Work with EC2 Fleets

To start using an EC2 Fleet, you create a request that includes the total target capacity, On-Demand capacity, Spot capacity, one or more launch specifications for the instances, and the maximum price that you are willing to pay. The fleet request must include a launch template that defines the information that the fleet needs to launch an instance, such as an AMI, instance type, subnet or Availability Zone, and one or more security groups. You can specify launch specification overrides for the instance type, subnet, Availability Zone, and maximum price you're willing to pay, and you can assign weighted capacity to each launch specification override.

The EC2 Fleet launches On-Demand Instances when there is available capacity, and launches Spot Instances when your maximum price exceeds the Spot price and capacity is available.

If your fleet includes Spot Instances, Amazon EC2 can attempt to maintain your fleet target capacity as Spot prices change.

An EC2 Fleet request of type maintain or request remains active until it expires or you delete it. When you delete a fleet of type maintain or request, you can specify whether deletion terminates the instances in that fleet. Otherwise, the On-Demand Instances run until you terminate them, and the Spot Instances run until they are interrupted or you terminate them.

EC2 Fleet request states

An EC2 Fleet request can be in one of the following states:

The following illustration represents the transitions between the EC2 Fleet request states. If you exceed your fleet limits, the request is deleted immediately.

EC2 Fleet prerequisites

Launch template

A launch template includes information about the instances to launch, such as the instance type, Availability Zone, and the maximum price that you are willing to pay. For more information, see Launch an instance from a launch template.

Service-linked role for EC2 Fleet

The AWSServiceRoleForEC2Fleet role grants the EC2 Fleet permission to request, launch, terminate, and tag instances on your behalf. Amazon EC2 uses this service-linked role to complete the following actions:

Ensure that this role exists before you use the Amazon CLI or an API to create an EC2 Fleet.

To create the role, use the IAM console as follows.

If you no longer need to use EC2 Fleet, we recommend that you delete the AWSServiceRoleForEC2Fleet role. After this role is deleted from your account, you can create the role again if you create another fleet.

For more information, see Using service-linked roles in the IAM User Guide.

Grant access to customer managed keys for use with encrypted AMIs and EBS snapshots

If you specify an encrypted AMI or an encrypted Amazon EBS snapshot in your EC2 Fleet and you use an Amazon KMS key for encryption, you must grant the AWSServiceRoleForEC2Fleet role permission to use the customer managed key so that Amazon EC2 can launch instances on your behalf. To do this, you must add a grant to the customer managed key, as shown in the following procedure.

When providing permissions, grants are an alternative to key policies. For more information, see Using grants and Using key policies in Amazon KMS in the Amazon Key Management Service Developer Guide.

Permissions for EC2 Fleet users

If your users will create or manage an EC2 Fleet, be sure to grant them the required permissions.

EC2 Fleet health checks

EC2 Fleet checks the health status of the instances in the fleet every two minutes. The health status of an instance is either healthy or unhealthy.

EC2 Fleet determines the health status of an instance by using the status checks provided by Amazon EC2. An instance is determined as unhealthy when the status of either the instance status check or the system status check is impaired for three consecutive health status checks. For more information, see Status checks for your instances.

You can configure your fleet to replace unhealthy Spot Instances. After setting ReplaceUnhealthyInstances to true, a Spot Instance is replaced when it is reported as unhealthy. The fleet can go below its target capacity for up to a few minutes while an unhealthy Spot Instance is being replaced.

Generate an EC2 Fleet JSON configuration file

To view the full list of EC2 Fleet configuration parameters, you can generate a JSON file. For a description of each parameter, see create-fleet in the Amazon CLI Command Reference.

Create an EC2 Fleet

To create an EC2 Fleet, you need only specify the following parameters:

You can specify multiple launch specifications that override the launch template. The launch specifications can vary by instance type, Availability Zone, subnet, and maximum price, and can include a different weighted capacity.

If you do not specify a parameter, the fleet uses the default value for the parameter.

Specify the fleet parameters in a JSON file. For more information, see Generate an EC2 Fleet JSON configuration file.

