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rewrote REQCliCommandCont pipe reading

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This commit is contained in:
postmannen 2021-09-27 14:45:49 +02:00
parent f77de0d17d
commit b7c12d27d7
2 changed files with 30 additions and 27 deletions
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7
README.md
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@ -354,6 +354,13 @@ Will run the command given, and return the stdout output of the command continou
]
```
**NB**: A github issue is filed on not killing all child processes when using pipes <https://github.com/golang/go/issues/23019>. This is relevant for this request type.
TODO: Check in later if there are any progress on the issue.
When testing the problem seems to appear when using sudo, or tcpdump without
the -l option. So for now, don't use sudo, and remember to use -l with tcpdump
which makes stdout line buffered.
#### REQTailFile
Tail log files on some node, and get the result for each new line read sent back in a reply message. Uses the methodTimeout to define for how long the command will run.

50
requests.go
View file

@ -1427,6 +1427,7 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
ctx, cancel := context.WithTimeout(proc.ctx, time.Second*time.Duration(message.MethodTimeout))
outCh := make(chan []byte)
errCh := make(chan string)
proc.processes.wg.Add(1)
go func() {
@ -1440,9 +1441,7 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
if err != nil {
er := fmt.Errorf("error: methodREQCliCommandCont: cmd.StdoutPipe failed : %v, methodArgs: %v", err, message.MethodArgs)
sendErrorLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
log.Printf("%v\n", er)
log.Printf("error: %v\n", err)
log.Printf("error: %v\n", er)
}
ErrorReader, err := cmd.StderrPipe()
@ -1450,8 +1449,6 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
er := fmt.Errorf("error: methodREQCliCommandCont: cmd.StderrPipe failed : %v, methodArgs: %v", err, message.MethodArgs)
sendErrorLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
log.Printf("%v\n", er)
log.Printf("error: %v\n", err)
}
if err := cmd.Start(); err != nil {
@ -1461,34 +1458,33 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
}
// Also send error messages that might happen during the time
// cmd.Start runs.
// Putting the scanner.Text value on a channel so we can make
// the scanner non-blocking, and also check context cancelation.
go func() {
errCh := make(chan string, 1)
scanner := bufio.NewScanner(ErrorReader)
for scanner.Scan() {
select {
case errCh <- scanner.Text():
er := fmt.Errorf("error: methodREQCliCommandCont: cmd.Start failed : %v, methodArgs: %v, error_output: %v", err, message.MethodArgs, <-errCh)
sendErrorLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
log.Printf("%v\n", er)
case <-ctx.Done():
return
}
errCh <- scanner.Text()
}
}()
scanner := bufio.NewScanner(outReader)
for scanner.Scan() {
select {
case outCh <- []byte(scanner.Text() + "\n"):
case <-ctx.Done():
return
go func() {
scanner := bufio.NewScanner(outReader)
for scanner.Scan() {
outCh <- []byte(scanner.Text() + "\n")
}
}()
// NB: sending cancel to command context, so processes are killed.
// A github issue is filed on not killing all child processes when using pipes:
// https://github.com/golang/go/issues/23019
// TODO: Check in later if there are any progress on the issue.
// When testing the problem seems to appear when using sudo, or tcpdump without
// the -l option. So for now, don't use sudo, and remember to use -l with tcpdump
// which makes stdout line buffered.
<-ctx.Done()
cancel()
if err := cmd.Wait(); err != nil {
log.Printf(" --------------- * error: REQCliCommandCont: cmd.Wait: %v\n", err)
}
}()
@ -1502,9 +1498,9 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
sendInfoLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
return
case out := <-outCh:
// Prepare and queue for sending a new message with the output
// of the action executed.
newReplyMessage(proc, message, out)
case out := <-errCh:
newReplyMessage(proc, message, []byte(out))
}
}
}()