[Heartbeat] Defer monitor / ICMP errors to monitor runtime / ES (#29413)

This PR generally improves the error behavior of all monitors, and some specific ICMP related errors as well. These two items are combined in one PR because the general theme here is improving the ICMP error experience, and improving ICMP required improving all monitors.

Fixes #29346
and incremental progress toward #29692

General monitor improvements
Generally speaking, per #29692 we are trying to send monitor output to ES wherever possible. With this PR we now send any monitor initialization errors (such as a lack of ICMP kernel capabilities) during monitor creation to ES. We do this by allowing the monitor to initialize and run on schedule, even though we know it will always send the same error message. This lets users more easily debug issues in Kibana.

ICMP Specific Improvement
This PR also Removes broken a IP capability check that caused heartbeat to be unable to start. We now just rely on return codes from attempts to actually send packets. This is the more specific fix for #29346 . I was not able to exactly reproduce the exact customer reported issue, where the user somehow disabled ipv6 in a way that the ICMP loop that I can't exactly reproduce. I tried disabling ipv6 fully with sudo sysctl net.ipv6.conf.all.disable_ipv6=1 but that didn't yield the error in #29346

The logic is now simplified, there's no truly reliable way to know if you can send an ipv6 (or ipv4) ping before you send it (settings can change at any time! network cards can disappear!), so we just let the error codes happen as the check is executed. This is also generally a better UX in that the errors will now be visible in the Uptime app, not just the logs.

It should be noted that the ipv4 and ipv6 boolean options only are documented to affect how DNS lookups happen. With this change the behavior matches the docs.

Note that ICMP is a bit weird in that there's a single ICMP loop in heartbeat, and all monitors are really just interacting with that.

Removal of .synthetics
This also ignores the .synthetics folder which has been inconvenient for some time for devs, in that it dirties the git path

(cherry picked from commit 616db13)

Author: andrewvc

CHANGELOG.next.asciidoc

@@ -50,6 +50,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 *Heartbeat*
 
 - Fix race condition in http monitors using `mode:all` that can cause crashes. {pull}29697[pull]
+- Fix broken ICMP availability check that prevented heartbeat from starting in rare cases. {pull}29413[pull]
 
 *Metricbeat*
 
@@ -82,6 +83,8 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 
 *Heartbeat*
 
+- More errors are now visible in ES with new logic failing monitors later to ease debugging. {pull}29413[pull]
+
 
 *Metricbeat*
 

heartbeat/monitors/active/icmp/icmp.go

@@ -91,10 +91,6 @@ func (jf *jobFactory) checkConfig() error {
 }
 
 func (jf *jobFactory) makePlugin() (plugin2 plugin.Plugin, err error) {
-	if err := jf.loop.checkNetworkMode(jf.ipVersion); err != nil {
-		return plugin.Plugin{}, err
-	}
-
 	pingFactory := jf.pingIPFactory(&jf.config)
 
 	var j []jobs.Job

heartbeat/monitors/active/icmp/loop.go

@@ -23,7 +23,6 @@ import (
 )
 
 type ICMPLoop interface {
-	checkNetworkMode(mode string) error
 	ping(
 		addr *net.IPAddr,
 		timeout time.Duration,

heartbeat/monitors/active/icmp/stdloop.go

@@ -20,7 +20,6 @@ package icmp
 import (
 	"bytes"
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"math/rand"
 	"net"
@@ -159,29 +158,6 @@ func newICMPLoop() (*stdICMPLoop, error) {
 	return l, nil
 }
 
