Rules

Action describes which Handler to invoke and what data to pass to it for processing.

The following example instructs Mixer to invoke ‘prometheus-handler’ handler and pass it the object constructed using the instance ‘RequestCountByService’.

  handler: prometheus-handler
  instances:
  - RequestCountByService

AttributeManifest describes a set of Attributes produced by some component of an Istio deployment.

Name = IDENT { SEPARATOR IDENT };

AttributeInfo describes the schema of an Istio Attribute.

Istio Attributes

Istio uses attributes to describe runtime activities of Istio services. An Istio attribute carries a specific piece of information about an activity, such as the error code of an API request, the latency of an API request, or the original IP address of a TCP connection. The attributes are often generated and consumed by different services. For example, a frontend service can generate an authenticated user attribute and pass it to a backend service for access control purpose.

To simplify the system and improve developer experience, Istio uses shared attribute definitions across all components. For example, the same authenticated user attribute will be used for logging, monitoring, analytics, billing, access control, auditing. Many Istio components provide their functionality by collecting, generating, and operating on attributes. For example, the proxy collects the error code attribute, and the logging stores it into a log.

Design

Each Istio attribute must conform to an AttributeInfo in an AttributeManifest in the current Istio deployment at runtime. An AttributeInfo is used to define an attribute’s metadata: the type of its value and a detailed description that explains the semantics of the attribute type. Each attribute’s name is globally unique; in other words an attribute name can only appear once across all manifests.

The runtime presentation of an attribute is intentionally left out of this specification, because passing attribute using JSON, XML, or Protocol Buffers does not change the semantics of the attribute. Different implementations can choose different representations based on their needs.

HTTP Mapping

Because many systems already have REST APIs, it makes sense to define a standard HTTP mapping for Istio attributes that are compatible with typical REST APIs. The design is to map one attribute to one HTTP header, the attribute name and value becomes the HTTP header name and value. The actual encoding scheme will be decided later.

Authentication allows the operator to specify the authentication of connections to out-of-process infrastructure backend.

Connection allows the operator to specify the endpoint for out-of-process infrastructure backend. Connection is part of the handler custom resource and is specified alongside adapter specific configuration.

An instance field of type DNSName denotes that the expression for the field must evaluate to ValueType.DNS_NAME

Objects of type DNSName are also passed to the adapters during request-time for the instance fields of type DNSName

Direct HTTP response for a client-facing error message which can be attached to an RPC error.

An instance field of type Duration denotes that the expression for the field must evaluate to ValueType.DURATION

Objects of type Duration are also passed to the adapters during request-time for the instance fields of type Duration

DO NOT USE !! Under Development An instance field of type EmailAddress denotes that the expression for the field must evaluate to ValueType.EMAIL_ADDRESS

Objects of type EmailAddress are also passed to the adapters during request-time for the instance fields of type EmailAddress

Fraction percentages support several fixed denominator values.

Handler allows the operator to configure a specific adapter implementation. Each adapter implementation defines its own params proto.

In the following example we define a metrics handler for the prometheus adapter. The example is in the form of a Kubernetes resource: * The metadata.name is the name of the handler * The kind refers to the adapter name * The spec block represents adapter-specific configuration as well as the connection information

### Sample-1: No connection specified (for compiled in adapters)
### Note: if connection information is not specified, the adapter configuration is directly inside
### `spec` block. This is going to be DEPRECATED in favor of Sample-2
apiVersion: "config.istio.io/v1alpha2"
kind: prometheus
metadata:
  name: handler
  namespace: istio-system
spec:
  metrics:
  - name: request_count
    instance_name: requestcount.metric.istio-system
    kind: COUNTER
    label_names:
    - source_service
    - source_version
    - destination_service
    - destination_version
---
### Sample-2: With connection information (for out-of-process adapters)
### Note: Unlike sample-1, the adapter configuration is parallel to `connection` and is nested inside `param` block.
apiVersion: "config.istio.io/v1alpha2"
kind: prometheus
metadata:
  name: handler
  namespace: istio-system
spec:
  param:
    metrics:
    - name: request_count
      instance_name: requestcount.metric.istio-system
      kind: COUNTER
      label_names:
      - source_service
      - source_version
      - destination_service
      - destination_version
  connection:
    address: localhost:8090
---

HTTP response codes. For more details: http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

An instance field of type IPAddress denotes that the expression for the field must evaluate to ValueType.IP_ADDRESS

Objects of type IPAddress are also passed to the adapters during request-time for the instance fields of type IPAddress

An Instance tells Mixer how to create instances for particular template.

Instance is defined by the operator. Instance is defined relative to a known template. Their purpose is to tell Mixer how to use attributes or literals to produce instances of the specified template at runtime.

The following example instructs Mixer to construct an instance associated with template ‘istio.mixer.adapter.metric.Metric’. It provides a mapping from the template’s fields to expressions. Instances produced with this instance can be referenced by Actions using name ‘RequestCountByService’

- name: RequestCountByService
  template: istio.mixer.adapter.metric.Metric
  params:
    value: 1
    dimensions:
      source: source.name
      destination_ip: destination.ip

params:
  # Pass the required attribute data to the adapter
  source_uid: source.uid | ""
attribute_bindings:
  # Fill the new attributes from the adapter produced output
  source.namespace: output.source_namespace

Mutual let operator specify TLS configuration for Mixer as client if mutual TLS is used to secure connection to adapter backend.

OAuth let operator specify config to fetch access token via oauth when using TLS for connection to the backend.

A Rule is a selector and a set of intentions to be executed when the selector is true

The following example instructs Mixer to invoke prometheus-handler handler for all services and pass it the instance constructed using the ‘RequestCountByService’ instance.

- match: match(destination.service.host, "*")
  actions:
  - handler: prometheus-handler
    instances:
    - RequestCountByService

A template for an HTTP header manipulation. Values in the template are expressions that may reference action outputs by name. For example, if an action x produces an output with a field f, then the header value expressions may use attribute x.output.f to reference the field value:

request_header_operations:
- name: x-istio-header
  values:
  - x.output.f

If the header value expression evaluates to an empty string, and the operation is to either replace or append a header, then the operation is not applied. This permits conditional behavior on behalf of the adapter to optionally modify the headers.

Header operation type.

An instance field of type TimeStamp denotes that the expression for the field must evaluate to ValueType.TIMESTAMP

Objects of type TimeStamp are also passed to the adapters during request-time for the instance fields of type TimeStamp

Tls let operator specify client authentication setting when TLS is used for connection to the backend.

AuthHeader specifies how to pass access token with authorization header.

DO NOT USE !! Under Development An instance field of type Uri denotes that the expression for the field must evaluate to ValueType.URI

Objects of type Uri are also passed to the adapters during request-time for the instance fields of type Uri

An instance field of type Value denotes that the expression for the field is of dynamic type and can evaluate to any ValueType enum values. For example, when authoring an instance configuration for a template that has a field data of type istio.policy.v1beta1.Value, both of the following expressions are valid data: source.ip | ip("0.0.0.0"), data: request.id | ""; the resulting type is either ValueType.IP_ADDRESS or ValueType.STRING for the two cases respectively.

Objects of type Value are also passed to the adapters during request-time. There is a 1:1 mapping between oneof fields in Value and enum values inside ValueType. Depending on the expression’s evaluated ValueType, the equivalent oneof field in Value is populated by Mixer and passed to the adapters.

ValueType describes the types that values in the Istio system can take. These are used to describe the type of Attributes at run time, describe the type of the result of evaluating an expression, and to describe the runtime type of fields of other descriptors.