetchSize  int32
+	maxFetchSize      int32
 }
 
 // kafkaLogsConsumer uses sarama to consume and handle messages from kafka.
@@ -85,6 +91,9 @@ type kafkaLogsConsumer struct {
 	messageMarking    MessageMarking
 	headerExtraction  bool
 	headers           []string
+	minFetchSize      int32
+	defaultFetchSize  int32
+	maxFetchSize      int32
 }
 
 var _ receiver.Traces = (*kafkaTracesConsumer)(nil)
@@ -112,6 +121,9 @@ func newTracesReceiver(config Config, set receiver.Settings, unmarshaler TracesU
 		headerExtraction:  config.HeaderExtraction.ExtractHeaders,
 		headers:           config.HeaderExtraction.Headers,
 		telemetryBuilder:  telemetryBuilder,
+		minFetchSize:      config.MinFetchSize,
+		defaultFetchSize:  config.DefaultFetchSize,
+		maxFetchSize:      config.MaxFetchSize,
 	}, nil
 }
 
@@ -125,6 +137,9 @@ func createKafkaClient(config Config) (sarama.ConsumerGroup, error) {
 	saramaConfig.Consumer.Offsets.AutoCommit.Interval = config.AutoCommit.Interval
 	saramaConfig.Consumer.Group.Session.Timeout = config.SessionTimeout
 	saramaConfig.Consumer.Group.Heartbeat.Interval = config.HeartbeatInterval
+	saramaConfig.Consumer.Fetch.Min = config.MinFetchSize
+	saramaConfig.Consumer.Fetch.Default = config.DefaultFetchSize
+	saramaConfig.Consumer.Fetch.Max = config.MaxFetchSize
 
 	var err error
 	if saramaConfig.Consumer.Offsets.Initial, err = toSaramaInitialOffset(config.InitialOffset); err != nil {
@@ -235,6 +250,9 @@ func newMetricsReceiver(config Config, set receiver.Settings, unmarshaler Metric
 		headerExtraction:  config.HeaderExtraction.ExtractHeaders,
 		headers:           config.HeaderExtraction.Headers,
 		telemetryBuilder:  telemetryBuilder,
+		minFetchSize:      config.MinFetchSize,
+		defaultFetchSize:  config.DefaultFetchSize,
+		maxFetchSize:      config.MaxFetchSize,
 	}, nil
 }
 
@@ -329,6 +347,9 @@ func newLogsReceiver(config Config, set receiver.Settings, unmarshaler LogsUnmar
 		headerExtraction:  config.HeaderExtraction.ExtractHeaders,
 		headers:           config.HeaderExtraction.Headers,
 		telemetryBuilder:  telemetryBuilder,
+		minFetchSize:      config.MinFetchSize,
+		defaultFetchSize:  config.DefaultFetchSize,
+		maxFetchSize:      config.MaxFetchSize,
 	}, nil
 }