Merge pull request #19060 from hashicorp/f-stx-etx

backend/remote: update `go-tfe` to support better log polling

backend/remote/backend_apply.go

@@ -165,6 +165,9 @@ func (b *Remote) opApply(stopCtx, cancelCtx context.Context, op *backend.Operati
 	scanner := bufio.NewScanner(logs)
 
 	for scanner.Scan() {
+		if scanner.Text() == "\x02" || scanner.Text() == "\x03" {
+			continue
+		}
 		if b.CLI != nil {
 			b.CLI.Output(b.Colorize().Color(scanner.Text()))
 		}

backend/remote/backend_plan.go

@@ -208,6 +208,9 @@ func (b *Remote) plan(stopCtx, cancelCtx context.Context, op *backend.Operation,
 	scanner := bufio.NewScanner(logs)
 
 	for scanner.Scan() {
+		if scanner.Text() == "\x02" || scanner.Text() == "\x03" {
+			continue
+		}
 		if b.CLI != nil {
 			b.CLI.Output(b.Colorize().Color(scanner.Text()))
 		}

vendor/github.com/hashicorp/go-tfe/logreader.go

@@ -1,9 +1,11 @@
 package tfe
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"io"
+	"math"
 	"net/http"
 	"net/url"
 	"time"
@@ -16,6 +18,19 @@ type LogReader struct {
 	done        func() (bool, error)
 	logURL      *url.URL
 	offset      int64
+	reads       int
+	startOfText bool
+	endOfText   bool
+}
+
+// backoff will perform exponential backoff based on the iteration and
+// limited by the provided min and max (in milliseconds) durations.
+func backoff(min, max float64, iter int) time.Duration {
+	backoff := math.Pow(2, float64(iter)/5) * min
+	if backoff > max {
+		backoff = max
+	}
+	return time.Duration(backoff) * time.Millisecond
 }
 
 func (r *LogReader) Read(l []byte) (int, error) {
@@ -26,11 +41,11 @@ func (r *LogReader) Read(l []byte) (int, error) {
 	// Loop until we can any data, the context is canceled or the
 	// run is finsished. If we would return right away without any
 	// data, we could and up causing a io.ErrNoProgress error.
-	for {
+	for r.reads = 1; ; r.reads++ {
 		select {
 		case <-r.ctx.Done():
 			return 0, r.ctx.Err()
-		case <-time.After(500 * time.Millisecond):
+		case <-time.After(backoff(500, 2000, r.reads)):
 			if written, err := r.read(l); err != io.ErrNoProgress {
 				return written, err
 			}
@@ -70,10 +85,26 @@ func (r *LogReader) read(l []byte) (int, error) {
 		return written, err
 	}
 
+	if written > 0 {
+		// Check for an STX (Start of Text) ASCII control marker.
+		if !r.startOfText && bytes.Contains(l, []byte("\x02")) {
+			r.startOfText = true
+		}
+
+		// If we found an STX ASCII control character, start looking for
+		// the ETX (End of Text) control character.
+		if r.startOfText && bytes.Contains(l, []byte("\x03")) {
+			r.endOfText = true
+		}
+	}
+
 	// Check if we need to continue the loop and wait 500 miliseconds
 	// before checking if there is a new chunk available or that the
 	// run is finished and we are done reading all chunks.
 	if written == 0 {
+		if (r.startOfText && r.endOfText) || // The logstream finished without issues.
+			(r.startOfText && r.reads%10 == 0) || // The logstream terminated unexpectedly.
+			(!r.startOfText && r.reads > 1) { // The logstream doesn't support STX/ETX.
 			done, err := r.done()
 			if err != nil {
 				return 0, err
@@ -81,6 +112,7 @@ func (r *LogReader) read(l []byte) (int, error) {
 			if done {
 				return 0, io.EOF
 			}
+		}
 		return 0, io.ErrNoProgress
 	}
 

vendor/vendor.json

@@ -1804,10 +1804,10 @@
 			"revisionTime": "2018-07-12T07:51:27Z"
 		},
 		{
-			"checksumSHA1": "9EZuhp7LWTAVsTDpP9DzajjmJxg=",
+			"checksumSHA1": "bZzpA/TNWpYzVGIFEWLpOz7AXCU=",
 			"path": "github.com/hashicorp/go-tfe",
-			"revision": "ed986a3b38aba4630ca6ae7dbc876eb0d0c95c57",
-			"revisionTime": "2018-10-10T13:21:10Z"
+			"revision": "937a37d8d40df424b1e47fe05de0548727154efc",
+			"revisionTime": "2018-10-11T20:03:11Z"
 		},
 		{
 			"checksumSHA1": "85XUnluYJL7F55ptcwdmN8eSOsk=",