-func (l *stdICMPLoop) checkNetworkMode(mode string) error {
-	ip4, ip6 := false, false
-	switch mode {
-	case "ip4":
-		ip4 = true
-	case "ip6":
-		ip6 = true
-	case "ip":
-		ip4, ip6 = true, true
-	default:
-		return fmt.Errorf("'%v' is not supported", mode)
-	}
-
-	if ip4 && l.conn4 == nil {
-		return errors.New("failed to initiate IPv4 support. Check log details for permission configuration")
-	}
-	if ip6 && l.conn6 == nil {
-		return errors.New("failed to initiate IPv6 support. Check log details for permission configuration")
-	}
-
-	return nil
-}
-
 func (l *stdICMPLoop) runICMPRecv(conn *icmp.PacketConn, proto int) {
 	for {
 		bytes := make([]byte, 512)
@@ -251,6 +227,14 @@ func (l *stdICMPLoop) ping(
 	timeout time.Duration,
 	interval time.Duration,
 ) (time.Duration, int, error) {
+	isIPv6 := addr.IP.To4() == nil
+	if isIPv6 && l.conn6 == nil {
+		return -1, -1, fmt.Errorf("cannot ping IPv6 address '%s', no IPv6 connection available", addr)
+	}
+	if !isIPv6 && l.conn4 == nil {
+		return -1, -1, fmt.Errorf("cannot ping IPv4 address '%s', no IPv4 connection available", addr)
+	}
+
 	var err error
 	toTimer := time.NewTimer(timeout)
 	defer toTimer.Stop()
@@ -379,7 +363,7 @@ func (l *stdICMPLoop) sendEchoRequest(addr *net.IPAddr) (*requestContext, error)
 
 	_, err := conn.WriteTo(encoded, addr)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("could not write to conn: %w", err)
 	}
 
 	ctx.ts = ts

heartbeat/monitors/factory_test.go

@@ -149,7 +149,7 @@ func TestPreProcessors(t *testing.T) {
 }
 
 func TestDuplicateMonitorIDs(t *testing.T) {
-	serverMonConf := mockPluginConf(t, "custom", "@every 1ms", "http://example.net")
+	serverMonConf := mockPluginConf(t, "custom", "custom", "@every 1ms", "http://example.net")
 	badConf := mockBadPluginConf(t, "custom", "@every 1ms")
 	reg, built, closed := mockPluginsReg()
 	pipelineConnector := &MockPipelineConnector{}
@@ -190,8 +190,9 @@ func TestDuplicateMonitorIDs(t *testing.T) {
 	m1.Stop()
 	m2.Stop()
 
-	// 3 are counted as built, even the bad config
-	require.Equal(t, 3, built.Load())
+	// Two are counted as built. The bad config is missing a stdfield so it
+	// doesn't complete construction
+	require.Equal(t, 2, built.Load())
 	// Only 2 closes, because the bad config isn't closed
 	require.Equal(t, 2, closed.Load())
 }

heartbeat/monitors/mocks_test.go

@@ -99,24 +99,28 @@ func (pc *MockPipelineConnector) ConnectWith(beat.ClientConfig) (beat.Client, er
 	return c, nil
 }
 
-func mockEventMonitorValidator(id string) validator.Validator {
+func baseMockEventMonitorValidator(id string, name string, status string) validator.Validator {
 	var idMatcher isdef.IsDef
 	if id == "" {
 		idMatcher = isdef.IsStringMatching(regexp.MustCompile(`^auto-test-.*`))
 	} else {
 		idMatcher = isdef.IsEqual(id)
 	}
+	return lookslike.MustCompile(map[string]interface{}{
+		"monitor": map[string]interface{}{
+			"id":          idMatcher,
+			"name":        name,
+			"type":        "test",
+			"duration.us": isdef.IsDuration,
+			"status":      status,
+			"check_group": isdef.IsString,
+		},
+	})
+}
+
+func mockEventMonitorValidator(id string, name string) validator.Validator {
 	return lookslike.Strict(lookslike.Compose(
-		lookslike.MustCompile(map[string]interface{}{
-			"monitor": map[string]interface{}{
-				"id":          idMatcher,
-				"name":        "",
-				"type":        "test",
-				"duration.us": isdef.IsDuration,
-				"status":      "up",
-				"check_group": isdef.IsString,
-			},
-		}),
+		baseMockEventMonitorValidator(id, name, "up"),
 		hbtestllext.MonitorTimespanValidator,
 		hbtest.SummaryChecks(1, 0),
 		lookslike.MustCompile(mockEventCustomFields()),
@@ -151,15 +155,19 @@ func mockPluginBuilder() (plugin.PluginFactory, *atomic.Int, *atomic.Int) {
 				unpacked := struct {
 					URLs []string `config:"urls" validate:"required"`
 				}{}
-				err := config.Unpack(&unpacked)
-				if err != nil {
-					return plugin.Plugin{}, err
-				}
-				j, err := createMockJob()
+
+				// track all closes, even on error
 				closer := func() error {
 					closed.Inc()
 					return nil
 				}
+
+				err := config.Unpack(&unpacked)
+				if err != nil {
+					return plugin.Plugin{DoClose: closer}, err
+				}
+				j, err := createMockJob()
+
 				return plugin.Plugin{Jobs: j, DoClose: closer, Endpoints: 1}, err
 			},
 			Stats: plugin.NewPluginCountersRecorder("test", reg)},
@@ -174,13 +182,15 @@ func mockPluginsReg() (p *plugin.PluginsReg, built *atomic.Int, closed *atomic.I
 	return reg, built, closed
 }
 