EC2 Fleets can only be created using the Amazon CLI.

aws ec2 create-fleet --cli-input-json file://file_name.json

For example configuration files, see EC2 Fleet example configurations.

The following is example output for a fleet of type request or maintain.

{
    "FleetId": "fleet-12a34b55-67cd-8ef9-ba9b-9208dEXAMPLE"
} 

The following is example output for a fleet of type instant that launched the target capacity.

{
  "FleetId": "fleet-12a34b55-67cd-8ef9-ba9b-9208dEXAMPLE",
  "Errors": [],
  "Instances": [
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c5.large",
          "AvailabilityZone": "us-east-1a"
        }
      },
      "Lifecycle": "on-demand",
      "InstanceIds": [
        "i-1234567890abcdef0",
        "i-9876543210abcdef9" 
      ],
      "InstanceType": "c5.large",
      "Platform": null
    },
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c4.large",
          "AvailabilityZone": "us-east-1a"
        }
      },
      "Lifecycle": "on-demand",
      "InstanceIds": [
        "i-5678901234abcdef0",
        "i-5432109876abcdef9" 
      ]
  ]
}

The following is example output for a fleet of type instant that launched part of the target capacity with errors for instances that were not launched.

{
  "FleetId": "fleet-12a34b55-67cd-8ef9-ba9b-9208dEXAMPLE",
  "Errors": [
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c4.xlarge",
          "AvailabilityZone": "us-east-1a",
        }
      },
      "Lifecycle": "on-demand",
      "ErrorCode": "InsufficientInstanceCapacity",
      "ErrorMessage": ""
    },
  ],
  "Instances": [
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c5.large",
          "AvailabilityZone": "us-east-1a"
        }
      },
      "Lifecycle": "on-demand",
      "InstanceIds": [
        "i-1234567890abcdef0",
        "i-9876543210abcdef9" 
      ]
  ]
}

The following is example output for a fleet of type instant that launched no instances.

{
  "FleetId": "fleet-12a34b55-67cd-8ef9-ba9b-9208dEXAMPLE",
  "Errors": [
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c4.xlarge",
          "AvailabilityZone": "us-east-1a",
        }
      },
      "Lifecycle": "on-demand",
      "ErrorCode": "InsufficientCapacity",
      "ErrorMessage": ""
    },
    {
      "LaunchTemplateAndOverrides": {
        "LaunchTemplateSpecification": {
          "LaunchTemplateId": "lt-01234a567b8910abcEXAMPLE",
          "Version": "1"
        },
        "Overrides": {
          "InstanceType": "c5.large",
          "AvailabilityZone": "us-east-1a",
        }
      },
      "Lifecycle": "on-demand",
      "ErrorCode": "InsufficientCapacity",
      "ErrorMessage": ""
    },
  ],
  "Instances": []
}

Tag an EC2 Fleet

To help categorize and manage your EC2 Fleet requests, you can tag them with custom metadata. You can assign a tag to an EC2 Fleet request when you create it, or afterward.

When you tag a fleet request, the instances and volumes that are launched by the fleet are not automatically tagged. You need to explicitly tag the instances and volumes launched by the fleet. You can choose to assign tags to only the fleet request, or to only the instances launched by the fleet, or to only the volumes attached to the instances launched by the fleet, or to all three.

For more information about how tags work, see Tag your Amazon EC2 resources.

Prerequisite

Grant the user the permission to tag resources. For more information, see Example: Tag resources.

To grant a user the permission to tag resources

Create a IAM policy that includes the following:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "TagEC2FleetRequest",
            "Effect": "Allow",
            "Action": [
                "ec2:CreateTags",
                "ec2:CreateFleet"
            ],
            "Resource": "*"
}

{
    "Effect": "Allow",
    "Action": [
        "ec2:CreateTags",
        "ec2:CreateFleet"
    ],
    "Resource": "arn:aws:ec2:us-east-1:111122223333:create-fleet/*"
}

To provide access, add permissions to your users, groups, or roles:

To tag a new EC2 Fleet request

To tag an EC2 Fleet request when you create it, specify the key-value pair in the JSON file used to create the fleet. The value for ResourceType must be fleet. If you specify another value, the fleet request fails.

