Application Load Balancer (ALB)

Target HTTP 4xx error rate

• The alarm changes state if there are 400 type status codes originating from the target (ECS). Reported as a percentage.

• This indicates a bad request or a possible configuration error. Check the CloudWatch logs to get further detail on the cause of the error.

• The alarm returns to the OK state if the error rate is within the acceptable threshold for 5 minutes.

• Metric: HTTPCode_Target_4xxErrorRate > 1%

Target HTTP 5xx error rate

• The alarm changes state if there are 500 type status codes originating from the target (ECS). Reported as a percentage.

• This indicates a server failure. Check the CloudWatch logs to get further detail on the cause of the error.

• The alarm returns to the OK state if the error rate is within the acceptable threshold for 5 minutes.

• Metric: HTTPCode_Target_5xxErrorRate > 0%

ALB HTTP 4xx error rate

• The alarm changes state if there are 400 type status codes originating from ALB. Reported as a percentage.

• This indicates a bad request or a possible configuration error. Check the CloudWatch logs to get further detail on the cause of the error.

• The alarm returns to the OK state if the error rate is within the acceptable threshold for 5 minutes.

• Metric: HTTPCode_ELB_4xxErrorRate > 1%

ALB HTTP 5xx error rate

• The alarm changes state if there are 500 type status codes originating from the target ALB. Reported as a percentage.

• This indicates a server failure. Check the CloudWatch logs to get further detail on the cause of the error.

• The alarm returns to the OK state if the data is within the acceptable threshold for 5 minutes.

• Metric: HTTPCode_ELB_5xxErrorRate > 0%

Target response time (Latency)

• The alarm changes state if there is a large amount of latency (greater than 100ms) reported within a 1-minute period.

• This could indicate a performance issue or scaling failure from ECS. Check the CloudWatch logs to get further detail on the cause of the error.

• The alarm returns to the OK state if the data is within the acceptable threshold for 5 minutes.

• Metric: TargetResponseTime average > 100 ms

Unhealthy host count

• The alarm changes state if there is a target that is considered unhealthy within a 1-minute period.

• The alarm returns to the OK state if the data is within the acceptable threshold for 5 minutes.

• Check the CloudWatch logs to get further detail on the cause of the error.

• Metric: UnhealthyHotCount > 0