// process a message from the SQS queue. This should be run inside a goroutine.
func processMessage(q *sqs.Queue, m sqs.Message, wo work_order.WorkOrder, wg *sync.WaitGroup) {
logger.Debug("Starting process on %d from '%s'", wo.Id, m.MessageId)
// start heartbeat
beat := heartbeat.Start(q, &m)
// execute the work
err := wo.Execute()
if err != nil {
logger.Error("Error executing: %d - %v", wo.Id, err)
}
// send response back to devops-web
wo.Report()
// stop the heartbeat
beat.Stop()
// delete message
logger.Debug("Deleting message: %s", m.MessageId)
_, err = q.DeleteMessage(&m)
if err != nil {
logger.Error("ERROR: Couldn't delete message: %s - %v", m.MessageId, err)
}
// exit this goroutine
wg.Done()
}
// Execute a WorkOrder and populate its response object
func (wo *WorkOrder) Execute() (error error) {
logger.Info("Starting work on WorkOrder: %d with \"%s\"", wo.Id, wo.Message)
// setup command to be run with arguments from the command line
wo_args := strings.Split(wo.Message, " ")
base_args := strings.Split(os.Getenv("CMD_BASE"), " ")
cmd := exec.Command(base_args[0])
cmd.Args = append(base_args[0:], wo_args[0:]...)
cmd.Dir = os.Getenv("CMD_DIR")
// collect stdout and stderr
var output bytes.Buffer
cmd.Stdout = &output
cmd.Stderr = &output
// start timing command
start_time := time.Now()
// execute the command
if err := cmd.Start(); err != nil {
logger.Error("cmd.Start:", err)
error = err
}
// http://stackoverflow.com/questions/10385551/get-exit-code-go
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 {
// logger.Info("Exit Status: %d", status.ExitStatus())
wo.response.Result.ExitStatus = status.ExitStatus()
}
} else {
logger.Error("cmd.Wait: %v", err)
error = err
}
}
// calculate the time taken to complete the command
end_time := time.Now()
wo.response.TimeTaken = end_time.Sub(start_time).Seconds()
wo.response.CompletedAt = &end_time
// attach the output of the command to the result message
wo.response.Result.Message = output.String()
logger.Info("Completed WorkOrder: %d", wo.Id)
return
}
// Report on the result of the WorkOrders execution.
// This method requires that the WorkOrder has been Executed.
func (wo *WorkOrder) Report() (error error) {
report_queue := os.Getenv("SQS_REPORT_QUEUE")
logger.Info("Sending response to '%s' for: %d", report_queue, wo.Id)
// prepare the response object
wo.response.Id = wo.Id
// create sqs client
client, err := sqs.NewFrom(os.Getenv("SQS_WORKER_ACCESS_KEY"), os.Getenv("SQS_WORKER_SECRET_KEY"), "us-east-1")
if err != nil {
logger.Error("Could not report: %d - %v", wo.Id, err)
error = err
return
}
// get the SQS queue
queue, err := client.GetQueue(report_queue)
if err != nil {
logger.Error("REPORT QUEUE ERROR: %d - %v", wo.Id, err)
error = err
return
}
// trim the message so that it will fit in SQS
if len(wo.response.Result.Message) > 60000 {
logger.Info("Trimming WorkOrder %d message down from %d chars", wo.Id, len(wo.response.Result.Message))
wo.response.Result.Message = wo.response.Result.Message[0:30000] + "\n\n...(truncated)...\n\n" + wo.response.Result.Message[len(wo.response.Result.Message)-30000:]
}
// marshal the response object into json
data, err := json.Marshal(wo.response)
if err != nil {
logger.Error("Could not convert response to JSON for: %d - %v", wo.Id, err)
error = err
return
}
// send the report to the queue
_, err = queue.SendMessage(string(data))
if err != nil {
logger.Error("Could not report: %d - %v", wo.Id, err)
error = err
}
return
}
// Send a heartbeat to SQS notifying it that we are still working on the message.
func (heartbeat *Heartbeat) beat(t time.Time) {
logger.Debug("Sending heartbeat for: %s", heartbeat.Message.MessageId)
// change the sqs message visibility
_, err := heartbeat.Queue.ChangeMessageVisibility(heartbeat.Message, 2*60)
if err != nil {
logger.Error("HEARTBEAT ERROR: messageId: %s - %v", heartbeat.Message.MessageId, err)
}
}
func main() {
logger.Info("Sending messages...")
// create sqs client
client, err := sqs.NewFrom(os.Getenv("ADMIN_AWS_ACCESS_KEY_ID"), os.Getenv("ADMIN_AWS_SECRET_ACCESS_KEY"), "us-east-1")
if err != nil {
logger.Fatal("CLIENT ERROR:", err, "asdf", "asdfdasfd")
}
// get the SQS queue
queue, err := client.GetQueue(os.Getenv("SQS_RECIEVE_QUEUE"))
if err != nil {
logger.Fatal("QUEUE ERROR:", err)
}
for i := 0; i < 100; i++ {
var wo work_order.WorkOrder
current_time := time.Now()
wo.Id = i
wo.JobId = 1
wo.Message = strconv.Itoa(rand.Intn(80))
wo.CreatedAt = ¤t_time
wo.UpdatedAt = ¤t_time
wo.Queue = os.Getenv("SQS_RECIEVE_QUEUE")
data, err := json.Marshal(wo)
if err != nil {
logger.Error("JSON error: %v", err)
}
queue.SendMessage(string(data))
}
// quit
logger.Info("Exiting.")
os.Exit(0)
}
func main() {
logger.Info("Starting worker v%s", VERSION)
// get worker count
workers, err := strconv.Atoi(os.Getenv("WORKER_COUNT"))
if err != nil {
workers = 10
}
logger.Info("Worker count: %d", workers)
// access key, secret key, receive queue and report queue should be in ENV variables
logger.Info("SQS queue: %s", os.Getenv("SQS_WORKER_QUEUE"))
// create sqs client
client, err := sqs.NewFrom(os.Getenv("SQS_WORKER_ACCESS_KEY"), os.Getenv("SQS_WORKER_SECRET_KEY"), "us-east-1")
if err != nil {
logger.Fatal("CLIENT ERROR: %v", err)
}
// get the SQS queue
queue, err := client.GetQueue(os.Getenv("SQS_WORKER_QUEUE"))
if err != nil {
logger.Fatal("QUEUE ERROR: %v", err)
}
logger.Info("Worker started.")
// create the wait group
var wg sync.WaitGroup
for {
// get some messages from the sqs queue
logger.Debug("Checking for messages on the queue...")
resp, err := queue.ReceiveMessageWithVisibilityTimeout(workers, 60)
if err != nil {
logger.Error("Could not receive messages: %v", err)
time.Sleep(10 * time.Second)
}
if cap(resp.Messages) == 0 {
logger.Debug("Did not find any messages on the queue.")
}
// for each message
for _, message := range resp.Messages {
// get the message details
wo, err := work_order.NewFromJson(message.Body)
if err != nil {
logger.Error("Could not process SQS message: %s with JSON ERROR: %v", message.MessageId, err)
} else {
// process the message in a goroutine
wg.Add(1)
go processMessage(queue, message, wo, &wg)
}
}
// wait for each goroutine to exit
wg.Wait()
}
}