/usr/share/gocode/src/github.com/hashicorp/serf/command/agent/agent.go is in golang-github-hashicorp-serf-dev 0.7.0~ds1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"encoding/base64"
"encoding/json"
"fmt"
"github.com/hashicorp/memberlist"
"github.com/hashicorp/serf/serf"
"io"
"io/ioutil"
"log"
"os"
"strings"
"sync"
)
// Agent starts and manages a Serf instance, adding some niceties
// on top of Serf such as storing logs that you can later retrieve,
// and invoking EventHandlers when events occur.
type Agent struct {
// Stores the serf configuration
conf *serf.Config
// Stores the agent configuration
agentConf *Config
// eventCh is used for Serf to deliver events on
eventCh chan serf.Event
// eventHandlers is the registered handlers for events
eventHandlers map[EventHandler]struct{}
eventHandlerList []EventHandler
eventHandlersLock sync.Mutex
// logger instance wraps the logOutput
logger *log.Logger
// This is the underlying Serf we are wrapping
serf *serf.Serf
// shutdownCh is used for shutdowns
shutdown bool
shutdownCh chan struct{}
shutdownLock sync.Mutex
}
// Start creates a new agent, potentially returning an error
func Create(agentConf *Config, conf *serf.Config, logOutput io.Writer) (*Agent, error) {
// Ensure we have a log sink
if logOutput == nil {
logOutput = os.Stderr
}
// Setup the underlying loggers
conf.MemberlistConfig.LogOutput = logOutput
conf.LogOutput = logOutput
// Create a channel to listen for events from Serf
eventCh := make(chan serf.Event, 64)
conf.EventCh = eventCh
// Setup the agent
agent := &Agent{
conf: conf,
agentConf: agentConf,
eventCh: eventCh,
eventHandlers: make(map[EventHandler]struct{}),
logger: log.New(logOutput, "", log.LstdFlags),
shutdownCh: make(chan struct{}),
}
// Restore agent tags from a tags file
if agentConf.TagsFile != "" {
if err := agent.loadTagsFile(agentConf.TagsFile); err != nil {
return nil, err
}
}
// Load in a keyring file if provided
if agentConf.KeyringFile != "" {
if err := agent.loadKeyringFile(agentConf.KeyringFile); err != nil {
return nil, err
}
}
return agent, nil
}
// Start is used to initiate the event listeners. It is separate from
// create so that there isn't a race condition between creating the
// agent and registering handlers
func (a *Agent) Start() error {
a.logger.Printf("[INFO] agent: Serf agent starting")
// Create serf first
serf, err := serf.Create(a.conf)
if err != nil {
return fmt.Errorf("Error creating Serf: %s", err)
}
a.serf = serf
// Start event loop
go a.eventLoop()
return nil
}
// Leave prepares for a graceful shutdown of the agent and its processes
func (a *Agent) Leave() error {
if a.serf == nil {
return nil
}
a.logger.Println("[INFO] agent: requesting graceful leave from Serf")
return a.serf.Leave()
}
// Shutdown closes this agent and all of its processes. Should be preceded
// by a Leave for a graceful shutdown.
func (a *Agent) Shutdown() error {
a.shutdownLock.Lock()
defer a.shutdownLock.Unlock()
if a.shutdown {
return nil
}
if a.serf == nil {
goto EXIT
}
a.logger.Println("[INFO] agent: requesting serf shutdown")
if err := a.serf.Shutdown(); err != nil {
return err
}
EXIT:
a.logger.Println("[INFO] agent: shutdown complete")
a.shutdown = true
close(a.shutdownCh)
return nil
}
// ShutdownCh returns a channel that can be selected to wait
// for the agent to perform a shutdown.
func (a *Agent) ShutdownCh() <-chan struct{} {
return a.shutdownCh
}
// Returns the Serf agent of the running Agent.
func (a *Agent) Serf() *serf.Serf {
return a.serf
}
// Returns the Serf config of the running Agent.
func (a *Agent) SerfConfig() *serf.Config {
return a.conf
}
// Join asks the Serf instance to join. See the Serf.Join function.
func (a *Agent) Join(addrs []string, replay bool) (n int, err error) {
a.logger.Printf("[INFO] agent: joining: %v replay: %v", addrs, replay)
ignoreOld := !replay
n, err = a.serf.Join(addrs, ignoreOld)
if n > 0 {
a.logger.Printf("[INFO] agent: joined: %d nodes", n)
}
if err != nil {
a.logger.Printf("[WARN] agent: error joining: %v", err)
}
return
}
// ForceLeave is used to eject a failed node from the cluster
func (a *Agent) ForceLeave(node string) error {
a.logger.Printf("[INFO] agent: Force leaving node: %s", node)
err := a.serf.RemoveFailedNode(node)
if err != nil {
a.logger.Printf("[WARN] agent: failed to remove node: %v", err)
}
return err
}
// UserEvent sends a UserEvent on Serf, see Serf.UserEvent.
