gocelery

package module
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README

gocelery

Go Client/Server for Celery Distributed Task Queue

Build Status Coverage Status Go Report Card GoDoc License FOSSA Status

Why?

Having been involved in several projects migrating servers from Python to Go, I have realized Go can improve performance of existing python web applications. As Celery distributed tasks are often used in such web applications, this library allows you to both implement celery workers and submit celery tasks in Go.

You can also use this library as pure go distributed task queue.

Go Celery Worker in Action

demo

Supported Brokers/Backends

Now supporting both Redis and AMQP!!

  • Redis (broker/backend)
  • AMQP (broker/backend) - does not allow concurrent use of channels

Celery Configuration

Celery must be configured to use json instead of default pickle encoding. This is because Go currently has no stable support for decoding pickle objects. Pass below configuration parameters to use json.

Starting from version 4.0, Celery uses message protocol version 2 as default value. GoCelery does not yet support message protocol version 2, so you must explicitly set CELERY_TASK_PROTOCOL to 1.

CELERY_TASK_SERIALIZER='json',
CELERY_ACCEPT_CONTENT=['json'],  # Ignore other content
CELERY_RESULT_SERIALIZER='json',
CELERY_ENABLE_UTC=True,
CELERY_TASK_PROTOCOL=1,

Example

GoCelery GoDoc has good examples.
Also take a look at example directory for sample python code.

GoCelery Worker Example

Run Celery Worker implemented in Go

// create redis connection pool
redisPool := &redis.Pool{
  Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := gocelery.NewCeleryClient(
	gocelery.NewRedisBroker(redisPool),
	&gocelery.RedisCeleryBackend{Pool: redisPool},
	5, // number of workers
)

// task
add := func(a, b int) int {
	return a + b
}

// register task
cli.Register("worker.add", add)

// start workers (non-blocking call)
cli.StartWorker()

// wait for client request
time.Sleep(10 * time.Second)

// stop workers gracefully (blocking call)
cli.StopWorker()
Python Client Example

Submit Task from Python Client

from celery import Celery

app = Celery('tasks',
    broker='redis://localhost:6379',
    backend='redis://localhost:6379'
)

@app.task
def add(x, y):
    return x + y

if __name__ == '__main__':
    ar = add.apply_async((5456, 2878), serializer='json')
    print(ar.get())
Python Worker Example

Run Celery Worker implemented in Python

from celery import Celery

app = Celery('tasks',
    broker='redis://localhost:6379',
    backend='redis://localhost:6379'
)

@app.task
def add(x, y):
    return x + y

celery -A worker worker --loglevel=debug --without-heartbeat --without-mingle
GoCelery Client Example

Submit Task from Go Client

// create redis connection pool
redisPool := &redis.Pool{
  Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := gocelery.NewCeleryClient(
	gocelery.NewRedisBroker(redisPool),
	&gocelery.RedisCeleryBackend{Pool: redisPool},
	1,
)

// prepare arguments
taskName := "worker.add"
argA := rand.Intn(10)
argB := rand.Intn(10)

// run task
asyncResult, err := cli.Delay(taskName, argA, argB)
if err != nil {
	panic(err)
}

// get results from backend with timeout
res, err := asyncResult.Get(10 * time.Second)
if err != nil {
	panic(err)
}

log.Printf("result: %+v of type %+v", res, reflect.TypeOf(res))

Sample Celery Task Message

Celery Message Protocol Version 1

{
    "expires": null,
    "utc": true,
    "args": [5456, 2878],
    "chord": null,
    "callbacks": null,
    "errbacks": null,
    "taskset": null,
    "id": "c8535050-68f1-4e18-9f32-f52f1aab6d9b",
    "retries": 0,
    "task": "worker.add",
    "timelimit": [null, null],
    "eta": null,
    "kwargs": {}
}

Projects

Please let us know if you use gocelery in your project!

Contributing

You are more than welcome to make any contributions. Please create Pull Request for any changes.

LICENSE

The gocelery is offered under MIT license.

Documentation

Overview

Package gocelery is Celery Distributed Task Queue in Go

Celery distributed tasks are used heavily in many python web applications and this library allows you to implement celery workers in Go as well as being able to submit celery tasks in Go.

This package can also be used as pure go distributed task queue.

Supported brokers/backends

  • Redis (broker/backend)
  • AMQP (broker/backend)

Celery must be configured to use json instead of default pickle encoding. This is because Go currently has no stable support for decoding pickle objects. Pass below configuration parameters to use json. 

