Task Definition Overrides
Task Definition overrides is an advanced use case. Overriding a field might cause the task not able to launch. Please use with caution!
Copilot generates CloudFormation templates using configuration specified in the manifest. However, there are fields that are not configurable in the manifest. For example, You might want to configure the
Ulimits for your workload container, but it is not exposed in our manifest.
You can configure additional ECS Task Definition settings by specifying
taskdef_overrides rules, which will be applied to the CloudFormation template that Copilot generates out of the manifest.
How to specify override rules?
For each override rule, you need to specify a path of the CloudFormation resource field you want to override, and a value of that field.
The following is an example valid
taskdef_overrides field that can be applied to a manifest file:
taskdef_overrides: - path: ContainerDefinitions.Cpu value: 512 - path: ContainerDefinitions.Memory value: 1024
Each rule is applied sequentially to the CloudFormation template. The resulting CloudFormation template becomes the target of the next rule. Evaluation continues until all rules are successfully applied or an error is encountered.
pathfield is a
'.'character separated path to a target Task Definition field under
Copilot recursively inserts fields if they don't exist in the CloudFormation template. For example: if a rule has the path
Cdon't exist), Copilot will insert the field
C. A concrete example can be found below.
If the target path specifies a member that already exists, that member's value is replaced.
To append a new member to a
listfield such as
Ulimitsyou can use the special character
The following fields in the task definition are not allowed to be modified.
In order to ensure that your override rules behave as expected, we recommend running
copilot svc package or
copilot job package to preview the generated CloudFormation template.
Ulimits to the main container
taskdef_overrides: - path: ContainerDefinitions.Ulimits[-] value: Name: "cpu" SoftLimit: 1024 HardLimit: 2048
Expose an extra UDP port
taskdef_overrides: - path: "ContainerDefinitions.PortMappings[-].ContainerPort" value: 2056 // PortMappings gets the port mapping added by the previous rule, since by default Copilot creates a port mapping. - path: "ContainerDefinitions.PortMappings.Protocol" value: "udp"
Give read-only access to the root file system
taskdef_overrides: - path: "ContainerDefinitions.ReadonlyRootFilesystem" value: true