Using the 3scale Istio adapter

The 3scale Istio Adapter is an optional adapter that allows you to label a service running within the Maistra Service Mesh and integrate that service with the 3scale API Management solution. It is not required for Maistra Service Mesh.

Integrate the 3scale adapter with Maistra Service Mesh

You can use these examples to configure requests to your services using the 3scale Istio Adapter.

Prerequisites:
  • Maistra Service Mesh version 2.x

  • A working 3scale account (SaaS or 3scale 2.9 On-Premises)

  • Enabling backend cache requires 3scale 2.9 or greater

  • Maistra Service Mesh prerequisites

  • Ensure Mixer policy enforcement is enabled. Update Mixer policy enforcement section provides instructions to check the current Mixer policy enforcement status and enable policy enforcement.

  • Mixer policy and telemetry must be enabled if you are using a mixer plug-in.

    • You will need to properly configure the Service Mesh Control Plane (SMCP) when upgrading.

Important
When you want to enable 3scale backend cache with the 3scale Istio adapter, you must also enable mixer policy and mixer telemetry. See Deploying the Red Hat OpenShift Service Mesh control plane.
Note

To configure the 3scale Istio Adapter, refer to Maistra Service Mesh custom resources for instructions on adding adapter parameters to the custom resource file.

Note

Pay particular attention to the kind: handler resource. You must update this with your 3scale credentials and the service ID of the API you want to manage.

  1. Modify the handler configuration with your 3scale configuration.

    Handler configuration example
      apiVersion: "config.istio.io/v1alpha2"
      kind: handler
      metadata:
       name: threescale
      spec:
       adapter: threescale
       params:
         service_id: "<SERVICE_ID>"
         system_url: "https://<organization>-admin.3scale.net/"
         access_token: "<ACCESS_TOKEN>"
       connection:
         address: "threescale-istio-adapter:3333"

Optionally, you can provide a backend_url field within the params section to override the URL provided by the 3scale configuration. This may be useful if the adapter runs on the same cluster as the 3scale on-premise instance, and you wish to leverage the internal cluster DNS.

  1. Modify the rule configuration with your 3scale configuration to dispatch the rule to the threescale handler.

    Rule configuration example
      apiVersion: "config.istio.io/v1alpha2"
      kind: rule
      metadata:
        name: threescale
      spec:
        match: destination.labels["service-mesh.3scale.net"] == "true"
        actions:
          - handler: threescale.handler
            instances:
              - threescale-authorization.instance

Generating 3scale custom resources

The adapter includes a tool that allows you to generate the handler, instance, and rule custom resources.

Table 1. Usage
Option Description Required Default value

-h, --help

Produces help output for available options

No

--name

Unique name for this URL, token pair

Yes

-n, --namespace

Namespace to generate templates

No

istio-system

-t, --token

3scale access token

Yes

-u, --url

3scale Admin Portal URL

Yes

--backend-url

3scale backend URL. If set, it overrides the value that is read from system configuration

No

-s, --service

3scale API/Service ID

No

--auth

3scale authentication pattern to specify (1=API Key, 2=App Id/App Key, 3=OIDC)

No

Hybrid

-o, --output

File to save produced manifests to

No

Standard output

--version

Outputs the CLI version and exits immediately

No

Generate templates from URL examples

  • This example generates templates allowing the token, URL pair to be shared by multiple services as a single handler:

    $ 3scale-gen-config --name=admin-credentials --url="https://<organization>-admin.3scale.net:443" --token="[redacted]"
  • This example generates the templates with the service ID embedded in the handler:

    $ 3scale-gen-config --url="https://<organization>-admin.3scale.net" --name="my-unique-id" --service="123456789" --token="[redacted]"

Generating manifests from a deployed adapter

  1. Run this command to generate manifests from a deployed adapter in the istio-system namespace:

    $ export NS="istio-system" URL="https://replaceme-admin.3scale.net:443" NAME="name" TOKEN="token"
    oc exec -n ${NS} $(oc get po -n ${NS} -o jsonpath='{.items[?(@.metadata.labels.app=="3scale-istio-adapter")].metadata.name}') \
    -it -- ./3scale-config-gen \
    --url ${URL} --name ${NAME} --token ${TOKEN} -n ${NS}
  2. This will produce sample output to the terminal. Edit these samples if required and create the objects using the oc create command.

