desiredCountForService.ts

import AWS = require('aws-sdk');
const ecs_sdk = new AWS.ECS();

function chunk(array: Array<any>, size: number) {
  const chunked_arr = [];
  for (let i = 0; i < array.length; i++) {
    const last = chunked_arr[chunked_arr.length - 1];
    if (!last || last.length === size) {
      chunked_arr.push([array[i]]);
    } else {
      last.push(array[i]);
    }
  }
  return chunked_arr;
}

export interface ServiceDesiredCount {
  [details: string] : number | undefined;
}

let serviceDesiredCounts: ServiceDesiredCount;
serviceDesiredCounts = {};

async function fetchDesiredCounts() {
  var nextToken = null;

  let clusterArns: Array<string>;
  clusterArns = [];

  // Enumerate all clusters
  do {
    let resp = await ecs_sdk.listClusters().promise();

    if (resp.clusterArns) {
      clusterArns = clusterArns.concat(resp.clusterArns);
    }
    nextToken = resp.nextToken;
  } while(nextToken)

  // Enumerate all services
  for (let cluster of clusterArns) {
    do {
      let resp = await ecs_sdk.listServices({ cluster }).promise();

      if (resp.serviceArns) {
        // Fetch desired count of all services in all clusters
        let chunked: Array<Array<string>>
        chunked = chunk(resp.serviceArns, 10);

        for (let chunk of chunked) {
          let resp = await ecs_sdk.describeServices({ cluster: cluster, services: chunk }).promise();

          if (resp.services) {
            for (let serviceDetail of resp.services) {
              serviceDesiredCounts[cluster + '|' + serviceDetail.serviceName] = serviceDetail.desiredCount;
            }
          }
        }
      }
      nextToken = resp.nextToken;
    } while(nextToken)
  }

  console.log(serviceDesiredCounts);
}

function desiredCountForService(cluster: string, serviceName: string) {
  return serviceDesiredCounts[cluster + '|' + serviceName];
}