Add entity-body compression to http output (#4807)

internal/internal.go

@@ -3,8 +3,10 @@ package internal
 import (
 	"bufio"
 	"bytes"
+	"compress/gzip"
 	"crypto/rand"
 	"errors"
+	"io"
 	"log"
 	"math/big"
 	"os"
@@ -208,3 +210,23 @@ func ExitStatus(err error) (int, bool) {
 	}
 	return 0, false
 }
+
+// CompressWithGzip takes an io.Reader as input and pipes
+// it through a gzip.Writer returning an io.Reader containing
+// the gzipped data.
+// An error is returned if passing data to the gzip.Writer fails
+func CompressWithGzip(data io.Reader) (io.Reader, error) {
+	pipeReader, pipeWriter := io.Pipe()
+	gzipWriter := gzip.NewWriter(pipeWriter)
+
+	var err error
+	go func() {
+		_, err = io.Copy(gzipWriter, data)
+		gzipWriter.Close()
+		// subsequent reads from the read half of the pipe will
+		// return no bytes and the error err, or EOF if err is nil.
+		pipeWriter.CloseWithError(err)
+	}()
+
+	return pipeReader, err
+}

internal/internal_test.go

@@ -1,6 +1,9 @@
 package internal
 
 import (
+	"bytes"
+	"compress/gzip"
+	"io/ioutil"
 	"os/exec"
 	"testing"
 	"time"
@@ -162,3 +165,20 @@ func TestDuration(t *testing.T) {
 	d.UnmarshalTOML([]byte(`1.5`))
 	assert.Equal(t, time.Second, d.Duration)
 }
+
+func TestCompressWithGzip(t *testing.T) {
+	testData := "the quick brown fox jumps over the lazy dog"
+	inputBuffer := bytes.NewBuffer([]byte(testData))
+
+	outputBuffer, err := CompressWithGzip(inputBuffer)
+	assert.NoError(t, err)
+
+	gzipReader, err := gzip.NewReader(outputBuffer)
+	assert.NoError(t, err)
+	defer gzipReader.Close()
+
+	output, err := ioutil.ReadAll(gzipReader)
+	assert.NoError(t, err)
+
+	assert.Equal(t, testData, string(output))
+}