  3. When the request reaches the adapter, the adapter needs to know how the service maps to an API on 3scale. You can provide this information in two ways:

    1. Label the workload (recommended)

    2. Hard code the handler as service_id

  4. Update the workload with the required annotations:

    Note

    You only need to update the service ID provided in this example if it is not already embedded in the handler. The setting in the handler takes precedence.

    $ export CREDENTIALS_NAME="replace-me"
    export SERVICE_ID="replace-me"
    export DEPLOYMENT="replace-me"
    patch="$(oc get deployment "${DEPLOYMENT}"
    patch="$(oc get deployment "${DEPLOYMENT}" --template='{"spec":{"template":{"metadata":{"labels":{ {{ range $k,$v := .spec.template.metadata.labels }}"{{ $k }}":"{{ $v }}",{{ end }}"service-mesh.3scale.net/service-id":"'"${SERVICE_ID}"'","service-mesh.3scale.net/credentials":"'"${CREDENTIALS_NAME}"'"}}}}}' )"
    oc patch deployment "${DEPLOYMENT}" --patch ''"${patch}"''

Routing service traffic through the adapter

Follow these steps to drive traffic for your service through the 3scale adapter.

Prerequisites
  • Credentials and service ID from your 3scale administrator.

Procedure
  1. Match the rule destination.labels["service-mesh.3scale.net/credentials"] == "threescale" that you previously created in the configuration, in the kind: rule resource.

  2. Add the above label to PodTemplateSpec on the Deployment of the target workload to integrate a service. the value, threescale, refers to the name of the generated handler. This handler stores the access token required to call 3scale.

  3. Add the destination.labels["service-mesh.3scale.net/service-id"] == "replace-me" label to the workload to pass the service ID to the adapter via the instance at request time.

Configure the integration settings in 3scale

Follow this procedure to configure the 3scale integration settings.

Note

For 3scale SaaS customers, Maistra Service Mesh is enabled as part of the Early Access program.

Procedure
  1. Navigate to [your_API_name]IntegrationConfiguration.

  2. At the top of the Integration page click on edit integration settings in the top right corner.

  3. Under the Service Mesh heading, click the Istio option.

  4. Scroll to the bottom of the page and click Update Service.

Caching behavior

Responses from 3scale System APIs are cached by default within the adapter. Entries will be purged from the cache when they become older than the cacheTTLSeconds value. Also by default, automatic refreshing of cached entries will be attempted seconds before they expire, based on the cacheRefreshSeconds value. You can disable automatic refreshing by setting this value higher than the cacheTTLSeconds value.

Caching can be disabled entirely by setting cacheEntriesMax to a non-positive value.

By using the refreshing process, cached values whose hosts become unreachable will be retried before eventually being purged when past their expiry.

Authenticating requests

This release supports the following authentication methods:

  • Standard API Keys: single randomized strings or hashes acting as an identifier and a secret token.

  • Application identifier and key pairs: immutable identifier and mutable secret key strings.

  • OpenID authentication method: client ID string parsed from the JSON Web Token.

Applying authentication patterns

Modify the instance custom resource, as illustrated in the following authentication method examples, to configure authentication behavior. You can accept the authentication credentials from:

  • Request headers

  • Request parameters

  • Both request headers and query parameters

Note

When specifying values from headers, they must be lower case. For example, if you want to send a header as User-Key, this must be referenced in the configuration as request.headers["user-key"].

API key authentication method

Maistra looks for the API key in query parameters and request headers as specified in the user option in the subject custom resource parameter. It checks the values in the order given in the custom resource file. You can restrict the search for the API key to either query parameters or request headers by omitting the unwanted option.

In this example, Maistra looks for the API key in the user_key query parameter. If the API key is not in the query parameter, Maistra then checks the user-key header.