CELERY_TASK_SERIALIZER='json'
CELERY_ACCEPT_CONTENT=['json']  # Ignore other content
CELERY_RESULT_SERIALIZER='json'
CELERY_ENABLE_UTC=True
Example (Client) 
// create redis connection pool
redisPool := &redis.Pool{
	Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := NewCeleryClient(
	NewRedisBroker(redisPool),
	&RedisCeleryBackend{Pool: redisPool},
	1,
)

// prepare arguments
taskName := "worker.add"
argA := rand.Intn(10)
argB := rand.Intn(10)

// run task
asyncResult, err := cli.Delay(taskName, argA, argB)
if err != nil {
	panic(err)
}

// get results from backend with timeout
res, err := asyncResult.Get(10 * time.Second)
if err != nil {
	panic(err)
}

log.Printf("result: %+v of type %+v", res, reflect.TypeOf(res))

Output:
Example (ClientWithNamedArguments) 
// create redis connection pool
// create redis connection pool
redisPool := &redis.Pool{
	Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := NewCeleryClient(
	NewRedisBroker(redisPool),
	&RedisCeleryBackend{Pool: redisPool},
	1,
)

// prepare arguments
taskName := "worker.add"
argA := rand.Intn(10)
argB := rand.Intn(10)

// run task
asyncResult, err := cli.DelayKwargs(
	taskName,
	map[string]interface{}{
		"a": argA,
		"b": argB,
	},
)
if err != nil {
	panic(err)
}

// get results from backend with timeout
res, err := asyncResult.Get(10 * time.Second)
if err != nil {
	panic(err)
}

log.Printf("result: %+v of type %+v", res, reflect.TypeOf(res))

Output:
Example (Worker) 
// create redis connection pool
redisPool := &redis.Pool{
	Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := NewCeleryClient(
	NewRedisBroker(redisPool),
	&RedisCeleryBackend{Pool: redisPool},
	5, // number of workers
)

// task
add := func(a, b int) int {
	return a + b
}

// register task
cli.Register("add", add)

// start workers (non-blocking call)
cli.StartWorker()

// wait for client request
time.Sleep(10 * time.Second)

// stop workers gracefully (blocking call)
cli.StopWorker()

Output:
Example (WorkerWithContext) 
// create redis connection pool
redisPool := &redis.Pool{
	Dial: func() (redis.Conn, error) {
		c, err := redis.DialURL("redis://")
		if err != nil {
			return nil, err
		}
		return c, err
	},
}

// initialize celery client
cli, _ := NewCeleryClient(
	NewRedisBroker(redisPool),
	&RedisCeleryBackend{Pool: redisPool},
	1,
)

// task
add := func(a, b int) int {
	return a + b
}

// register task
cli.Register("add", add)

// context with cancelFunc to handle exit gracefully
ctx, cancel := context.WithCancel(context.Background())

// start workers (non-blocking call)
cli.StartWorkerWithContext(ctx)

// wait for client request
time.Sleep(10 * time.Second)

// stop workers by cancelling context
cancel()

// optional: wait for all workers to terminate
cli.WaitForStopWorker()

Output:
Example (WorkerWithNamedArguments) 
package main

import (
	"fmt"
	"time"

	"github.com/gomodule/redigo/redis"
)

// exampleAddTask is integer addition task
// with named arguments
type exampleAddTask struct {
	a int
	b int
}

func (a *exampleAddTask) ParseKwargs(kwargs map[string]interface{}) error {
	kwargA, ok := kwargs["a"]
	if !ok {
		return fmt.Errorf("undefined kwarg a")
	}
	kwargAFloat, ok := kwargA.(float64)
	if !ok {
		return fmt.Errorf("malformed kwarg a")
	}
	a.a = int(kwargAFloat)
	kwargB, ok := kwargs["b"]
	if !ok {
		return fmt.Errorf("undefined kwarg b")
	}
	kwargBFloat, ok := kwargB.(float64)
	if !ok {
		return fmt.Errorf("malformed kwarg b")
	}
	a.b = int(kwargBFloat)
	return nil
}

func (a *exampleAddTask) RunTask() (interface{}, error) {
	result := a.a + a.b
	return result, nil
}

func main() {

	// create redis connection pool
	redisPool := &redis.Pool{
		Dial: func() (redis.Conn, error) {
			c, err := redis.DialURL("redis://")
			if err != nil {
				return nil, err
			}
			return c, err
		},
	}

	// initialize celery client
	cli, _ := NewCeleryClient(
		NewRedisBroker(redisPool),
		&RedisCeleryBackend{Pool: redisPool},
		5, // number of workers
	)

	// register task
	cli.Register("add", &exampleAddTask{})

