LambdaFunction

Implements: Container, ILambdaFunctionOverrides

Description

The LambdaFunction class allows you to create an abstract AWS Lambda function that acts as a container to instantiate and run components, and expose them via an external entry point.

Important points

• When handling calls the “cmd” parameter determines what action shall be called, while the other parameters are passed to the action itself.

• Container configuration for this Lambda function is stored in "./config/config.yml" file. But this path can be overriden by CONFIG_PATH environment variable.

Configuration parameters

• dependencies:
  • controller: override for Controller dependency
• connections:
  • discovery_key: (optional) key to retrieve the connection from IDiscovery
  • region: (optional) AWS region
• credentials:
  • store_key: (optional) key to retrieve the credentials from ICredentialStore
  • access_id: AWS access/client id
  • access_key: AWS access/client key

References

• *:logger:*:*:1.0: (optional) ILogger components to pass log messages.
• *:counters:*:*:1.0: (optional) ICounters components to pass collected measurements.
• *:service:lambda:*:1.0: (optional) ILambdaController services to handle action requests
• *:service:commandable-lambda:*:1.0: (optional) ILambdaController services to handle action requests

Constructors

InheriteLambdaFunction

Creates a new instance of this lambda function.

InheriteLambdaFunction(overrides ILambdaFunctionOverrides, name string, description string) *LambdaFunction

• overrides: ILambdaFunctionOverrides - overrides.
• name: string - (optional) container name (accessible via ContextInfo).
• description: string - (optional) container description (accessible via ContextInfo).

Fields

Methods

Act

Calls registered action in this lambda function. The “cmd” parameter in the action parameters determines what action shall be called.

• This method shall only be used in testing.

(c *LambdaFunction) Act(params map[string]any) (string, error)

• params: map[string]any - action parameters.
• returns: (string, error) - result

Handler

Executes this AWS Lambda function and returns the result. This method can be overloaded in child classes if it is necessary to change the default behavior

(c *LambdaFunction) Handler(ctx context.Context, event map[string]any) (string, error)

• ctx: context.Context - operation context.
• event: map[string]any - event parameters (or function arguments)
• returns: (string, error) - result of the function execution.

GetHandler

Gets an entry point into this lambda function.

(c *LambdaFunction) GetHandler() func(ctx context.Context, event map[string]any) (string, error)

• returns: func(ctx context.Context, event map[string]any) (string, error) - incoming event object with invocation parameters.
  • context: context.Context - context object with local references.
  • event: map[string]any - incoming event object with invocation parameters.

Instrument

Gets entry point into this lambda function.

(c *LambdaFunction) Instrument(ctx context.Context, context IContext, name string) *InstrumentTiming

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• name: string - method name.
• returns: *InstrumentTiming - object to end the time measurement.

Open

Opens the component.

(c *LambdaFunction) Open(ctx context.Context, context IContext) error

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• returns: error - error or nil if no errors occurred.

RegisterAction

Registers an action in this lambda function.

• Note: This method has been deprecated. Use LambdaController instead.

(c *LambdaFunction) RegisterAction(cmd string, schema *Schema, action func(ctx context.Context, params map[string]any) (result any, err error)) error

• cmd: string - action/command name.
• schema: *Schema - validation schema used to validate received parameters.
• action: func(ctx context.Context, params map[string]any) - action function that is called when the action is invoked.
• returns: error - error or nil if no errors occured.

RegisterServices

Registers all actions in this lambda function.

• Note: Overloading of this method has been deprecated. Use LambdaController instead.

(c *LambdaFunction) RegisterServices()

Run

Runs this lambda function, loads container configuration, instantiates components and manages their lifecycle. Makes this function ready to access action calls.

(c *LambdaFunction) Run(ctx context.Context) error

• ctx: context.Context - operation context.
• returns: error - error or nil no errors occured.

SetReferences

Sets references to dependent components.

(c *LambdaFunction) SetReferences(ctx context.Context, references IReferences)

• сеч: context.Context - operation context.
• references: IReferences - references to locate the component’s dependencies.

Examples

type MyLambdaFunction struct {
	*awscont.LambdaFunction
	controller awstest.IMyController
}

func NewMyLambdaFunction() *MyLambdaFunction {
	c := &MyLambdaFunction{}
	c.LambdaFunction = awscont.InheriteLambdaFunction(c, "mygroup", "MyGroup lambda function")

	c.DependencyResolver.Put(context.Background(), "controller", cref.NewDescriptor("mygroup", "controller", "*", "*", "1.0"))
	return c
}

func (c *MyLambdaFunction) SetReferences(ctx context.Context, references cref.IReferences) {
	c.LambdaFunction.SetReferences(ctx, references)
	depRes, depErr := c.DependencyResolver.GetOneRequired("controller")
	if depErr == nil && depRes != nil {
		c.controller = depRes.(awstest.IMyController)
	}
}

func (c *MyLambdaFunction) getOneById(ctx context.Context, params map[string]any) (any, error) {
	context, _ := params["correlation_id"].(string)
	return c.controller.GetOneById(
		ctx,
		context,
		params["mydata_id"].(string),
	)
}

func (c *MyLambdaFunction) Register() {

	c.RegisterAction(
		"get_mydata_by_id",
		cvalid.NewObjectSchema().
			WithOptionalProperty("mydata_id", cconv.String).Schema,
		c.getOneById)
}


lambda := NewMyLambdaFunction()

lambda.Run(context.Context())

See also

• LambdaClient