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rewrote REQCliCommandCont pipe reading

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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 #### 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. 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.

46
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)) ctx, cancel := context.WithTimeout(proc.ctx, time.Second*time.Duration(message.MethodTimeout))
outCh := make(chan []byte) outCh := make(chan []byte)
errCh := make(chan string)
proc.processes.wg.Add(1) proc.processes.wg.Add(1)
go func() { go func() {
@ -1440,9 +1441,7 @@ func (m methodREQCliCommandCont) handler(proc process, message Message, node str
if err != nil { if err != nil {
er := fmt.Errorf("error: methodREQCliCommandCont: cmd.StdoutPipe failed : %v, methodArgs: %v", err, message.MethodArgs) 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) sendErrorLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
log.Printf("%v\n", er) log.Printf("error: %v\n", er)
log.Printf("error: %v\n", err)
} }
ErrorReader, err := cmd.StderrPipe() 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) 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) sendErrorLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
log.Printf("%v\n", er) log.Printf("%v\n", er)
log.Printf("error: %v\n", err)
} }
if err := cmd.Start(); err != nil { 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() { go func() {
errCh := make(chan string, 1)
scanner := bufio.NewScanner(ErrorReader) scanner := bufio.NewScanner(ErrorReader)
for scanner.Scan() { for scanner.Scan() {
select { errCh <- scanner.Text()
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
}
} }
}() }()
go func() {
scanner := bufio.NewScanner(outReader) scanner := bufio.NewScanner(outReader)
for scanner.Scan() { for scanner.Scan() {
select { outCh <- []byte(scanner.Text() + "\n")
case outCh <- []byte(scanner.Text() + "\n"):
case <-ctx.Done():
return
} }
}()
// 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) sendInfoLogMessage(proc.configuration, proc.processes.metrics, proc.toRingbufferCh, proc.node, er)
return return
case out := <-outCh: case out := <-outCh:
// Prepare and queue for sending a new message with the output
// of the action executed.
newReplyMessage(proc, message, out) newReplyMessage(proc, message, out)
case out := <-errCh:
newReplyMessage(proc, message, []byte(out))
} }
} }
}() }()