API key authentication method example
apiVersion: "config.istio.io/v1alpha2"
kind: instance
metadata:
  name: threescale-authorization
  namespace: istio-system
spec:
  template: authorization
  params:
    subject:
      user: request.query_params["user_key"] | request.headers["user-key"] | ""
    action:
      path: request.url_path
      method: request.method | "get"

If you want the adapter to examine a different query parameter or request header, change the name as appropriate. For example, to check for the API key in a query parameter named “key”, change request.query_params["user_key"] to request.query_params["key"].

Application ID and application key pair authentication method

Maistra looks for the application ID and application key in query parameters and request headers, as specified in the properties option in the subject custom resource parameter. The application key is optional. It checks the values in the order given in the custom resource file. You can restrict the search for the credentials to either query parameters or request headers by not including the unwanted option.

In this example, Maistra looks for the application ID and application key in the query parameters first, moving on to the request headers if needed.

Application ID and application key pair authentication method example
apiVersion: "config.istio.io/v1alpha2"
kind: instance
metadata:
  name: threescale-authorization
  namespace: istio-system
spec:
  template: authorization
  params:
    subject:
        app_id: request.query_params["app_id"] | request.headers["app-id"] | ""
        app_key: request.query_params["app_key"] | request.headers["app-key"] | ""
    action:
      path: request.url_path
      method: request.method | "get"

If you want the adapter to examine a different query parameter or request header, change the name as appropriate. For example, to check for the application ID in a query parameter named identification, change request.query_params["app_id"] to request.query_params["identification"].

OpenID authentication method

To use the OpenID Connect (OIDC) authentication method, use the properties value on the subject field to set client_id, and optionally app_key.

You can manipulate this object using the methods described previously. In the example configuration shown below, the client identifier (application ID) is parsed from the JSON Web Token (JWT) under the label azp. You can modify this as needed.

OpenID authentication method example
  apiVersion: "config.istio.io/v1alpha2"
  kind: instance
  metadata:
    name: threescale-authorization
  spec:
    template: threescale-authorization
    params:
      Subject:
  properties:
          app_key: request.query_params["app_key"] | request.headers["app-key"] | ""
          client_id: request.auth.claims["azp"] | ""
      action:
        path: request.url_path
        method: request.method | "get"
          service: destination.labels["service-mesh.3scale.net/service-id"] | ""

For this integration to work correctly, OIDC must still be done in 3scale for the client to be created in the identity provider (IdP). You should create a Request authorization for the service you want to protect in the same namespace as that service. The JWT is passed in the Authorization header of the request.

In the sample RequestAuthentication defined below, replace issuer, jwksUri, and selector as appropriate.

OpenID Policy example
apiVersion: security.istio.io/v1beta1
kind: RequestAuthentication
metadata:
  name: jwt-example
  namespace: bookinfo
spec:
  selector:
    matchLabels:
      app: productpage
  jwtRules:
  - issuer: >-
      http://keycloak-keycloak.34.242.107.254.nip.io/auth/realms/3scale-keycloak
    jwksUri: >-
      http://keycloak-keycloak.34.242.107.254.nip.io/auth/realms/3scale-keycloak/protocol/openid-connect/certs

Hybrid authentication method

You can choose to not enforce a particular authentication method and accept any valid credentials for either method. If both an API key and an application ID/application key pair are provided, Maistra uses the API key.

In this example, Maistra checks for an API key in the query parameters, then the request headers. If there is no API key, it then checks for an application ID and key in the query parameters, then the request headers.

Hybrid authentication method example
apiVersion: "config.istio.io/v1alpha2"
kind: instance
metadata:
  name: threescale-authorization
spec:
  template: authorization
  params:
    subject:
      user: request.query_params["user_key"] | request.headers["user-key"] |
      properties:
        app_id: request.query_params["app_id"] | request.headers["app-id"] | ""
        app_key: request.query_params["app_key"] | request.headers["app-key"] | ""
        client_id: request.auth.claims["azp"] | ""
    action:
      path: request.url_path
      method: request.method | "get"
        service: destination.labels["service-mesh.3scale.net/service-id"] | ""

3scale Adapter metrics

The adapter, by default reports various Prometheus metrics that are exposed on port 8080 at the /metrics endpoint. These metrics provide insight into how the interactions between the adapter and 3scale are performing. The service is labeled to be automatically discovered and scraped by Prometheus.

