Add gzip compression and "disable_compression" to HTTP client exporters

All exporters that use HTTPClientSettings will now have a config option
"compression". The default value is empty and results in no compression,
which is the same as the old behavior. You can also specify "compression: gzip"
which will result in gzip encoding of outgoing http requests.

config/configgrpc/README.md

@@ -16,7 +16,7 @@ configuration. For more information, see [configtls
 README](../configtls/README.md).
 
 - [`balancer_name`](https://github.com/grpc/grpc-go/blob/master/examples/features/load_balancing/README.md)
-- `compression` (default = gzip): Compression type to use (only gzip is supported today)
+- `compression` (default = none): Compression type to use (only gzip is supported today)
 - `endpoint`: Valid value syntax available [here](https://github.com/grpc/grpc/blob/master/doc/naming.md)
 - `headers`: name/value pairs added to the request
 - [`keepalive`](https://godoc.org/google.golang.org/grpc/keepalive#ClientParameters)

config/confighttp/README.md

@@ -15,6 +15,7 @@ configuration. For more information, see [configtls
 README](../configtls/README.md).
 
 - `endpoint`: address:port
+- `compression` (default = none): Compression type to use (only gzip is supported today)
 - `headers`: name/value pairs added to the HTTP request headers
 - [`read_buffer_size`](https://golang.org/pkg/net/http/#Transport)
 - [`timeout`](https://golang.org/pkg/net/http/#Client)

config/confighttp/confighttp.go

@@ -16,12 +16,15 @@ package confighttp
 
 import (
 	"crypto/tls"
+	"fmt"
 	"net"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/rs/cors"
 
+	"go.opentelemetry.io/collector/config/configgrpc"
 	"go.opentelemetry.io/collector/config/configtls"
 	"go.opentelemetry.io/collector/internal/middleware"
 )
@@ -46,6 +49,10 @@ type HTTPClientSettings struct {
 	// Existing header values are overwritten if collision happens.
 	Headers map[string]string `mapstructure:"headers,omitempty"`
 
+	// The compression key for supported compression types within
+	// collector. Currently the only supported mode is `gzip`.
+	Compression string `mapstructure:"compression"`
+
 	// Custom Round Tripper to allow for individual components to intercept HTTP requests
 	CustomRoundTripper func(next http.RoundTripper) (http.RoundTripper, error)
 }
@@ -74,6 +81,14 @@ func (hcs *HTTPClientSettings) ToClient() (*http.Client, error) {
 		}
 	}
 
+	if hcs.Compression != "" {
+		if strings.ToLower(hcs.Compression) == configgrpc.CompressionGzip {
+			clientTransport = middleware.NewCompressRoundTripper(clientTransport)
+		} else {
+			return nil, fmt.Errorf("unsupported compression type %q", hcs.Compression)
+		}
+	}
+
 	if hcs.CustomRoundTripper != nil {
 		clientTransport, err = hcs.CustomRoundTripper(clientTransport)
 		if err != nil {

exporter/otlphttpexporter/README.md

@@ -33,6 +33,8 @@ The following settings can be optionally configured:
 - `key_file` path to the TLS key to use for TLS required connections. Should
   only be used if `insecure` is set to false.
 
+- `compression` (default = none): Compression type to use (only gzip is supported today)
+
 - `timeout` (default = 30s): HTTP request time limit. For details see https://golang.org/pkg/net/http/#Client
 - `read_buffer_size` (default = 0): ReadBufferSize for HTTP client.
 - `write_buffer_size` (default = 512 * 1024): WriteBufferSize for HTTP client.

exporter/zipkinexporter/README.md

@@ -26,6 +26,7 @@ As a result, the following parameters are also required:
 
 The following settings are optional:
 
+- `compression` (default = none): Compression type to use (only gzip is supported today)
 - `defaultservicename` (default = `<missing service name>`): What to name
   services missing this information.
 

