chore: improve log handling when container is stopping (#2601)

* Unindent to improve readability

* Proper error check for net.ErrClosed

* Use switch for readability

* Return cleanly on io.EOF

docker.go

@@ -12,6 +12,7 @@ import (
  "fmt"
  "io"
  "io/fs"
+ "net"
  "net/url"
  "os"
  "path/filepath"
@@ -752,57 +753,59 @@ func (c *DockerContainer) startLogProduction(ctx context.Context, opts ...LogPro
  c.logProductionError <- r.Close()
  return
  default:
- h := make([]byte, 8)
- _, err := io.ReadFull(r, h)
- if err != nil {
- // proper type matching requires https://go-review.googlesource.com/c/go/+/250357/ (go 1.16)
- if strings.Contains(err.Error(), "use of closed network connection") {
- now := time.Now()
- since = fmt.Sprintf("%d.%09d", now.Unix(), int64(now.Nanosecond()))
- goto BEGIN
- }
- if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled) {
- // Probably safe to continue here
- continue
- }
+ }
+ h := make([]byte, 8)
+ _, err := io.ReadFull(r, h)
+ if err != nil {
+ switch {
+ case err == io.EOF:
+ // No more logs coming
+ case errors.Is(err, net.ErrClosed):
+ now := time.Now()
+ since = fmt.Sprintf("%d.%09d", now.Unix(), int64(now.Nanosecond()))
+ goto BEGIN
+ case errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled):
+ // Probably safe to continue here
+ continue
+ default:
  _, _ = fmt.Fprintf(os.Stderr, "container log error: %+v. %s", err, logStoppedForOutOfSyncMessage)
  // if we would continue here, the next header-read will result into random data...
- return
  }
+ return
+ }
 
-  count := binary.BigEndian.Uint32(h[4:])
-  if count == 0 {
-  continue
-  }
-  logType := h[0]
-  if logType > 2 {
-  _, _ = fmt.Fprintf(os.Stderr, "received invalid log type: %d", logType)
-  // sometimes docker returns logType = 3 which is an undocumented log type, so treat it as stdout
-  logType = 1
-  }
+ count := binary.BigEndian.Uint32(h[4:])
+ if count == 0 {
+ continue
+ }
+ logType := h[0]
+ if logType > 2 {
+ _, _ = fmt.Fprintf(os.Stderr, "received invalid log type: %d", logType)
+ // sometimes docker returns logType = 3 which is an undocumented log type, so treat it as stdout
+ logType = 1
+ }
 
-  // a map of the log type --> int representation in the header, notice the first is blank, this is stdin, but the go docker client doesn't allow following that in logs
-  logTypes := []string{"", StdoutLog, StderrLog}
+ // a map of the log type --> int representation in the header, notice the first is blank, this is stdin, but the go docker client doesn't allow following that in logs
+ logTypes := []string{"", StdoutLog, StderrLog}
 
- b := make([]byte, count)
- _, err = io.ReadFull(r, b)
- if err != nil {
- // TODO: add-logger: use logger to log out this error
- _, _ = fmt.Fprintf(os.Stderr, "error occurred reading log with known length %s", err.Error())
- if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled) {
- // Probably safe to continue here
- continue
- }
- // we can not continue here as the next read most likely will not be the next header
- _, _ = fmt.Fprintln(os.Stderr, logStoppedForOutOfSyncMessage)
- return
- }
- for _, c := range c.consumers {
- c.Accept(Log{
- LogType: logTypes[logType],
- Content: b,
- })
+ b := make([]byte, count)
+ _, err = io.ReadFull(r, b)
+ if err != nil {
+ // TODO: add-logger: use logger to log out this error
+ _, _ = fmt.Fprintf(os.Stderr, "error occurred reading log with known length %s", err.Error())
+ if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled) {
+ // Probably safe to continue here
+ continue
  }
+ // we can not continue here as the next read most likely will not be the next header
+ _, _ = fmt.Fprintln(os.Stderr, logStoppedForOutOfSyncMessage)
+ return
+ }
+ for _, c := range c.consumers {
+ c.Accept(Log{
+ LogType: logTypes[logType],
+ Content: b,
+ })
  }
  }
  }()