tailscale/health/health.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package health is a registry for other packages to report & check
// overall health status of the node.
package health
import (
"errors"
"fmt"
"net/http"
"os"
"runtime"
"sort"
"sync"
"sync/atomic"
"time"
"tailscale.com/envknob"
"tailscale.com/tailcfg"
"tailscale.com/types/opt"
"tailscale.com/util/cibuild"
"tailscale.com/util/mak"
"tailscale.com/util/multierr"
"tailscale.com/util/set"
"tailscale.com/version"
)
var (
mu sync.Mutex
debugHandler map[string]http.Handler
)
// ReceiveFunc is one of the three magicsock Receive funcs (IPv4, IPv6, or
// DERP).
type ReceiveFunc int
// ReceiveFunc indices for Tracker.MagicSockReceiveFuncs.
const (
ReceiveIPv4 ReceiveFunc = 0
ReceiveIPv6 ReceiveFunc = 1
ReceiveDERP ReceiveFunc = 2
)
func (f ReceiveFunc) String() string {
if f < 0 || int(f) >= len(receiveNames) {
return fmt.Sprintf("ReceiveFunc(%d)", f)
}
return receiveNames[f]
}
var receiveNames = []string{
ReceiveIPv4: "ReceiveIPv4",
ReceiveIPv6: "ReceiveIPv6",
ReceiveDERP: "ReceiveDERP",
}
// Tracker tracks the health of various Tailscale subsystems,
// comparing each subsystems' state with each other to make sure
// they're consistent based on the user's intended state.
type Tracker struct {
// MagicSockReceiveFuncs tracks the state of the three
// magicsock receive functions: IPv4, IPv6, and DERP.
MagicSockReceiveFuncs [3]ReceiveFuncStats // indexed by ReceiveFunc values
// mu guards everything that follows.
mu sync.Mutex
warnables []*Warnable // keys ever set
warnableVal map[*Warnable]error
sysErr map[Subsystem]error // subsystem => err (or nil for no error)
watchers set.HandleSet[func(Subsystem, error)] // opt func to run if error state changes
timer *time.Timer
latestVersion *tailcfg.ClientVersion // or nil
checkForUpdates bool
inMapPoll bool
inMapPollSince time.Time
lastMapPollEndedAt time.Time
lastStreamedMapResponse time.Time
derpHomeRegion int
derpHomeless bool
derpRegionConnected map[int]bool
derpRegionHealthProblem map[int]string
derpRegionLastFrame map[int]time.Time
lastMapRequestHeard time.Time // time we got a 200 from control for a MapRequest
ipnState string
ipnWantRunning bool
anyInterfaceUp opt.Bool // empty means unknown (assume true)
udp4Unbound bool
controlHealth []string
lastLoginErr error
localLogConfigErr error
tlsConnectionErrors map[string]error // map[ServerName]error
}
// Subsystem is the name of a subsystem whose health can be monitored.
type Subsystem string
const (
// SysOverall is the name representing the overall health of
// the system, rather than one particular subsystem.
SysOverall = Subsystem("overall")
// SysRouter is the name of the wgengine/router subsystem.
SysRouter = Subsystem("router")
// SysDNS is the name of the net/dns subsystem.
SysDNS = Subsystem("dns")
// SysDNSOS is the name of the net/dns OSConfigurator subsystem.
SysDNSOS = Subsystem("dns-os")
// SysDNSManager is the name of the net/dns manager subsystem.
SysDNSManager = Subsystem("dns-manager")
// SysTKA is the name of the tailnet key authority subsystem.
SysTKA = Subsystem("tailnet-lock")
)
// NewWarnable returns a new warnable item that the caller can mark as health or
// in warning state via Tracker.SetWarnable.
