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curator.go
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curator.go
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package main
import (
"bufio"
"encoding/json"
"flag"
"fmt"
"gopkg.in/yaml.v2"
"io"
"io/ioutil"
"log"
"net/http"
_ "net/http/pprof"
"os"
"os/exec"
"path"
"path/filepath"
"strings"
"syscall"
"bytes"
"github.com/gorilla/mux"
"text/template"
)
type OutputStreams struct {
Stdout OutputStream
Stderr OutputStream
}
type OutputStream struct {
LogFile LogFile `yaml:"log_file"`
}
type LogFile struct {
Path string
Maxbytes int
Backups int
}
type Program struct {
Name string
Command string
ProcessName string `yaml:"process_name"`
Numprocs int
NumprocsStart int `yaml:"numprocs_start"`
Priority int
Autostart bool
Autorestart bool
StartSecs int `yaml:"start_secs"`
StartRetries int `yaml:"start_retries"`
ExitCodes []int `yaml:"exit_codes"`
StopSignal string `yaml:"stop_signal"`
StopWaitSecs int `yaml:"stop_wait_secs"`
User string
RedirectStderr bool `yaml:"redirect_stderr"`
Environment map[string]string
Directory string
ServerURL string `yaml:"server_url"`
OutputStreams OutputStreams `yaml:"output_streams"`
}
type State int
const (
STOPPED State = iota
STARTING
RUNNING
STOPPING
FAILED
)
func (s State) String() string {
switch s {
case STOPPED:
return "STOPPED"
case STARTING:
return "STARTING"
case RUNNING:
return "RUNNING"
case STOPPING:
return "STOPPING"
case FAILED:
return "FAILED"
}
return ""
}
type ManagedProcess struct {
Title string
Command string
Process *exec.Cmd
State State
OutputStreams OutputStreams
ProgramName string
StartCount int
Terminated bool
}
type ProcessMetadata struct {
ProcessNumber int
ProcessName string
}
var processTable map[string]*ManagedProcess
var programTable map[string]*Program
// TODO: check output file size and rotate.
func flushStream(stdoutPipe *BlockReadWriter, writer *bufio.Writer) {
buffer := make([]byte, 100, 1000)
for {
n, err := stdoutPipe.Read(buffer)
buffer = buffer[0:n]
writer.Write(buffer)
writer.Flush()
if err == io.EOF {
//stdoutPipe.Close()
fmt.Printf("EOF\n")
break
}
}
}
func spawnProcess(proc ManagedProcess) {
log.Printf("[%s] Spawning process...\n", proc.Title)
program := programTable[proc.ProgramName]
for i := 0; i < program.StartRetries && !proc.Terminated; i++ {
proc.StartCount++
log.Printf("[%s] Running %d/%d times...\n", proc.Title, i, program.StartRetries)
stdoutPath := proc.OutputStreams.Stdout.LogFile.Path
stderrPath := proc.OutputStreams.Stderr.LogFile.Path
// Handle stdout
outw := bufio.NewWriter(ioutil.Discard)
errw := bufio.NewWriter(ioutil.Discard)
if stdoutPath != "" {
log.Printf("[%s] Writing STDOUT to %s\n", proc.Title, stdoutPath)
outf, err := os.Create(stdoutPath)
if err != nil {
panic(err)
}
outw = bufio.NewWriter(outf)
}
if stderrPath != "" {
log.Printf("[%s] Writing STDERR to %s\n", proc.Title, stderrPath)
errf, err := os.Create(stderrPath)
if err != nil {
panic(err)
}
errw = bufio.NewWriter(errf)
}
stdoutPipe := NewBlockReadWriter()
go flushStream(stdoutPipe, outw)
stderrPipe := NewBlockReadWriter()
go flushStream(stderrPipe, errw)
log.Printf("[%s] Command: %s\n", proc.Title, proc.Command)
cmdParts := strings.Split(proc.Command, " ")
cmd := exec.Command(cmdParts[0], cmdParts[1:]...)
cmd.Stdout = stdoutPipe
cmd.Stderr = stderrPipe
proc.State = STARTING
proc.Process = cmd
log.Printf("[%s] Adding '%s' to process table\n", proc.Title, proc.Title)
processTable[proc.Title] = &proc
e := cmd.Start()
if e != nil {
panic(e)
}
proc.State = RUNNING
if err := cmd.Wait(); err != nil {
if exiterr, ok := err.(*exec.ExitError); ok {
// The program has exited with an exit code != 0
// This works on both Unix and Windows. Although package
// syscall is generally platform dependent, WaitStatus is
// defined for both Unix and Windows and in both cases has
// an ExitStatus() method with the same signature.
if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
log.Printf("[%s] Exit Status: %d", proc.Title, status.ExitStatus())
}
proc.State = STOPPED
} else {
log.Fatalf("[%s] cmd.Wait: %v", proc.Title, err)
}
} else {
log.Printf("[%s] Exited gracefully.", proc.Title)
proc.State = STOPPED
}
}
if proc.StartCount == program.StartRetries {
log.Printf("[%s] Tried to startup %d times, marking as FAILED", proc.Title, program.StartRetries)
proc.State = FAILED
}
if proc.Terminated {
log.Printf("[%s] Terminated on command", proc.Title)
proc.State = STOPPED
}
}
func startProgram(programName string) {
if proc, present := processTable[programName]; present {
if proc.State == RUNNING {
log.Print("[curator] Not starting a running program!")