	// start workers (non-blocking call)
	cli.StartWorker()

	// wait for client request
	time.Sleep(10 * time.Second)

	// stop workers gracefully (blocking call)
	cli.StopWorker()
}

Output:

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func GetRealValue 

func GetRealValue(val *reflect.Value) interface{}

GetRealValue returns real value of reflect.Value Required for JSON Marshalling

func NewAMQPConnection 

func NewAMQPConnection(host string) (*amqp.Connection, *amqp.Channel)

NewAMQPConnection creates new AMQP channel

func NewRedisPool deprecated 

func NewRedisPool(uri string) *redis.Pool

NewRedisPool creates pool of redis connections from given connection string

Deprecated: newRedisPool exists for historical compatibility and should not be used. Pool should be initialized outside of gocelery package.

Types

type AMQPCeleryBackend 

type AMQPCeleryBackend struct {
	*amqp.Channel
	// contains filtered or unexported fields
}

AMQPCeleryBackend CeleryBackend for AMQP

func NewAMQPCeleryBackend 

func NewAMQPCeleryBackend(host string) *AMQPCeleryBackend

NewAMQPCeleryBackend creates new AMQPCeleryBackend

func NewAMQPCeleryBackendByConnAndChannel 

func NewAMQPCeleryBackendByConnAndChannel(conn *amqp.Connection, channel *amqp.Channel) *AMQPCeleryBackend

NewAMQPCeleryBackendByConnAndChannel creates new AMQPCeleryBackend by AMQP connection and channel

func (*AMQPCeleryBackend) GetResult 

func (b *AMQPCeleryBackend) GetResult(taskID string) (*ResultMessage, error)

GetResult retrieves result from AMQP queue

func (*AMQPCeleryBackend) Reconnect 

func (b *AMQPCeleryBackend) Reconnect()

Reconnect reconnects to AMQP server

func (*AMQPCeleryBackend) SetResult 

func (b *AMQPCeleryBackend) SetResult(taskID string, result *ResultMessage) error

SetResult sets result back to AMQP queue

type AMQPCeleryBroker 

type AMQPCeleryBroker struct {
	*amqp.Channel
	// contains filtered or unexported fields
}

AMQPCeleryBroker is RedisBroker for AMQP

func NewAMQPCeleryBroker 

func NewAMQPCeleryBroker(host string) *AMQPCeleryBroker

NewAMQPCeleryBroker creates new AMQPCeleryBroker

func NewAMQPCeleryBrokerByConnAndChannel 

func NewAMQPCeleryBrokerByConnAndChannel(conn *amqp.Connection, channel *amqp.Channel) *AMQPCeleryBroker

NewAMQPCeleryBrokerByConnAndChannel creates new AMQPCeleryBroker using AMQP conn and channel

func (*AMQPCeleryBroker) CreateExchange 

func (b *AMQPCeleryBroker) CreateExchange() error

CreateExchange declares AMQP exchange with stored configuration

func (*AMQPCeleryBroker) CreateQueue 

func (b *AMQPCeleryBroker) CreateQueue() error

CreateQueue declares AMQP Queue with stored configuration

func (*AMQPCeleryBroker) GetTaskMessage 

func (b *AMQPCeleryBroker) GetTaskMessage() (*TaskMessage, error)

GetTaskMessage retrieves task message from AMQP queue

func (*AMQPCeleryBroker) SendCeleryMessage 

func (b *AMQPCeleryBroker) SendCeleryMessage(message *CeleryMessage) error

SendCeleryMessage sends CeleryMessage to broker

func (*AMQPCeleryBroker) StartConsumingChannel 

func (b *AMQPCeleryBroker) StartConsumingChannel() error

StartConsumingChannel spawns receiving channel on AMQP queue

type AMQPExchange 

type AMQPExchange struct {
	Name       string
	Type       string
	Durable    bool
	AutoDelete bool
}

AMQPExchange stores AMQP Exchange configuration

func NewAMQPExchange 

func NewAMQPExchange(name string) *AMQPExchange

NewAMQPExchange creates new AMQPExchange

type AMQPQueue 

type AMQPQueue struct {
	Name       string
	Durable    bool
	AutoDelete bool
}

AMQPQueue stores AMQP Queue configuration

func NewAMQPQueue 

func NewAMQPQueue(name string) *AMQPQueue

NewAMQPQueue creates new AMQPQueue

type AsyncResult 

type AsyncResult struct {
	TaskID string
	// contains filtered or unexported fields
}

AsyncResult represents pending result

func (*AsyncResult) AsyncGet 

func (ar *AsyncResult) AsyncGet() (interface{}, error)

