Header Modification via APK Conf

This functionality enables the addition, modification, and removal of request and response headers for APIs. By customizing headers, you can enhance the control and flexibility of API interactions, ensuring that both incoming requests and outgoing responses meet specific requirements.

Step 1 - Get the API configuration

Save the following content into a file named SampleService.apk-conf. You can use this apk-conf file for the rest of this guide.

id: "header-modifier-api" name: "Sample API" basePath: "/sample-api" version: "0.1.0" type: "REST" defaultVersion: false subscriptionValidation: false endpointConfigurations: production: - endpoint: "https://dev-tools.wso2.com/gs/helpers/v1.0" operations: - target: "/ai/spelling" verb: "POST" secured: true scopes: [] - target: "/base64/decode/{value}" verb: "POST" secured: true scopes: [] - target: "/base64/encode/{value}" verb: "POST" secured: true scopes: [] - target: "/ip" verb: "GET" secured: true scopes: [] - target: "/user-agent" verb: "GET" secured: true scopes: [] - target: "/uuid" verb: "GET" secured: true scopes: []

Step 2 - Add the header modification policy to the apk-conf file

A sample header modification configuration is given below.

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: request: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Test-Request-Header" headerValue: "Test-Value"

This policy adds a header with the name "Test-Request-Header" and value "Test-Value" to the request sent to this particular path.

The complete apk-conf file with this configuration is given below.

id: "header-modifier-api" name: "Sample API" basePath: "/sample-api" version: "0.1.0" type: "REST" defaultVersion: false subscriptionValidation: false endpointConfigurations: production: - endpoint: "https://dev-tools.wso2.com/gs/helpers/v1.0" operations: - target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: request: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Test-Request-Header" headerValue: "Test-Value" - target: "/ai/spelling" verb: "POST" secured: true scopes: [] - target: "/base64/decode/{value}" verb: "POST" secured: true scopes: [] - target: "/base64/encode/{value}" verb: "POST" secured: true scopes: [] - target: "/ip" verb: "GET" secured: true scopes: [] - target: "/user-agent" verb: "GET" secured: true scopes: []

Similarly, you can do the following to both request and response headers.

1. Add headers
2. Update existing headers
3. Remove headers

Sample configurations for each of them have been provided under the Sample Configurations section.

Step 3 - Deploy the API in APK

Refer to the Deploy the API to deploy the API using APK configuration.

Step 4 - Generate an access token

Follow the Generate Access Token documentation to generate an access token.

Step 5 - Invoke the API

You can invoke the API using the following command.

curl --location 'https://default.gw.wso2.com:9095/sample-api/0.1.0/uuid' \ --header 'Host: default.gw.wso2.com' \ --header 'Authorization: Bearer <accessToken>

Since this guide uses the httpbin service which echoes the request and all of its headers, when you invoke the API, you will see the header "Test-Request-Header" with the value "Test-Value".

Sample Configurations

Operation Level Request Header Modification

1. Add Request Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: request: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

2. Update Request Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: request: - policyName: SetHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

3. Remove Request Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: request: - policyName: RemoveHeader policyVersion: v1 parameters: headerName: "Header-Name"

Operation Level Response Header Modification

1. Add Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: response: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

2. Update Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: response: - policyName: SetHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

3. Remove Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] operationPolicies: response: - policyName: RemoveHeader policyVersion: v1 parameters: headerName: "Header-Name"

API Level Request Header Modification

1. Add Request Header

- target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: request: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

2. Update Request Header

- target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: request: - policyName: SetHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

3. Remove Request Header

``` - target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: request: - policyName: RemoveHeader policyVersion: v1 parameters: headerName: "Header-Name"

```

API Level Response Header Modification

1. Add Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: response: - policyName: AddHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

2. Update Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: response: - policyName: SetHeader policyVersion: v1 parameters: headerName: "Header-Name" headerValue: "Header-Value"

3. Remove Response Header

- target: "/uuid" verb: "GET" secured: false scopes: [] apiPolicies: response: - policyName: RemoveHeader policyVersion: v1 parameters: headerName: "Header-Name"