Apache2 status to CloudWatch metrics shovel/export script

a2cw.js

/*
-----------------------------------------------------------

The world's simplest Apache2-to-CloudWatch metrics shovel,
by Rick Osborne (rickosborne.org, github:rickosborne)

LICENSE: CC BY-NC-SA 4.0
Creative Commons Attribution-NonCommercial-ShareAlike 4.0
https://creativecommons.org/licenses/by-nc-sa/4.0/

Basically:

1. Enable mod_status:
    $ a2enmod status
    It will likely tell you it's already enabled.
2. If you don't already have one, add a localhost vhost:
    /etc/apache2/sites-available/localhost.conf

    <VirtualHost localhost:80>
      ServerName localhost:80
      KeepAlive Off

      LogLevel warn
      CustomLog "/var/log/apache2/localhost/nossl.log" "combined"
      ErrorLog  "/var/log/apache2/localhost/nossl-err.log"

      <Location "/server-status">
        SetHandler server-status
        Require host localhost
      </Location>
    </VirtualHost>
3. Make sure that site works:
    $ a2ensite localhost
4. Make sure that status page is available:
    $ curl -v 'http://localhost/server-status?auto'
5. Add this script somewhere, such as:
    /opt/cloudwatch/a2cw.js
    Make sure you change the `aws` and `host` variables
    if your system is weird.
6. Figure out where your node is installed:
    $ which node
7. Run the script manually once just to be sure it's okay:
    $ node /opt/cloudwatch/a2cw.js
    You should see a bunch of aws commands logged.
8. Copy and run one of those commands to make sure your
    awscli setup is correct.  If you don't have awscli:
    $ apt install awscli
    Or yum or whatever.
9. If awscli tells you to configure the region or credentials,
    do so now.  Re-rerun one of the logged commands to test.
10. Add a crontab entry for 1-minute intervals:
    $ crontab -e
    And then a line like:
    * * * * * /usr/bin/node /opt/cloudwatch/a2cw.js
11. Give it a few minutes and you should see the metrics
   in CloudWatch.
12. Optionally, add more entries to the `units` map below.

-----------------------------------------------------------
 */

const child = require("child_process");
const http = require("http");

const aws = child.execSync("which aws", {encoding: "utf-8"}).trim();
const host = child.execSync("hostname", {encoding: "utf-8"}).trim();

const units = {
    "ServerUptimeSeconds": "Seconds",
    "Load1": "Count",
    "Load5": "Count",
    "Load15": "Count",
    "TotalAccesses": "Count",
    "TotalkBytes": "Kilobytes",
    "ReqPerSec": "Count/Second",
    "BytesPerSec": "Bytes/Second",
    "BytesPerReq": "Bytes",
    "BusyWorkers": "Count",
    "IdleWorkers": "Count",
    "ConnsTotal": "Count",
    "CacheUsage": "Percent",
};

http.get({
    host: "localhost",
    protocol: "http:",
    path: "/server-status?auto",
    method: "GET",
    timeout: 30,
    agent: false,
}, (res) => {
    if (res.statusCode < 200 || res.statusCode >= 300) {
        console.error("Bad status code: " + res.statusCode);
        process.exit(0);
    }
    res.on("error", (e) => {
        console.error(e);
        process.exit(0);
    });
    let data = '';
    res.on("data", (chunk) => {
        data += chunk;
    });
    res.on("end", () => {
        const lines = data.split("\n");
        for (const line of lines) {
            const match = line.match(/^([^:]+):\s+(\d+(\.\d+)?)%?$/);
            if (match) {
                const key = (match[1] || '').replace(/\s+/g, "");
                const value = parseFloat(match[2]);
                const unit = units[key];
                if (unit != null) {
                    const command = `${aws} cloudwatch put-metric-data --metric-name 'httpd-${key}' --unit '${unit}' --value ${value} --dimensions 'host=${host}' --namespace 'HTTP:Apache'`;
                    console.log(command);
                    child.execSync(command);
                }
            }
        }
    });
});