To tag instances and volumes launched by an EC2 Fleet

To tag instances and volumes when they are launched by the fleet, specify the tags in the launch template that is referenced in the EC2 Fleet request.

To tag an existing EC2 Fleet request, instance, and volume (Amazon CLI)

Use the create-tags command to tag existing resources.

aws ec2 create-tags \
    --resources fleet-12a34b55-67cd-8ef9-ba9b-9208dEXAMPLE i-1234567890abcdef0 vol-1234567890EXAMPLE \
    --tags Key=purpose,Value=test

Describe your EC2 Fleet

You can describe your EC2 Fleet configuration, the instances in your EC2 Fleet, and the event history of your EC2 Fleet.

To describe your EC2 Fleets (Amazon CLI)

Use the describe-fleets command to describe your EC2 Fleets.

aws ec2 describe-fleets

aws ec2 describe-fleets --fleet-ids fleet-8a22eee4-f489-ab02-06b8-832a7EXAMPLE

Example output

{
    "Fleets": [
        {
            "ActivityStatus": "fulfilled",
            "CreateTime": "2022-02-09T03:35:52+00:00",
            "FleetId": "fleet-364457cd-3a7a-4ed9-83d0-7b63e51bb1b7",
            "FleetState": "active",
            "ExcessCapacityTerminationPolicy": "termination",
            "FulfilledCapacity": 2.0,
            "FulfilledOnDemandCapacity": 0.0,
            "LaunchTemplateConfigs": [
                {
                    "LaunchTemplateSpecification": {
                        "LaunchTemplateName": "my-launch-template",
                        "Version": "$Latest"
                    }
                }
            ],
            "TargetCapacitySpecification": {
                "TotalTargetCapacity": 2,
                "OnDemandTargetCapacity": 0,
                "SpotTargetCapacity": 2,
                "DefaultTargetCapacityType": "spot"
            },
            "TerminateInstancesWithExpiration": false,
            "Type": "maintain",
            "ReplaceUnhealthyInstances": false,
            "SpotOptions": {
                "AllocationStrategy": "capacity-optimized",
                "InstanceInterruptionBehavior": "terminate"
            },
            "OnDemandOptions": {
                "AllocationStrategy": "lowestPrice"
            }
        }
    ]
}

Use the describe-fleet-instances command to describe the instances for the specified EC2 Fleet. The returned list of running instances is refreshed periodically and might be out of date.

aws ec2 describe-fleet-instances  --fleet-id fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE

Example output

{
    "ActiveInstances": [
        {
            "InstanceId": "i-09cd595998cb3765e", 
            "InstanceHealth": "healthy", 
            "InstanceType": "m4.large", 
            "SpotInstanceRequestId": "sir-86k84j6p"
        }, 
        {
            "InstanceId": "i-09cf95167ca219f17", 
            "InstanceHealth": "healthy", 
            "InstanceType": "m4.large", 
            "SpotInstanceRequestId": "sir-dvxi7fsm"
        }
    ], 
    "FleetId": "fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE"
}

Use the describe-fleet-history command to describe the history for the specified EC2 Fleet for the specified time.

aws ec2 describe-fleet-history --fleet-id fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE --start-time 2018-04-10T00:00:00Z

Example output

{
    "HistoryRecords": [
        {
            "EventInformation": {
                "EventSubType": "submitted"
            },
            "EventType": "fleetRequestChange",
            "Timestamp": "2020-09-01T18:26:05.000Z"
        },
        {
            "EventInformation": {
                "EventSubType": "active"
            },
            "EventType": "fleetRequestChange",
            "Timestamp": "2020-09-01T18:26:15.000Z"
        },
        {
            "EventInformation": {
                "EventDescription": "t2.small, ami-07c8bc5c1ce9598c3, ...",
                "EventSubType": "progress"
            },
            "EventType": "fleetRequestChange",
            "Timestamp": "2020-09-01T18:26:17.000Z"
        },
        {
            "EventInformation": {
                "EventDescription": "{\"instanceType\":\"t2.small\", ...}",
                "EventSubType": "launched",
                "InstanceId": "i-083a1c446e66085d2"
            },
            "EventType": "instanceChange",
            "Timestamp": "2020-09-01T18:26:17.000Z"
        },
        {
            "EventInformation": {
                "EventDescription": "{\"instanceType\":\"t2.small\", ...}",
                "EventSubType": "launched",
                "InstanceId": "i-090db02406cc3c2d6"
            },
            "EventType": "instanceChange",
            "Timestamp": "2020-09-01T18:26:17.000Z"
        }
    ], 
    "FleetId": "fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE", 
    "LastEvaluatedTime": "1970-01-01T00:00:00.000Z", 
    "StartTime": "2018-04-09T23:53:20.000Z"
}