AsyncGet gets actual result from backend and returns nil if not available

func (*AsyncResult) Get 

func (ar *AsyncResult) Get(timeout time.Duration) (interface{}, error)

Get gets actual result from backend It blocks for period of time set by timeout and returns error if unavailable

func (*AsyncResult) Ready 

func (ar *AsyncResult) Ready() (bool, error)

Ready checks if actual result is ready

type CeleryBackend 

type CeleryBackend interface {
	GetResult(string) (*ResultMessage, error) // must be non-blocking
	SetResult(taskID string, result *ResultMessage) error
}

CeleryBackend is interface for celery backend database

type CeleryBroker 

type CeleryBroker interface {
	SendCeleryMessage(*CeleryMessage) error
	GetTaskMessage() (*TaskMessage, error) // must be non-blocking
}

CeleryBroker is interface for celery broker database

type CeleryClient 

type CeleryClient struct {
	// contains filtered or unexported fields
}

CeleryClient provides API for sending celery tasks

func NewCeleryClient 

func NewCeleryClient(broker CeleryBroker, backend CeleryBackend, numWorkers int) (*CeleryClient, error)

NewCeleryClient creates new celery client

func (*CeleryClient) Delay 

func (cc *CeleryClient) Delay(task string, args ...interface{}) (*AsyncResult, error)

Delay gets asynchronous result

func (*CeleryClient) DelayKwargs 

func (cc *CeleryClient) DelayKwargs(task string, args map[string]interface{}) (*AsyncResult, error)

DelayKwargs gets asynchronous results with argument map

func (*CeleryClient) Register 

func (cc *CeleryClient) Register(name string, task interface{})

Register task

func (*CeleryClient) StartWorker 

func (cc *CeleryClient) StartWorker()

StartWorker starts celery workers

func (*CeleryClient) StartWorkerWithContext 

func (cc *CeleryClient) StartWorkerWithContext(ctx context.Context)

StartWorkerWithContext starts celery workers with given parent context

func (*CeleryClient) StopWorker 

func (cc *CeleryClient) StopWorker()

StopWorker stops celery workers

func (*CeleryClient) WaitForStopWorker 

func (cc *CeleryClient) WaitForStopWorker()

WaitForStopWorker waits for celery workers to terminate

type CeleryDeliveryInfo 

type CeleryDeliveryInfo struct {
	Priority   int    `json:"priority"`
	RoutingKey string `json:"routing_key"`
	Exchange   string `json:"exchange"`
}

CeleryDeliveryInfo represents deliveryinfo json

type CeleryMessage 

type CeleryMessage struct {
	Body            string                 `json:"body"`
	Headers         map[string]interface{} `json:"headers,omitempty"`
	ContentType     string                 `json:"content-type"`
	Properties      CeleryProperties       `json:"properties"`
	ContentEncoding string                 `json:"content-encoding"`
}

CeleryMessage is actual message to be sent to Redis

func (*CeleryMessage) GetTaskMessage 

func (cm *CeleryMessage) GetTaskMessage() *TaskMessage

GetTaskMessage retrieve and decode task messages from broker

type CeleryProperties 

type CeleryProperties struct {
	BodyEncoding  string             `json:"body_encoding"`
	CorrelationID string             `json:"correlation_id"`
	ReplyTo       string             `json:"reply_to"`
	DeliveryInfo  CeleryDeliveryInfo `json:"delivery_info"`
	DeliveryMode  int                `json:"delivery_mode"`
	DeliveryTag   string             `json:"delivery_tag"`
}

CeleryProperties represents properties json

type CeleryTask 

type CeleryTask interface {

	// ParseKwargs - define a method to parse kwargs
	ParseKwargs(map[string]interface{}) error

	// RunTask - define a method for execution
	RunTask() (interface{}, error)
}

CeleryTask is an interface that represents actual task Passing CeleryTask interface instead of function pointer avoids reflection and may have performance gain. ResultMessage must be obtained using GetResultMessage()

type CeleryWorker 

type CeleryWorker struct {
	// contains filtered or unexported fields
}

CeleryWorker represents distributed task worker

func NewCeleryWorker 

func NewCeleryWorker(broker CeleryBroker, backend CeleryBackend, numWorkers int) *CeleryWorker

NewCeleryWorker returns new celery worker

func (*CeleryWorker) GetNumWorkers 

func (w *CeleryWorker) GetNumWorkers() int

GetNumWorkers returns number of currently running workers

func (*CeleryWorker) GetTask 

func (w *CeleryWorker) GetTask(name string) interface{}

GetTask retrieves registered task

func (*CeleryWorker) Register 

func (w *CeleryWorker) Register(name string, task interface{})