} else {
proc.Terminated = false
proc.StartCount = 0
log.Printf("[curator] Spawning process for %s", proc.Title)
go spawnProcess(*proc)
}
}
}
func terminateProgram(programName string) {
if proc, present := processTable[programName]; present {
cmd := proc.Process
if proc.State == STOPPED {
log.Printf("[curator] Nothing to do, process %s already stopped\n", programName)
} else {
log.Printf("[curator] Terminating program %s\n", programName)
proc.State = STOPPED
proc.Terminated = true
cmd.Process.Kill()
proc.Process = nil
}
}
}
func handleConfig(configFile string) {
var p *Program = new(Program)
var fileData, err = ioutil.ReadFile(configFile)
if err != nil {
panic(err)
}
err = yaml.Unmarshal(fileData, p)
if err != nil {
fmt.Printf("Error parsing YAML file '%s': %s", configFile, err)
return
}
p.Name = strings.Replace(configFile, ".yml", "", 1)
programTable[p.Name] = p
if p.Autostart {
for i := p.NumprocsStart; i < p.Numprocs+p.NumprocsStart; i++ {
pm := ProcessMetadata{
ProcessNumber: i,
ProcessName: p.ProcessName,
}
processTitle, _ := injectProcessMetadata(p.ProcessName, &pm)
commandString, _ := injectProcessMetadata(p.Command, &pm)
stderrLogFile, _ := injectProcessMetadata(p.OutputStreams.Stderr.LogFile.Path, &pm)
stdoutLogFile, _ := injectProcessMetadata(p.OutputStreams.Stdout.LogFile.Path, &pm)
newOutputStreams := p.OutputStreams
newOutputStreams.Stderr.LogFile.Path = stderrLogFile
newOutputStreams.Stdout.LogFile.Path = stdoutLogFile
// TODO: handle forced reloading, which would terminate the
// process and then reload. For now only load new things.
if _, present := processTable[processTitle]; !present {
log.Printf("[curator] Spawning %s\n", processTitle)
proc := ManagedProcess{
ProgramName: p.Name,
Title: processTitle,
Command: commandString,
OutputStreams: newOutputStreams,
Terminated: false,
StartCount: 0,
}
go spawnProcess(proc)
}
}
}
}
func injectProcessMetadata(templateData string, metadata *ProcessMetadata) (string, error) {
var doc bytes.Buffer
tmpl, err := template.New("processname").Parse(templateData)
if err != nil {
return "", fmt.Errorf("Unable to process '%s': %s", templateData, err)
}
tmpl.Execute(&doc, *metadata)
return doc.String(), nil
}
func loadConfigs(srcDir string) {
globStr := path.Join(srcDir, "*.yml")
log.Printf("[curator] Loading files matching %s\n", globStr)
configFiles, _ := filepath.Glob(globStr)
for _, configFile := range configFiles {
log.Printf("[curator] Processing %s...\n", configFile)
handleConfig(configFile)
}
}
func Index(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Content-Type", "application/json")
processes := make(map[string]string)
for k, p := range processTable {
processes[k] = fmt.Sprintf("%s", p.State)
}
json.NewEncoder(w).Encode(processes)
}
func ShowProcess(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
processName := vars["processName"]
w.Header().Add("Content-Type", "application/json")
json.NewEncoder(w).Encode(processTable[processName])
}
func StopProcess(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
processName := vars["processName"]
terminateProgram(processName)
w.Header().Add("Content-Type", "application/json")
fmt.Fprint(w, "OK")
}
func StartProcess(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
processName := vars["processName"]
startProgram(processName)
w.Header().Add("Content-Type", "application/json")
fmt.Fprint(w, "OK")
}
func ReloadConfigs(w http.ResponseWriter, r *http.Request) {
cwd, _ := os.Getwd()
configDir := cwd
loadConfigs(configDir)
w.Header().Add("Content-Type", "application/json")
fmt.Fprint(w, "OK")
}
func main() {
processTable = make(map[string]*ManagedProcess)
programTable = make(map[string]*Program)
configDir := flag.String("configDir", ".", "Where to load YAML files from")
flag.Parse()
if *configDir == "." {
cwd, _ := os.Getwd()
configDir = &cwd
}
loadConfigs(*configDir)
router := mux.NewRouter().StrictSlash(true)
router.HandleFunc("/", Index)
router.HandleFunc("/reload", ReloadConfigs)
router.HandleFunc("/processes/{processName}", ShowProcess)
router.HandleFunc("/processes/{processName}/stop", StopProcess)
router.HandleFunc("/processes/{processName}/start", StartProcess)
log.Fatal(http.ListenAndServe(":8080", router))
}