//
// NewWarnable is generally called in init and stored in a package global. It
// can be used by multiple Trackers.
func NewWarnable(opts ...WarnableOpt) *Warnable {
w := new(Warnable)
for _, o := range opts {
o.mod(w)
}
return w
}
// WarnableOpt is an option passed to NewWarnable.
type WarnableOpt interface {
mod(*Warnable)
}
// WithMapDebugFlag returns a WarnableOpt for NewWarnable that makes the returned
// Warnable report itself to the coordination server as broken with this
// string in MapRequest.DebugFlag when Set to a non-nil value.
func WithMapDebugFlag(name string) WarnableOpt {
return warnOptFunc(func(w *Warnable) {
w.debugFlag = name
})
}
// WithConnectivityImpact returns an option which makes a Warnable annotated as
// something that could be breaking external network connectivity on the
// machine. This will make the warnable returned by OverallError alongside
// network connectivity errors.
func WithConnectivityImpact() WarnableOpt {
return warnOptFunc(func(w *Warnable) {
w.hasConnectivityImpact = true
})
}
type warnOptFunc func(*Warnable)
func (f warnOptFunc) mod(w *Warnable) { f(w) }
// Warnable is a health check item that may or may not be in a bad warning state.
// The caller of NewWarnable is responsible for calling Tracker.SetWarnable to update the state.
type Warnable struct {
debugFlag string // optional MapRequest.DebugFlag to send when unhealthy
// If true, this warning is related to configuration of networking stack
// on the machine that impacts connectivity.
hasConnectivityImpact bool
}
// nil reports whether t is nil.
// It exists to accept nil *Tracker receivers on all methods
// to at least not crash. But because a nil receiver indicates
// some lost Tracker plumbing, we want to capture stack trace
// samples when it occurs.
func (t *Tracker) nil() bool {
if t != nil {
return false
}
if cibuild.On() {
stack := make([]byte, 1<<10)
stack = stack[:runtime.Stack(stack, false)]
fmt.Fprintf(os.Stderr, "## WARNING: (non-fatal) nil health.Tracker (being strict in CI):\n%s\n", stack)
}
// TODO(bradfitz): open source our "unexpected" package
// and use it here to capture samples of stacks where
// t is nil.
return true
}
// Set updates the Warnable's state.
// If non-nil, it's considered unhealthy.
func (t *Tracker) SetWarnable(w *Warnable, err error) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
l0 := len(t.warnableVal)
mak.Set(&t.warnableVal, w, err)
if len(t.warnableVal) != l0 {
t.warnables = append(t.warnables, w)
}
}
// AppendWarnableDebugFlags appends to base any health items that are currently in failed
// state and were created with MapDebugFlag.
func (t *Tracker) AppendWarnableDebugFlags(base []string) []string {
if t.nil() {
return base
}
ret := base
t.mu.Lock()
defer t.mu.Unlock()
for w, err := range t.warnableVal {
if w.debugFlag == "" {
continue
}
if err != nil {
ret = append(ret, w.debugFlag)
}
}
sort.Strings(ret[len(base):]) // sort the new ones
return ret
}
// RegisterWatcher adds a function that will be called if an
// error changes state either to unhealthy or from unhealthy. It is
// not called on transition from unknown to healthy. It must be non-nil
// and is run in its own goroutine. The returned func unregisters it.
func (t *Tracker) RegisterWatcher(cb func(key Subsystem, err error)) (unregister func()) {
if t.nil() {
return func() {}
}
t.mu.Lock()
defer t.mu.Unlock()
if t.watchers == nil {
t.watchers = set.HandleSet[func(Subsystem, error)]{}
}
handle := t.watchers.Add(cb)
if t.timer == nil {
t.timer = time.AfterFunc(time.Minute, t.timerSelfCheck)
}
return func() {
t.mu.Lock()
defer t.mu.Unlock()
delete(t.watchers, handle)
if len(t.watchers) == 0 && t.timer != nil {
t.timer.Stop()
t.timer = nil
}
}
}
// SetRouterHealth sets the state of the wgengine/router.Router.
func (t *Tracker) SetRouterHealth(err error) { t.setErr(SysRouter, err) }
// RouterHealth returns the wgengine/router.Router error state.
