Merge pull request #57 from Clever/add-zlib-decompression

Add zlib decompression to batch consumer.

batchconsumer/writer.go

@@ -1,9 +1,12 @@
 package batchconsumer
 
 import (
+	"bytes"
+	"compress/zlib"
 	"context"
 	"encoding/base64"
 	"fmt"
+	"io/ioutil"
 	"math/big"
 
 	"golang.org/x/time/rate"
@@ -58,18 +61,30 @@ func (b *batchedWriter) Initialize(shardID string, checkpointer kcl.Checkpointer
 }
 
 func (b *batchedWriter) splitMessageIfNecessary(record []byte) ([][]byte, error) {
-	// We handle two types of records:
-	// - records emitted from CWLogs Subscription
-	// - records emitted from KPL
-	if !splitter.IsGzipped(record) {
-		// Process a single message, from KPL
-		return [][]byte{record}, nil
-	}
-
+	// We handle three types of records:
+	// - records emitted from CWLogs Subscription (which are gzip compressed)
+	// - uncompressed records emitted from KPL
+	// - zlib compressed records (e.g. as compressed and emitted by Kinesis plugin for Fluent Bit)
+	if splitter.IsGzipped(record) {
 		// Process a batch of messages from a CWLogs Subscription
 		return splitter.GetMessagesFromGzippedInput(record)
 	}
 
+	// Try to read it as a zlib-compressed record
+	// zlib.NewReader checks for a zlib header and returns an error if not found
+	zlibReader, err := zlib.NewReader(bytes.NewReader(record))
+	if err == nil {
+		unzlibRecord, err := ioutil.ReadAll(zlibReader)
+		if err != nil {
+			return nil, fmt.Errorf("reading zlib-compressed record: %v", err)
+		}
+		return [][]byte{unzlibRecord}, nil
+	}
+	// Process a single message, from KPL
+	return [][]byte{record}, nil
+
+}
+
 func (b *batchedWriter) ProcessRecords(records []kcl.Record) error {
 	var pair kcl.SequencePair
 	prevPair := b.lastProcessedSeq

batchconsumer/writer_test.go

@@ -1,7 +1,11 @@
 package batchconsumer
 
 import (
+	"bytes"
+	"compress/gzip"
+	"compress/zlib"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"testing"
 	"time"
@@ -10,6 +14,7 @@ import (
 	"gopkg.in/Clever/kayvee-go.v6/logger"
 
 	"github.com/Clever/amazon-kinesis-client-go/kcl"
+	"github.com/Clever/amazon-kinesis-client-go/splitter"
 )
 
 type ignoringSender struct{}
@@ -352,7 +357,7 @@ func TestProcessRecordsMutliBatchWithIgnores(t *testing.T) {
 	assert.Equal("tag3", string(mocksender.batches["tag3"][0][2]))
 }
 
-func TestStaggeredCheckpionting(t *testing.T) {
+func TestStaggeredCheckpointing(t *testing.T) {
 	assert := assert.New(t)
 
 	mockFailedLogsFile := logger.New("testing")
@@ -421,3 +426,75 @@ func TestStaggeredCheckpionting(t *testing.T) {
 	assert.Equal("tag3", string(mocksender.batches["tag3"][2][0]))
 	assert.Equal("tag3", string(mocksender.batches["tag3"][2][1]))
 }
+
+func TestSplitIfNecesary(t *testing.T) {
+
+	// We provide three different inputs to batchedWriter.splitMessageIfNecessary
+	// plain text
+	// zlib compressed text
+	// gzip compressed CloudWatch logs batch
+	// we verify that the split function matches the input against the correct splitter
+	// and decodes it.
+
+	assert := assert.New(t)
+
+	mockFailedLogsFile := logger.New("testing")
+	mockconfig := withDefaults(Config{
+		BatchInterval:  10 * time.Millisecond,
+		CheckpointFreq: 20 * time.Millisecond,
+	})
+
+	wrt := NewBatchedWriter(mockconfig, ignoringSender{}, mockFailedLogsFile)
+
+	plainTextInput := []byte("hello, world!")
+
+	records, err := wrt.splitMessageIfNecessary(plainTextInput)
+	assert.NoError(err)
+	assert.Equal(
+		records,
+		[][]byte{[]byte("hello, world!")},
+	)
+
+	var z bytes.Buffer
+	zbuf := zlib.NewWriter(&z)
+	zbuf.Write([]byte("hello, world!"))
+	zbuf.Close()
+	zlibSingleInput := z.Bytes()
+
+	records, err = wrt.splitMessageIfNecessary(zlibSingleInput)
+	assert.NoError(err)
+	assert.Equal(
+		records,
+		[][]byte{[]byte("hello, world!")},
+	)
+
+	// the details of this part aren't super important since the actual functionality is
+	// tested in the splitter package, we just want to make sure that OUR split function
+	// correctly realizes it's gzip and call the splitter package's functionality
+	var g bytes.Buffer
+	gbuf := gzip.NewWriter(&g)
+	cwLogBatch := splitter.LogEventBatch{
+		MessageType:         "test",
+		Owner:               "test",
+		LogGroup:            "test",
+		LogStream:           "test",
+		SubscriptionFilters: []string{""},
+		LogEvents: []splitter.LogEvent{{
+			ID:        "test",
+			Timestamp: splitter.UnixTimestampMillis(time.Date(2020, time.September, 9, 9, 10, 10, 0, time.UTC)),
+			Message:   "test",
+		}},
+	}
+	cwLogBatchJSON, _ := json.Marshal(cwLogBatch)
+	gbuf.Write(cwLogBatchJSON)
+	gbuf.Close()
+	gzipBatchInput := g.Bytes()
+
+	expectedRecord := []byte("2020-09-09T09:10:10.000001+00:00 test test--test/arn%3Aaws%3Aecs%3Aus-east-1%3A999988887777%3Atask%2F12345678-1234-1234-1234-555566667777: test")
+	records, err = wrt.splitMessageIfNecessary(gzipBatchInput)
+	assert.NoError(err)
+	assert.Equal(
+		records,
+		[][]byte{expectedRecord},
+	)
+}