First version

- Add first version of function to compute file size
- Add documentation
- Add package information
- Add project config

.editorconfig

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+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true

README.md

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-# algolia-mcm-filesize
-Simple script to get per cluster index size while using Algolia MCM feature
+# Algolia MCM File Size
+
+![npm](https://img.shields.io/npm/dm/algolia-mcm-filesize)
+![node-lts](https://img.shields.io/node/v-lts/algolia-mcm-filesize)
+[![JavaScript Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://standardjs.com)
+
+**Important note:** in Algolia's context, **file size** and **index size**
+are interchangeable.
+The index size represents the space used in RAM, whereas data size is the raw
+JSON data stored on disk and used as a backup for e.g. doing a full reindex.
+
+## What is it?
+
+This package is a simple script that helps you compute the index size while using Algolia's [MCM](https://www.algolia.com/doc/guides/scaling/managing-multiple-clusters-mcm/)
+architecture.
+
+## How to use it?
+
+Regular install through npm or yarn:
+
+```bash
+npm i algolia-mcm-filesize
+# or
+yarn add algolia-mcm-filesize
+```
+
+It has been designed to be used in a shell environment so it returns JSON
+instead of a pure JS object. Here is a quick usage suggestion:
+
+### index.js
+```javascript
+const mcmFileSize = require('algolia-mcm-filesize')
+
+mcmFileSize('APPID', 'ADMIN_APIKEY').then(res => console.log(res))
+```
+
+Optionally, you can pass a custom domain (default is `algolia.net`)
+
+```javascript
+const mcmFileSize = require('algolia-mcm-filesize')
+
+mcmFileSize('APPID', 'ADMIN_APIKEY', 'algolianet.com').then(res => console.log(res))
+```
+
+### shell
+
+Using [jq](https://stedolan.github.io/jq/) for the sake of the example
+```bach
+node index.js | jq .
+```
+
+## Technical details
+
+The only dependency is the [JS API client](https://www.algolia.com/doc/api-client/getting-started/what-is-the-api-client/javascript/) (v4)
+
+You need to use the [Admin API key](https://www.algolia.com/doc/guides/security/api-keys/#admin-api-key)
+(required for all MCM endpoints)
+
+Under the hood, the package uses the following endpoints:
+- [List Clusters](https://www.algolia.com/doc/api-reference/api-methods/list-clusters/)
+- [List Indices](https://www.algolia.com/doc/api-reference/api-methods/list-indices/)
+
+## Disclaimer
+
+This package is not officially supported by [Algolia](https://www.algolia.com/),
+so it cannot be held responsible for any use in production. If you need support,
+use GitHub issues or the [community forum](https://discourse.algolia.com/), but
+**not** Algolia email support.

mcm-filesize.js

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+const algoliasearch = require('algoliasearch')
+const CallEnum = require('@algolia/transporter').CallEnum
+
+const bytesToGB = (bytesNumber) => Math.round(bytesNumber / 1000 / 1000 / 1000)
+
+const getHosts = (clusterName, domain) => {
+  // https://www.algolia.com/doc/api-client/getting-started/upgrade-guides/javascript/#the-hosts-parameter
+  return [1, 2, 3].map(n => `${clusterName}-${n}.${domain}`).map(host => {
+    return {
+      protocol: 'https',
+      url: host,
+      accept: CallEnum.Read // CallEnum.Any or CallEnum.Write
+    }
+  })
+}
+
+const mcmFileSize = (appId, adminKey, domain = 'algolia.net') => {
+  return algoliasearch(appId, adminKey).listClusters().then(({ clusters }) => {
+    const clusterNames = clusters.map(cluster => cluster.clusterName)
+
+    const indexLists = clusters.map(cluster => {
+      const hosts = getHosts(cluster.clusterName, domain)
+      const client = algoliasearch(appId, adminKey, { hosts })
+      return client.listIndices()
+    })
+
+    return Promise.all(indexLists)
+      .then(indices => {
+        const report = {}
+        let total = 0
+        clusterNames.forEach((clusterName, i) => {
+          const clusterFileSize = indices[i].items.reduce(
+            (fileSize, index) => fileSize + bytesToGB(index.fileSize),
+            0
+          )
+          total += clusterFileSize
+          report[clusterName] = clusterFileSize
+        })
+        return JSON.stringify({ ...report, total })
+      })
+      .catch(err => {
+        throw err
+      })
+  })
+}
+
+module.exports = mcmFileSize