remote: Add distributed converged timeout

This patch extends the --converged-timeout argument so that when used
with --remote it waits for the entire set of remote mgmt agents to
converge simultaneously before exiting.

purpleidea says: This particular part of the patch probably took as much
work as all of the work required for the initial remote patches alone!

config.go

@@ -56,6 +56,7 @@ type GraphConfig struct {
 	Collector []collectorResConfig `yaml:"collect"`
 	Edges     []edgeConfig         `yaml:"edges"`
 	Comment   string               `yaml:"comment"`
+	Hostname  string               `yaml:"hostname"` // uuid for the host
 	Remote    string               `yaml:"remote"`
 }
 
@@ -87,7 +88,10 @@ func ParseConfigFromFile(filename string) *GraphConfig {
 
 // NewGraphFromConfig returns a new graph from existing input, such as from the
 // existing graph, and a GraphConfig struct.
-func (g *Graph) NewGraphFromConfig(config *GraphConfig, embdEtcd *EmbdEtcd, hostname string, noop bool) (*Graph, error) {
+func (g *Graph) NewGraphFromConfig(config *GraphConfig, embdEtcd *EmbdEtcd, noop bool) (*Graph, error) {
+	if config.Hostname == "" {
+		return nil, fmt.Errorf("Config: Error: Hostname can't be empty!")
+	}
 
 	var graph *Graph // new graph to return
 	if g == nil {    // FIXME: how can we check for an empty graph?
@@ -154,7 +158,7 @@ func (g *Graph) NewGraphFromConfig(config *GraphConfig, embdEtcd *EmbdEtcd, host
 		}
 	}
 	// store in etcd
-	if err := EtcdSetResources(embdEtcd, hostname, resources); err != nil {
+	if err := EtcdSetResources(embdEtcd, config.Hostname, resources); err != nil {
 		return nil, fmt.Errorf("Config: Could not export resources: %v", err)
 	}
 

etcd.go

@@ -1849,6 +1849,65 @@ func EtcdEndpoints(obj *EmbdEtcd) (etcdtypes.URLsMap, error) {
 	return endpoints, nil
 }
 
+// EtcdSetHostnameConverged sets whether a specific hostname is converged.
+func EtcdSetHostnameConverged(obj *EmbdEtcd, hostname string, isConverged bool) error {
+	if TRACE {
+		log.Printf("Trace: Etcd: EtcdSetHostnameConverged(%s): %v", hostname, isConverged)
+		defer log.Printf("Trace: Etcd: EtcdSetHostnameConverged(%v): Finished!", hostname)
+	}
+	converged := fmt.Sprintf("/%s/converged/%s", NS, hostname)
+	op := []etcd.Op{etcd.OpPut(converged, fmt.Sprintf("%t", isConverged))}
+	if _, err := obj.Txn(nil, op, nil); err != nil { // TODO: do we need a skipConv flag here too?
+		return fmt.Errorf("Etcd: Set converged failed!") // exit in progress?
+	}
+	return nil
+}
+
+// EtcdHostnameConverged returns a map of every hostname's converged state.
+func EtcdHostnameConverged(obj *EmbdEtcd) (map[string]bool, error) {
+	if TRACE {
+		log.Printf("Trace: Etcd: EtcdHostnameConverged()")
+		defer log.Printf("Trace: Etcd: EtcdHostnameConverged(): Finished!")
+	}
+	path := fmt.Sprintf("/%s/converged/", NS)
+	keyMap, err := obj.ComplexGet(path, true, etcd.WithPrefix()) // don't un-converge
+	if err != nil {
+		return nil, fmt.Errorf("Etcd: Converged values aren't available: %v", err)
+	}
+	converged := make(map[string]bool)
+	for key, val := range keyMap { // loop through directory...
+		if !strings.HasPrefix(key, path) {
+			continue
+		}
+		name := key[len(path):] // get name of key
+		if val == "" {          // skip "erased" values
+			continue
+		}
+		b, err := strconv.ParseBool(val)
+		if err != nil {
+			return nil, fmt.Errorf("Etcd: Converged: Data format error!: %v", err)
+		}
+		converged[name] = b // add to map
+	}
+	return converged, nil
+}
+
+// EtcdAddHostnameConvergedWatcher adds a watcher with a callback that runs on
+// hostname state changes.
+func EtcdAddHostnameConvergedWatcher(obj *EmbdEtcd, callbackFn func(map[string]bool) error) (func(), error) {
+	path := fmt.Sprintf("/%s/converged/", NS)
+	internalCbFn := func(re *RE) error {
+		// TODO: get the value from the response, and apply delta...
+		// for now, just run a get operation which is easier to code!
+		if m, err := EtcdHostnameConverged(obj); err == nil {
+			return callbackFn(m) // call my function
+		} else {
+			return err
+		}
+	}
+	return obj.AddWatcher(path, internalCbFn, true, true, etcd.WithPrefix()) // no block and no converger reset
+}
+
 // EtcdSetClusterSize sets the ideal target cluster size of etcd peers
 func EtcdSetClusterSize(obj *EmbdEtcd, value uint16) error {
 	if TRACE {

