carnival-ecs-parrot

ECS Parrot is a Lambda that subscribes to interesting ECS events and posts the useful/interesting ones to Slack.

Deployment

A site-specific configuration file needs to be created. This contains all settings for the Lambda.

cp serverless.env.yml.example serverless.env.yml
# edit as appropriate.

To deploy or update the Lambda:

serverless deploy

The serverless deploy command will advise what endpoint is created in API gateway, or you can request it at any time with serverless info.

Additionally, we need to associate a cloudwatch event to the Lambda. This is currently not configurable via the Serverless framework itself. To do this:

1. AWS Console -> CloudWatch Dashboard
2. Events -> Rules
3. Click Create rule
4. Select EC2 Container Service (ECS) as the event service. Use AWS API Call via CloudTrail and specific operations SubmitTaskStateChange, StartTask, StopTask, RunTask, DeregisterContainerInstance and RegisterContainerInstance.
5. Click Add target
6. Select the Lambda to validate against.
7. Keep all other details.
8. Click Configure details when done.

TODO: We could probably script the above, but best solution is doing for some form of native integration into Serverless framework. It might be possible to use custom CFN resources to do this.

Developer Notes

Python dependencies are installed to the local vendored/ directory and then get packaged and deployed to Lambda by the Serverless framework. We ship these dependencies as part of this repo, so you don't need to install them yourself unless you are developing and adding new requirements to the application.

 pip install -t vendored/ -r requirements.txt

API Events from ECS

We see the following events when a container is replaced due to the task definition being updated, or if the container has been terminated.

SubmitContainerStateChange
SubmitTaskStateChange
SubmitTaskStateChange
SubmitContainerStateChange

If a Task Definition or Service is adjusted, we also see:

UpdateService
RegisterTaskDefinition

The Stop/Start/Run Task API calls only occur if those specific APIs are invoked by a human or tool.

If an EC2 instance is rebooted, we may see a RegisterContainerInstance but without an associated DeregisterContainerInstance

Testing

You can quickly deploy a single changed function with:

serverless deploy function --function parrot

After deploying the Lambda, it can be involved with test data - for example:

serverless invoke --function parrot --path samples/event.json

Contributions

All contributions are welcome via Pull Requests including documentation fixes.

License

Copyright (c) 2017 Sailthru, Inc., https://www.sailthru.com/

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.