Chapter 6. APIcast Policies

The 3scale Auth Caching policy caches authentication calls made to APIcast. You can select an operating mode to configure the cache operations.

3scale Auth Caching is available in the following modes:

1. Strict - Cache only authorized calls.

"Strict" mode only caches authorized calls. If a policy is running under the "strict" mode and if a call fails or is denied, the policy invalidates the cache entry. If the backend becomes unreachable, all cached calls are rejected, regardless of their cached status.

2. Resilient – Authorize according to last request when backend is down.

The "Resilient" mode caches both authorized and denied calls. If the policy is running under the "resilient" mode, failed calls do not invalidate an existing cache entry. If the backend becomes unreachable, calls hitting the cache continue to be authorized or denied based on their cached status.

3. Allow - When backend is down, allow everything unless seen before and denied.

The "Allow" mode caches both authorized and denied calls. If the policy is running under the "allow" mode, cached calls continue to be denied or allowed based on the cached status. However, any new calls are cached as authorized.

4. None - Disable caching.

The "None" mode disables caching. This mode is useful if you want the policy to remain active, but do not want to use caching.

Configuration properties

Policy object example

{
  "name": "caching",
  "version": "builtin",
  "configuration": {
    "caching_type": "allow"
  }
}

For information on how to configure policies, see the Creating a policy chain section of the documentation.

The 3scale Batcher policy provides an alternative to the standard APIcast authorization mechanism, in which one call to the 3scale backend (Service Management API) is made for each API request APIcast receives.

The 3scale Batcher policy reduces latency and increases throughput by significantly reducing the number of requests to the 3scale backend. In order to achieve this, this policy caches authorization statuses and batches usage reports.

When the 3scale Batcher policy is enabled, APIcast uses the following authorization flow:

The 3scale Batcher policy improves the throughput, but with reduced accuracy. The usage limits and the current utilization are stored in 3scale, and APIcast can only get the correct authorization status when making calls to the 3scale backend. When the 3scale Batcher policy is enabled, there is a period of time APIcast is not sending calls to 3scale. During this window, applications making calls might go over the defined limits.

Use this policy for high-load APIs if the throughput is more important than the accuracy of the rate limiting. The 3scale Batcher policy gives better results in terms of accuracy when the reporting frequency and authorization TTL are much less than the rate limiting period. For example, if the limits are per day and the reporting frequency and authorization TTL are configured to be several minutes.

The 3scale Batcher policy supports the following configuration settings:

The Anonymous access policy exposes a service without authentication. It can be useful, for example, for legacy applications that cannot be adapted to send the authentication parameters. The Anonymous policy only supports services with API Key and App Id / App Key authentication options. When the policy is enabled for API requests that do not have any credentials provided, APIcast will authorize the calls using the default credentials configured in the policy. For the API calls to be authorized, the application with the configured credentials must exist and be active.

Using the Application Plans, you can configure the rate limits on the application used for the default credentials.

Following are the required configuration properties for the policy:

Figure 6.1. Anonymous Access Policy

The Cross Origin Resource Sharing (CORS) request handling policy allows you to control CORS behavior by allowing you to specify:

The CORS request handling policy will block all unspecified CORS requests.

Configuration properties

Policy object example

{
  "name": "cors",
  "version": "builtin",
  "configuration": {
    "allow_headers": [
      "App-Id", "App-Key",
      "Content-Type", "Accept"
    ],
    "allow_credentials": true,
    "allow_methods": [
      "GET", "POST"
    ],
    "allow_origin": "https://example.com"
  }
}

For information on how to configure policies, refer to the Creating a policy chain section of the documentation.

The echo policy prints an incoming request back to the client, along with an optional HTTP status code.

Configuration properties

Policy object example

{
  "name": "echo",
  "version": "builtin",
  "configuration": {
    "status": 404,
    "exit": "request"
  }
}

For information on how to configure policies, refer to the Creating a policy chain section of the documentation.

The Edge Limiting policy aims to provide flexible rate limiting for the traffic sent to the backend API and can be used with the default 3scale authorization. Some examples of the use cases supported by the policy include:

{
  "key": { "name": "{{ jwt.sub }}", "name_type": "liquid" },
  "count": 10,
  "window": 60
}

"condition": {
  "combine_op": "and",
  "operations": [
    {
      "op": "==",
      "right": "GET",
      "left_type": "liquid",
      "left": "{{ http_method }}",
      "right_type": "plain"
    }
  ]
}

The Header modification policy allows you to modify the existing headers or define additional headers to add to or remove from an incoming request or response. You can modify both response and request headers.