main.go

@@ -69,9 +69,19 @@ func run(c *cli.Context) error {
 	log.Printf("This is: %v, version: %v", program, version)
 	log.Printf("Main: Start: %v", start)
 
-	hostname := c.String("hostname")
+	hostname, _ := os.Hostname()
-	if hostname == "" {
+	// allow passing in the hostname, instead of using --hostname
-		hostname, _ = os.Hostname()
+	if c.IsSet("file") {
+		if config := ParseConfigFromFile(c.String("file")); config != nil {
+			if h := config.Hostname; h != "" {
+				hostname = h
+			}
+		}
+	}
+	if c.IsSet("hostname") { // override by cli
+		if h := c.String("hostname"); h != "" {
+			hostname = h
+		}
 	}
 	noop := c.Bool("noop")
 
@@ -123,6 +133,17 @@ func run(c *cli.Context) error {
 		return cli.NewExitError("", 1)
 	}
 
+	if c.IsSet("converged-timeout") && cConns > 0 && len(c.StringSlice("remote")) > c.Int("cconns") {
+		log.Printf("Main: Error: combining --converged-timeout with more remotes than available connections will never converge!")
+		return cli.NewExitError("", 1)
+	}
+
+	depth := uint16(c.Int("depth"))
+	if depth < 0 { // user should not be using this argument manually
+		log.Printf("Main: Error: negative values for --depth are not permitted!")
+		return cli.NewExitError("", 1)
+	}
+
 	if c.IsSet("prefix") && c.Bool("tmp-prefix") {
 		log.Println("Main: Error: combining --prefix and the request for a tmp prefix is illogical!")
 		return cli.NewExitError("", 1)
@@ -162,13 +183,7 @@ func run(c *cli.Context) error {
 	// setup converger
 	converger := NewConverger(
 		c.Int("converged-timeout"),
-		func(b bool) error { // lambda to run when converged
+		nil, // stateFn gets added in by EmbdEtcd
-			if b {
-				log.Printf("Converged for %d seconds, exiting!", c.Int("converged-timeout"))
-				exit <- true // trigger an exit!
-			}
-			return nil
-		},
 	)
 	go converger.Loop(true) // main loop for converger, true to start paused
 
@@ -196,6 +211,24 @@ func run(c *cli.Context) error {
 		log.Printf("Main: Etcd: Startup failed: %v", err)
 		exit <- true
 	}
+	convergerStateFn := func(b bool) error {
+		// exit if we are using the converged-timeout and we are the
+		// root node. otherwise, if we are a child node in a remote
+		// execution hierarchy, we should only notify our converged
+		// state and wait for the parent to trigger the exit.
+		if depth == 0 && c.Int("converged-timeout") >= 0 {
+			if b {
+				log.Printf("Converged for %d seconds, exiting!", c.Int("converged-timeout"))
+				exit <- true // trigger an exit!
+			}
+			return nil
+		}
+		// send our individual state into etcd for others to see
+		return EtcdSetHostnameConverged(EmbdEtcd, hostname, b) // TODO: what should happen on error?
+	}
+	if EmbdEtcd != nil {
+		converger.SetStateFn(convergerStateFn)
+	}
 
 	exitchan := make(chan Event) // exit event
 	go func() {
@@ -250,6 +283,12 @@ func run(c *cli.Context) error {
 				continue
 			}
 
