You can configure Fusion Server to use JSON Web Tokens (JWTs) for user authentication and authorization. Fusion can also use a shared secret key between the issuer and Fusion to encrypt the JWT payload.
Fusion 4.1.0 and 4.1.1 have known issues with JWT signature validations. If you are using either of these versions and want to utilize JWT, consider Upgrading to Fusion 4.x of Fusion.

​
How the JWT realm works

A JWT is comprised of three distinct parts: the header, payload, and signing key. Each of these parts are separately encoded using Base64url encoding.
  • The header identifies the algorithm used to generate the token.
    Fusion uses both the HS256 and RS256 signature algorithms.
  • The payload consists of data that will be passed with the token.
  • The signing key validates the integrity of the token by using a “secret” to ensure the header and payload being submitted in the token match the header and payload stored in the signing key.
Within Fusion, the JWT realm uses an authorization header in the request to authenticate the user and the data inside the JWT token for the authorization. This authorization header uses the following format: 
Bearer <jwt-token>
Upon receiving the authorization header, Fusion authenticates the token and emits a response accordingly.

​
Configure JWT for Fusion

​
Create a JWT token

Using the tool you use to validate users, create a JWT token. The token requires the following properties:
  • iss: Issuer value. If the issuer value does not match the value configured in Fusion, the user will be denied access.
  • iat: A JSON numeric date value. This value is calculated by counting the number of seconds between 1970-01-01T00:00:00Z UTC and the specified UTC date/time, ignoring leap seconds.
  • sub: Subject. The name/id of the user. The user is logged in by this name.
  • groups: The groups from the group-role mappings that this user belongs to. The groups key should match the one you specify while creating the JWT realm.
Example data inside token: 
{
"iss":"fusion-enterprise-app",
"iat":"1562633069",
"sub":"username",
"groups": [“group-1”, “group-2”]
}

​
Create the Fusion JWT realm

To create a Fusion realm, in the Fusion UI:
  1. Click System > Access Control.
  2. Click the Security Realms tab, then Add Security Realm.
  3. Enter a realm name. Under type, select jwt.
  4. Create the security realm with the following values:
PropertyDescription
sourceThe name of the source field. This will be the name of the field in the Pipeline document that should be mapped to another field. Java regular expressions can be used in the source field by surrounding the regular expression with forward slashes (’/’). For example, /(.*)text(.*)/ is a valid expression that will find field names in the incoming document that contain the string ‘text’ between any number of preceding or succeeding characters. If a regular expression is not used, the value supplied for the source will be treated as a literal field name and will be matched ignoring the case (for example, “text” will match “tExt” or “Text”, etc.).
targetThe name of the target field. If the value for the source was a regular expression, then this can also be a regular expression. It can also contain substitutions using references to capture groups (using Java’s Matcher.replaceAll). Otherwise, the source field name will be simply substituted by the value of target according to the operation rules described below.
operation

What to do with the field during mapping. Several options are available:
• copy. Content contained in fields matching source will be copied to target.
• move. Content contained in fields matching source will be moved to target (it may also help to think of this as the field name being replaced by the value of target).
• delete. Content contained in fields matching source will be dropped from the document and not indexed. In this case, the target can be null or not defined at all.
• add. The literal value of target will be added to the source if source is a regular expression. If source is not a regular expression, target will be added as a new field.
• set. The literal value of target will be set as the new value of the source if source is a regular expression. If source is not a regular expression, target will be set as a new field.
• keep. Content contained in fields matching source will be retained and unchanged, and the fields will be added to a list of known fields and they will not be affected by however the renameUnknown rule has been set.

  1. Click Save.

​
Validate the new realm

When you send a request to Fusion, you should receive a response. The request to Fusion looks like this: 
curl http://127.0.0.1:8764/api/users -H 'authorization: Bearer <token-header>.<token-payload>.<token-signing-key>'
Bearer is case sensitive.
If no signing key is used, truncate the JWT to read …​ Bearer <token-header>.<token-payload>..

​
Enable diagnostic logs for debugging

  1. Navigate to your Fusion home directory, then open the conf folder.
  2. Edit the file proxy-log4j2.xml.
  3. In the <Loggers> element, add the following: 
    <logger name="com.lucidworks.apollo-admin.models.realm-config" level="DEBUG" />
<logger name="com.lucidworks.apollo-admin.middleware.authc.jwt" level="DEBUG" />
  4. Restart proxy for this change to take effect: bin/proxy restart
Now var/log/proxy/proxy.log will show some diagnostic logs to help you troubleshoot your issues.

​
Resources

JWT.io is an excellent resource for learning about JWT, creating tokens, debugging tokens, and more.

​
Example of generating a JWT using PyJWT

Typically, you will generate your JWT token from the application you are integrating with Fusion APIs. This example, however, uses Python to create a JWT token with the PyJWT Python egg.
  1. Install the PyJWT egg: 
    pip install pyjwt
  2. Inside a Python console, run the following command using your realm configurations: 
    import jwt
from datetime import datetime, timedelta

key = '<signing key>'
jwt_issuer = '<jwt issuer>'
username = '<username>'
groups = ['<groups assigned to user>']
iat = datetime.utcnow()
exp = iat + timedelta(minutes=5)
payload = {'iss': jwt_issuer, 'iat': iat, 'exp': exp,'sub': username, 'groups': groups}

print (jwt.encode(payload, key, algorithm='HS256'))
A Bearer token will be printed for use in API requests: 
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJmdXNpb24tYXBwIiwiaWF0IjoxNTYyNjMzMDY5LCJzdWIiOiJhZG1pbiIsImdyb3VwcyI6WyJncm91cDEiXX0.HYyv_XlijDeO1zdZ1Cd_gifgcIAFiZ1ldkbgk0hnWro
  1. You can now use this as a bearer token in an authorization header to authenticate to Fusion.
    Test your Fusion API web service call with cURL. For example, if your role is an administrator, call:     
    curl -H "Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJmdXNpb24iLCJpYXQiOjE1MzY3ODI1MTc4NjQsInN1YiI6InRlc3QtZnVzaW9uIiwiZ3JvdXBzIjpbImdyb3VwLW9uZSIsImdyb3VwLXR3byJdfQ._ACGk4q3Y5g8QgvLFUUQIcMN2ynACypcpei2JmYFlzc" http://localhost:8764/api/roles