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Implement virt-tail in golang adding custom logic to quickly terminate it when the serial socket get closed or a termination signalling file got created by virt-launcher-monitor. Signed-off-by: Simone Tiraboschi <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,21 @@ | ||
| load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library") | ||
|
|
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| go_library( | ||
| name = "go_default_library", | ||
| srcs = ["main.go"], | ||
| importpath = "kubevirt.io/kubevirt/cmd/virt-tail", | ||
| visibility = ["//visibility:private"], | ||
| deps = [ | ||
| "//staging/src/kubevirt.io/client-go/log:go_default_library", | ||
| "//vendor/github.com/fsnotify/fsnotify:go_default_library", | ||
| "//vendor/github.com/nxadm/tail:go_default_library", | ||
| "//vendor/github.com/spf13/pflag:go_default_library", | ||
| "//vendor/golang.org/x/sync/errgroup:go_default_library", | ||
| ], | ||
| ) | ||
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| go_binary( | ||
| name = "virt-tail", | ||
| embed = [":go_default_library"], | ||
| visibility = ["//visibility:public"], | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,230 @@ | ||
| /* | ||
| * This file is part of the KubeVirt project | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| * | ||
| * Copyright 2023 Red Hat, Inc. | ||
| * | ||
| */ | ||
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| package main | ||
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| import ( | ||
| "context" | ||
| "errors" | ||
| goflag "flag" | ||
| "fmt" | ||
| "os" | ||
| "os/signal" | ||
| "path/filepath" | ||
| "strconv" | ||
| "strings" | ||
| "time" | ||
|
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| "github.com/fsnotify/fsnotify" | ||
| "github.com/nxadm/tail" | ||
| "github.com/spf13/pflag" | ||
| "golang.org/x/sync/errgroup" | ||
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| "kubevirt.io/client-go/log" | ||
| ) | ||
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| type TermFileError struct{} | ||
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| func (m *TermFileError) Error() string { | ||
| return "termFile got detected" | ||
| } | ||
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| type VirtTail struct { | ||
| ctx context.Context | ||
| logFile string | ||
| g *errgroup.Group | ||
| } | ||
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| func (v *VirtTail) checkFile(socketFile string) bool { | ||
| _, err := os.Stat(socketFile) | ||
| return !os.IsNotExist(err) | ||
| } | ||
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| func (v *VirtTail) tailLogs() error { | ||
| t, err := tail.TailFile(v.logFile, tail.Config{ | ||
| Follow: true, | ||
| CompleteLines: true, | ||
| MustExist: false, | ||
| ReOpen: true, | ||
| Logger: tail.DiscardingLogger, | ||
| }) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer func() { | ||
| serr := t.Stop() | ||
| if serr != nil { | ||
| log.Log.V(3).Infof("tail error: %v", serr) | ||
| } | ||
| t.Cleanup() | ||
| }() | ||
|
|
||
| for { | ||
| select { | ||
| case line, ok := <-t.Lines: | ||
| if !ok { | ||
| log.Log.V(4).Info("tail error: line not ok") | ||
| } else if line != nil { | ||
| if line.Err != nil { | ||
| log.Log.V(3).Infof("tail error: %v", line.Err) | ||
| } else { | ||
| fmt.Println(line.Text) | ||
| } | ||
| } | ||
| case <-v.ctx.Done(): | ||
| return v.ctx.Err() | ||
| } | ||
| } | ||
| } | ||
|
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| func (v *VirtTail) watchFS() error { | ||
| socketFile := strings.TrimSuffix(v.logFile, "-log") | ||
| termFile := v.logFile + "-sigTerm" | ||
| socketExists := v.checkFile(socketFile) | ||
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| watcher, err := fsnotify.NewWatcher() | ||
| if err != nil { | ||
| log.Log.V(3).Infof("watcher error: %v", err) | ||
| return err | ||
| } | ||
| defer watcher.Close() | ||
|
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||
| // Add a path. | ||
| dirPath := filepath.Dir(v.logFile) | ||
| found := false | ||
| i := 0 | ||
| for i < 30 && !found { | ||
| i = i + 1 | ||
| if _, derr := os.Stat(dirPath); derr == nil { | ||
| found = true | ||
| if err = watcher.Add(dirPath); err != nil { | ||
