How to do it...

1. Create the project from the following template:

$ sls create --template-url https://github.com/danteinc/js-cloud-native-cookbook/tree/master/ch2/materialized-view-es --path cncb-materialized-view-es

2. Navigate to the cncb-materialized-view-es directory with cd cncb-materialized-view-es.
3. Review the file named serverless.yml with the following content:

service: cncb-materialized-view-es

provider:
  name: aws
  runtime: nodejs8.10
  iamRoleStatements:
    ...
  environment:
    DOMAIN_ENDPOINT:
      Fn::GetAtt: [ Domain, DomainEndpoint ]

...

functions:
  listener:
    handler: handler.listener
    events:
      - stream:
          type: kinesis
          arn: ${cf:cncb-event-stream-${opt:stage}.streamArn}
          ...
  search:
    handler: handler.search

resources:
  Resources:
    Domain:
      Type: AWS::Elasticsearch::Domain
      Properties:
        ...

  Outputs:
    DomainName:
      Value:
        Ref: Domain
    DomainEndpoint:
      Value:
        Fn::GetAtt: [ Domain, DomainEndpoint ]

4. Review the file named handler.js with the following content:

const client = require('elasticsearch').Client({
  hosts: [`https://${process.env.DOMAIN_ENDPOINT}`],
  connectionClass: require('http-aws-es'),
  log: 'trace',
});

module.exports.listener = (event, context, cb) => {
  _(event.Records)
    .map(recordToEvent)
    .filter(forThingCreated)
    .map(toThing)
    .flatMap(index)
    .collect()
    .toCallback(cb);
};

...
const forThingCreated = e => e.type === 'thing-created';

const toThing = event => ({
  id: event.thing.new.id,
  name: event.thing.new.name,
  description: event.thing.new.description,
  asOf: event.timestamp,
});

const index = thing => {
  const params = {
    index: 'things',
    type: 'thing',
    id: thing.id,
    body: thing,
  };

  return _(client.index(params));
};

module.exports.search = (query, context, callback) => {
  const params = {
    index: 'things',
    q: query,
  };

  client.search(params, callback);
};

5. Install the dependencies with npm install.
6. Run the tests with npm test -- -s $MY_STAGE.
   
7. Review the contents generated in the .serverless directory.
8. Deploy the stack:

$ npm run dp:lcl -- -s $MY_STAGE

> cncb-materialized-view-es@1.0.0 dp:lcl <path-to-your-workspace>/cncb-materialized-view-es
> sls deploy -v -r us-east-1 "-s" "john"

Serverless: Packaging service...
...
Serverless: Stack update finished...
...
functions:
  listener: cncb-materialized-view-es-john-listener
  search: cncb-materialized-view-es-john-search

Stack Outputs
...
DomainEndpoint: search-cncb-ma-domain-gw419rzj26hz-p2g37av7sdlltosbqhag3qhwnq.us-east-1.es.amazonaws.com
DomainName: cncb-ma-domain-gw419rzj26hz
...

9. Review the stack, function, and Elasticsearch domain in the AWS Console.
10. Publish an event from a separate Terminal with the following commands:

$ cd <path-to-your-workspace>/cncb-event-stream
$ $ sls invoke -r us-east-1 -f publish -s $MY_STAGE -d '{"type":"thing-created","thing":{"new":{"name":"thing four","id":"44444444-4444-4444-4444-444444444444"}}}'

{
    "ShardId": "shardId-000000000000",
    "SequenceNumber": "49583655996852917476267785004768832452002332571160543234"
}

11. Take a look at the listener function logs:

$ sls logs -f listener -r us-east-1 -s $MY_STAGE

START ...
2018-04-19 01:54:33 ... {"type":"thing-created","thing":{"new":{"name":"thing four","id":"44444444-4444-4444-4444-444444444444"}},"id":"0e1a68c0-4395-11e8-b455-8144cebc5972","partitionKey":"8082a69c-00ee-4388-9697-c590c523c061","timestamp":1524116810060,"tags":{"region":"us-east-1"}}
2018-04-19 01:54:33 ... params: {"index":"things","type":"thing","id":"44444444-4444-4444-4444-444444444444","body":{"id":"44444444-4444-4444-4444-444444444444","name":"thing four","asOf":1524116810060}}
2018-04-19 01:54:33 ... {"_index":"things","_type":"thing","_id":"44444444-4444-4444-4444-444444444444","_version":1,"result":"created","_shards":{"total":2,"successful":1,"failed":0},"_seq_no":0,"_primary_term":1}
END ...
REPORT ... Duration: 31.00 ms    Billed Duration: 100 ms ... Max Memory Used: 42 MB    

12. Invoke the search command:

$ sls invoke -r us-east-1 -f search -s $MY_STAGE -d four

{
    ...
    "hits": {
        "total": 1,
        "max_score": 0.2876821,
        "hits": [
            {
                "_index": "things",
                "_type": "thing",
                "_id": "44444444-4444-4444-4444-444444444444",
                "_score": 0.2876821,
                "_source": {
                    "id": "44444444-4444-4444-4444-444444444444",
                    "name": "thing four",
                    "asOf": 1524116810060
                }
            }
        ]
    }
}

13. Remove the stack once you have finished with npm run rm:lcl -- -s $MY_STAGE.