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Gateway

Routes​

Routes are the main elements of the Gateway. They are defined by a destination URI, a set of predicates, and a set of filters. A route is considered if the aggregated predicate is true.

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The URI is generally the DNS of the microservice.

Predicates​

Predicates are the operations that condition the route. If all predicates are evaluated to true, then the route is taken.

These predicates can be an HTTP header, a cookie, or something else, but it's generally an element of the path, the path of the request.

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The first route whose all predicates are verified is taken. It is therefore important to pay attention to the order of the routes.

Filters​

Filters allow modifying the flow.

We can distinguish 3 types of filters.

Request Filters​

Request filters modify the elements constituting the request before sending it to the microservice designated by the URI.

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For example, the stripPrefix=1 filter allows removing from the path the piece that would have served as a predicate.

They also allow defining specific HTTP headers or other modifications before being transmitted to the target service.

Response Filters​

Response filters allow modifying the response returned by the target service.

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This kind of filter can add a button in the UI.

Other Filters​

Other filters are those that do not fit into the first two categories.

These are for example the filters for status modifications.

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Most of the time you will set up a path type predicate with a stripPrefix request filter or a host type predicate.

Security​

Security is an important component of ARCHWAY.

2 types of requirements can be defined:

  • Authentication is required
  • The necessity to possess a role (implicit authentication)

These requirements can be defined at 2 levels:

Route Security​

The 2 requirements can be defined at the route level.

This can be defined directly during the creation of the route.

Endpoint Security​

If the route exposes an endpoint allowing to retrieve the open-api specifications, ARCHWAY allows defining for each endpoint the security requirements.

Practical Case​

For example, consider the foo-service microservice that listens on port 3000.

The route could be:

  • Predicate: path=/foo/** defining that all requests starting with /foo/** will be redirected to foo-service But the foo-service does not have foo in its context path. So we will use the request filter to remove this unnecessary part.
  • Filter: stripPrefix=1 Now the web application that wants to request the foo-service can just request /foo/...
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Thus the API Gateway will route the request /foo/v1/item to http://foo-service:3000/v1/item

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ARCHWAY can transmit user information to the foo-service

  • via HTTP headers
  • via a JWT token