func (a *Agent) UserEvent(name string, payload []byte, coalesce bool) error {
a.logger.Printf("[DEBUG] agent: Requesting user event send: %s. Coalesced: %#v. Payload: %#v",
name, coalesce, string(payload))
err := a.serf.UserEvent(name, payload, coalesce)
if err != nil {
a.logger.Printf("[WARN] agent: failed to send user event: %v", err)
}
return err
}
// Query sends a Query on Serf, see Serf.Query.
func (a *Agent) Query(name string, payload []byte, params *serf.QueryParam) (*serf.QueryResponse, error) {
// Prevent the use of the internal prefix
if strings.HasPrefix(name, serf.InternalQueryPrefix) {
// Allow the special "ping" query
if name != serf.InternalQueryPrefix+"ping" || payload != nil {
return nil, fmt.Errorf("Queries cannot contain the '%s' prefix", serf.InternalQueryPrefix)
}
}
a.logger.Printf("[DEBUG] agent: Requesting query send: %s. Payload: %#v",
name, string(payload))
resp, err := a.serf.Query(name, payload, params)
if err != nil {
a.logger.Printf("[WARN] agent: failed to start user query: %v", err)
}
return resp, err
}
// RegisterEventHandler adds an event handler to receive event notifications
func (a *Agent) RegisterEventHandler(eh EventHandler) {
a.eventHandlersLock.Lock()
defer a.eventHandlersLock.Unlock()
a.eventHandlers[eh] = struct{}{}
a.eventHandlerList = nil
for eh := range a.eventHandlers {
a.eventHandlerList = append(a.eventHandlerList, eh)
}
}
// DeregisterEventHandler removes an EventHandler and prevents more invocations
func (a *Agent) DeregisterEventHandler(eh EventHandler) {
a.eventHandlersLock.Lock()
defer a.eventHandlersLock.Unlock()
delete(a.eventHandlers, eh)
a.eventHandlerList = nil
for eh := range a.eventHandlers {
a.eventHandlerList = append(a.eventHandlerList, eh)
}
}
// eventLoop listens to events from Serf and fans out to event handlers
func (a *Agent) eventLoop() {
serfShutdownCh := a.serf.ShutdownCh()
for {
select {
case e := <-a.eventCh:
a.logger.Printf("[INFO] agent: Received event: %s", e.String())
a.eventHandlersLock.Lock()
handlers := a.eventHandlerList
a.eventHandlersLock.Unlock()
for _, eh := range handlers {
eh.HandleEvent(e)
}
case <-serfShutdownCh:
a.logger.Printf("[WARN] agent: Serf shutdown detected, quitting")
a.Shutdown()
return
case <-a.shutdownCh:
return
}
}
}
// InstallKey initiates a query to install a new key on all members
func (a *Agent) InstallKey(key string) (*serf.KeyResponse, error) {
a.logger.Print("[INFO] agent: Initiating key installation")
manager := a.serf.KeyManager()
return manager.InstallKey(key)
}
// UseKey sends a query instructing all members to switch primary keys
func (a *Agent) UseKey(key string) (*serf.KeyResponse, error) {
a.logger.Print("[INFO] agent: Initiating primary key change")
manager := a.serf.KeyManager()
return manager.UseKey(key)
}
// RemoveKey sends a query to all members to remove a key from the keyring
func (a *Agent) RemoveKey(key string) (*serf.KeyResponse, error) {
a.logger.Print("[INFO] agent: Initiating key removal")
manager := a.serf.KeyManager()
return manager.RemoveKey(key)
}
// ListKeys sends a query to all members to return a list of their keys
func (a *Agent) ListKeys() (*serf.KeyResponse, error) {
a.logger.Print("[INFO] agent: Initiating key listing")
manager := a.serf.KeyManager()
return manager.ListKeys()
}
// SetTags is used to update the tags. The agent will make sure to
// persist tags if necessary before gossiping to the cluster.