func (t *Tracker) RouterHealth() error { return t.get(SysRouter) }
// SetDNSHealth sets the state of the net/dns.Manager
func (t *Tracker) SetDNSHealth(err error) { t.setErr(SysDNS, err) }
// DNSHealth returns the net/dns.Manager error state.
func (t *Tracker) DNSHealth() error { return t.get(SysDNS) }
// SetDNSOSHealth sets the state of the net/dns.OSConfigurator
func (t *Tracker) SetDNSOSHealth(err error) { t.setErr(SysDNSOS, err) }
// SetDNSManagerHealth sets the state of the Linux net/dns manager's
// discovery of the /etc/resolv.conf situation.
func (t *Tracker) SetDNSManagerHealth(err error) { t.setErr(SysDNSManager, err) }
// DNSOSHealth returns the net/dns.OSConfigurator error state.
func (t *Tracker) DNSOSHealth() error { return t.get(SysDNSOS) }
// SetTKAHealth sets the health of the tailnet key authority.
func (t *Tracker) SetTKAHealth(err error) { t.setErr(SysTKA, err) }
// TKAHealth returns the tailnet key authority error state.
func (t *Tracker) TKAHealth() error { return t.get(SysTKA) }
// SetLocalLogConfigHealth sets the error state of this client's local log configuration.
func (t *Tracker) SetLocalLogConfigHealth(err error) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.localLogConfigErr = err
}
// SetTLSConnectionError sets the error state for connections to a specific
// host. Setting the error to nil will clear any previously-set error.
func (t *Tracker) SetTLSConnectionError(host string, err error) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
if err == nil {
delete(t.tlsConnectionErrors, host)
} else {
mak.Set(&t.tlsConnectionErrors, host, err)
}
}
func RegisterDebugHandler(typ string, h http.Handler) {
mu.Lock()
defer mu.Unlock()
mak.Set(&debugHandler, typ, h)
}
func DebugHandler(typ string) http.Handler {
mu.Lock()
defer mu.Unlock()
return debugHandler[typ]
}
func (t *Tracker) get(key Subsystem) error {
if t.nil() {
return nil
}
t.mu.Lock()
defer t.mu.Unlock()
return t.sysErr[key]
}
func (t *Tracker) setErr(key Subsystem, err error) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.setLocked(key, err)
}
func (t *Tracker) setLocked(key Subsystem, err error) {
if t.sysErr == nil {
t.sysErr = map[Subsystem]error{}
}
old, ok := t.sysErr[key]
if !ok && err == nil {
// Initial happy path.
t.sysErr[key] = nil
t.selfCheckLocked()
return
}
if ok && (old == nil) == (err == nil) {
// No change in overall error status (nil-vs-not), so
// don't run callbacks, but exact error might've
// changed, so note it.
if err != nil {
t.sysErr[key] = err
}
return
}
t.sysErr[key] = err
t.selfCheckLocked()
for _, cb := range t.watchers {
go cb(key, err)
}
}
func (t *Tracker) SetControlHealth(problems []string) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.controlHealth = problems
t.selfCheckLocked()
}
// GotStreamedMapResponse notes that we got a tailcfg.MapResponse
// message in streaming mode, even if it's just a keep-alive message.
//
// This also notes that a map poll is in progress. To unset that, call
// SetOutOfPollNetMap().
func (t *Tracker) GotStreamedMapResponse() {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.lastStreamedMapResponse = time.Now()
if !t.inMapPoll {
t.inMapPoll = true
t.inMapPollSince = time.Now()
}
t.selfCheckLocked()
}
// SetOutOfPollNetMap records that the client is no longer in
// an HTTP map request long poll to the control plane.
func (t *Tracker) SetOutOfPollNetMap() {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
if !t.inMapPoll {
return
}
t.inMapPoll = false
t.lastMapPollEndedAt = time.Now()
t.selfCheckLocked()
}
// GetInPollNetMap reports whether the client has an open
// HTTP long poll open to the control plane.
func (t *Tracker) GetInPollNetMap() bool {
if t.nil() {
return false
}
t.mu.Lock()
defer t.mu.Unlock()
return t.inMapPoll
}
// SetMagicSockDERPHome notes what magicsock's view of its home DERP is.
