Amazon EC2 Container Service
Developer Guide (API Version 2014-11-13)

Creating a Task Definition

Before you can run Docker containers on Amazon ECS, you must create a task definition.

To create a new task definition

  1. Open the Amazon ECS console at

  2. From the navigation bar, select the region in which to register your task definition.

  3. In the navigation pane, choose Task Definitions.

  4. On the Task Definitions page, choose Create new Task Definition.

  5. (Optional) If you have a JSON representation of your task definition, complete the following steps:

    1. On the Create a Task Definition page, scroll to the bottom of the page and choose Configure via JSON.

    2. Paste your task definition JSON into the text area and choose Save.

    3. Verify your information and choose Create.

  6. For Task Definition Name, type a name for your task definition. Up to 255 letters (uppercase and lowercase), numbers, hyphens, and underscores are allowed.

  7. (Optional) For Task Role, choose an IAM role that provides permissions for containers in your task to make calls to AWS APIs on your behalf. For more information, see IAM Roles for Tasks.


    Only roles that have the Amazon EC2 Container Service Task Role trust relationship are shown here. For help creating an IAM role for your tasks, see Creating an IAM Role and Policy for your Tasks.

  8. (Optional) For Network Mode, choose the Docker network mode to use for the containers in your task. The available network modes correspond to those described in Network settings in the Docker run reference.

    The default Docker network mode is bridge. If the network mode is set to none, you cannot specify port mappings in your container definitions, and the task's containers do not have external connectivity. The host network mode offers the highest networking performance for containers because they use the host network stack instead of the virtualized network stack provided by the bridge mode; however, exposed container ports are mapped directly to the corresponding host port, so you cannot take advantage of dynamic host port mappings or run multiple instantiations of the same task on a single container instance if port mappings are used.

  9. (Optional) For Constraint, define how tasks that are created from this task definition are placed in your cluster (for example, on container instances with a specific instance type or specific custom attributes). For more information, see Amazon ECS Task Placement Constraints.

  10. For each container in your task definition, complete the following steps.

    1. Choose Add container.

    2. Fill out each required field and any optional fields to use in your container definitions (more container definition parameters are available in the Advanced container configuration menu). For more information, see Task Definition Parameters.

    3. Choose Add to add your container to the task definition.

  11. (Optional) To define data volumes for your task, choose Add volume. For more information, see Using Data Volumes in Tasks.

    1. For Name, type a name for your volume. Up to 255 letters (uppercase and lowercase), numbers, hyphens, and underscores are allowed.

    2. (Optional) For Source Path, type the path on the host container instance to present to the container. If you leave this field empty, the Docker daemon assigns a host path for you. If you specify a source path, the data volume persists at the specified location on the host container instance until you delete it manually. If the source path does not exist on the host container instance, the Docker daemon creates it. If the location does exist, the contents of the source path folder are exported to the container.

  12. Choose Create.

Task Definition Template

An empty task definition template is shown below. You can use this template to create your task definition which can then be pasted into the console JSON input area or saved to a file and used with the AWS CLI --cli-input-json option. For more information about these parameters, see Task Definition Parameters.

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{ "family": "", "taskRoleArn": "", "networkMode": "", "containerDefinitions": [ { "name": "", "image": "", "cpu": 0, "memory": 0, "memoryReservation": 0, "links": [ "" ], "portMappings": [ { "containerPort": 0, "hostPort": 0, "protocol": "" } ], "essential": true, "entryPoint": [ "" ], "command": [ "" ], "environment": [ { "name": "", "value": "" } ], "mountPoints": [ { "sourceVolume": "", "containerPath": "", "readOnly": true } ], "volumesFrom": [ { "sourceContainer": "", "readOnly": true } ], "hostname": "", "user": "", "workingDirectory": "", "disableNetworking": true, "privileged": true, "readonlyRootFilesystem": true, "dnsServers": [ "" ], "dnsSearchDomains": [ "" ], "extraHosts": [ { "hostname": "", "ipAddress": "" } ], "dockerSecurityOptions": [ "" ], "dockerLabels": { "KeyName": "" }, "ulimits": [ { "name": "", "softLimit": 0, "hardLimit": 0 } ], "logConfiguration": { "logDriver": "", "options": { "KeyName": "" } } } ], "placementConstraints": [ { "expression": "", "type": "memberOf" } ], "volumes": [ { "name": "", "host": { "sourcePath": "" } } ] }

Note that you can generate this task definition template using the following AWS CLI command.

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$ aws ecs register-task-definition --generate-cli-skeleton