The Header modification policy supports the following configuration parameters:

Each operation consists of the following parameters:

Policy object example

{
  "name": "headers",
  "version": "builtin",
  "configuration": {
    "response": [
      {
        "op": "add",
        "header": "Custom-Header",
        "value_type": "plain",
        "value": "any-value"
      }
    ],
    "request": [
      {
        "op": "set",
        "header": "Authorization",
        "value_type": "plain",
        "value": "Basic dXNlcm5hbWU6cGFzc3dvcmQ="
      },
      {
        "op": "set",
        "header": "Service-ID",
        "value_type": "liquid",
        "value": "{{service.id}}"
      }
    ]
  }
}

For information on how to configure policies, see the Creating a policy chain section of the documentation.

This policy responds to the API request with a JSON, containing the objects and values that are available in the context and can be used for evaluating Liquid templates. When combined with the 3scale APIcast or Upstream policy, Liquid Context Debug must be placed before them in the policy chain in order to work correctly. To avoid circular references, the policy only includes duplicated objects once and replaces them with a stub value.

An example of the value returned by APIcast when the policy is enabled:

{
  "jwt": {
    "azp": "972f7b4f",
    "iat": 1537538097,
    ...
    "exp": 1537574096,
    "typ": "Bearer"
  },
  "credentials": {
    "app_id": "972f7b4f"
  },
  "usage": {
    "deltas": {
      "hits": 1
    },
    "metrics": [
      "hits"
    ]
  },
  "service": {
    "id": "2",
    ...
  }
  ...
}

The logging policy allows enabling or disabling APIcast (NGINX) access logs for each API service individually. By default, this policy is not enabled in policy chains.

This policy only supports the enable_access_logs configuration parameter. To disable access logging for a service, enable the policy, unselect the enable_access_logs parameter and click the Submit button. To enable the access logs, select the enable_access_logs parameter or disable the Logging policy.

You can combine the Logging policy with the global setting for the location of access logs. Set the APICAST_ACCESS_LOG_FILE environment variable to configure the location of APIcast access logs. By default, this variable is set to /dev/stdout, which is the standard output device. For further details about global APIcast parameters, see Chapter 7, APIcast Environment Variables.

The OAuth 2.0 Token Introspection policy allows validating the JSON Web Token (JWT) token used for services with the OpenID Connect authentication option using the Token Introspection Endpoint of the token issuer (Red Hat Single Sign-On).

APIcast supports the following authentication types in the auth_type field to determine the Token Introspection Endpoint and the credentials APIcast uses when calling this endpoint:

Regardless of the setting in the auth_type field, APIcast uses Basic Authentication to authorize the Token Introspection call (Authorization: Basic <token> header, where <token> is Base64-encoded <client_id>:<client_secret> setting).

The response of the Token Introspection Endpoint contains the active attribute. APIcast checks the value of this attribute. Depending on the value of the attribute, APIcast authorizes or rejects the call:

The policy allows enabling caching of the tokens to avoid calling the Token Introspection Endpoint on every call for the same JWT token. To enable token caching for the Token Introspection Policy, set the max_cached_tokens field to a value from 0, which disables the feature, and 10000. Additionally, you can set a Time to Live (TTL) value from 1 to 3600 seconds for tokens in the max_ttl_tokens field.

The 3scale Referrer policy enables the Referrer Filtering feature. When the policy is enabled in the service policy chain, APIcast sends the value of the Referer policy of the upcoming request to the Service Management API (AuthRep call) in the referrer parameter. For more information on how Referrer Filtering works, see the Referrer Filtering section in Authentication Patterns.

This policy adds role check when used with the OpenID Connect authentication option. This policy verifies realm roles and client roles in the access token issued by Red Hat Single Sign-On. The realm roles are specified when you want to add role check to every client’s resources or 3Scale.

Following are the two types of role checks that the type property specifies in the policy configuration:

It is not possible to configure both checks – blacklist and whitelist in the same policy, but you can add more than one instances of the RH-SSO/Keycloak role check policy to the APIcast policy chain.

You can configure a list of scopes via the scopes property of the policy configuration.

Each scope object has the following properties:

Prometheus is a stand-alone, open source systems monitoring and alerting toolkit.

Prometheus metrics availability

APIcast integration with Prometheus is available for the following deployment options:

Prometheus metrics list

The following metrics are always available:

Metrics with no value

If a metric has no value, the metric is hidden. For example, if nginx_error_log has no errors to report, the nginx_error_log metric is not displayed. It will only be visible once it has a value.