//
// The homeless parameter is whether magicsock is running in DERP-disconnected
// mode, without discovering and maintaining a connection to its home DERP.
func (t *Tracker) SetMagicSockDERPHome(region int, homeless bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.derpHomeRegion = region
t.derpHomeless = homeless
t.selfCheckLocked()
}
// NoteMapRequestHeard notes whenever we successfully sent a map request
// to control for which we received a 200 response.
func (t *Tracker) NoteMapRequestHeard(mr *tailcfg.MapRequest) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
// TODO: extract mr.HostInfo.NetInfo.PreferredDERP, compare
// against SetMagicSockDERPHome and
// SetDERPRegionConnectedState
t.lastMapRequestHeard = time.Now()
t.selfCheckLocked()
}
func (t *Tracker) SetDERPRegionConnectedState(region int, connected bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
mak.Set(&t.derpRegionConnected, region, connected)
t.selfCheckLocked()
}
// SetDERPRegionHealth sets or clears any problem associated with the
// provided DERP region.
func (t *Tracker) SetDERPRegionHealth(region int, problem string) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
if problem == "" {
delete(t.derpRegionHealthProblem, region)
} else {
mak.Set(&t.derpRegionHealthProblem, region, problem)
}
t.selfCheckLocked()
}
// NoteDERPRegionReceivedFrame is called to note that a frame was received from
// the given DERP region at the current time.
func (t *Tracker) NoteDERPRegionReceivedFrame(region int) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
mak.Set(&t.derpRegionLastFrame, region, time.Now())
t.selfCheckLocked()
}
// GetDERPRegionReceivedTime returns the last time that a frame was received
// from the given DERP region, or the zero time if no communication with that
// region has occurred.
func (t *Tracker) GetDERPRegionReceivedTime(region int) time.Time {
if t.nil() {
return time.Time{}
}
t.mu.Lock()
defer t.mu.Unlock()
return t.derpRegionLastFrame[region]
}
// state is an ipn.State.String() value: "Running", "Stopped", "NeedsLogin", etc.
func (t *Tracker) SetIPNState(state string, wantRunning bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.ipnState = state
t.ipnWantRunning = wantRunning
t.selfCheckLocked()
}
// SetAnyInterfaceUp sets whether any network interface is up.
func (t *Tracker) SetAnyInterfaceUp(up bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.anyInterfaceUp.Set(up)
t.selfCheckLocked()
}
// SetUDP4Unbound sets whether the udp4 bind failed completely.
func (t *Tracker) SetUDP4Unbound(unbound bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.udp4Unbound = unbound
t.selfCheckLocked()
}
// SetAuthRoutineInError records the latest error encountered as a result of a
// login attempt. Providing a nil error indicates successful login, or that
// being logged in w/coordination is not currently desired.
func (t *Tracker) SetAuthRoutineInError(err error) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
if err == nil && t.lastLoginErr == nil {
return
}
t.lastLoginErr = err
t.selfCheckLocked()
}
// SetLatestVersion records the latest version of the Tailscale client.
