Amazon ECS
User Guide for AWS Fargate (API Version 2014-11-13)

Service Event Messages

If you are troubleshooting a problem with a service, the first place you should check for diagnostic information is the service event log.

To check the service event log in the Amazon ECS console

  1. Open the Amazon ECS console at https://console.aws.amazon.com/ecs/.

  2. On the Clusters page, select the cluster in which your service resides.

  3. On the Cluster : clustername page, select the service to inspect.

  4. On the Service : servicename page, choose Events.

    
                        Service event messages
  5. Examine the Message column for errors or other helpful information.

Service Event Messages

The following are examples of service event messages you may see in the console:

(service service-name) was unable to place a task because the resources could not be found.

In the above image, this service could not find the available resources to add another task. The possible causes for this are:

Not enough ports

If your task uses fixed host port mapping (for example, your task uses port 80 on the host for a web server), you must have at least one container instance per task, because only one container can use a single host port at a time. You should add container instances to your cluster or reduce your number of desired tasks.

Not enough memory

If your task definition specifies 1000 MiB of memory, and the container instances in your cluster each have 1024 MiB of memory, you can only run one copy of this task per container instance. You can experiment with less memory in your task definition so that you could launch more than one task per container instance, or launch more container instances into your cluster.

Not enough CPU

A container instance has 1,024 CPU units for every CPU core. If your task definition specifies 1,000 CPU units, and the container instances in your cluster each have 1,024 CPU units, you can only run one copy of this task per container instance. You can experiment with fewer CPU units in your task definition so that you could launch more than one task per container instance, or launch more container instances into your cluster.

Not enough available ENI attachment points

Tasks that use the awsvpc network mode each receive their own elastic network interface, which is attached to the container instance that hosts it. Amazon EC2 instances have a limit to the number of network interfaces that can be attached to them, and the primary network interface counts as one. For example, a c4.large instance may have three network interfaces attached to it. The primary network adapter for the instance counts as one, so you can attach 2 more ENIs to the instance. Because each awsvpc task requires a network interface, you can only run two such tasks on this instance type. For more information about how many network interfaces are supported per instance type, see IP Addresses Per Network Interface Per Instance Type in the Amazon EC2 User Guide for Linux Instances. You can add container instances to your cluster to provide more available network adapters.

(service service-name) (instance instance-id) is unhealthy in (elb elb-name) due to (reason Instance has failed at least the UnhealthyThreshold number of health checks consecutively.)

This service is registered with a load balancer and the load balancer health checks are failing. For more information, see Troubleshooting Service Load Balancers.

(service service-name) is unable to consistently start tasks successfully.

This service contains tasks that have failed to start after consecutive attempts. At this point, the service scheduler begins to incrementally increase the time between retries. You should troubleshoot why your tasks are failing to launch. For more information, see Service Throttle Logic.

After the service is updated, for example with an updated task definition, the service scheduler resumes normal behavior.

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