Disable telemetry

We are removing all of the telemetry code as it is not needed, and being
on by default it may be contrary to CNCF policies around telemetry.

* remove check function

With no telemetry, there's no need for these function implementations or
this syscall in this package anymore.

We need to preserve the cadence of checkpoint.go to avoid disturbing any
thing that would constitute a breaking change, but basically all of the
underlying behavior of check can go away, since every Flux v1 version is
out of date every time, we don't need any remote service or lookup to
tell if an update is needed. (It's always needed)

Users should follow the link to upgrade (eg. the migration guide)

Signed-off-by: Kingdon Barrett <kingdon@weave.works>

cmd/fluxd/main.go

@@ -640,10 +640,10 @@ func main() {
 	// until we have failed or succeeded.
 	updateCheckLogger := log.With(logger, "component", "checkpoint")
 	checkpointFlags := map[string]string{
-		"cluster-version": clusterVersion,
-		"git-configured":  strconv.FormatBool(*gitURL != ""),
+		"cluster-version": "XXXXX",
+		"git-configured":  "XXXXX",
 	}
-	checkpoint.CheckForUpdates(product, version, checkpointFlags, updateCheckLogger)
+	checkpoint.CheckForUpdates(product, "XXXXX", checkpointFlags, updateCheckLogger)
 
 	gitRemote := git.Remote{URL: *gitURL}
 	gitConfig := git.Config{

go.mod

@@ -58,7 +58,6 @@ require (
 	github.com/stretchr/testify v1.8.0
 	// Latest versions of github.com/weaveworks/common are not supporterd by Flux.
 	github.com/weaveworks/common v0.0.0-20190410110702-87611edc252e
-	github.com/weaveworks/go-checkpoint v0.0.0-20220223124739-fd9899e2b4f2
 	github.com/whilp/git-urls v1.0.0
 	github.com/xeipuuv/gojsonschema v1.2.0
 	go.mozilla.org/sops/v3 v3.7.3

pkg/checkpoint/checkpoint.go

@@ -4,39 +4,62 @@ import (
 	"time"
 
 	"github.com/go-kit/kit/log"
-	"github.com/weaveworks/go-checkpoint"
 )
 
 const (
 	versionCheckPeriod = 6 * time.Hour
 )
 
-func CheckForUpdates(product, version string, extra map[string]string, logger log.Logger) *checkpoint.Checker {
-	handleResponse := func(r *checkpoint.CheckResponse, err error) {
-		if err != nil {
-			logger.Log("err", err)
-			return
-		}
-		if r.Outdated {
-			logger.Log("msg", "update available", "latest", r.CurrentVersion, "URL", r.CurrentDownloadURL)
-			return
-		}
-		logger.Log("msg", "up to date", "latest", r.CurrentVersion)
+func CheckForUpdates(product, version string, extra map[string]string, logger log.Logger) *checker {
+	handleResponse := func() {
+		logger.Log("msg", "update available", "latest", "v0.33.0", "URL", "https://fluxcd.io/docs/migration/")
 	}
 
 	flags := map[string]string{
-		"kernel-version": getKernelVersion(),
+		"kernel-version": "XXXXX",
 	}
 	for k, v := range extra {
 		flags[k] = v
 	}
 
-	params := checkpoint.CheckParams{
+	params := checkParams{
 		Product:       product,
 		Version:       version,
 		SignatureFile: "",
 		Flags:         flags,
 	}
 
-	return checkpoint.CheckInterval(&params, versionCheckPeriod, handleResponse)
+	return checkInterval(&params, versionCheckPeriod, handleResponse)
+}
+
+func checkInterval(p *checkParams, interval time.Duration,
+	cb func()) *checker {
+
+	state := &checker{
+		doneCh: make(chan struct{}),
+	}
+
+	if isCheckDisabled() {
+		return state
+	}
+
+	go func() {
+		cb()
+
+		for {
+			after := randomStagger(interval)
+			state.nextCheckAtLock.Lock()
+			state.nextCheckAt = time.Now().Add(after)
+			state.nextCheckAtLock.Unlock()
+
+			select {
+			case <-time.After(after):
+				cb()
+			case <-state.doneCh:
+				return
+			}
+		}
+	}()
+
+	return state
 }

pkg/checkpoint/types.go

@@ -0,0 +1,31 @@
+package checkpoint
+
+import (
+	"sync"
+	"time"
+)
+
+type flag struct {
+	Key   string
+	Value string
+}
+
+type checkParams struct {
+	Product       string
+	Version       string
+	Flags         map[string]string
+	ExtraFlags    func() []flag
+	Arch          string
+	OS            string
+	Signature     string
+	SignatureFile string
+	CacheFile     string
+	CacheDuration time.Duration
+	Force         bool
+}
+
+type checker struct {
+	doneCh          chan struct{}
+	nextCheckAt     time.Time
+	nextCheckAtLock sync.RWMutex
+}

pkg/checkpoint/util.go

@@ -0,0 +1,16 @@
+package checkpoint
+
+import (
+	mrand "math/rand"
+	"os"
+	"time"
+)
+
+func isCheckDisabled() bool {
+	return os.Getenv("CHECKPOINT_DISABLE") != ""
+}
+
+func randomStagger(interval time.Duration) time.Duration {
+	stagger := time.Duration(mrand.Int63()) % (interval / 2)
+	return 3*(interval/4) + stagger
+}