Register registers tasks (functions)

func (*CeleryWorker) RunTask 

func (w *CeleryWorker) RunTask(message *TaskMessage) (*ResultMessage, error)

RunTask runs celery task

func (*CeleryWorker) StartWorker 

func (w *CeleryWorker) StartWorker()

StartWorker starts celery workers

func (*CeleryWorker) StartWorkerWithContext 

func (w *CeleryWorker) StartWorkerWithContext(ctx context.Context)

StartWorkerWithContext starts celery worker(s) with given parent context

func (*CeleryWorker) StopWait 

func (w *CeleryWorker) StopWait()

StopWait waits for celery workers to terminate

func (*CeleryWorker) StopWorker 

func (w *CeleryWorker) StopWorker()

StopWorker stops celery workers

type RedisCeleryBackend 

type RedisCeleryBackend struct {
	*redis.Pool
}

RedisCeleryBackend is celery backend for redis

func NewRedisBackend 

func NewRedisBackend(conn *redis.Pool) *RedisCeleryBackend

NewRedisBackend creates new RedisCeleryBackend with given redis pool. RedisCeleryBackend can be initialized manually as well.

func NewRedisCeleryBackend deprecated 

func NewRedisCeleryBackend(uri string) *RedisCeleryBackend

NewRedisCeleryBackend creates new RedisCeleryBackend

Deprecated: NewRedisCeleryBackend exists for historical compatibility and should not be used. Pool should be initialized outside of gocelery package.

func (*RedisCeleryBackend) GetResult 

func (cb *RedisCeleryBackend) GetResult(taskID string) (*ResultMessage, error)

GetResult queries redis backend to get asynchronous result

func (*RedisCeleryBackend) SetResult 

func (cb *RedisCeleryBackend) SetResult(taskID string, result *ResultMessage) error

SetResult pushes result back into redis backend

type RedisCeleryBroker 

type RedisCeleryBroker struct {
	*redis.Pool
	// contains filtered or unexported fields
}

RedisCeleryBroker is celery broker for redis

func NewRedisBroker 

func NewRedisBroker(conn *redis.Pool) *RedisCeleryBroker

NewRedisBroker creates new RedisCeleryBroker with given redis connection pool

func NewRedisCeleryBroker deprecated 

func NewRedisCeleryBroker(uri string) *RedisCeleryBroker

NewRedisCeleryBroker creates new RedisCeleryBroker based on given uri

Deprecated: NewRedisCeleryBroker exists for historical compatibility and should not be used. Use NewRedisBroker instead to create new RedisCeleryBroker.

func (*RedisCeleryBroker) GetCeleryMessage 

func (cb *RedisCeleryBroker) GetCeleryMessage() (*CeleryMessage, error)

GetCeleryMessage retrieves celery message from redis queue

func (*RedisCeleryBroker) GetTaskMessage 

func (cb *RedisCeleryBroker) GetTaskMessage() (*TaskMessage, error)

GetTaskMessage retrieves task message from redis queue

func (*RedisCeleryBroker) SendCeleryMessage 

func (cb *RedisCeleryBroker) SendCeleryMessage(message *CeleryMessage) error

SendCeleryMessage sends CeleryMessage to redis queue

func (*RedisCeleryBroker) SetQueueName 

func (cb *RedisCeleryBroker) SetQueueName(queueName string)

Set custom queue name

type ResultMessage 

type ResultMessage struct {
	ID        string        `json:"task_id"`
	Status    string        `json:"status"`
	Traceback interface{}   `json:"traceback"`
	Result    interface{}   `json:"result"`
	Children  []interface{} `json:"children"`
}

ResultMessage is return message received from broker

type TaskMessage 

type TaskMessage struct {
	ID      string                 `json:"id"`
	Task    string                 `json:"task"`
	Args    []interface{}          `json:"args"`
	Kwargs  map[string]interface{} `json:"kwargs"`
	Retries int                    `json:"retries"`
	ETA     *string                `json:"eta"`
}

TaskMessage is celery-compatible message

func DecodeTaskMessage 

func DecodeTaskMessage(encodedBody string) (*TaskMessage, error)

DecodeTaskMessage decodes base64 encrypted body and return TaskMessage object

func (*TaskMessage) Encode 

func (tm *TaskMessage) Encode() (string, error)

Encode returns base64 json encoded string

Source Files

View all Source files

Directories

Path Synopsis
example
goclient
goworker

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