Gorabbit

Gorabbit is a wrapper that provides high level and robust RabbitMQ operations through a client or a manager.

This wrapper depends on the official Go RabbitMQ plugin.

• Installation
  • Go Module
  • Environment Variables
• Always On Mechanism
• Client
  • Initialization
  • Options
  • Default Options
  • Custom Options
    • Builder
    • Struct
  • Disconnection
  • Publishing
  • Consuming
  • Ready and Health Checks
• Manager
  • Initialization
  • Options
  • Default Options
  • Custom Options
    • Builder
    • Struct
  • Disconnection
  • Operations
    • Exchange Creation
    • Queue Creation
    • Binding Creation
    • Message Count
    • Push Message
    • Pop Message
    • Purge Queue
    • Delete Queue
    • Delete Exchange
    • Setup From Definitions

Installation

Go module

go get github.com/KardinalAI/gorabbit

Environment variables

The client's and manager's Mode can also be set via an environment variable that will override the manually entered value.

GORABBIT_MODE: debug    # possible values: release or debug

The client and manager can also be completely disabled via the following environment variable:

GORABBIT_DISABLED: true     # possible values: true, false, 1, or 0 

Always-on mechanism

Here is a visual representation of the always-on mechanism of a connection and channel when the KeepAlive flag is set to true.

Client

The gorabbit client offers 2 main functionalities:

• Publishing
• Consuming

Additionally, the client also provides a ready check and a health check.

Client initialization

A client can be initialized via the constructor NewClient. This constructor takes ClientOptions as an optional parameter.

Client options

Client with default options

Passing nil options will trigger the client to use default values (host, port, credentials, etc...) via DefaultClientOptions().

client := gorabbit.NewClient(nil)

You can also explicitly pass DefaultClientOptions() for a cleaner initialization.

client := gorabbit.NewClient(gorabbit.DefaultClientOptions())

Finally, passing a NewClientOptions() method also initializes default values if not overwritten.

client := gorabbit.NewClient(gorabbit.NewClientOptions())

Client with options from environment variables

You can instantiate a client from environment variables, without the need of manually specifying options in the code.

client := gorabbit.NewClientFromEnv()

Here are the following supported environment variables:

• RABBITMQ_HOST: Defines the host,
• RABBITMQ_PORT: Defines the port,
• RABBITMQ_USERNAME: Defines the username,
• RABBITMQ_PASSWORD: Defines the password,
• RABBITMQ_VHOST: Defines the vhost,
• RABBITMQ_USE_TLS: Defines whether to use TLS or no.

Note that environment variables are all optional, so missing keys will be replaced by their corresponding default.

Client with custom options

We can input custom values for a specific property, either via the built-in builder or via direct struct initialization.

Client options using the builder

NewClientOptions() and DefaultClientOptions() both return an instance of *ClientOptions that can act as a builder.

options := gorabbit.NewClientOptions().
    SetMode(gorabbit.Debug).
    SetCredentials("root", "password").
    SetRetryDelay(5 * time.Second)

client := gorabbit.NewClient(options)

:information_source: There is a setter method for each property.

Client options using struct initialization

ClientOptions is an exported type, so it can be used directly.

options := gorabbit.ClientOptions {
    Host:     "localhost",
    Port:     5673,
    Username: "root",
    Password: "password",
    ...
}

client := gorabbit.NewClient(&options)

:warning: Direct initialization via the struct does not use default values on missing properties, so be sure to fill in every property available.

Client disconnection

When a client is initialized, to prevent a leak, always disconnect it when no longer needed.

client := gorabbit.NewClient(gorabbit.DefaultClientOptions())
defer client.Disconnect()

Publishing

To send a message, the client offers two simple methods: Publish and PublishWithOptions. The required arguments for publishing are:

• Exchange (which exchange the message should be sent to)
• Routing Key
• Payload (interface{}, the object will be marshalled internally)

Example of sending a simple string

err := client.Publish("events_exchange", "event.foo.bar.created", "foo string")

Example of sending an object

type foo struct {
    Action string
}

err := client.Publish("events_exchange", "event.foo.bar.created", foo{Action: "bar"})

Optionally, you can set the message's Priority and DeliveryMode via the PublishWithOptions method.

options := gorabbit.SendOptions().
    SetPriority(gorabbit.PriorityMedium).
    SetDeliveryMode(gorabbit.Persistent)

err := client.PublishWithOptions("events_exchange", "event.foo.bar.created", "foo string", options)

:information_source: If the KeepAlive flag is set to true when initializing the client, failed publishing will be cached once and re-published as soon as the channel is back up.

Consuming

To consume messages, gorabbit offers a very simple asynchronous consumer method Consume that takes a MessageConsumer as argument. Error handling, acknowledgement, negative acknowledgement and rejection are all done internally by the consumer.

err := client.RegisterConsumer(gorabbit.MessageConsumer{
    Queue:             "events_queue",
    Name:              "toto_consumer",
    PrefetchSize:      0,
    PrefetchCount:     10,
    AutoAck:           false,
    ConcurrentProcess: false,
    Handlers: gorabbit.MQTTMessageHandlers{
        "event.foo.bar.created": func (payload []byte) error {
            fmt.Println(string(payload))

            return nil
        },
    },
})

• Queue: The queue to consume messages from
• Name: Unique identifier for the consumer
• PrefetchSize: The maximum size of messages that can be processed at the same time
• PrefetchCount: The maximum number of messages that can be processed at the same time
• AutoAck: Automatic acknowledgement of messages upon reception
• ConcurrentProcess: Asynchronous handling of deliveries
• Handlers: A list of handlers for specified routes

NB: RabbitMQ Wildcards are also supported. If multiple routing keys have the same handler, a wildcard can be used, for example: event.foo.bar.* or event.foo.#.

