This topic describes how to implement lifecycle hooks for function instances in the C# runtime environment.
Background
After you configure a lifecycle hook for a function instance, Function Compute invokes the hook when a related lifecycle event for the instance occurs. The following lifecycle hooks can be configured for a function instance: Initializer, PreFreeze, and PreStop. For more information, see Function instance lifecycle.
The billing rules for the lifecycle hooks of function instances are the same as those for common invocation requests. However, the execution logs can be queried only in Function Logs, Instance Logs, and Advanced Logs. Log for lifecycle hooks are not displayed in Call Request List.
Method signature
- Initializer hook
The Initializer hook is executed after the function instance is started and before the handler runs. Function Compute ensures that the Initializer hook is successfully executed only once in the lifecycle of a function instance. If the initializer hook fails to be executed, an error is returned for the function invocation. When you invoke the function next time, the system creates another function instance to execute the Initializer hook.
- PreFreeze hook
The PreFreeze hook is executed before the function instance is frozen.
- PreStop hook
The PreStop hook is executed before the function instance is destroyed.
public void FunctionName(IFcContext context);public static void FunctionName(IFcContext context);Example: StreamRequestHandler
using System;
using System.IO;
using System.Threading.Tasks;
using Aliyun.Serverless.Core;
using Microsoft.Extensions.Logging;
namespace Example
{
public class Hello
{
public void Initialize(IFcContext context)
{
IFcLogger logger = context.Logger;
logger.LogInformation("Initialize start");
logger.LogInformation("Handle initializer: {0}", context.RequestId);
logger.LogInformation("Initialize end");
}
public void PreStop(IFcContext context)
{
IFcLogger logger = context.Logger;
logger.LogInformation("PreStop start");
logger.LogInformation("Handle PreStop: {0}", context.RequestId);
logger.LogInformation("PreStop end");
}
public void PreFreeze(IFcContext context)
{
IFcLogger logger = context.Logger;
logger.LogInformation("PreFreeze start");
logger.LogInformation("Handle PreFreeze: {0}", context.RequestId);
logger.LogInformation("PreFreeze end");
}
public async Task<Stream> StreamHandler(Stream input, IFcContext context)
{
IFcLogger logger = context.Logger;
logger.LogInformation("Handle request: {0}", context.RequestId);
MemoryStream copy = new MemoryStream();
await input.CopyToAsync(copy);
copy.Seek(0, SeekOrigin.Begin);
return copy;
}
static void Main(string[] args){}
}
}Configure lifecycle hooks
Use the Function Compute console
You can configure the lifecycle hooks on the Function Details page in the Function Compute console. For more information, see Configure the PreFreeze hook and the PreStop hook in the Function Compute console. The format of the hook method is the same as that of the request handler. The format
is Assembly name::Namespace.Class name::Method name. For more information, see Handler.
- The Initializer hook:
HelloFcApp::Example.Hello::Initialize - The PreFreeze hook:
HelloFcApp::Example.Hello::PreFreeze - The PreStop hook:
HelloFcApp::Example.Hello::PreStop
Use Serverless Devs
- Initializer hook
Add the initializer and initializationTimeout fields to the function parameter.
- PreFreeze hook
Add the instanceLifecycleConfig.preFreeze field, including handler and timeout, to the function parameter.
- PreStop hook
Add the instanceLifecycleConfig.preStop field, including handler and timeout, to the function parameter.
edition: 1.0.0
name: hello-world # The name of the project.
access: default # The alias of the key.
vars: # The global variables.
region: cn-shanghai # The ID of the region.
service:
name: fc-example
description: 'fc example by serverless devs'
services:
helloworld: # The name of the service or module.
component: fc
actions: # The custom execution logic.
pre-deploy: # The operation before the deployment.
- run: mvn package # The command to run.
path: ./ # The path in which the command runs.
props: # The property value of the component.
region: ${vars.region}
service: ${vars.service}
function:
name: dotnet-lifecycle-hook-demo
description: 'fc example by serverless devs'
runtime: dotnetcore3.1
codeUri: ./target
handler: example.App::handleRequest
memorySize: 128
timeout: 60
initializer: HelloFcApp::Example.Hello::Initialize
initializationTimeout: 30
instanceLifecycleConfig:
preStop:
Handler: HelloFcApp::Example.Hello::PreStop
Timeout: 30
preFreeze:
Handler: HelloFcApp::Example.Hello::PreFreeze
Timeout: 30For more information about the YAML syntax of Serverless Devs, see Serverless Devs commands.
View the logs of instance lifecycle hooks.
You can view the logs for lifecycle hook in Function Logs.