internal/middleware/compression.go

@@ -15,12 +15,60 @@
 package middleware
 
 import (
+	"bytes"
 	"compress/gzip"
 	"compress/zlib"
 	"io"
 	"net/http"
 )
 
+const (
+	headerContentEncoding = "Content-Encoding"
+	headerValueGZIP       = "gzip"
+)
+
+type CompressRoundTripper struct {
+	http.RoundTripper
+	gzipWriter *gzip.Writer
+}
+
+func NewCompressRoundTripper(rt http.RoundTripper) *CompressRoundTripper {
+	return &CompressRoundTripper{
+		RoundTripper: rt,
+		gzipWriter:   gzip.NewWriter(nil),
+	}
+}
+
+func (r *CompressRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+
+	// Gzip the body.
+	buf := bytes.NewBuffer([]byte{})
+	r.gzipWriter.Reset(buf)
+	_, err := io.Copy(r.gzipWriter, req.Body)
+
+	defer req.Body.Close()
+
+	if err != nil {
+		return nil, err
+	}
+
+	if err := r.gzipWriter.Close(); err != nil {
+		return nil, err
+	}
+
+	// Create a new request since the docs say that we cannot modify the "req".
+	cReq, err := http.NewRequestWithContext(req.Context(), req.Method, req.URL.String(), buf)
+	if err != nil {
+		return nil, err
+	}
+
+	// Clone the headers and add gzip encoding header.
+	cReq.Header = req.Header.Clone()
+	cReq.Header.Add(headerContentEncoding, headerValueGZIP)
+
+	return r.RoundTripper.RoundTrip(cReq)
+}
+
 type ErrorHandler func(w http.ResponseWriter, r *http.Request, errorMsg string, statusCode int)
 
 type decompressor struct {

internal/middleware/compression_test.go

@@ -31,6 +31,68 @@ import (
 	"go.opentelemetry.io/collector/testutil"
 )
 
+func TestHTTPClientCompression(t *testing.T) {
+	testBody := []byte("uncompressed_text")
+	compressedBody, _ := compressGzip(testBody)
+
+	tests := []struct {
+		name     string
+		encoding string
+		reqBody  []byte
+	}{
+		{
+			name:     "NoCompression",
+			encoding: "",
+			reqBody:  testBody,
+		},
+		{
+			name:     "ValidGzip",
+			encoding: "gzip",
+			reqBody:  compressedBody.Bytes(),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				body, err := ioutil.ReadAll(r.Body)
+				require.NoError(t, err, "failed to read request body: %v", err)
+				assert.EqualValues(t, tt.reqBody, body)
+				w.WriteHeader(200)
+			})
+
+			addr := testutil.GetAvailableLocalAddress(t)
+			ln, err := net.Listen("tcp", addr)
+			require.NoError(t, err, "failed to create listener: %v", err)
+			srv := &http.Server{
+				Handler: handler,
+			}
+			go func() {
+				_ = srv.Serve(ln)
+			}()
+			// Wait for the servers to start
+			<-time.After(10 * time.Millisecond)
+
+			serverURL := fmt.Sprintf("http://%s", ln.Addr().String())
+			reqBody := bytes.NewBuffer(testBody)
+
+			req, err := http.NewRequest("GET", serverURL, reqBody)
+			require.NoError(t, err, "failed to create request to test handler")
+			req.Header.Set("Content-Encoding", tt.encoding)
+
+			client := http.Client{}
+			if tt.encoding == "gzip" {
+				client.Transport = NewCompressRoundTripper(http.DefaultTransport)
+			}
+			res, err := client.Do(req)
+			require.NoError(t, err)
+
+			ioutil.ReadAll(res.Body)
+			require.NoError(t, res.Body.Close(), "failed to close request body: %v", err)
+			require.NoError(t, srv.Close())
+		})
+	}
+}
+
 func TestHTTPContentDecompressionHandler(t *testing.T) {
 	testBody := []byte("uncompressed_text")
 	tests := []struct {