| log.Log.V(3).Infof("watcher error: %v - %s", err, dirPath) | ||
| return err | ||
| } | ||
| } else { | ||
| time.Sleep(100 * time.Millisecond) | ||
| } | ||
| } | ||
| if !found { | ||
| rerr := errors.New("expected directory is still not ready") | ||
| log.Log.V(3).Infof("watchFS error: %v", rerr) | ||
| return rerr | ||
| } | ||
|
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| // initial timeout for serial console socket creation | ||
| const initialSocketTimeout = time.Second * 20 | ||
| socketCheckCh := make(chan int) | ||
| time.AfterFunc(initialSocketTimeout, func() { | ||
| socketCheckCh <- 1 | ||
| }) | ||
|
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||
| // Start listening for events. | ||
| for { | ||
| select { | ||
| case <-socketCheckCh: | ||
| if !socketExists { | ||
| if socketExists = v.checkFile(socketFile); !socketExists { | ||
| rerr := errors.New("socketFile is still not ready") | ||
| log.Log.V(3).Infof("watchFS error: %v", rerr) | ||
| return rerr | ||
| } | ||
| } | ||
| if v.checkFile(termFile) { | ||
| log.Log.V(3).Infof("watchFS error: termFile was already there") | ||
| return &TermFileError{} | ||
| } | ||
| case event := <-watcher.Events: | ||
| if event.Has(fsnotify.Create) { | ||
| if event.Name == termFile { | ||
| // termination file got created, we should quickly terminate | ||
| terr := &TermFileError{} | ||
| log.Log.V(3).Infof("watchFS error: %v", terr) | ||
| return terr | ||
| } else if event.Name == socketFile { | ||
| // socket file got created | ||
| socketExists = true | ||
| } | ||
| } else if event.Has(fsnotify.Remove) { | ||
| if event.Name == socketFile { | ||
| // socket file got deleted, we should quickly terminate | ||
| rerr := errors.New("socketFile got removed") | ||
| log.Log.V(3).Infof("watchFS error: %v", rerr) | ||
| return rerr | ||
| } | ||
| } | ||
| case werr := <-watcher.Errors: | ||
| log.Log.V(3).Infof("watcher error: %v", werr) | ||
| return werr | ||
| case <-v.ctx.Done(): | ||
| return v.ctx.Err() | ||
| } | ||
| } | ||
| } | ||
|
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| func main() { | ||
| // set new default verbosity, was set to 0 by glog | ||
| goflag.Set("v", "2") | ||
| pflag.CommandLine.AddGoFlag(goflag.CommandLine.Lookup("v")) | ||
| pflag.CommandLine.ParseErrorsWhitelist = pflag.ParseErrorsWhitelist{UnknownFlags: true} | ||
| logFile := pflag.String("logfile", "", "path of the logfile to be streamed") | ||
| pflag.Parse() | ||
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| log.InitializeLogging("virt-tail") | ||
| setTailLogverbosity() | ||
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| if logFile == nil || *logFile == "" { | ||
| log.Log.V(3).Infof("logfile flags must be provided") | ||
| os.Exit(1) | ||
| } | ||
|
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| // Create context that listens for the interrupt signal from the container runtime. | ||
| ctx, _ := signal.NotifyContext(context.Background(), os.Interrupt) | ||
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| g, gctx := errgroup.WithContext(ctx) | ||
|
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| v := &VirtTail{ | ||
| ctx: gctx, | ||
| logFile: *logFile, | ||
| g: g, | ||
| } | ||
|
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| g.Go(v.tailLogs) | ||
| g.Go(v.watchFS) | ||
|
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| // wait for all errgroup goroutines | ||
| if err := g.Wait(); err != nil { | ||
| // Exit cleanly on clean termination errors | ||
| if !(errors.Is(err, context.Canceled) || errors.Is(err, &TermFileError{})) { | ||
| log.Log.V(3).Infof("received error: %v", err) | ||
| os.Exit(1) | ||
| } | ||
| } | ||
| } | ||
|
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| func setTailLogverbosity() { | ||
| // check if virt-launcher verbosity should be changed | ||
| if verbosityStr, ok := os.LookupEnv("VIRT_LAUNCHER_LOG_VERBOSITY"); ok { | ||
| if verbosity, err := strconv.Atoi(verbosityStr); err == nil { | ||
| log.Log.SetVerbosityLevel(verbosity) | ||
| log.Log.V(3).Infof("set log verbosity to %d", verbosity) | ||
| } else { | ||
| log.Log.Warningf("failed to set log verbosity. The value of logVerbosity label should be an integer, got %s instead.", verbosityStr) | ||
| } | ||
| } | ||
| } |
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