An initializer function is used to ensure specific business logic is successfully executed on the same instance only once. This topic describes the structure and features of Node.js initializer functions.
Definition
The following code defines a simple initializer function.
exports.my_initializer = function(context, callback) {
console.log('hello world');
callback(null, "");
};
Function name
The my_initializer
parameter must correspond to the initializer
field that you specify when you add the initializer function. For example, if you
set the initializer
field to main.my_initializer
when you create a function, after the initializer function is configured, Function
Compute loads the my_initializer
function you defined in the main.js
file.
Features
- Input parameters of an
initializer
function containcontext
andcallback
parameters. These parameters are defined the same as those in event functions. For more information, see context parameter and callback function. - The
initializer
andinitializationTimeout
fields in the context parameter are specifically designed for initializer functions. If these two parameters are not specified, the initializer function is not executed. Initializer
functions do not return any value.