Modify an EC2 Fleet

You can modify an EC2 Fleet that is in the submitted or active state. When you modify a fleet, it enters the modifying state.

You can only modify an EC2 Fleet that is of type maintain. You cannot modify an EC2 Fleet of type request or instant.

You can modify the following parameters of an EC2 Fleet:

When you increase the target capacity, the EC2 Fleet launches the additional instances according to the instance purchasing option specified for DefaultTargetCapacityType, which are either On-Demand Instances or Spot Instances.

If the DefaultTargetCapacityType is spot, the EC2 Fleet launches the additional Spot Instances according to its allocation strategy. If the allocation strategy is lowest-price, the fleet launches the instances from the lowest priced Spot capacity pool in the request. If the allocation strategy is diversified, the fleet distributes the instances across the pools in the request.

When you decrease the target capacity, the EC2 Fleet deletes any open requests that exceed the new target capacity. You can request that the fleet terminate instances until the size of the fleet reaches the new target capacity. If the allocation strategy is lowest-price, the fleet terminates the instances with the highest price per unit. If the allocation strategy is diversified, the fleet terminates instances across the pools. Alternatively, you can request that EC2 Fleet keep the fleet at its current size, but not replace any Spot Instances that are interrupted or any instances that you terminate manually.

When an EC2 Fleet terminates a Spot Instance because the target capacity was decreased, the instance receives a Spot Instance interruption notice.

To modify an EC2 Fleet (Amazon CLI)

Use the modify-fleet command to update the target capacity of the specified EC2 Fleet.

aws ec2 modify-fleet \
    --fleet-id fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
    --target-capacity-specification TotalTargetCapacity=20

If you are decreasing the target capacity but want to keep the fleet at its current size, you can modify the previous command as follows.

aws ec2 modify-fleet \
    --fleet-id fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
    --target-capacity-specification TotalTargetCapacity=10 \
    --excess-capacity-termination-policy no-termination

Delete an EC2 Fleet

If you no longer require an EC2 Fleet, you can delete it. After you delete a fleet, all Spot requests associated with the fleet are canceled, so that no new Spot Instances are launched.

When you delete an EC2 Fleet, you must also specify if you want to terminate all of its instances. These include both On-Demand Instances and Spot Instances.

If you specify that the instances must be terminated when the fleet is deleted, the fleet enters the deleted_terminating state. Otherwise, it enters the deleted_running state, and the instances continue to run until they are interrupted or you terminate them manually.

To delete an EC2 Fleet and terminate its instances (Amazon CLI)

Use the delete-fleets command and the --terminate-instances parameter to delete the specified EC2 Fleet and terminate its associated instances.

aws ec2 delete-fleets \
    --fleet-ids fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
    --terminate-instances

Example output

{
    "UnsuccessfulFleetDeletions": [], 
    "SuccessfulFleetDeletions": [
        {
            "CurrentFleetState": "deleted_terminating", 
            "PreviousFleetState": "active", 
            "FleetId": "fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE"
        }
    ]
}

To delete an EC2 Fleet without terminating its instances (Amazon CLI)

You can modify the previous command using the --no-terminate-instances parameter to delete the specified EC2 Fleet without terminating its associated instances.

aws ec2 delete-fleets \
    --fleet-ids fleet-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
    --no-terminate-instances

Example output

{
    "UnsuccessfulFleetDeletions": [], 
    "SuccessfulFleetDeletions": [
        {
            "CurrentFleetState": "deleted_running", 
            "PreviousFleetState": "active", 
            "FleetId": "fleet-4b8aaae8-dfb5-436d-a4c6-3dafa4c6b7dcEXAMPLE"
        }
    ]
}

Troubleshoot when a fleet fails to delete

If an EC2 Fleet fails to delete, UnsuccessfulFleetDeletions in the output returns the ID of the EC2 Fleet, an error code, and an error message.

