Filtering and Modifying Requests

Documentation / java / extensibility / filtering_and_modifying_requests

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Requests to both stubs and the admin API can be intercepted and either modified or halted with an immediate response. This supports a number of use cases including: authentication, URL rewriting and request header injection.

To intercept stub requests, create a class that extends StubRequestFilter. For instance, to perform simple authentication:

Java

public class SimpleAuthRequestFilter implements StubRequestFilterV2 {

    @Override
    public RequestFilterAction filter(Request request, ServeEvent serveEvent) {
        if (request.header("Authorization").firstValue().equals("Basic abc123")) {
            return RequestFilterAction.continueWith(request);
        }

        return RequestFilterAction.stopWith(ResponseDefinition.notAuthorised());
    }

    @Override
    public String getName() {
        return "simple-auth";
    }
}

Then add it as an extension as usual e.g.

Java

new WireMockRule(wireMockConfig().extensions(new SimpleAuthRequestFilter()));

To intercept admin API follow the same process, but extend AdminRequestFilter.

Modifying the request during interception

To modify the HTTP request, the simplest approach is to wrap the original request with a RequestWrapper then continue e.g.

Java

public static class UrlAndHeadersModifyingFilter extends StubRequestFilterV2 {

    @Override
    public RequestFilterAction filter(Request request, ServeEvent serveEvent) {
        Request wrappedRequest = RequestWrapper.create()
                .transformAbsoluteUrl(url -> url + "?extraQueryParam=123")
                .addHeader("X-Custom-Header", "headerval")
                .wrap(request);

        return RequestFilterAction.continueWith(wrappedRequest);
    }

    @Override
    public String getName() {
        return "url-and-header-modifier";
    }
}

RequestWrapper is a builder pattern and allows any number of changes to the request. It supports the following changes:

• Transformation of the URL. transformAbsoluteUrl takes a FieldTransformer as a parameter (or equivalent lambda) which maps from the old to the new URL. Note that the URL passed in is absolute, and the returned URL must also be.
• Addition, removal and transformation (via FieldTransformer) of headers.
• Addition, removal and transformation of cookies.
• Changing the HTTP method.
• Transformation of the request body.
• Transformation of body parts (if a multipart encoded request).