feat: Kafka eventsource supports Sarama config customization (#2161)

Signed-off-by: Derek Wang <whynowy@gmail.com>

api/jsonschema/schema.json

@@ -1831,6 +1831,10 @@
     "io.argoproj.eventsource.v1alpha1.KafkaEventSource": {
       "description": "KafkaEventSource refers to event-source for Kafka related events",
       "properties": {
+        "config": {
+          "description": "Yaml format Sarama config for Kafka connection. It follows the struct of sarama.Config. See https://github.com/Shopify/sarama/blob/main/config.go e.g.\n\nconsumer:\n  fetch:\n    min: 1\nnet:\n  MaxOpenRequests: 5",
+          "type": "string"
+        },
         "connectionBackoff": {
           "$ref": "#/definitions/io.argoproj.common.Backoff",
           "description": "Backoff holds parameters applied to connection."

common/saramaconfig.go

@@ -0,0 +1,28 @@
+package common
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/Shopify/sarama"
+	"github.com/spf13/viper"
+)
+
+// GetSaramaConfigFromYAMLString parse yaml string to sarama.config.
+// Note: All the time.Duration config can not be correctly decoded because it does not implement the decode function.
+func GetSaramaConfigFromYAMLString(yaml string) (*sarama.Config, error) {
+	v := viper.New()
+	v.SetConfigType("yaml")
+	if err := v.ReadConfig(bytes.NewBufferString(yaml)); err != nil {
+		return nil, err
+	}
+	cfg := sarama.NewConfig()
+	cfg.Producer.Return.Successes = true
+	if err := v.Unmarshal(cfg); err != nil {
+		return nil, fmt.Errorf("unable to decode into struct, %w", err)
+	}
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("failed validating sarama config, %w", err)
+	}
+	return cfg, nil
+}

common/saramaconfig_test.go

@@ -0,0 +1,43 @@
+package common
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetSaramaConfigFromYAMLString(t *testing.T) {
+	t.Run("YAML Config", func(t *testing.T) {
+		var yamlExample = string(`
+admin:
+  retry:
+    max: 105
+producer:
+  maxMessageBytes: 800
+consumer:
+  fetch: 
+    min: 2
+net:
+  MaxOpenRequests: 5
+`)
+		conf, err := GetSaramaConfigFromYAMLString(yamlExample)
+		assert.NoError(t, err)
+		assert.Equal(t, 800, conf.Producer.MaxMessageBytes)
+		assert.Equal(t, 105, conf.Admin.Retry.Max)
+		assert.Equal(t, int32(2), conf.Consumer.Fetch.Min)
+		assert.Equal(t, 5, conf.Net.MaxOpenRequests)
+	})
+	t.Run("Empty config", func(t *testing.T) {
+		conf, err := GetSaramaConfigFromYAMLString("")
+		assert.NoError(t, err)
+		assert.Equal(t, 1000000, conf.Producer.MaxMessageBytes)
+		assert.Equal(t, 5, conf.Admin.Retry.Max)
+		assert.Equal(t, int32(1), conf.Consumer.Fetch.Min)
+		assert.Equal(t, 5, conf.Net.MaxOpenRequests)
+	})
+
+	t.Run("NON yaml config", func(t *testing.T) {
+		_, err := GetSaramaConfigFromYAMLString("welcome")
+		assert.Error(t, err)
+	})
+}

eventsources/sources/kafka/start.go

@@ -262,7 +262,10 @@ func (el *EventListener) partitionConsumer(ctx context.Context, log *zap.Sugared
 }
 
 func getSaramaConfig(kafkaEventSource *v1alpha1.KafkaEventSource, log *zap.SugaredLogger) (*sarama.Config, error) {
-	config := sarama.NewConfig()
+	config, err := common.GetSaramaConfigFromYAMLString(kafkaEventSource.Config)
+	if err != nil {
+		return nil, err
+	}
 
 	if kafkaEventSource.Version == "" {
 		config.Version = sarama.V1_0_0_0