Condition types for listener rules

Conditions define the criteria that incoming requests must meet for a listener rule to take effect. If a request matches the conditions for a rule, the request is handled as specified by the rule's actions. Each rule condition has a type and configuration information. Application Load Balancers support the following condition types for listener rules.

Demos

For demos, see Advanced request routing.

HTTP header conditions

You can use HTTP header conditions to configure rules that route requests based on the HTTP headers for the request. You can specify the names of standard or custom HTTP header fields. The header name and the match evaluation are not case-sensitive. The following wildcard characters are supported in the comparison strings: * (matches 0 or more characters) and ? (matches exactly 1 character). Wildcard characters are not supported in the header name.

When the Application Load Balancer attribute routing.http.drop_invalid_header_fields is enabled, it will drop header names that don't conform to the regular expressions (A-Z,a-z,0-9). Header names that don't conform to the regular expressions can also be added.

[
  {
      "Field": "http-header",
      "HttpHeaderConfig": {
          "HttpHeaderName": "User-Agent",
          "Values": ["*Chrome*", "*Safari*"]
      }
  }
]

HTTP request method conditions

You can use HTTP request method conditions to configure rules that route requests based on the HTTP request method of the request. You can specify standard or custom HTTP methods. The match evaluation is case-sensitive. Wildcard characters are not supported; therefore, the method name must be an exact match.

We recommend that you route GET and HEAD requests in the same way, because the response to a HEAD request may be cached.

[
  {
      "Field": "http-request-method",
      "HttpRequestMethodConfig": {
          "Values": ["CUSTOM-METHOD"]
      }
  }
]

Host conditions

You can use host conditions to define rules that route requests based on the host name in the host header (also known as host-based routing). This enables you to support multiple subdomains and different top-level domains using a single load balancer.

A hostname is not case-sensitive, can be up to 128 characters in length, and can contain any of the following characters:

You must include at least one "." character. You can include only alphabetical characters after the final "." character.

The rule *.example.com matches test.example.com but doesn't match example.com.

[
  {
      "Field": "host-header",
      "HostHeaderConfig": {
          "Values": ["*.example.com"]
      }
  }
]

Path conditions

You can use path conditions to define rules that route requests based on the URL in the request (also known as path-based routing).

The path pattern is applied only to the path of the URL, not to its query parameters. It is applied only to visible ASCII characters; control characters (0x00 to 0x1f and 0x7f) are excluded.

The rule evaluation is performed only after URI normalization occurs.

A path pattern is case-sensitive, can be up to 128 characters in length, and can contain any of the following characters.

If the protocol version is gRPC, conditions can be specific to a package, service, or method.

The path pattern is used to route requests but does not alter them. For example, if a rule has a path pattern of /img/*, the rule forwards a request for /img/picture.jpg to the specified target group as a request for /img/picture.jpg.

[
  {
      "Field": "path-pattern",
      "PathPatternConfig": {
          "Values": ["/img/*"]
      }
  }
]

Query string conditions

You can use query string conditions to configure rules that route requests based on key/value pairs or values in the query string. The match evaluation is not case-sensitive. The following wildcard characters are supported: * (matches 0 or more characters) and ? (matches exactly 1 character).

[
  {
      "Field": "query-string",
      "QueryStringConfig": {
          "Values": [
            {
                "Key": "version", 
                "Value": "v1"
            },
            {
                "Value": "*example*"
            }
          ]
      }
  }
]

Source IP address conditions

You can use source IP address conditions to configure rules that route requests based on the source IP address of the request. The IP address must be specified in CIDR format. You can use both IPv4 and IPv6 addresses. Wildcard characters are not supported. You cannot specify the 255.255.255.255/32 CIDR for the source IP rule condition.

If a client is behind a proxy, this is the IP address of the proxy, not the IP address of the client.

This condition is not satisfied by the addresses in the X-Forwarded-For header. To search for addresses in the X-Forwarded-For header, use an http-header condition.

[
  {
      "Field": "source-ip",
      "SourceIpConfig": {
          "Values": ["192.0.2.0/24", "198.51.100.10/32"]
      }
  }
]