Merge pull request #323 from docker/fix-log-lines

Count the lines from the terminal, not from ACI

azure/aci.go

@@ -27,6 +27,7 @@ import (
 	"github.com/Azure/azure-sdk-for-go/services/containerinstance/mgmt/2018-10-01/containerinstance"
 	"github.com/Azure/go-autorest/autorest"
 	"github.com/Azure/go-autorest/autorest/to"
+	"github.com/buger/goterm"
 	tm "github.com/buger/goterm"
 	"github.com/gobwas/ws"
 	"github.com/gobwas/ws/wsutil"
@@ -242,7 +243,8 @@ func getACIContainerLogs(ctx context.Context, aciContext store.AciContext, conta
 }
 
 func streamLogs(ctx context.Context, aciContext store.AciContext, containerGroupName, containerName string, out io.Writer) error {
-	lastOutput := 0
+	terminalWidth := goterm.Width()
+	numLines := 0
 	for {
 		select {
 		case <-ctx.Done():
@@ -260,20 +262,32 @@ func streamLogs(ctx context.Context, aciContext store.AciContext, containerGroup
 			// the kind of logs ACI is giving us. Hopefully Azue will give us
 			// a real logs streaming api soon.
 			b := aec.EmptyBuilder
-			b = b.Up(uint(lastOutput))
+			b = b.Up(uint(numLines))
 			fmt.Fprint(out, b.Column(0).ANSI)
 
+			numLines = getBacktrackLines(logLines, terminalWidth)
+
 			for i := 0; i < currentOutput-1; i++ {
 				fmt.Fprintln(out, logLines[i])
 			}
 
-			lastOutput = currentOutput - 1
-
 			time.Sleep(2 * time.Second)
 		}
 	}
 }
 
+func getBacktrackLines(lines []string, terminalWidth int) int {
+	numLines := 0
+	for i := 0; i < len(lines)-1; i++ {
+		numLines++
+		if len(lines[i]) > terminalWidth {
+			numLines += len(lines[i]) / terminalWidth
+		}
+	}
+
+	return numLines
+}
+
 func getContainerGroupsClient(subscriptionID string) (containerinstance.ContainerGroupsClient, error) {
 	containerGroupsClient := containerinstance.NewContainerGroupsClient(subscriptionID)
 	err := setupClient(&containerGroupsClient.Client)

azure/aci_test.go

@@ -0,0 +1,12 @@
+package azure
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetLinesWritten(t *testing.T) {
+	assert.Equal(t, 0, getBacktrackLines([]string{"Hello"}, 10))
+	assert.Equal(t, 3, getBacktrackLines([]string{"Hello", "world"}, 2))
+}