middleware.md

type	title	linkTitle	weight	description
docs	Configure middleware components	Configure middleware	2000	Customize processing pipelines via the middleware components

{{% alert title="Note" color="primary" %}} Configuring middleware components using the [configuration schema]({{< ref configuration-schema.md >}}) is deprecated. {{% /alert %}}

With Dapr, you can define custom processing pipelines by chaining a series of middleware components. There are two places that you can use a middleware pipeline:

1. Building block APIs - HTTP middleware components are executed when invoking any Dapr HTTP APIs.
2. Service-to-Service invocation - HTTP middleware components are applied to service-to-service invocation calls.

In this guide, you learn how to configure middleware using its component YAML. To learn how to create middleware components, see the [Author middleware components how-to guides.]({{< ref develop-middleware.md >}})

Configure API middleware pipelines

When launched, a Dapr sidecar constructs a middleware processing pipeline for incoming HTTP calls. By default, the pipeline consists of the [tracing]({{< ref tracing-overview.md >}}) and CORS middlewares. Additional middlewares, configured by a Dapr [Configuration]({{< ref configuration-concept.md >}}), can be added to the pipeline in the order they are defined. The pipeline applies to all Dapr API endpoints, including state, pub/sub, service invocation, bindings, secrets, configuration, distributed lock, etc.

A request goes through all the defined middleware components before it's routed to user code, and then goes through the defined middleware, in reverse order, before it's returned to the client, as shown in the following diagram.

HTTP middleware components are executed when invoking Dapr HTTP APIs using the httpPipeline setting.

The following example defines a custom pipeline that uses a [RouterChecker middleware]({{< ref middleware-routerchecker.md >}}). In this case, all requests are authorized against the ^[A-Za-z0-9/._-]+$:regex before they are forwarded to user code. The priority field determines the order in which requests are executed once all handler components are collected.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: routerchecker1
spec:
  type: middleware.http.routerchecker
  version: v1
  metadata:
  - name: rule
    value: "^[A-Za-z0-9/._-]+$"
  - name: pipelineType
    value: httpPipeline
  - name: priority
    value: 1 

As with other components, supported middleware components can be found in the [supported Middleware reference guide]({{< ref supported-middleware >}}) and in the dapr/components-contrib repo.

Configure app middleware

You can also use any middleware component when making service-to-service invocation calls. For example, to add token validation in a zero-trust environment, to transform a request for a specific app endpoint, or to apply OAuth policies.

Service-to-service invocation middleware components apply to all outgoing calls from a Dapr sidecar to the receiving application (service), as shown in the diagram below.

Any middleware component that can be used as HTTP middleware can also be applied to service-to-service invocation calls as a middleware component using the appHttpPipeline configuration. The example below adds the routerchecker middleware component for all outgoing calls from the Dapr sidecar (target of service invocation) to the application that this configuration is applied to.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: routerchecker1
spec:
  type: middleware.http.routerchecker
  version: v1
  metadata:
  - name: rule
    value: "^[A-Za-z0-9/._-]+$"
  - name: pipelineType
    value: appHttpPipeline
  - name: priority
    value: 1 

Related links

• [Learn how to author middleware components]({{< ref develop-middleware.md >}})
• API middleware sample