Health state. The health state provides real-time insight into the overall health and performance of your monitored entities. The health state is determined based on anomalies detected for the entity, alerts triggered for the entity's metrics, and the status of the entity. The health state is displayed as one of the following four states and colors: Good, Moderate, Bad, or Unknown. You can determine the impact of the alerts, anomalies, and statuses on the health of an entity type by going to Settings > Health, and selecting a specific entity type. You can also customize the impact.

To view the health of AWS Application ELB entities in the Metrics Explorer, filter the sw.metrics.healthscore metric by entity_types and select awsapplicationelb.

ActiveConnectionCount. The total number of concurrent TCP connections active from clients to the load balancer and from the load balancer to targets.

The number of TLS connections initiated by the client that did not establish a session with the load balancer due to a TLS error.

ConsumedLCUs. The total number of load balancer capacity units (LCU) used by load balancer.

The number of requests that do not comply with RFC 7230 and are classified as non-compliant.

The number of requests that were dropped because they contained invalid headers.

The number of authentication errors encountered by the load balancer.

The number of authentication failures.

Time taken by the load balancer to authenticate requests. It includes the time from when the request is received to when the authentication process is completed.

The number of successful token refresh operations performed by the load balancer.

The number of successful authentication attempts by the load balancer.

The number of authentication requests that were rejected because the size of the user claims exceeded the allowed limit.

The number of requests with invalid headers that were forwarded to the backend servers. The load balancer forwards these requests even though they contain invalid headers.

The number of gRPC requests processed by the load balancer. It includes both IPv4 and IPv6 requests.

HealthyHostCount. The average number of targets that are considered healthy.

The rate at which the registered targets in an Application Load Balancer (ALB) are healthy.

Indicates the health status of the DNS endpoints for the ALB. It shows whether the DNS endpoints are healthy and able to route traffic correctly.

Reflects the health status of the routing components of the ALB. It indicates whether the load balancer is successfully routing traffic to healthy targets.

the number of HTTP responses with a status code of 503 (Service Unavailable) returned by the ALB.

The number of HTTP responses with a status code of 301 (Moved Permanently) or 302 (Found) returned by the ALB.

The number of times the ALB has exceeded the limit for the number of URLs that can be included in HTTP redirect responses.

The number of HTTP responses with a status code in the 300-399 range (Multiple Choices, Redirection) returned by the ALB.

HTTPCode_ELB_4XX_Count. The total number of HTTP 4XX client error codes that originate from the load balancer.

HTTPCode_ELB_5XX_Count. The total number of HTTP 5XX client error codes that originate from the load balancer.

The number of HTTP 500 (Internal Server Error) responses returned by the Application Load Balancer (ALB).

The number of HTTP 502 (Bad Gateway) responses returned by the ALB. It indicates that the ALB received an invalid response from an inbound server while acting as a gateway or proxy.

The number of HTTP 503 (Service Unavailable) responses returned by the ALB. It indicates that the ALB is temporarily unable to handle the request, usually due to a temporary overloading or maintenance of the server.

The number of HTTP 504 (Gateway Timeout) responses returned by the ALB. It indicates that the ALB did not receive a timely response from an upstream server while acting as a gateway or proxy.

The number of HTTP 2xx (Success) responses returned by the targets in response to the ALB. It indicates that the request was successfully processed by the target.

The number of HTTP 3xx (Redirection) responses returned by the targets in response to the ALB. It indicates that further action needs to be taken by the client to complete the request.

HTTPCode_Target_4XX_Count. The total number of HTTP response with 4xx status codes generated by the targets. This does not include any response codes generated by the load balancer.

HTTPCode_Target_5XX_Count. The total number of HTTP response with 5xx status codes generated by the targets. This does not include any response codes generated by the load balancer.

The total number of bytes processed by the load balancer for IPv6 traffic.

The total number of IPv6 requests received by the load balancer.

The number of errors that occurred within the Lambda function when it was invoked by the load balancer.

The total number of bytes processed by the Lambda target.

The number of errors returned by the Lambda function due to user requests.

NewConnectionCount. The total number of new TCP connections established from clients to the load balancer and from the load balancer to targets.

The number of requests that are not handled by sticky sessions. Sticky sessions ensure that a client's requests are always sent to the same target during a session. When sticky sessions are disabled, or if the load balancer cannot determine the session stickiness, the requests are considered non-sticky.

ProcessedBytes. The total number of bytes processed by the load balancer over IPv4 and IPv6 (HTTP header and HTTP payload).

RejectedConnectionCount. The total number of connections that were rejected because the load balancer had reached its maximum number of connections.

RequestCount. The total number of requests processed over IPv4 and IPv6. This metric is only incremented for requests where the load balancer node was able to choose a target.

RequestCountPerTarget. The total number of requests received by each target in a target group.

This metric counts the number of times the rules defined for your Application Load Balancer (ALB) are evaluated. Each rule determines how the load balancer routes requests to the targets in one or more target groups.

TargetConnectionErrorCount. The total number of connections that were not successfully established between the load balancer and target. This metric does not apply if the target is a Lambda function.

TargetResponseTime. The average time elapsed, in seconds, after the request leaves the load balancer until a response from the target is received.

The 50th percentile (median) of the target response times. It means that 50% of the responses have a lower response time, and 50% have a higher response time

The 95th percentile of the target response times. It means that 95% of the responses have a lower response time, and 5% have a higher response time.

The 99th percentile of the target response times. It indicates that 99% of the responses have a lower response time, and 1% have a higher response time.

The number of TLS negotiation errors that occur when the load balancer tries to establish a secure connection with the target.