Rules

The RuleContext middleware evaluates incoming requests against defined rules. If a request fails validation, an error is returned; otherwise, the request proceeds to the next step.

Rule Types and Definitions

Rule Type	Description	Example
HEADER	Matches the exact value of a specific HTTP header.	Header('Content-Type', 'application/json') matches Content-Type: application/json.
HEADER_PREFIX	Matches when the header value starts with the given prefix.	HeaderPrefix('User-Agent', 'Mozilla') matches User-Agent: Mozilla/5.0.
HEADER_REGEX	Matches the header value using a regular expression.	HeaderRegex('X-Custom-Header', '^[a-zA-Z0-9]{10}$') matches a 10-character alphanumeric string.
QUERY	Matches an exact query parameter key-value pair.	Query('status', 'active') matches ?status=active.
QUERY_PREFIX	Matches when the query parameter value starts with the specified prefix.	QueryPrefix('filter', 'user_') matches ?filter=user_123.
QUERY_REGEX	Matches the query parameter value using a regex.	QueryRegex('id', '\\d+') matches ?id=123.
PATH	Matches the exact request path.	Path('/tasks') matches /tasks.
PATH_PREFIX	Matches paths with the specified prefix.	PathPrefix('/api') matches /api/tasks.
PATH_REGEX	Matches the path using a regex.	PathRegex('/user/[a-z]+') matches /user/john.
HOST	Matches the exact hostname.	Host('example.com') matches example.com.
HOST_PREFIX	Matches when the hostname starts with the specified prefix.	HostPrefix('api.') matches api.example.com.
HOST_REGEX	Matches the hostname using a regex.	HostRegex('.*\\.example\\.com') matches sub.example.com.

Configuring Rules

proxies:
  - path: /task
    service: tasksApi
    middleware:
      basicAuth: 'basicAuth:roleB'
      rule: "(Header('Content-Type', 'application/json') && HeaderPrefix('User-Agent', 'Mozilla')) || HeaderRegex('X-Custom-Header', '^[a-zA-Z0-9]{10}$')"
    ttl: 10000
service:
  - name: tasksApi
    url: http://localhost:5173/template/1on1-meeting-agenda/tasks.json
    methods: ['GET', 'POST', 'PUT']

The rule in the configuration defines the conditions that must be met for a request to proceed:

• It checks that the Content-Type header equals application/json AND the User-Agent header starts with Mozilla.
• OR it validates that the X-Custom-Header matches the regex pattern ^[a-zA-Z0-9]10$ (exactly 10 alphanumeric characters).