Help Center/ FunctionGraph/ API Reference/ APIs/ Function Invocation/ Executing a Function Synchronously
Updated on 2026-10-27 GMT+08:00

Executing a Function Synchronously

Function

This API is used to execute a function synchronously. Clients must wait for explicit responses to their requests from the function. Responses are returned only after function invocation is complete.

Calling Method

For details, see Calling APIs.

Authorization Information

Each account has all the permissions required to call all APIs, but IAM users must be assigned the required permissions. For details about the required permissions, see Permissions Policies and Supported Actions.

URI

POST /v2/{project_id}/fgs/functions/{function_urn}/invocations

Table 1 Path Parameters

Parameter

Mandatory

Type

Description

project_id

Yes

String

Parameter description:

Project ID. For details, see Obtaining a Project ID.

Constraints

N/A

Value range:

32 characters, including letters and digits.

Default value:

N/A

function_urn

Yes

String

Parameter description:

URN of the function. For details, see Function Model.

Constraints

N/A

Value range:

Only letters, digits, underscores (_), hyphens (-), and colons (:) are allowed.

Default value:

N/A

Request Parameters

Table 2 Request header parameters

Parameter

Mandatory

Type

Description

X-Auth-Token

Yes

String

Parameter description:

User token.

The token can be obtained by calling the IAM API. The value of X-Subject-Token in the response header is the user token.

Constraints

N/A

Value range:

N/A

Default value:

N/A

Content-Type

Yes

String

Parameter description:

The request body type or format.

Constraints

N/A

Value range:

N/A

Default value:

N/A

X-Cff-Log-Type

No

String

Definition

Specifies whether to return logs.

Constraints

N/A

Range

tail (Returns 4 KB logs after function execution.)

"" (Does not return logs.)

Default Value

N/A

X-CFF-Request-Version

No

String

Definition

Specifies the return format.

Constraints

This value is required by the SDK.

Range

v0: text format.

v1: The JSON format is returned by default.

Default Value

N/A

X-Cff-Instance-Memory

No

String

Definition

Specifies the memory size used for executing the function. in MB.

Constraints

None

Range

  • 128

  • 256

  • 512

  • 768

  • 1024

  • 1280

  • 1536

  • 1792

  • 2048

  • 2560

  • 3072

  • 3584

  • 4096

  • 8192

  • 10240

Default Value

N/A

Table 3 Request body parameters

Parameter

Mandatory

Type

Description

{User defined key}

Yes

Object

Definition

Function execution request body, in JSON format.

Constraints

N/A

Response Parameters

Status code: 200

Table 4 Response header parameters

Parameter

Type

Description

X-Cff-Invoke-Summary

String

Definition

Specifies the digest of the synchronous call execution information.

Range

N/A

X-Cff-Request-Id

String

Definition

Specifies the ID of the synchronous call request.

Range

N/A

X-Cff-Function-Log

String

Definition

Specifies the user logs of the synchronous call. You need to set X-Cff-Log-Type:tail in the request header. 2000 bytes of the end of the logs are captured and encoded using Base64.

Range

N/A

X-CFF-Billing-Duration

String

Definition

Specifies the billing information of the synchronous call.

Range

N/A

X-Cff-Response-Version

String

Definition

Response Body Format

Range

v0: text format.

v1: The JSON format is returned by default.

X-Func-Err-Code

String

Definition

Specifies the error code of the synchronous call. If the execution is successful, the value is 0.

Range

N/A

X-Is-Func-Err

String

Definition

Specifies whether the error is caused by the user function.

Range

N/A

Table 5 Response body parameters

Parameter

Type

Description

request_id

String

Definition

Request ID.

Range

The value can contain only letters, digits, and hyphens (-), and contains 36 characters.

result

String

Definition

Function execution result.

Range

N/A

log

String

Definition

Function execution log.

Range

N/A

status

Integer

Definition

Execution status.

Range

N/A

Status code: 400

Table 6 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 401

Table 7 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 403

Table 8 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 404

Table 9 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 500

Table 10 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 503

Table 11 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Example Requests

Execute a function synchronously.

POST /v2/{project_id}/fgs/functions/{function_urn}/invocations

{
  "body" : "",
  "requestContext" : {
    "apiId" : "bc1dcffd-xx",
    "requestId" : "xxx",
    "stage" : "RELEASE"
  },
  "queryStringParameters" : {
    "responseType" : "html"
  },
  "httpMethod" : "GET",
  "pathParameters" : null,
  "headers" : {
    "accept-language" : "zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2",
    "accept-encoding" : "gzip, deflate, br",
    "x-forwarded-port" : "443",
    "x-forwarded-for" : "127.0.0.1",
    "x-forwarded-proto" : "https"
  },
  "path" : "/apig-event-template",
  "isBase64Encoded" : true
}

Example Responses

Status code: 200

{
  "result" : "{\"statusCode\": 200, \"isBase64Encoded\": false, \"body\": \"{\\\"key\\\": \\\"value\\\"}\", \"headers\": {\"Content-Type\": \"application/json\"}}",
  "log" : "2022-09-20T11:43:57Z Start invoke request '1cbe80f3-3c65-475e-ad88-76ac518d386a', version: v1\nHello, World!\n\n2022-09-20T11:43:58Z Finish invoke request '1cbe80f3-3c65-475e-ad88-76ac518d386a', duration: 65.828ms, billing duration: 66ms, memory used: 21.473MB, billing memory: 128MB",
  "status" : 200,
  "request_id" : "1cbe80f3-3c65-475e-ad88-76ac518d386x"
}

SDK Sample Code

The SDK sample code is as follows.