-func mockPluginConf(t *testing.T, id string, schedule string, url string) *common.Config {
+func mockPluginConf(t *testing.T, id string, name string, schedule string, url string) *common.Config {
 	confMap := map[string]interface{}{
 		"type":     "test",
 		"urls":     []string{url},
 		"schedule": schedule,
+		"name":     name,
 	}
 
+	// Optional to let us simulate this key missing
 	if id != "" {
 		confMap["id"] = id
 	}
@@ -197,7 +207,6 @@ func mockBadPluginConf(t *testing.T, id string, schedule string) *common.Config
 	confMap := map[string]interface{}{
 		"type":        "test",
 		"notanoption": []string{"foo"},
-		"schedule":    schedule,
 	}
 
 	if id != "" {
@@ -210,8 +219,6 @@ func mockBadPluginConf(t *testing.T, id string, schedule string) *common.Config
 	return conf
 }
 
-// mockInvalidPlugin conf returns a config that invalid at the basic level of
-// what's expected in heartbeat, i.e. no type.
 func mockInvalidPluginConf(t *testing.T) *common.Config {
 	confMap := map[string]interface{}{
 		"hoeutnheou": "oueanthoue",
@@ -222,3 +229,17 @@ func mockInvalidPluginConf(t *testing.T) *common.Config {
 
 	return conf
 }
+
+func mockInvalidPluginConfWithStdFields(t *testing.T, id string, name string, schedule string) *common.Config {
+	confMap := map[string]interface{}{
+		"type":     "test",
+		"id":       id,
+		"name":     name,
+		"schedule": schedule,
+	}
+
+	conf, err := common.NewConfigFrom(confMap)
+	require.NoError(t, err)
+
+	return conf
+}

heartbeat/monitors/monitor.go

@@ -163,13 +163,26 @@ func newMonitorUnsafe(
 		return p.Close()
 	}
 
-	wrappedJobs := wrappers.WrapCommon(p.Jobs, m.stdFields)
-	m.endpoints = p.Endpoints
-
+	// If we've hit an error at this point, still run on schedule, but always return an error.
+	// This way the error is clearly communicated through to kibana.
+	// Since the error is not recoverable in these instances, the user will need to reconfigure
+	// the monitor, which will destroy and recreate it in heartbeat, thus clearing this error.
+	//
+	// Note: we do this at this point, and no earlier, because at a minimum we need the
+	// standard monitor fields (id, name and schedule) to deliver an error to kibana in a way
+	// that it can render.
 	if err != nil {
-		return m, fmt.Errorf("job err %v", err)
+		// Note, needed to hoist err to this scope, not just to add a prefix
+		fullErr := fmt.Errorf("job could not be initialized: %s", err)
+		// A placeholder job that always returns an error
+		p.Jobs = []jobs.Job{func(event *beat.Event) ([]jobs.Job, error) {
+			return nil, fullErr
+		}}
 	}
 
