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API Gateway
API Gateway
- What's New
- Function Overview
- Product Bulletin
- Service Overview
- Getting Started
-
User Guide
- Overview
- Gateway Management
- API Group Management
- API Management
- Request Throttling
- Access Control
- Environment Management
- Signature Key Management
- VPC Channel Management
- Custom Authorizers
- Plug-ins
- Monitoring
- App Management
- Log Analysis
- SDKs
- Calling Published APIs
- Permissions Management
- Key Operations Recorded by CTS
-
Developer Guide
- Overview
- Authentication Mode Selection
- Calling APIs Through App Authentication
- Calling APIs Through IAM Authentication
- Creating a Function for Frontend Custom Authentication
- Creating a Function for Backend Custom Authentication
- Creating Signatures for Backend Requests
-
Importing and Exporting APIs
- Restrictions and Compatibility
- Extended Definition
- API Import Precautions
- Examples of Importing APIs
- API Export Precautions
-
API Reference
- Before You Start
- Calling APIs
-
Dedicated Gateway APIs (V2)
- API Group Management
- Environment Management
- Environment Variable Management
- Request Throttling Policy Management
-
API Management
- Registering an API
- Modifying an API
- Deleting an API
- Publishing an API or Taking an API Offline
- Querying API Details
- Querying APIs
- Debugging an API
- Publishing APIs or Taking APIs Offline
- Querying Historical Versions of an API
- Switching the Version of an API
- Querying the Runtime Definition of an API
- Querying API Version Details
- Taking an API Version Offline
- Signature Key Management
- Binding/Unbinding Signature Keys
- Binding/Unbinding Request Throttling Policies
- Excluded Request Throttling Configuration
- App Authorization Management
- Resource Query
- App Management
- Domain Name Management
- Access Control Policy Management
- Binding/Unbinding Access Control Policies
- Custom Authorizer Management
- API Import and Export
- VPC Channel Management
- Monitoring Information Query
- Group Response Management
- Tag Management
- Gateway Feature Management
- Configuration Management
-
Gateway Management
- Creating a Dedicated Gateway
- Querying Dedicated Gateway Details
- Updating a Dedicated Gateway
- Querying the Creation Progress of a Dedicated Gateway
- Updating or Binding an EIP to a Dedicated Gateway
- Unbinding the EIP of a Dedicated Gateway
- Enabling Public Access for a Dedicated Gateway
- Updating the Outbound Access Bandwidth of a Dedicated Gateway
- Disabling Public Access for a Dedicated Gateway
- Querying AZs
- Querying Dedicated Gateways
- Deleting a Dedicated Gateway
- Permissions Policies and Supported Actions
- Appendix
- Change History
- SDK Reference
- Best Practices
-
FAQs
- Common FAQs
-
API Creation
- Why Can't I Create APIs?
- How Do I Define Response Codes for an API?
- How Do I Specify the Host Port for a VPC Channel (or Load Balance Channel)?
- How Do I Set the Backend Address If I Will Not Use a VPC Channel (or Load Balance Channel)?
- How Can I Configure the Backend Service Address?
- Can I Specify a Private Network Load Balancer Address for the Backend Service?
- Can I Specify the Backend Address as a Subnet IP Address?
- Does APIG Support Multiple Backend Endpoints?
- What Should I Do After Applying for an Independent Domain Name?
- Can I Bind Private Domain Names for API Access?
- Why Does an API Failed to Be Called Across Domains?
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API Calling
- What Are the Possible Causes for an API Calling Failure?
- What Should I Do If an Error Code Is Returned During API Calling?
- Why Am I Seeing the Error Message "414 Request-URI Too Large" When I Call an API?
- What Should I Do If "The API does not exist or has not been published in the environment." Is Displayed?
- Why Am I Seeing the Message "No backend available"?
- What Are the Possible Causes If the Message "Backend unavailable" or "Backend timeout" Is Displayed?
- Why Am I Seeing the Message "Backend domain name resolution failed" When a Backend Service Is Called?
- Why Doesn't Modification of the backend_timeout Parameter Take Effect?
- How Do I Switch the Environment for API Calling?
- What Is the Maximum Size of an API Request Package?
- How Do I Perform App Authentication in iOS System?
- Why Can't I Create a Header Parameter Named x-auth-token for an API Called Through IAM Authentication?
- App FAQs
- Can Mobile Apps Call APIs?
- Can Applications Deployed in a VPC Call APIs?
- How Do I Implement WebSocket Data Transmission?
- Does APIG Support Persistent Connections?
- How Will the Requests for an API with Multiple Backend Policies Be Matched and Executed?
- Is There a Limit on the Size of the Response to an API Request?
- How Can I Access Backend Services over Public Networks Through APIG?
-
API Authentication
- Does APIG Support HTTPS Two-Way Authentication?
- How Do I Call an API That Does Not Require Authentication?
- Which TLS Versions Does APIG Support?
- Does APIG Support Custom Authentication?
- Will the Request Body Be Signed for Security Authentication?
- Common Errors Related to IAM Authentication Information
- API Control Policies
- API Publishing
- API Import and Export
- API Security
-
Other FAQs
- What Are the Relationships Between an API, Environment, and App?
- How Can I Use APIG?
- What SDK Languages Does APIG Support?
- Can I Upload Files Using the POST Method?
- What Are the Error Messages Returned by APIG Like?
- How Do I Use APIG to Open Up Services Deployed on Huawei Cloud?
- Can APIG Be Deployed in a Local Data Center?
- Videos
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Why Am I Seeing the Message "No backend available"?
Updated on 2023-04-06 GMT+08:00
- Check whether the backend service is accessible, and modify the backend service if it is inaccessible.
- Check the ECS security group configurations of the backend service and verify that the required port has been enabled.
- Check whether ACL configurations of the VPC restrict the communication between the API gateway and the subnet where the backend service is located.
- If you use a VPC channel, check whether the service port, health check port, and backend servers of the VPC channel have been correctly configured.
Parent topic: API Calling
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