CloudFormation Custom Task Definition POC

custom-task-definition.yml

# Sources:
# https://cloudonaut.io/how-to-create-a-customized-cloudwatch-dashboard-with-cloudformation/
# https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-custom-resources.html
# https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/ECS.html

Resources:
  CustomTaskDefinition:
    Type: 'Custom::TaskDefinition'
    Version: '1.0'
    Properties: 
      ServiceToken: !GetAtt 'CustomResourceFunction.Arn'
      TaskDefinition: |
        {
          containerDefinitions: [
            {
              name: "sleep",
              image: "busybox",
              command: [
                "sleep", 
                "360"
              ],
              mountPoints: [
                {sourceVolume: "efs", containerPath: "/efs"}
              ]
            }
          ], 
          family: "sleep360",
          taskRoleArn: "", // required for EFS permissions
          cpu: "256",
          memory: "512",
          networkMode: "awsvpc",
          volumes: [
            {
              name: "efs",
              efsVolumeConfiguration: {
                fileSystemId: "" // required for EFS
              }
            }
          ]
        }
  CustomResourceFunction:
    Type: 'AWS::Lambda::Function'
    Properties:
      Code:
        ZipFile: |
          const aws = require('aws-sdk')
          const response = require('cfn-response')
          const ecs = new aws.ECS({apiVersion: '2014-11-13'})
          exports.handler = function(event, context) {
            console.log(`AWS SDK Version: ${aws.VERSION}`)
            console.log("REQUEST RECEIVED:\n" + JSON.stringify(event))
            if (event.RequestType === 'Create' || event.RequestType === 'Update') {
              ecs.registerTaskDefinition(eval(`(${event.ResourceProperties.TaskDefinition})`))
                .promise()
                .then(data => {
                  console.log(`Created/Updated task definition ${data.taskDefinition.taskDefinitionArn}`)
                  response.send(event, context, response.SUCCESS, {}, data.taskDefinition.taskDefinitionArn)
                })
                .catch(err => {
                  console.error(err);
                  response.send(event, context, response.FAILED)
                })
            } else if (event.RequestType === 'Delete') {
              ecs.deregisterTaskDefinition({taskDefinition: event.PhysicalResourceId})
                .promise()
                .then(data => {
                  console.log(`Removed task definition ${event.PhysicalResourceId}`)
                  response.send(event, context, response.SUCCESS)
                })
                .catch(err => {
                  if (err.code === 'InvalidParameterException') {
                    console.log(`Task definition: ${event.PhysicalResourceId} does not exist. Skipping deletion.`)
                    response.send(event, context, response.SUCCESS)
                  } else {
                    console.error(err)
                    response.send(event, context, response.FAILED)
                  }
                })
            } else {
              console.error(`Unsupported request type: ${event.RequestType}`)
              response.send(event, context, response.FAILED)
            }
          }
      Handler: 'index.handler'
      MemorySize: 128
      Role: !GetAtt 'CustomResourceRole.Arn'
      Runtime: 'nodejs12.x'
      Timeout: 30
  CustomResourceRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
        - Effect: Allow
          Principal:
            Service: 'lambda.amazonaws.com'
          Action: 'sts:AssumeRole'
      Policies:
      - PolicyName: 'customresource'
        PolicyDocument:
          Statement:
          - Effect: Allow
            Action:
            - 'ecs:DeregisterTaskDefinition'
            - 'ecs:RegisterTaskDefinition'
            Resource: '*'
          - Effect: Allow
            Action:
            - 'logs:CreateLogGroup'
            - 'logs:CreateLogStream'
            - 'logs:PutLogEvents'
            Resource: '*'
          - Effect: Allow
            Action:
            - 'iam:PassRole'
            Resource: '*' # replace with value of taskRoleArn

For those having issues with permissions, doing a chmod from the Dockerfile will not help since those commands are run when building the image, not when running in ECS

the best thing you can do is mount the EFS in a temporary EC2 instance, create the folder and chmod it accordingly from there and your task should run fine afterwards.

@guillaumesmo Can't believe I missed that. You're right of course.

Another option is to run the chmod and chown in the entrypoint of the image, but that would add startup time (and be superfluous after the first time).

I forgot to reply and thank you guys!

@mapoulos I had almost the same setup but anyway go to do a double check that everything was ok on the cf side.

@guillaumesmo Thank you for your solution - worked like a charm.

So.. those of you having permission problems, keep in mind that doing chmod while creating your container won't work, since the mount folder is available only while running container. That's why you should use temporary Bastion host and mount EFS there when doing your first deployment.

Executing sudo chmod -R 777 /mnt/efs from Bastion worked where /mnt/efs is the folder where EFS was mounted in the first place.

I'm trying to follow this... I'm getting this error when using EFS volume for my container:

Error response from daemon: create ecs-LinkedDataHubStackLDHTaskDefinitionF106B511-162-FusekiAdminDataVolume-e69dae89abd09e9de901:
VolumeDriver.Create: mounting volume failed: b'mount.nfs4: mounting fs-468514f2.efs.us-east-1.amazonaws.com:/var/fuseki/data/admin failed, reason given by server:
No such file or directory'

What could be the issue here?

I'm trying to follow this... I'm getting this error when using EFS volume for my container:

Error response from daemon: create ecs-LinkedDataHubStackLDHTaskDefinitionF106B511-162-FusekiAdminDataVolume-e69dae89abd09e9de901:
VolumeDriver.Create: mounting volume failed: b'mount.nfs4: mounting fs-468514f2.efs.us-east-1.amazonaws.com:/var/fuseki/data/admin failed, reason given by server:
No such file or directory'

What could be the issue here?

Make sure your /var/fuseki/data/admin exists. Also, I don’t think this is needed anymore as the support was added natively awhile back iirc.

@jedis00 exists where -- in EFS or in the container? If EFS, how do I create it there?
P.S. Yes I'm using native support.

You are telling it what directory to mount the EFS to inside of the container. Your container pipeline should be running a ‘mkdir -p /var/fuseki/data/admin‘ to create it if it doesn’t already exist.

OK. This is not required with host mounts though -- so the EFS volumes are different in this respect?

OK. This is not required with host mounts though -- so the EFS volumes are different in this respect?

Yes it is required for mounting an EFS volume to a host. You’re telling it what directory to mount the EFS to on the host. Since the idea of this is to not mount to the host, you’re mounting it directly inside of the container.

Doesn't the fs-468514f2.efs.us-east-1.amazonaws.com:/var/fuseki/data/admin syntax refer to EFS host:path? Meaning the missing directory is within EFS?