Context - Function Compute - Alibaba Cloud Documentation Center

This topic describes the contex-related concepts when you use the Node.js runtime in Function Compute for coding.

What is a context?

When Function Compute runs a function, the system passes a context object to the method that is used to execute the function. The context object contains information about invocations, services, functions, tracing analysis, and runtimes.

The following table describes the parameters that are contained in a context.

Field	Type	Description
requestId	String	The unique ID of the request that is used to invoke the function. You can record the ID for troubleshooting if an error occurs.
credentials	Credentials structure, which consists of the following fields: accessKeyId accessKeySecret securityToken	The temporary AccessKey pair that Function Compute obtains by assuming your service-linked role. The temporary AccessKey pair is valid for 36 hours. You can use `credentials` in your code to access related services such as Object Storage Service (OSS). This way, you can access the services without the need to write your AccessKey pair in the function code. For more information, see Grant Function Compute permissions to access other Alibaba Cloud services.
function	FunctionMeta structure, which contains the following fields: name handler memory timeout	The basic information about the invoked function, such as the name, handler, memory, and timeout period of the function.
service	ServiceMeta structure, which contains the following fields: logProject logStore qualifier versionId	The information about the service to which the function belongs, such as the name, the related project, and Logstore in Simple Log Service, the version, and the alias of the service. The `qualifier` parameter indicates the version or alias of the service that is specified when you invoke a function. The `versionId` parameter indicates the version of the service that is actually invoked.
region	String	The ID of the region in which the function is invoked. For example, if the function is invoked in the China (Shanghai) region, the region ID is cn-shanghai. For more information, see Service endpoints.
accountId	String	The ID of the Alibaba Cloud account to which the function belongs.
logger	ContextLog structure defined by Function Compute. The structure consists of the following fields: debug info warn error log	Specifies the log object, which is used to print logs. The logs are printed in the Date Request ID [Level] Log content format. Example: 2022-04-01T10:04:19.024Z 19b394a3-4fff-480c-9b5c-cbdfd6952f4e [info] hello,fc.