func (a *Agent) SetTags(tags map[string]string) error {
// Update the tags file if we have one
if a.agentConf.TagsFile != "" {
if err := a.writeTagsFile(tags); err != nil {
a.logger.Printf("[ERR] agent: %s", err)
return err
}
}
// Set the tags in Serf, start gossiping out
return a.serf.SetTags(tags)
}
// loadTagsFile will load agent tags out of a file and set them in the
// current serf configuration.
func (a *Agent) loadTagsFile(tagsFile string) error {
// Avoid passing tags and using a tags file at the same time
if len(a.agentConf.Tags) > 0 {
return fmt.Errorf("Tags config not allowed while using tag files")
}
if _, err := os.Stat(tagsFile); err == nil {
tagData, err := ioutil.ReadFile(tagsFile)
if err != nil {
return fmt.Errorf("Failed to read tags file: %s", err)
}
if err := json.Unmarshal(tagData, &a.conf.Tags); err != nil {
return fmt.Errorf("Failed to decode tags file: %s", err)
}
a.logger.Printf("[INFO] agent: Restored %d tag(s) from %s",
len(a.conf.Tags), tagsFile)
}
// Success!
return nil
}
// writeTagsFile will write the current tags to the configured tags file.
func (a *Agent) writeTagsFile(tags map[string]string) error {
encoded, err := json.MarshalIndent(tags, "", " ")
if err != nil {
return fmt.Errorf("Failed to encode tags: %s", err)
}
// Use 0600 for permissions, in case tag data is sensitive
if err = ioutil.WriteFile(a.agentConf.TagsFile, encoded, 0600); err != nil {
return fmt.Errorf("Failed to write tags file: %s", err)
}
// Success!
return nil
}
// MarshalTags is a utility function which takes a map of tag key/value pairs
// and returns the same tags as strings in 'key=value' format.
func MarshalTags(tags map[string]string) []string {
var result []string
for name, value := range tags {
result = append(result, fmt.Sprintf("%s=%s", name, value))
}
return result
}
// UnmarshalTags is a utility function which takes a slice of strings in
// key=value format and returns them as a tag mapping.
func UnmarshalTags(tags []string) (map[string]string, error) {
result := make(map[string]string)
for _, tag := range tags {
parts := strings.SplitN(tag, "=", 2)
if len(parts) != 2 || len(parts[0]) == 0 {
return nil, fmt.Errorf("Invalid tag: '%s'", tag)
}
result[parts[0]] = parts[1]
}
return result, nil
}
// loadKeyringFile will load a keyring out of a file
func (a *Agent) loadKeyringFile(keyringFile string) error {
// Avoid passing an encryption key and a keyring file at the same time
if len(a.agentConf.EncryptKey) > 0 {
return fmt.Errorf("Encryption key not allowed while using a keyring")
}
if _, err := os.Stat(keyringFile); err != nil {
return err
}
// Read in the keyring file data
keyringData, err := ioutil.ReadFile(keyringFile)
if err != nil {
return fmt.Errorf("Failed to read keyring file: %s", err)
}
// Decode keyring JSON
keys := make([]string, 0)
if err := json.Unmarshal(keyringData, &keys); err != nil {
return fmt.Errorf("Failed to decode keyring file: %s", err)
}
// Decode base64 values
keysDecoded := make([][]byte, len(keys))
for i, key := range keys {
keyBytes, err := base64.StdEncoding.DecodeString(key)
if err != nil {
return fmt.Errorf("Failed to decode key from keyring: %s", err)
}
keysDecoded[i] = keyBytes
}
// Guard against empty keyring file
if len(keysDecoded) == 0 {
return fmt.Errorf("Keyring file contains no keys")
}
// Create the keyring
keyring, err := memberlist.NewKeyring(keysDecoded, keysDecoded[0])
if err != nil {
return fmt.Errorf("Failed to restore keyring: %s", err)
}
a.conf.MemberlistConfig.Keyring = keyring
a.logger.Printf("[INFO] agent: Restored keyring with %d keys from %s",
len(keys), keyringFile)
// Success!
return nil
}
// Stats is used to get various runtime information and stats
func (a *Agent) Stats() map[string]map[string]string {
local := a.serf.LocalMember()
event_handlers := make(map[string]string)
// Convert event handlers from a string slice to a string map
for _, script := range a.agentConf.EventScripts() {
script_filter := fmt.Sprintf("%s:%s", script.EventFilter.Event, script.EventFilter.Name)
event_handlers[script_filter] = script.Script
}
output := map[string]map[string]string{
"agent": map[string]string{
"name": local.Name,
},
"runtime": runtimeStats(),
"serf": a.serf.Stats(),
"tags": local.Tags,
"event_handlers": event_handlers,
}
return output
}
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