// v can be nil if unknown.
func (t *Tracker) SetLatestVersion(v *tailcfg.ClientVersion) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.latestVersion = v
t.selfCheckLocked()
}
// SetCheckForUpdates sets whether the client wants to check for updates.
func (t *Tracker) SetCheckForUpdates(v bool) {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
if t.checkForUpdates == v {
return
}
t.checkForUpdates = v
t.selfCheckLocked()
}
func (t *Tracker) timerSelfCheck() {
if t.nil() {
return
}
t.mu.Lock()
defer t.mu.Unlock()
t.checkReceiveFuncsLocked()
t.selfCheckLocked()
if t.timer != nil {
t.timer.Reset(time.Minute)
}
}
func (t *Tracker) selfCheckLocked() {
if t.ipnState == "" {
// Don't check yet.
return
}
t.setLocked(SysOverall, t.overallErrorLocked())
}
// AppendWarnings appends all current health warnings to dst and returns the
// result.
func (t *Tracker) AppendWarnings(dst []string) []string {
err := t.OverallError()
if err == nil {
return dst
}
if me, ok := err.(multierr.Error); ok {
for _, err := range me.Errors() {
dst = append(dst, err.Error())
}
} else {
dst = append(dst, err.Error())
}
return dst
}
// OverallError returns a summary of the health state.
//
// If there are multiple problems, the error will be of type
// multierr.Error.
func (t *Tracker) OverallError() error {
if t.nil() {
return nil
}
t.mu.Lock()
defer t.mu.Unlock()
return t.overallErrorLocked()
}
var fakeErrForTesting = envknob.RegisterString("TS_DEBUG_FAKE_HEALTH_ERROR")
// networkErrorfLocked creates an error that indicates issues with outgoing network
// connectivity. Any active warnings related to network connectivity will
// automatically be appended to it.
//
// t.mu must be held.
func (t *Tracker) networkErrorfLocked(format string, a ...any) error {
errs := []error{
fmt.Errorf(format, a...),
}
for _, w := range t.warnables {
if !w.hasConnectivityImpact {
continue
}
if err := t.warnableVal[w]; err != nil {
errs = append(errs, err)
}
}
if len(errs) == 1 {
return errs[0]
}
return multierr.New(errs...)
}
var errNetworkDown = errors.New("network down")
var errNotInMapPoll = errors.New("not in map poll")
var errNoDERPHome = errors.New("no DERP home")
var errNoUDP4Bind = errors.New("no udp4 bind")
var errUnstable = errors.New("This is an unstable (development) version of Tailscale; frequent updates and bugs are likely")
func (t *Tracker) overallErrorLocked() error {
var errs []error
add := func(err error) {
if err != nil {
errs = append(errs, err)
}
}
merged := func() error {
return multierr.New(errs...)
}
if t.checkForUpdates {
if cv := t.latestVersion; cv != nil && !cv.RunningLatest && cv.LatestVersion != "" {
if cv.UrgentSecurityUpdate {
add(fmt.Errorf("Security update available: %v -> %v, run `tailscale update` or `tailscale set --auto-update` to update", version.Short(), cv.LatestVersion))
} else {
add(fmt.Errorf("Update available: %v -> %v, run `tailscale update` or `tailscale set --auto-update` to update", version.Short(), cv.LatestVersion))
}
}
}
if version.IsUnstableBuild() {
add(errUnstable)
}
if v, ok := t.anyInterfaceUp.Get(); ok && !v {
add(errNetworkDown)
return merged()
}
if t.localLogConfigErr != nil {
add(t.localLogConfigErr)
return merged()
}
if !t.ipnWantRunning {
add(fmt.Errorf("state=%v, wantRunning=%v", t.ipnState, t.ipnWantRunning))
return merged()
}
if t.lastLoginErr != nil {
add(fmt.Errorf("not logged in, last login error=%v", t.lastLoginErr))
return merged()
}
now := time.Now()
if !t.inMapPoll && (t.lastMapPollEndedAt.IsZero() || now.Sub(t.lastMapPollEndedAt) > 10*time.Second) {
add(errNotInMapPoll)
return merged()
}
const tooIdle = 2*time.Minute + 5*time.Second