Note
There are incompatible changes in the 3scale Istio Adapter metrics since the previous releases in Service Mesh 1.x.

In Prometheus, metrics have been renamed with one addition for the backend cache, so that the following metrics exist as of Service Mesh 2.0:

Table 2. Prometheus metrics
Metric Type Description

threescale_latency

Histogram

Request latency between adapter and 3scale.

threescale_http_total

Counter

HTTP Status response codes for requests to 3scale backend.

threescale_system_cache_hits

Counter

Total number of requests to the 3scale system fetched from the configuration cache.

threescale_backend_cache_hits

Counter

Total number of requests to 3scale backend fetched from the backend cache.

3scale backend cache

The 3scale backend cache provides an authorization and reporting cache for clients of the 3scale Service Management API. This cache is embedded in the adapter to enable lower latencies in responses in certain situations assuming the administrator is willing to accept the trade-offs.

Note
3scale backend cache is disabled by default. 3scale backend cache functionality trades inaccuracy in rate limiting and potential loss of hits since the last flush was performed for low latency and higher consumption of resources in the processor and memory.

Advantages of enabling backend cache

The following are advantages to enabling the backend cache:

  • Enable the backend cache when you find latencies are high while accessing services managed by the 3scale Istio Adapter.

  • Enabling the backend cache will stop the adapter from continually checking with the 3scale API manager for request authorizations, which will lower the latency.

    • This creates an in-memory cache of 3scale authorizations for the 3scale Istio Adapter to store and reuse before attempting to contact the 3scale API manager for authorizations. Authorizations will then take much less time to be granted or denied.

  • Backend caching is useful in cases when you are hosting the 3scale API manager in another geographical location from the service mesh running the 3scale Istio Adapter.

    • This is generally the case with the 3scale Hosted (SaaS) platform, but also if a user hosts their 3scale API manager in another cluster located in a different geographical location, in a different availability zone, or in any case where the network overhead to reach the 3scale API manager is noticeable.

Trade-offs for having lower latencies

The following are trade-offs for having lower latencies:

  • Each 3scale adapter’s authorization state updates every time a flush happens.

    • This means two or more instances of the adapter will introduce more inaccuracy between flushing periods.

    • There is a greater chance of too many requests being granted that exceed limits and introduce erratic behavior, which leads to some requests going through and some not, depending on which adapter processes each request.

  • An adapter cache that cannot flush its data and update its authorization information risks shut down or crashing without reporting its information to the API manager.

  • A fail open or fail closed policy will be applied when an adapter cache cannot determine whether a request must be granted or denied, possibly due to network connectivity issues in contacting the API manager.

  • When cache misses occur, typically right after booting the adapter or after a long period of no connectivity, latencies will grow in order to query the API manager.

  • An adapter cache must do much more work on computing authorizations than it would without an enabled cache, which will tax processor resources.

  • Memory requirements will grow proportionally to the combination of the amount of limits, applications, and services managed by the cache.

Backend cache configuration settings

The following points explain the backend cache configuration settings:

  • Find the settings to configure the backend cache in the Example 3scale configuration options.

  • The last 3 settings control enabling of backend cache:

    • PARAM_USE_CACHE_BACKEND - set to true to enable backend cache.

    • PARAM_BACKEND_CACHE_FLUSH_INTERVAL_SECONDS - sets time in seconds between consecutive attempts to flush cache data to the API manager.

    • PARAM_BACKEND_CACHE_POLICY_FAIL_CLOSED - set whether or not to allow/open or deny/close requests to the services when there is not enough cached data and the 3scale API manager cannot be reached.

3scale Istio Adapter APIcast emulation

The 3scale Istio Adapter performs as APIcast would when the following conditions occur:

  • When a request cannot match any mapping rule defined, the returned HTTP code is 404 Not Found. This was previously 403 Forbidden.

  • When a request is denied because it goes over limits, the returned HTTP code is 429 Too Many Requests. This was previously 403 Forbidden.

  • When generating default templates via the CLI, it will use underscores rather than dashes for the headers, for example: user_key rather than user-key.