Make version check run as best effort

cmd/root.go

@@ -23,6 +23,7 @@ import (
  "strconv"
  "time"
 
+ "github.com/Masterminds/semver/v3"
  "github.com/apex/log"
  "github.com/apex/log/handlers/json"
  "github.com/apex/log/handlers/multi"
@@ -43,10 +44,12 @@ var outputFormat string
 const FSOC_NO_VERSION_CHECK = "FSOC_NO_VERSION_CHECK"
 
 const (
- secondsInDay = 24 * 60 * 60
- timestampFileName = "fsoc.timestamp"
+ versionCheckInterval = 24 * 60 * 60 // 1 day
+ versionFileName = "fsoc.latest-version"
 )
 
+var updateChannel chan *semver.Version
+
 // rootCmd represents the base command when called without any subcommands
 // TODO: replace github link "for more info" with Cisco DevNet link for fsoc once published
 var rootCmd = &cobra.Command{
@@ -77,6 +80,7 @@ For more information, see https://github.com/cisco-open/fsoc
 
 NOTE: fsoc is in alpha; breaking changes may occur`,
  PersistentPreRun: preExecHook,
+ PersistentPostRun: postExecHook,
  TraverseChildren: true,
  DisableAutoGenTag: true,
 }
@@ -223,38 +227,27 @@ func preExecHook(cmd *cobra.Command, args []string) {
  }
 
  // Do version checking
- noVerCheck, _ := cmd.Flags().GetBool("no-version-check")
- envNoVerCheck, err := strconv.ParseBool(os.Getenv(FSOC_NO_VERSION_CHECK))
- if err != nil {
- envNoVerCheck = false
- }
- noVerCheck = noVerCheck || envNoVerCheck
- updateCheckNeeded := !noVerCheck && int(time.Now().Unix())-getLastVersionCheckTime() > secondsInDay
- if updateCheckNeeded {
- func() {
- defer func() {
- if r := recover(); r != nil {
- log.Warnf("Failed to perform version check")
- }
- }()
- var updateSemVar = version.CheckForUpdate()
- version.CompareAndLogVersions(updateSemVar)
- // Create new timestamp file (only if version was checked)
- _ = os.Remove(getTimestampFilePath())
- _, err := os.Create(getTimestampFilePath())
- if err != nil {
- log.Warnf("failed to create version check timestamp file: %v", err)
- }
+ if versionCheckEnabled(cmd) && int(time.Now().Unix())-getLastVersionCheckTime() > versionCheckInterval {
+ updateChannel = make(chan *semver.Version)
+ go func() {
+ updateChannel <- version.CheckForUpdate()
  }()
  }
 }
 
-func getTimestampFilePath() string {
- return os.TempDir() + "/" + timestampFileName
+func postExecHook(cmd *cobra.Command, args []string) {
+ latestVersion := completeVersionCheck()
+ if versionCheckEnabled(cmd) {
+ reportNewVersionAvailable(latestVersion)
+ }
+}
+
+func getVersionFilePath() string {
+ return os.TempDir() + "/" + versionFileName
 }
 
 func getLastVersionCheckTime() int {
- fInfo, err := os.Stat(getTimestampFilePath())
+ fInfo, err := os.Stat(getVersionFilePath())
  if err != nil {
  return 0 // makes it a really old file
  }
@@ -270,3 +263,75 @@ func isCompletionCommand(cmd *cobra.Command) bool {
  p := cmd.Parent()
  return (p != nil && p.Name() == "completion")
 }
+
+func versionCheckEnabled(cmd *cobra.Command) bool {
+ noVerCheck, _ := cmd.Flags().GetBool("no-version-check")
+ if noVerCheck {
+ return false
+ }
+ envNoVerCheck, err := strconv.ParseBool(os.Getenv(FSOC_NO_VERSION_CHECK))
+ if err == nil && envNoVerCheck {
+ return false
+ }
+ return true
+}
+
+// Complete the version check if it was started, in a non-blocking way. Returns the latest version if we could get it
+func completeVersionCheck() (latestVersion *semver.Version) {
+ if updateChannel == nil {
+ return nil // nothing to do
+ }
+
+ // See if we have a result, but don't block on it
+ select {
+ case latestVersion = <-updateChannel:
+ if latestVersion != nil {
+ // We got the latest version, store it in a file
+ f, err := os.Create(getVersionFilePath())
+ if err != nil {
+ log.Errorf("failed to create version file: %v", err)
+ } else {
+ _, err = f.WriteString(latestVersion.String())
+ if err != nil {
+ log.Errorf("failed to write to version file: %v", err)
+ }
+ f.Close()
+ }
+ }
+ default:
+ log.Infof("Did not finish checking for latest version in time, will try next time")
+ }
+
+ return latestVersion
+}
+
+func reportNewVersionAvailable(latestVersion *semver.Version) {
+ // If we did not do a successful version check, try to read from file, if it exists
+ if latestVersion == nil {
+ _, err := os.Stat(getVersionFilePath())
+ if err != nil {
+ return // no file, no version
+ }
+ f, err := os.Open(getVersionFilePath())
+ if err != nil {
+ log.Warnf("failed to open fsoc version file: %v", err)
+ } else {
+ defer f.Close()
+ // Read version from file
+ var versionString string
+ _, err = fmt.Fscanf(f, "%s", &versionString)
+ if err != nil {
+ log.Warnf("failed to read from fsoc version file: %v", err)
+ } else {
+ latestVersion, err = semver.NewVersion(versionString)
+ if err != nil {
+ log.Warnf("failed to parse fsoc version file: %v", err)
+ }
+ }
+ }
+ }
+ if latestVersion != nil {
+ version.CompareAndLogVersions(latestVersion)
+ }
+
+}