if d := now.Sub(t.lastStreamedMapResponse).Round(time.Second); d > tooIdle {
add(t.networkErrorfLocked("no map response in %v", d))
return merged()
}
if !t.derpHomeless {
rid := t.derpHomeRegion
if rid == 0 {
add(errNoDERPHome)
return merged()
}
if !t.derpRegionConnected[rid] {
add(t.networkErrorfLocked("not connected to home DERP region %v", rid))
return merged()
}
if d := now.Sub(t.derpRegionLastFrame[rid]).Round(time.Second); d > tooIdle {
add(t.networkErrorfLocked("haven't heard from home DERP region %v in %v", rid, d))
return merged()
}
}
if t.udp4Unbound {
add(errNoUDP4Bind)
return merged()
}
// TODO: use
_ = t.inMapPollSince
_ = t.lastMapPollEndedAt
_ = t.lastStreamedMapResponse
_ = t.lastMapRequestHeard
for i := range t.MagicSockReceiveFuncs {
f := &t.MagicSockReceiveFuncs[i]
if f.missing {
errs = append(errs, fmt.Errorf("%s is not running", f.name))
}
}
for sys, err := range t.sysErr {
if err == nil || sys == SysOverall {
continue
}
errs = append(errs, fmt.Errorf("%v: %w", sys, err))
}
for _, w := range t.warnables {
if err := t.warnableVal[w]; err != nil {
errs = append(errs, err)
}
}
for regionID, problem := range t.derpRegionHealthProblem {
errs = append(errs, fmt.Errorf("derp%d: %v", regionID, problem))
}
for _, s := range t.controlHealth {
errs = append(errs, errors.New(s))
}
if err := envknob.ApplyDiskConfigError(); err != nil {
errs = append(errs, err)
}
for serverName, err := range t.tlsConnectionErrors {
errs = append(errs, fmt.Errorf("TLS connection error for %q: %w", serverName, err))
}
if e := fakeErrForTesting(); len(errs) == 0 && e != "" {
return errors.New(e)
}
sort.Slice(errs, func(i, j int) bool {
// Not super efficient (stringifying these in a sort), but probably max 2 or 3 items.
return errs[i].Error() < errs[j].Error()
})
return multierr.New(errs...)
}
// ReceiveFuncStats tracks the calls made to a wireguard-go receive func.
type ReceiveFuncStats struct {
// name is the name of the receive func.
// It's lazily populated.
name string
// numCalls is the number of times the receive func has ever been called.
// It is required because it is possible for a receive func's wireguard-go goroutine
// to be active even though the receive func isn't.
// The wireguard-go goroutine alternates between calling the receive func and
// processing what the func returned.
numCalls atomic.Uint64
// prevNumCalls is the value of numCalls last time the health check examined it.
prevNumCalls uint64
// inCall indicates whether the receive func is currently running.
inCall atomic.Bool
// missing indicates whether the receive func is not running.
missing bool
}
func (s *ReceiveFuncStats) Enter() {
s.numCalls.Add(1)
s.inCall.Store(true)
}
func (s *ReceiveFuncStats) Exit() {
s.inCall.Store(false)
}
// ReceiveFuncStats returns the ReceiveFuncStats tracker for the given func
// type.
//
// If t is nil, it returns nil.
func (t *Tracker) ReceiveFuncStats(which ReceiveFunc) *ReceiveFuncStats {
if t == nil {
return nil
}
return &t.MagicSockReceiveFuncs[which]
}
func (t *Tracker) checkReceiveFuncsLocked() {
for i := range t.MagicSockReceiveFuncs {
f := &t.MagicSockReceiveFuncs[i]
if f.name == "" {
f.name = (ReceiveFunc(i)).String()
}
if runtime.GOOS == "js" && i < 2 {
// Skip IPv4 and IPv6 on js.
continue
}
f.missing = false
prev := f.prevNumCalls
numCalls := f.numCalls.Load()
f.prevNumCalls = numCalls
if numCalls > prev {
// OK: the function has gotten called since last we checked
continue
}
if f.inCall.Load() {
// OK: the function is active, probably blocked due to inactivity
continue
}
// Not OK: The function is not active, and not accumulating new calls.
// It is probably MIA.
f.missing = true
}
}