Suggests optimal EC2 instance mix for single-core apps, like CS:GO servers

optimal-ec2-single-core.js

const hosts = [
  {
    name: "z1d.12xlarge",
    capacity: 48,
    cost: 5.273,
  },
  {
    name: "z1d.6xlarge",
    capacity: 24,
    cost: 2.636,
  },
  {
    name: "z1d.3xlarge",
    capacity: 12,
    cost: 1.318,
  },
  {
    name: "z1d.2xlarge",
    capacity: 8,
    cost: 0.879,
  },
  {
    name: "z1d.xlarge",
    capacity: 4,
    cost: 0.439,
  },
  {
    name: "z1d.large",
    capacity: 2,
    cost: 0.22,
  },
].sort((a, b) => a.capacity - b.capacity);

function suggestHostSizes(instanceCount) {
  const calculateUtilisation = (definition, instanceCount) => {
    return instanceCount / definition.capacity;
  };

  const findBestUtilisation = (instanceCount) => {
    return hosts.reduce(
      (currentBest, definition) => {
        const utilisation = calculateUtilisation(definition, instanceCount);

        console.log(`current best: ${currentBest.utilisation}`);
        console.log(`${definition.name}, utilisation would be ${utilisation}`);

        if (Math.abs(utilisation - 1) < Math.abs(currentBest.utilisation - 1)) {
          return { definition, utilisation };
        }

        return currentBest;
      },
      { utilisation: -Infinity, definition: undefined }
    );
  };

  const suggestions = [];
  let remainingToAllocate = instanceCount;

  while (remainingToAllocate > 0) {
    console.log("------");
    console.log(`---  got ${remainingToAllocate} to allocate  ---`);
    console.log("------");
    const suggestion = findBestUtilisation(remainingToAllocate);

    if (!suggestion) {
      console.log(`unable to find suitable host`);
      process.exit(-1);
    }

    remainingToAllocate -= suggestion.definition.capacity;
    suggestions.push(suggestion);
  }

  return suggestions;
}

const [_, __, instances = 1] = process.argv;
console.log(`provisioning ${instances} instances`);

const suggestions = suggestHostSizes(instances);
console.log(" ");
console.log(
  `suggested hosts: ${suggestions
    .map(({ definition: d }) => `${d.name} (${d.capacity})`)
    .join(", ")}`
);