+			if config.Hostname != "" && config.Hostname != hostname {
+				log.Printf("Config: Hostname changed, ignoring config!")
+				continue
+			}
+			config.Hostname = hostname // set it in case it was ""
+
 			// run graph vertex LOCK...
 			if !first { // TODO: we can flatten this check out I think
 				converger.Pause() // FIXME: add sync wait?
@@ -258,7 +297,7 @@ func run(c *cli.Context) error {
 
 			// build graph from yaml file on events (eg: from etcd)
 			// we need the vertices to be paused to work on them
-			if newFullgraph, err := fullGraph.NewGraphFromConfig(config, EmbdEtcd, hostname, noop); err == nil { // keep references to all original elements
+			if newFullgraph, err := fullGraph.NewGraphFromConfig(config, EmbdEtcd, noop); err == nil { // keep references to all original elements
 				fullGraph = newFullgraph
 			} else {
 				log.Printf("Config: Error making new graph from config: %v", err)
@@ -303,6 +342,11 @@ func run(c *cli.Context) error {
 		events = nil // signal that no-watch is true
 	}
 
+	// initialize the add watcher, which calls the f callback on map changes
+	convergerCb := func(f func(map[string]bool) error) (func(), error) {
+		return EtcdAddHostnameConvergedWatcher(EmbdEtcd, f)
+	}
+
 	// build remotes struct for remote ssh
 	remotes := NewRemotes(
 		EmbdEtcd.LocalhostClientURLs().StringSlice(),
@@ -314,7 +358,10 @@ func run(c *cli.Context) error {
 		c.Bool("allow-interactive"),
 		c.String("ssh-priv-id-rsa"),
 		!c.Bool("no-caching"),
+		depth,
 		prefix,
+		converger,
+		convergerCb,
 	)
 
 	// TODO: is there any benefit to running the remotes above in the loop?
@@ -503,6 +550,12 @@ func main() {
 					Name:  "no-caching",
 					Usage: "don't allow remote caching of remote execution binary",
 				},
+				cli.IntFlag{
+					Name:   "depth",
+					Hidden: true, // internal use only
+					Value:  0,
+					Usage:  "specify depth in remote hierarchy",
+				},
 				cli.StringFlag{
 					Name:   "prefix",
 					Usage:  "specify a path to the working prefix directory",

remote.go

@@ -78,6 +78,8 @@ const (
 
 // The SSH struct is the unit building block for a single remote SSH connection.
 type SSH struct {
+	hostname string // uuid of the host, as used by the --hostname argument
+
 	host string           // remote host to connect to
 	port uint16           // remote port to connect to (usually 22)
 	user string           // username to connect with
@@ -89,8 +91,10 @@ type SSH struct {
 	noop       bool     // whether to run the remote process with --noop
 	noWatch    bool     // whether to run the remote process with --no-watch
 
-	caching bool   // whether to try and cache the copy of the binary
+	depth     uint16 // depth of this node in the remote execution hierarchy
-	prefix  string // location we're allowed to put data on the remote server
+	caching   bool   // whether to try and cache the copy of the binary
+	prefix    string // location we're allowed to put data on the remote server
+	converger Converger
 
 	client   *ssh.Client  // client object
 	sftp     *sftp.Client // sftp object
@@ -475,19 +479,24 @@ func (obj *SSH) Exec() error {
 	obj.session.Stdout = &b
 	obj.session.Stderr = &b
 
+	hostname := fmt.Sprintf("--hostname '%s'", obj.hostname)
 	// TODO: do something less arbitrary about which one we pick?
 	url := cleanURL(obj.remoteURLs[0])                           // arbitrarily pick the first one
 	seeds := fmt.Sprintf("--no-server --seeds 'http://%s'", url) // XXX: escape dangerous untrusted input?
 	file := fmt.Sprintf("--file '%s'", obj.filepath)             // XXX: escape dangerous untrusted input!
-	args := []string{seeds, file}
+	depth := fmt.Sprintf("--depth %d", obj.depth+1)              // child is +1 distance
+	args := []string{hostname, seeds, file, depth}
 	if obj.noop {
 		args = append(args, "--noop")
 	}
 	if obj.noWatch {
 		args = append(args, "--no-watch")
 	}
-
+	if timeout := obj.converger.Timeout(); timeout >= 0 {
-	// TODO: add --converged-timeout support for group
+		args = append(args, fmt.Sprintf("--converged-timeout=%d", timeout))
+	}
+	// TODO: we use a depth parameter instead of a simple bool, in case we
+	// want to have outwardly expanding trees of remote execution...
 
