render_macros

JWT Extension for WireMock

Adds Handlebars helpers for generating JWT, claims and JWKS.

Java/JVM usage

Step 1: Add to your build file

For Maven users:

<dependency>
    <groupId>org.wiremock.extensions</groupId>
    <artifactId>wiremock-jwt-extension</artifactId>
    <version>0.2.0</version>
</dependency>

For Gradle users:

dependencies {
    implementation 'org.wiremock.extensions:wiremock-jwt-extension:0.2.0'
}

Step 2: Register the extension with your server

new WireMockServer(wireMockConfig().extensions(JwtExtensionFactory.class));

Step 3: Create a JWKS endpoint

wm.stubFor(
    get(urlPathEqualTo("/.well-known/jwks.json"))
        .willReturn(okJson("{{jwks}}").withTransformers("response-template")));

Step 4: Create a token endpoint

wm.stubFor(
    get(urlPathEqualTo("/oauth/token"))
        .willReturn(okJson("{{jwt}}").withTransformers("response-template")));

Customising the JWT

The jwt helper has a number of parameters you can use to customise the generated token.

Expiry date

You can customise expiry term either by setting the maxAge parameter e.g.

{% raw %}

{{{jwt maxAge='12 days'}}}

{% endraw %}

or by setting an absolute expiry date e.g.

{% raw %}

{{{jwt exp=(parseDate '2040-02-23T21:22:23Z')}}}

{% endraw %}

You can similarly set the nbf (not before) date:

{% raw %}

{{{jwt nbf=(parseDate '2018-02-23T21:22:23Z')}}}

{% endraw %}

Standard claims

Standard claims can be set as follows.

Issuer:

{% raw %}

{{{jwt iss='https://jwt-example.wiremockapi.cloud/'}}}

{% endraw %}

Audience:

{% raw %}

{{{jwt aud='https://jwt-target.wiremockapi.cloud/'}}}

{% endraw %}

Subject:

{% raw %}

{{{jwt sub='jonsmith'}}}

{% endraw %}

Custom claims

You can also set any custom claim you wish via named parameters e.g.

{% raw %}

{{{jwt
    isAdmin=true
    quota=23
    score=0.96
    email='jonsmith@example.wiremockapi.cloud'
    signupDate=(parseDate '2017-01-02T03:04:05Z')
}}}

{% endraw %}

Signing with RS256

By setting the alg parameter, the token can be signed using the public/private key algorithm:

{% raw %}

{{{jwt alg='RS256'}}}

{% endraw %}

Retrieving keys

For clients to be able to validate JWTs, they need to be able to retrieve either the shared secret or the public key, depending on the signing algorithm.

Getting all keys for your mock API

The keys used to sign tokens for a particular mock API can be retrieved via the settings admin API resource. To fetch these via curl, you can do the following:

curl http://localhost:8080/__admin/settings

This will return a JSON document like this, from which you can retrieve the any of the keys:

{
  "settings": {
    "extended": {
      "jwt": {
        "hs256Secret": "...",
        "rs256PublicKeyId": "...",
        "rs256PublicKey": "-----BEGIN RSA PUBLIC KEY-----\n...\n-----END RSA PUBLIC KEY-----\n",
        "rs256PrivateKey": "-----BEGIN RSA PRIVATE KEY-----\n...\n-----END RSA PRIVATE KEY-----\n"
      }
    }
  }
}

The JSON Web Key Set (JWKS)

When using RS256 (public/private key) signing, it is common for clients to fetch the public key for verification via a JSON Web Key Set (JWKS) endpoint. You serve a JWKS from your mock API simply by adding a stub containing the following response body (with templating enabled):

{% raw %}

{{{jwks}}}

{% endraw %}