The error codes are:

Troubleshooting ExceededInstantFleetNumForDeletion

If you try to delete more than 25 instant fleets in a single request, the ExceededInstantFleetNumForDeletion error is returned. The following is example output for this error.

{
    "UnsuccessfulFleetDeletions": [
     {
          "FleetId": " fleet-5d130460-0c26-bfd9-2c32-0100a098f625",
          "Error": {
                  "Message": "Can’t delete more than 25 instant fleets in a single request.",
                  "Code": "ExceededInstantFleetNumForDeletion"
           }
     },
     {
           "FleetId": "fleet-9a941b23-0286-5bf4-2430-03a029a07e31",
           "Error": {
                  "Message": "Can’t delete more than 25 instant fleets in a single request.",
                  "Code": "ExceededInstantFleetNumForDeletion"
            }
     }
     .
     .
     .
     ],
     "SuccessfulFleetDeletions": []
}

Troubleshoot NoTerminateInstancesNotSupported

If you specify that the instances in an instant fleet must not be terminated when you delete the fleet, the NoTerminateInstancesNotSupported error is returned. --no-terminate-instances is not supported for instant fleets. The following is example output for this error.

{
      "UnsuccessfulFleetDeletions": [
            {
                  "FleetId": "fleet-5d130460-0c26-bfd9-2c32-0100a098f625",
                  "Error": {
                          "Message": "NoTerminateInstances option is not supported for instant fleet",
                          "Code": "NoTerminateInstancesNotSupported"
                   }
            }
       ],
       "SuccessfulFleetDeletions": []

Troubleshoot UnauthorizedOperation

If you do not have permission to terminate instances, you get the UnauthorizedOperation error when deleting a fleet that must terminate its instances. The following is the error response.

<Response><Errors><Error><Code>UnauthorizedOperation</Code><Message>You are not authorized to perform this 
operation. Encoded authorization failure message: VvuncIxj7Z_CPGNYXWqnuFV-YjByeAU66Q9752NtQ-I3-qnDLWs6JLFd
KnSMMiq5s6cGqjjPtEDpsnGHzzyHasFHOaRYJpaDVravoW25azn6KNkUQQlFwhJyujt2dtNCdduJfrqcFYAjlEiRMkfDHt7N63SKlweKUl
BHturzDK6A560Y2nDSUiMmAB1y9UNtqaZJ9SNe5sNxKMqZaqKtjRbk02RZu5V2vn9VMk6fm2aMVHbY9JhLvGypLcMUjtJ76H9ytg2zRlje
VPiU5v2s-UgZ7h0p2yth6ysUdhlONg6dBYu8_y_HtEI54invCj4CoK0qawqzMNe6rcmCQHvtCxtXsbkgyaEbcwmrm2m01-EMhekLFZeJLr
DtYOpYcEl4_nWFX1wtQDCnNNCmxnJZAoJvb3VMDYpDTsxjQv1PxODZuqWHs23YXWVywzgnLtHeRf2o4lUhGBw17mXsS07k7XAfdPMP_brO
PT9vrHtQiILor5VVTsjSPWg7edj__1rsnXhwPSu8gI48ZLRGrPQqFq0RmKO_QIE8N8s6NWzCK4yoX-9gDcheurOGpkprPIC9YPGMLK9tug
</Message></Error></Errors><RequestID>89b1215c-7814-40ae-a8db-41761f43f2b0</RequestID></Response>

To resolve the error, you must add the ec2:TerminateInstances action to the IAM policy, as shown in the following example.

{
       "Version": "2012-10-17",
       "Statement": [
            {
                "Sid": "DeleteFleetsAndTerminateInstances",
                "Effect": "Allow",
                "Action": [
                       "ec2:DeleteFleets"
                       "ec2:TerminateInstances"
                ],
                "Resource": "*"
            }
       ]
    }