 	cmd := fmt.Sprintf("%s run %s", obj.execpath, strings.Join(args, " "))
 	log.Printf("Remote: Running: %s", cmd)
@@ -669,17 +678,26 @@ type Remotes struct {
 	interactive  bool   // allow interactive prompting
 	sshPrivIdRsa string // path to ~/.ssh/id_rsa
 	caching      bool   // whether to try and cache the copy of the binary
+	depth        uint16 // depth of this node in the remote execution hierarchy
 	prefix       string // folder prefix to use for misc storage
+	converger    Converger
+	convergerCb  func(func(map[string]bool) error) (func(), error)
+
+	wg                 sync.WaitGroup           // keep track of each running SSH connection
+	lock               sync.Mutex               // mutex for access to sshmap
+	sshmap             map[string]*SSH          // map to each SSH struct with the remote as the key
+	exiting            bool                     // flag to let us know if we're exiting
+	exitChan           chan struct{}            // closes when we should exit
+	semaphore          Semaphore                // counting semaphore to limit concurrent connections
+	hostnames          []string                 // list of hostnames we've seen so far
+	cuuid              ConvergerUUID            // convergerUUID for the remote itself
+	cuuids             map[string]ConvergerUUID // map to each SSH struct with the remote as the key
+	callbackCancelFunc func()                   // stored callback function cancel function
 
-	wg        sync.WaitGroup  // keep track of each running SSH connection
-	lock      sync.Mutex      // mutex for access to sshmap
-	sshmap    map[string]*SSH // map to each SSH struct with the remote as the key
-	exiting   bool            // flag to let us know if we're exiting
-	semaphore Semaphore       // counting semaphore to limit concurrent connections
 }
 
 // The NewRemotes function builds a Remotes struct.
-func NewRemotes(clientURLs, remoteURLs []string, noop bool, remotes []string, fileWatch chan string, cConns uint16, interactive bool, sshPrivIdRsa string, caching bool, prefix string) *Remotes {
+func NewRemotes(clientURLs, remoteURLs []string, noop bool, remotes []string, fileWatch chan string, cConns uint16, interactive bool, sshPrivIdRsa string, caching bool, depth uint16, prefix string, converger Converger, convergerCb func(func(map[string]bool) error) (func(), error)) *Remotes {
 	return &Remotes{
 		clientURLs:   clientURLs,
 		remoteURLs:   remoteURLs,
@@ -690,9 +708,15 @@ func NewRemotes(clientURLs, remoteURLs []string, noop bool, remotes []string, fi
 		interactive:  interactive,
 		sshPrivIdRsa: sshPrivIdRsa,
 		caching:      caching,
+		depth:        depth,
 		prefix:       prefix,
+		converger:    converger,
+		convergerCb:  convergerCb,
 		sshmap:       make(map[string]*SSH),
+		exitChan:     make(chan struct{}),
 		semaphore:    NewSemaphore(int(cConns)),
+		hostnames:    make([]string, len(remotes)),
+		cuuids:       make(map[string]ConvergerUUID),
 	}
 }
 
@@ -757,7 +781,17 @@ func (obj *Remotes) NewSSH(file string) (*SSH, error) {
 		return nil, fmt.Errorf("No authentication methods available!")
 	}
 
