AWS Solutions Architect · Lesson

Listener Rules and Path-Based Routing

Write listener rules on the ALB to route requests to different target groups based on host headers, path patterns, or query strings.

ALB Listeners Explained

An ALB listener is a process that checks for connection requests using a protocol and port you specify (e.g., HTTP on port 80 or HTTPS on port 443). Each listener has one or more rules that determine where to forward requests based on their content.

A listener must have a default rule (the catch-all action when no other rule matches) and can have up to 100 additional rules. Rules are evaluated in priority order (lowest number = highest priority). When a request matches a rule's condition, the corresponding action is applied and no further rules are evaluated.

# Create an HTTP listener on port 80
aws elbv2 create-listener \
  --load-balancer-arn arn:aws:elasticloadbalancing:us-east-1:123456789:loadbalancer/app/my-alb/abc123 \
  --protocol HTTP \
  --port 80 \
  --default-actions Type=forward,TargetGroupArn=arn:aws:elasticloadbalancing:us-east-1:123456789:targetgroup/default-tg/def456

Rule Conditions

Listener rules match requests based on conditions. You can combine multiple conditions in one rule (all conditions must match for the rule to apply). Available condition types:

host-header: matches the Host HTTP header (e.g., api.example.com)
path-pattern: matches the URL path (e.g., /api/*, /images/*.jpg)
http-header: matches any HTTP header name and value pattern
http-request-method: matches HTTP methods (GET, POST, DELETE, etc.)
query-string: matches key-value pairs in the query string
source-ip: matches client IP CIDR ranges

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