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[feat] Standalone control commands (slimtoolkit#596)
To control sensor execution when running in the standalone mode. This PR ships the machinery and the very first command: ``` /opt/_slim/sensor control stop-target-app ``` The command writes to the commands FIFO file and then waits for the StopMonitorDone event to show up in the events file. Signed-off-by: Ivan Velichko <iximiuz@gmail.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,7 @@ | ||
| package control | ||
|
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| type Command string | ||
|
|
||
| const ( | ||
| StopTargetAppCommand Command = "stop-target-app" | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| package control | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "context" | ||
| "io" | ||
| "os" | ||
| "syscall" | ||
| "time" | ||
|
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| log "github.com/sirupsen/logrus" | ||
|
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| "github.com/docker-slim/docker-slim/pkg/ipc/command" | ||
| ) | ||
|
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| func HandleControlCommandQueue(ctx context.Context, commandsFile string, commandCh chan command.Message) { | ||
| fifoPath := getFIFOPath(commandsFile) | ||
| if !createFIFOIfNeeded(fifoPath) { | ||
| return | ||
| } | ||
| go func() { | ||
| <-ctx.Done() | ||
| os.Remove(fifoPath) | ||
| }() | ||
|
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| processCommandsFromFIFO(ctx, fifoPath, commandCh) | ||
| } | ||
|
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| func getFIFOPath(commandsFile string) string { | ||
| return commandsFile + ".fifo" | ||
| } | ||
|
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| func createFIFOIfNeeded(fifoPath string) bool { | ||
| if _, err := os.Stat(fifoPath); os.IsNotExist(err) { | ||
| if err = syscall.Mkfifo(fifoPath, 0600); err != nil { | ||
| log.Warnf("sensor: control commands not activated - cannot create %s FIFO file: %s", fifoPath, err) | ||
| return false | ||
| } | ||
| log.Info("sensor: control commands activated") | ||
| } | ||
| return true | ||
| } | ||
|
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| func processCommandsFromFIFO(ctx context.Context, fifoPath string, commandCh chan command.Message) { | ||
| for ctx.Err() == nil { | ||
| fifo, err := os.Open(fifoPath) | ||
| if err != nil { | ||
| log.Debugf("sensor: control commands - cannot open %s FIFO file: %s", fifoPath, err) | ||
| time.Sleep(1 * time.Second) | ||
| continue | ||
| } | ||
|
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| readAndHandleCommands(fifo, commandCh) | ||
| fifo.Close() | ||
| } | ||
| } | ||
|
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| func readAndHandleCommands(fifo *os.File, commandCh chan command.Message) { | ||
| reader := bufio.NewReader(fifo) | ||
| for { | ||
| line, err := reader.ReadBytes('\n') | ||
| if len(line) > 0 { | ||
| handleCommand(line, commandCh) | ||
| } | ||
|
|
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| if err == io.EOF { | ||
| return | ||
| } | ||
| if err != nil { | ||
| log.Warnf("sensor: error reading control command: %s", err) | ||
| time.Sleep(1 * time.Second) | ||
| } | ||
| } | ||
| } | ||
|
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| func handleCommand(line []byte, commandCh chan command.Message) { | ||
| msg, err := command.Decode(line) | ||
| if err == nil { | ||
| commandCh <- msg | ||
| } else { | ||
| log.Warnf("sensor: cannot decode control command %#q: %s", line, err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| package control | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "context" | ||
| "fmt" | ||
| "os" | ||
| "strings" | ||
| "time" | ||
|
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| "github.com/docker-slim/docker-slim/pkg/ipc/command" | ||
| "github.com/docker-slim/docker-slim/pkg/ipc/event" | ||
| "github.com/docker-slim/docker-slim/pkg/util/fsutil" | ||
| ) | ||
|
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| func ExecuteStopTargetAppCommand( | ||
| ctx context.Context, | ||
| commandsFile string, | ||
| eventsFile string, | ||
| ) error { | ||
| msg, err := command.Encode(&command.StopMonitor{}) | ||
| if err != nil { | ||
| return fmt.Errorf("cannot encode stop command: %w", err) | ||
| } | ||
|
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| if err := fsutil.AppendToFile(getFIFOPath(commandsFile), msg, false); err != nil { | ||
| return fmt.Errorf("cannot append stop command to FIFO file: %w", err) | ||
| } | ||
|
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| if err := waitForEvent(ctx, eventsFile, event.StopMonitorDone); err != nil { | ||
| return fmt.Errorf("waiting for %v event: %w", event.StopMonitorDone, err) | ||
| } | ||
|
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| return nil | ||
| } | ||
|
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| func waitForEvent(ctx context.Context, eventsFile string, target event.Type) error { | ||
| for ctx.Err() == nil { | ||
| found, err := findEvent(eventsFile, target) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
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| if found { | ||
| return nil | ||
| } | ||
|
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| time.Sleep(1 * time.Second) | ||
| } | ||
|
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| return ctx.Err() | ||
| } | ||
|
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| func findEvent(eventsFile string, target event.Type) (bool, error) { | ||
| file, err := os.Open(eventsFile) | ||
| if err != nil { | ||
| return false, err | ||
| } | ||
| defer file.Close() | ||
|
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| scanner := bufio.NewScanner(file) | ||
| for scanner.Scan() { | ||
| line := scanner.Text() | ||
| // A bit hacky - we probably need to parse the event struct properly. | ||
| if strings.Contains(line, string(target)) { | ||
| return true, nil | ||
| } | ||
| } | ||
|
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| if scanner.Err() != nil { | ||
| return false, scanner.Err() | ||
| } | ||
|
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| return false, nil | ||
| } |
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