:information_source: If the KeepAlive flag is set to true when initializing the client, consumers will auto-reconnect after a connection loss. This mechanism is indefinite and therefore, consuming from a non-existent queue will trigger an error repeatedly but will not affect other consumptions. This is because each consumer has its own channel.

Ready and Health checks

The client offers IsReady() and IsHealthy() checks that can be used for monitoring.

Ready: Verifies that connections are opened and ready to launch new operations.

Healthy: Verifies that both connections and channels are opened, ready and ongoing operations are working (Consumers are consuming).

Manager

The gorabbit manager offers multiple management operations:

• Exchange, queue and bindings creation
• Exchange and queue deletion
• Queue evaluation: Exists, number of messages
• Queue operations: Pop message, push message, purge

:warning: A manager should only be used for either testing RabbitMQ functionalities or setting up a RabbitMQ server. The manager does not provide robust mechanisms of retry and reconnection like the client.

Manager initialization

A manager can be initialized via the constructor NewManager. This constructor takes ManagerOptions as an optional parameter.

Manager options

Manager with default options

Passing nil options will trigger the manager to use default values (host, port, credentials, etc...) via DefaultManagerOptions().

manager := gorabbit.NewManager(nil)

You can also explicitly pass DefaultManagerOptions() for a cleaner initialization.

manager := gorabbit.NewManager(gorabbit.DefaultManagerOptions())

Finally, passing a NewManagerOptions() method also initializes default values if not overwritten.

manager := gorabbit.NewManager(gorabbit.NewManagerOptions())

Manager with options from environment variables

You can instantiate a manager from environment variables, without the need of manually specifying options in the code.

manager := gorabbit.NewManagerFromEnv()

Here are the following supported environment variables:

• RABBITMQ_HOST: Defines the host,
• RABBITMQ_PORT: Defines the port,
• RABBITMQ_USERNAME: Defines the username,
• RABBITMQ_PASSWORD: Defines the password,
• RABBITMQ_VHOST: Defines the vhost,
• RABBITMQ_USE_TLS: Defines whether to use TLS or no.

Note that environment variables are all optional, so missing keys will be replaced by their corresponding default.

Manager with custom options

We can input custom values for a specific property, either via the built-in builder or via direct struct initialization.

Manager options using the builder

NewManagerOptions() and DefaultManagerOptions() both return an instance of *ManagerOptions that can act as a builder.

options := gorabbit.NewManagerOptions().
    SetMode(gorabbit.Debug).
    SetCredentials("root", "password")

manager := gorabbit.NewManager(options)

:information_source: There is a setter method for each property.

Manager options using struct initialization

ManagerOptions is an exported type, so it can be used directly.

options := gorabbit.ManagerOptions {
    Host:     "localhost",
    Port:     5673,
    Username: "root",
    Password: "password",
    Mode:     gorabbit.Debug,
}

manager := gorabbit.NewManager(&options)

:warning: Direct initialization via the struct does not use default values on missing properties, so be sure to fill in every property available.

Manager disconnection

When a manager is initialized, to prevent a leak, always disconnect it when no longer needed.

manager := gorabbit.NewManager(gorabbit.DefaultManagerOptions())
defer manager.Disconnect()

Manager operations

The manager offers all necessary operations to manager a RabbitMQ server.

Exchange creation

Creates an exchange with optional arguments.

err := manager.CreateExchange(gorabbit.ExchangeConfig{
    Name:      "events_exchange",
    Type:      gorabbit.ExchangeTypeTopic,
    Persisted: false,
    Args:      nil,
})

Queue creation

Creates a queue with optional arguments and bindings if declared.

err := manager.CreateQueue(gorabbit.QueueConfig{
    Name:      "events_queue",
    Durable:   false,
    Exclusive: false,
    Args:      nil,
    Bindings: &[]gorabbit.BindingConfig{
        {
            RoutingKey: "event.foo.bar.created",
            Exchange:   "events_exchange",
        },
    },
})

Binding creation

Binds a queue to an exchange via a given routing key.

err := manager.BindExchangeToQueueViaRoutingKey("events_exchange", "events_queue", "event.foo.bar.created")

Queue messages count

Returns the number of messages in a queue, or an error if the queue does not exist. This method can also evaluate the existence of a queue.

messageCount, err := manager.GetNumberOfMessages("events_queue")

Push message

Pushes a single message to a given exchange.

err := manager.PushMessageToExchange("events_exchange", "event.foo.bar.created", "single_message_payload")

Pop message

Retrieves a single message from a given queue and auto acknowledges it if autoAck is set to true.

message, err := manager.PopMessageFromQueue("events_queue", true)

Purge queue

Deletes all messages from a given queue.

err := manager.PurgeQueue("events_queue")

Delete queue

Deletes a given queue.

err := manager.DeleteQueue("events_queue")

Delete exchange

Deletes a given exchange.

err := manager.DeleteExchange("events_exchange")

Setup from schema definition file

You can setup exchanges, queues and bindings automatically by referencing a RabbitMQ Schema Definition JSON file.

err := manager.SetupFromDefinitions("/path/to/definitions.json")

:warning: The standard RabbitMQ definitions file contains configurations for users, vhosts and permissions. Those configurations are not taken into consideration in the SetupFromDefinitions method.

Launch Local RabbitMQ Server

To run a local rabbitMQ server quickly with a docker container, simply run the following command:

docker run -it --rm --name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:3-management

It will launch a local RabbitMQ server mapped on port 5672, and the management dashboard will be mapped on port 15672 accessible on localhost:15672 with a username "guest" and password "guest".

License

Gorabbit is licensed under the MIT.