Fix streaming API request error

Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com>

alpine/packages/diagnostics/http.go

@@ -52,6 +52,10 @@ func dockerHTTPGet(ctx context.Context, url string) (*http.Response, error) {
 		Transport: &UnixSocketRoundTripper{},
 	}
 
+	return dockerHTTPGetWithClient(ctx, url, client)
+}
+
+func dockerHTTPGetWithClient(ctx context.Context, url string, client *http.Client) (*http.Response, error) {
 	req, err := http.NewRequest(http.MethodGet, url, nil)
 	if err != nil {
 		return nil, err
@@ -69,11 +73,24 @@ func dockerHTTPGet(ctx context.Context, url string) (*http.Response, error) {
 	}
 
 	return resp, err
+
 }
 
 // UnixSocketRoundTripper provides a way to make HTTP request to Docker socket
 // directly.
-type UnixSocketRoundTripper struct{}
+type UnixSocketRoundTripper struct {
+	Stream bool
+	conn   *httputil.ClientConn
+}
+
+// Close will close the connection if the caller needs to clean up after
+// themselves in a streaming request.
+func (u UnixSocketRoundTripper) Close() error {
+	if u.conn != nil {
+		return u.conn.Close()
+	}
+	return nil
+}
 
 // RoundTrip dials the Docker UNIX socket to make a HTTP request.
 func (u UnixSocketRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
@@ -81,9 +98,16 @@ func (u UnixSocketRoundTripper) RoundTrip(req *http.Request) (*http.Response, er
 	if err != nil {
 		return nil, err
 	}
-	conn := httputil.NewClientConn(dial, nil)
-	defer conn.Close()
-	return conn.Do(req)
+	u.conn = httputil.NewClientConn(dial, nil)
+
+	// If the client makes a streaming request (e.g., /container/x/logs)
+	// it's their responsibility to close the connection, because it needs
+	// to remain open to stream the response body.
+	if !u.Stream {
+		defer u.conn.Close()
+	}
+
+	return u.conn.Do(req)
 }
 
 // Listen starts the HTTPDiagnosticListener and sets up handlers for its endpoints

alpine/packages/diagnostics/system_log_capture.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"io/ioutil"
 	"log"
+	"net/http"
 )
 
 const (
@@ -20,15 +21,15 @@ type SystemContainerCapturer struct{}
 
 // Capture writes output from a CommandCapturer to a tar archive
 func (s SystemContainerCapturer) Capture(parentCtx context.Context, w *tar.Writer) {
-	done := make(chan struct{})
-
 	ctx, cancel := context.WithTimeout(context.Background(), defaultCaptureTimeout)
 	defer cancel()
 
+	errCh := make(chan error)
+
 	go func() {
 		resp, err := dockerHTTPGet(ctx, "/containers/json?all=1&label="+systemContainerLabel)
 		if err != nil {
-			log.Println("ERROR:", err)
+			errCh <- err
 			return
 		}
 
@@ -40,22 +41,35 @@ func (s SystemContainerCapturer) Capture(parentCtx context.Context, w *tar.Write
 		}{}
 
 		if err := json.NewDecoder(resp.Body).Decode(&names); err != nil {
-			log.Println("ERROR:", err)
+			errCh <- err
 			return
 		}
 
 		for _, c := range names {
-			resp, err := dockerHTTPGet(ctx, "/containers/"+c.ID+"/logs?stderr=1&stdout=1&timestamps=1")
+			transport := &UnixSocketRoundTripper{
+				Stream: true,
+			}
+
+			client := &http.Client{
+				Transport: transport,
+			}
+
+			resp, err := dockerHTTPGetWithClient(ctx, "/containers/"+c.ID+"/logs?stderr=1&stdout=1&timestamps=1&tail=all", client)
 			if err != nil {
-				log.Println("ERROR:", err)
+				log.Println("ERROR (get request):", err)
 				continue
 			}
 
 			defer resp.Body.Close()
 
+			// logs makes streaming request where the original http
+			// conn is left open so we must clean up after
+			// ourselves when we're done reading
+			defer transport.Close()
+
 			logLines, err := ioutil.ReadAll(resp.Body)
 			if err != nil {
-				log.Println("ERROR:", err)
+				log.Println("ERROR (reading response):", err)
 				continue
 			}
 
@@ -72,13 +86,16 @@ func (s SystemContainerCapturer) Capture(parentCtx context.Context, w *tar.Write
 			tarWrite(w, bytes.NewBuffer(logLines), systemLogDir+c.Names[0])
 		}
 
-		done <- struct{}{}
+		errCh <- nil
 	}()
 
 	select {
 	case <-ctx.Done():
-		log.Println("System container log capture error", ctx.Err())
-	case <-done:
-		log.Println("System container log capture finished")
+		log.Println("System container log capture context error", ctx.Err())
+	case err := <-errCh:
+		if err != nil {
+			log.Println("System container log capture error", err)
+		}
+		log.Println("System container log capture finished successfully")
 	}
 }