The SOAP policy matches SOAP action URIs provided in the SOAPAction or Content-Type header of an HTTP request with mapping rules specified in the policy.

Configuration properties

Policy object example

{
  "name": "soap",
  "version": "builtin",
  "configuration": {
    "mapping_rules": [
      {
        "pattern": "http://example.com/soap#request",
        "metric_system_name": "soap",
        "delta": 1
      }
    ]
  }
}

For information on how to configure policies, refer to the Creating a policy chain section of the documentation.

The Upstream policy allows you to parse the Host request header using regular expressions and replace the upstream URL defined in the Private Base URL with a different URL.

For Example:

A policy with a regex /foo, and URL field newexample.com would replace the URL https://www.example.com/foo/123/ with newexample.com

Policy chain reference:

Policy object example

{
  "name": "upstream",
  "version": "builtin",
  "configuration": {
    "rules": [
      {
        "regex": "^/v1/.*",
        "url": "https://api-v1.example.com",

      }
    ]
  }
}

For information on how to configure policies, refer to the Creating a policy chain section of the documentation.

The URL rewriting policy allows you to modify the path of a request and the query string.

When combined with the 3scale APIcast policy, if the URL rewriting policy is placed before the 3scale APIcast policy in the policy chain, the APIcast mapping rules will apply to the modified path. If the URL rewriting policy is placed after APIcast in the policy chain, then the mapping rules will apply to the original path.

The policy supports the following two sets of operations:

{
  "name": "url_rewriting",
  "version": "builtin",
  "configuration": {
    "query_args_commands": [
      {
        "op": "add",
        "arg": "addarg",
        "value_type": "plain",
        "value": "addvalue"
      },
      {
        "op": "delete",
        "arg": "user_key",
        "value_type": "plain",
        "value": "any"
      },
      {
        "op": "push",
        "arg": "pusharg",
        "value_type": "plain",
        "value": "pushvalue"
      },
      {
        "op": "set",
        "arg": "setarg",
        "value_type": "plain",
        "value": "setvalue"
      }
    ],
    "commands": [
      {
        "op": "sub",
        "regex": "^/api/v\\d+/",
        "replace": "/internal/",
        "options": "i"
      }
    ]
  }

https://api.example.com/api/v1/products/123/details?user_key=abc123secret&pusharg=first&setarg=original

https://api-backend.example.com/internal/products/123/details?pusharg=first&pusharg=pushvalue&setarg=setvalue

The URL Rewriting with Captures policy is an alternative to the Section 6.1.16, “URL Rewriting Policy” policy and allows rewriting the URL of the API request before passing it to the API backend.

The URL Rewriting with Captures policy captures arguments in the URL and uses their values in the rewritten URL.

The policy supports the transformations configuration parameter. It is a list of objects that describe which transformations are applied to the request URL. Each tranformation object consist of two properties:

The query parameters of the original URL are merged with the query parameters specified in the template.

Example

The URL Rewriting with Captures is configured as follows:

{
  "name": "rewrite_url_captures",
  "version": "builtin",
  "configuration": {
    "transformations": [
      {
        "match_rule": "/api/v1/products/{productId}/details",
        "template": "/internal/products/details?id={productId}&extraparam=anyvalue"
      }
    ]
  }
}

The original request URI that is sent to the APIcast:

https://api.example.com/api/v1/products/123/details?user_key=abc123secret

The URI that APIcast sends to the API backend after applying the URL rewriting:

https://api-backend.example.com/internal/products/details?user_key=abc123secret&extraparam=anyvalue&id=123

To add custom APIcast policies to an On-Premises deployment, you must build an OpenShift image containing your custom policies and add it to your deployment. Red Hat 3scale provides a sample repository you can use as a framework to create and add custom policies to an on-premises deployment.

This sample repository contains the correct directory structure for a custom policy, as well as a template which creates an image stream and BuildConfigs for building a new APIcast OpenShift image containing any custom policies you create.

Follow these steps to add a custom policy to an on-premises deployment:

If the build-in APIcast images have a trigger on them tracking the changes in the amp-apicast:latest image stream, the new deployment for APIcast will start. After apicast-staging has restarted, go to the Integration page on the admin portal, and click the Add Policy button to see your custom policy listed. After selecting and configuring it, click Update & test in Staging Environment to make your custom policy work in the staging APIcast.

You can add custom policies to APIcast on OpenShift Container Platform (OCP) by fetching APIcast images containing your custom policies from the the Integrated OpenShift Container Registry.

Add custom policies to APIcast on another OpenShift Container Platform