Java

Execute a function synchronously.

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package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.functiongraph.v2.region.FunctionGraphRegion;
import com.huaweicloud.sdk.functiongraph.v2.*;
import com.huaweicloud.sdk.functiongraph.v2.model.*;

import java.util.Map;
import java.util.HashMap;

public class InvokeFunctionSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");
        String projectId = "{project_id}";

        ICredential auth = new BasicCredentials()
                .withProjectId(projectId)
                .withAk(ak)
                .withSk(sk);

        FunctionGraphClient client = FunctionGraphClient.newBuilder()
                .withCredential(auth)
                .withRegion(FunctionGraphRegion.valueOf("<YOUR REGION>"))
                .build();
        InvokeFunctionRequest request = new InvokeFunctionRequest();
        request.withFunctionUrn("{function_urn}");
        Map<String, Object> listbodyInvokeFunctionRequestBody = new HashMap<>();
        listbodyInvokeFunctionRequestBody.put("body", "");
        listbodyInvokeFunctionRequestBody.put("requestContext", "{\"stage\":\"RELEASE\",\"requestId\":\"xxx\",\"apiId\":\"bc1dcffd-xx\"}");
        listbodyInvokeFunctionRequestBody.put("queryStringParameters", "{\"responseType\":\"html\"}");
        listbodyInvokeFunctionRequestBody.put("httpMethod", "GET");
        listbodyInvokeFunctionRequestBody.put("headers", "{\"accept-language\":\"zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2\",\"x-forwarded-proto\":\"https\",\"x-forwarded-port\":\"443\",\"x-forwarded-for\":\"127.0.0.1\",\"accept-encoding\":\"gzip, deflate, br\"}");
        listbodyInvokeFunctionRequestBody.put("path", "/apig-event-template");
        listbodyInvokeFunctionRequestBody.put("isBase64Encoded", "true");
        request.withBody(listbodyInvokeFunctionRequestBody);
        try {
            InvokeFunctionResponse response = client.invokeFunction(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

Python

Execute a function synchronously.

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# coding: utf-8

import os
from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkfunctiongraph.v2.region.functiongraph_region import FunctionGraphRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkfunctiongraph.v2 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.environ["CLOUD_SDK_AK"]
    sk = os.environ["CLOUD_SDK_SK"]
    projectId = "{project_id}"

    credentials = BasicCredentials(ak, sk, projectId)

    client = FunctionGraphClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(FunctionGraphRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = InvokeFunctionRequest()
        request.function_urn = "{function_urn}"
        listInvokeFunctionRequestBodybody = {
            "body": "",
            "requestContext": "{\"stage\":\"RELEASE\",\"requestId\":\"xxx\",\"apiId\":\"bc1dcffd-xx\"}",
            "queryStringParameters": "{\"responseType\":\"html\"}",
            "httpMethod": "GET",
            "headers": "{\"accept-language\":\"zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2\",\"x-forwarded-proto\":\"https\",\"x-forwarded-port\":\"443\",\"x-forwarded-for\":\"127.0.0.1\",\"accept-encoding\":\"gzip, deflate, br\"}",
            "path": "/apig-event-template",
            "isBase64Encoded": "true"
        }
        request.body = listInvokeFunctionRequestBodybody
        response = client.invoke_function(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

Go

Execute a function synchronously.

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package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    functiongraph "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/functiongraph/v2"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/functiongraph/v2/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/functiongraph/v2/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")
    projectId := "{project_id}"

    auth, err := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        WithProjectId(projectId).
        SafeBuild()

    if err != nil {
        fmt.Println(err)
        return
    }

    hcClient, err := functiongraph.FunctionGraphClientBuilder().
         WithRegion(region.ValueOf("<YOUR REGION>")).
         WithCredential(auth).
         SafeBuild()


    if err != nil {
        fmt.Println(err)
        return
    }

    client := functiongraph.NewFunctionGraphClient(hcClient)

    request := &model.InvokeFunctionRequest{}
	request.FunctionUrn = "{function_urn}"
	var listInvokeFunctionRequestBodybody = map[string]interface{}{
        "body": "",
        "requestContext": "{\"stage\":\"RELEASE\",\"requestId\":\"xxx\",\"apiId\":\"bc1dcffd-xx\"}",
        "queryStringParameters": "{\"responseType\":\"html\"}",
        "httpMethod": "GET",
        "headers": "{\"accept-language\":\"zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2\",\"x-forwarded-proto\":\"https\",\"x-forwarded-port\":\"443\",\"x-forwarded-for\":\"127.0.0.1\",\"accept-encoding\":\"gzip, deflate, br\"}",
        "path": "/apig-event-template",
        "isBase64Encoded": "true",
    }
	request.Body = listInvokeFunctionRequestBodybody
	response, err := client.InvokeFunction(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

More

For SDK sample code of more programming languages, see the Sample Code tab in API Explorer. SDK sample code can be automatically generated.

Status Codes

Status Code

Description

200

Definition

If the following message is displayed, the script is successfully executed.

Range

N/A

400

Bad request.

401

Unauthorized.

403

Forbidden.

404

Not found.

500

Internal server error.

503

Service unavailable.

Error Codes

See Error Codes.