wings/server/state.go

144 lines
4.4 KiB
Go

package server
import (
"encoding/json"
"fmt"
"github.com/pkg/errors"
"github.com/pterodactyl/wings/config"
"go.uber.org/zap"
"io"
"io/ioutil"
"os"
"sync"
)
var stateMutex sync.Mutex
// Returns the state of the servers.
func getServerStates() (map[string]string, error) {
// Request a lock after we check if the file exists.
stateMutex.Lock()
defer stateMutex.Unlock()
// Open the states file.
f, err := os.OpenFile(config.Get().System.GetStatesPath(), os.O_RDONLY|os.O_CREATE, 0644)
if err != nil {
return nil, errors.WithStack(err)
}
defer f.Close()
// Convert the json object to a map.
states := map[string]string{}
if err := json.NewDecoder(f).Decode(&states); err != nil && err != io.EOF {
return nil, errors.WithStack(err)
}
return states, nil
}
// saveServerStates .
func saveServerStates() error {
// Get the states of all servers on the daemon.
states := map[string]string{}
for _, s := range GetServers().All() {
states[s.Uuid] = s.GetState()
}
// Convert the map to a json object.
data, err := json.Marshal(states)
if err != nil {
return errors.WithStack(err)
}
stateMutex.Lock()
defer stateMutex.Unlock()
// Write the data to the file
if err := ioutil.WriteFile(config.Get().System.GetStatesPath(), data, 0644); err != nil {
return errors.WithStack(err)
}
return nil
}
const (
ProcessOfflineState = "offline"
ProcessStartingState = "starting"
ProcessRunningState = "running"
ProcessStoppingState = "stopping"
)
// Sets the state of the server internally. This function handles crash detection as
// well as reporting to event listeners for the server.
func (s *Server) SetState(state string) error {
if state != ProcessOfflineState && state != ProcessStartingState && state != ProcessRunningState && state != ProcessStoppingState {
return errors.New(fmt.Sprintf("invalid server state received: %s", state))
}
prevState := s.GetState()
// Obtain a mutex lock and update the current state of the server.
s.Lock()
s.State = state
// Emit the event to any listeners that are currently registered.
s.Log().WithField("status", s.State).Debug("saw server status change event")
s.Events().Publish(StatusEvent, s.State)
// Release the lock as it is no longer needed for the following actions.
s.Unlock()
// Persist this change to the disk immediately so that should the Daemon be stopped or
// crash we can immediately restore the server state.
//
// This really only makes a difference if all of the Docker containers are also stopped,
// but this was a highly requested feature and isn't hard to work with, so lets do it.
//
// We also get the benefit of server status changes always propagating corrected configurations
// to the disk should we forget to do it elsewhere.
go func() {
if err := saveServerStates(); err != nil {
zap.S().Warnw("failed to write server states to disk", zap.Error(err))
}
}()
// If server was in an online state, and is now in an offline state we should handle
// that as a crash event. In that scenario, check the last crash time, and the crash
// counter.
//
// In the event that we have passed the thresholds, don't do anything, otherwise
// automatically attempt to start the process back up for the user. This is done in a
// separate thread as to not block any actions currently taking place in the flow
// that called this function.
if (prevState == ProcessStartingState || prevState == ProcessRunningState) && s.GetState() == ProcessOfflineState {
zap.S().Infow("detected server as entering a potentially crashed state; running handler", zap.String("server", s.Uuid))
go func(server *Server) {
if err := server.handleServerCrash(); err != nil {
if IsTooFrequentCrashError(err) {
zap.S().Infow("did not restart server after crash; occurred too soon after last", zap.String("server", server.Uuid))
} else {
zap.S().Errorw("failed to handle server crash state", zap.String("server", server.Uuid), zap.Error(err))
}
}
}(s)
}
return nil
}
// Returns the current state of the server in a race-safe manner.
func (s *Server) GetState() string {
s.RLock()
defer s.RUnlock()
return s.State
}
// Determines if the server state is running or not. This is different than the
// environment state, it is simply the tracked state from this daemon instance, and
// not the response from Docker.
func (s *Server) IsRunning() bool {
return s.GetState() == ProcessRunningState || s.GetState() == ProcessStartingState
}