+	wrappedJobs := wrappers.WrapCommon(p.Jobs, m.stdFields)
+	m.endpoints = p.Endpoints
+
 	m.configuredJobs, err = m.makeTasks(config, wrappedJobs)
 	if err != nil {
 		return m, err

heartbeat/monitors/monitor_test.go

@@ -25,19 +25,49 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/elastic/beats/v7/heartbeat/scheduler"
+	"github.com/elastic/beats/v7/libbeat/common"
 	"github.com/elastic/beats/v7/libbeat/monitoring"
+	"github.com/elastic/go-lookslike"
+	"github.com/elastic/go-lookslike/isdef"
 	"github.com/elastic/go-lookslike/testslike"
+	"github.com/elastic/go-lookslike/validator"
 )
 
-func TestMonitor(t *testing.T) {
-	serverMonConf := mockPluginConf(t, "", "@every 1ms", "http://example.net")
+// TestMonitorBasic tests a basic config
+func TestMonitorBasic(t *testing.T) {
+	testMonitorConfig(
+		t,
+		mockPluginConf(t, "myId", "myName", "@every 1ms", "http://example.net"),
+		mockEventMonitorValidator("myId", "myName"),
+	)
+}
+
+// TestMonitorBasic tests a config that errors out at plugin creation, but still has stdfields defined.
+// This should cause the monitor to run, but only produce error documents
+func TestMonitorCfgError(t *testing.T) {
+	testMonitorConfig(
+		t,
+		mockInvalidPluginConfWithStdFields(t, "invalidTestId", "invalidTestName", "@every 10s"),
+		lookslike.Compose(
+			baseMockEventMonitorValidator("invalidTestId", "invalidTestName", "down"),
+			lookslike.MustCompile(common.MapStr{
+				"error": common.MapStr{
+					"message": isdef.IsStringContaining("missing required field"),
+					"type":    "io",
+				},
+			}),
+		),
+	)
+}
+
+func testMonitorConfig(t *testing.T, conf *common.Config, eventValidator validator.Validator) {
 	reg, built, closed := mockPluginsReg()
 	pipelineConnector := &MockPipelineConnector{}
 
 	sched := scheduler.Create(1, monitoring.NewRegistry(), time.Local, nil, false)
 	defer sched.Stop()
 
-	mon, err := newMonitor(serverMonConf, reg, pipelineConnector, sched.Add, nil, false)
+	mon, err := newMonitor(conf, reg, pipelineConnector, sched.Add, nil, false)
 	require.NoError(t, err)
 
 	mon.Start()
@@ -56,7 +86,7 @@ func TestMonitor(t *testing.T) {
 			pcClient.Close()
 
 			for _, event := range pcClient.Publishes() {
-				testslike.Test(t, mockEventMonitorValidator(""), event.Fields)
+				testslike.Test(t, eventValidator, event.Fields)
 			}
 		} else {
 			// Let's yield this goroutine so we don't spin

heartbeat/monitors/stdfields/stdfields.go

@@ -18,10 +18,9 @@
 package stdfields
 
 import (
+	"fmt"
 	"time"
 
-	"github.com/pkg/errors"
-
 	"github.com/elastic/beats/v7/heartbeat/scheduler/schedule"
 	"github.com/elastic/beats/v7/libbeat/common"
 )
@@ -46,7 +45,7 @@ func ConfigToStdMonitorFields(config *common.Config) (StdMonitorFields, error) {
 	mpi := StdMonitorFields{Enabled: true}
 
 	if err := config.Unpack(&mpi); err != nil {
-		return mpi, errors.Wrap(err, "error unpacking monitor plugin config")
+		return mpi, fmt.Errorf("error unpacking monitor plugin config: %w", err)
 	}
 
 	// Use `service_name` if `service.name` is unspecified

heartbeat/monitors/task.go

@@ -108,7 +108,7 @@ func runPublishJob(job jobs.Job, client *WrappedClient) []scheduler.TaskFunc {
 
 	conts, err := job(event)
 	if err != nil {
-		logp.Err("Job %v failed with: ", err)
+		logp.Err("Job failed with: %s", err)
 	}
 
 	hasContinuations := len(conts) > 0