+	hostname := config.Hostname
+	if hostname == "" {
+		hostname = host // default to above
+	}
+	if StrInList(hostname, obj.hostnames) {
+		return nil, fmt.Errorf("Remote: Hostname `%s` already exists!", hostname)
+	}
+	obj.hostnames = append(obj.hostnames, hostname)
+
 	return &SSH{
+		hostname:   hostname,
 		host:       host,
 		port:       port,
 		user:       user,
@@ -767,7 +801,9 @@ func (obj *Remotes) NewSSH(file string) (*SSH, error) {
 		remoteURLs: obj.remoteURLs,
 		noop:       obj.noop,
 		noWatch:    obj.fileWatch == nil,
+		depth:      obj.depth,
 		caching:    obj.caching,
+		converger:  obj.converger,
 		prefix:     obj.prefix,
 	}, nil
 }
@@ -846,13 +882,72 @@ func (obj *Remotes) passwordCallback(user, host string) func() (string, error) {
 // The Run method of the Remotes struct kicks it all off. It is usually run from
 // a go routine.
 func (obj *Remotes) Run() {
+	// TODO: we can disable a lot of this if we're not using --converged-timeout
+	// link in all the converged timeout checking and callbacks...
+	obj.cuuid = obj.converger.Register() // one for me!
+	obj.cuuid.SetName("Remote: Run")
+	for _, f := range obj.remotes { // one for each remote...
+		obj.cuuids[f] = obj.converger.Register() // save a reference
+		obj.cuuids[f].SetName(fmt.Sprintf("Remote: %s", f))
+		//obj.cuuids[f].SetConverged(false) // everyone starts off false
+	}
+
+	// watch for converged state in the group of remotes...
+	cFunc := func(m map[string]bool) error {
+		// The hosts state has changed. Here is what it is now. Is this
+		// now converged, or not? Run SetConverged(b) to update status!
+		// The keys are hostnames, not filenames as in the sshmap keys.
+
+		// update converged status for each remote
+		for _, f := range obj.remotes {
+			// TODO: add obj.lock.Lock() ?
+			sshobj, exists := obj.sshmap[f]
+			// TODO: add obj.lock.Unlock() ?
+			if !exists || sshobj == nil {
+				continue // skip, this hasn't happened yet
+			}
+			hostname := sshobj.hostname
+			b, ok := m[hostname]
+			if !ok { // no status on hostname means unconverged!
+				continue
+			}
+			if DEBUG {
+				log.Printf("Remote: Converged: Status: %+v", obj.converger.Status())
+			}
+			// if exiting, don't update, it will be unregistered...
+			if !sshobj.exiting { // this is actually racy, but safe
+				obj.cuuids[f].SetConverged(b) // ignore errors!
+			}
+		}
+
+		return nil
+	}
+	if cancel, err := obj.convergerCb(cFunc); err != nil { // register the callback to run
+		obj.callbackCancelFunc = cancel
+	}
+
 	// kick off the file change notifications
+	// NOTE: if we ever change a config after a host has converged but has
+	// been let to exit before the group, then it won't see the changes...
 	if obj.fileWatch != nil {
+		obj.wg.Add(1)
 		go func() {
+			defer obj.wg.Done()
+			var f string
+			var more bool
 			for {
-				f, more := <-obj.fileWatch // read from channel
+				select {
-				if !more {
+				case <-obj.exitChan: // closes when we're done
 					return
+				case f, more = <-obj.fileWatch: // read from channel
+					if !more {
+						return
+					}
+					obj.cuuid.SetConverged(false) // activity!
+
+				case <-obj.cuuid.ConvergedTimer():
+					obj.cuuid.SetConverged(true) // converged!
+					continue
 				}
 				obj.lock.Lock()
 				sshobj, exists := obj.sshmap[f]
@@ -893,6 +988,8 @@ func (obj *Remotes) Run() {
 				defer obj.semaphore.V(1)
 			}
 			defer obj.wg.Done()
+			defer obj.cuuids[f].Unregister()
+
 			if err := sshobj.Go(); err != nil {
 				log.Printf("Remote: Error: %s", err)
 			}
@@ -907,6 +1004,7 @@ func (obj *Remotes) Exit() {
 	obj.lock.Lock()
 	obj.exiting = true // don't spawn new ones once this flag is set!
 	obj.lock.Unlock()
+	close(obj.exitChan)
 	for _, f := range obj.remotes {
 		sshobj, exists := obj.sshmap[f]
 		if !exists || sshobj == nil {
@@ -919,6 +1017,11 @@ func (obj *Remotes) Exit() {
 		}
 	}
 
+	if obj.callbackCancelFunc != nil {
+		obj.callbackCancelFunc() // cancel our callback
+	}
+
+	defer obj.cuuid.Unregister()
 	obj.wg.Wait() // wait for everyone to exit
 }