Cloudflare Workers and API Usage Collection

12/16/2020

Cloudflare Workers and API Usage Collection
Cloudflare Workers provides a serverless execution environment that allows you to create entirely new applications or augment existing ones without configuring or maintaining infrastructure. Your Service Worker will intercept all HTTP requests destined for your domain, and can return any valid HTTP response. Your worker can make outgoing HTTP requests to any server on the public internet.

In this post, I lists some of my usage how Cloudflare Workers helps me to achieve my ideas. Before you can start creating your Cloudflare Workers, at least, you will need to have a free Cloudflare account created. It will work better if your own domain integrated with Cloudflare.

Hosting a Serverless Static Web Page
Using your own domain for your Workers

Hosting a Serverless Static Web Page

1 Check Cloudflare examples

Return HTML example page: https://developers.cloudflare.com/workers/examples

Deliver an HTML page from an HTML string directly inside the Worker script.

const html = `<!DOCTYPE html><body>  <h1>Hello World</h1>  <p>This markup was generated by a Cloudflare Worker.</p></body>`
async function handleRequest(request) {  return new Response(html, {    headers: {      "content-type": "text/html;charset=UTF-8",    },  })}
addEventListener("fetch", event => {  return event.respondWith(handleRequest(event.request))})

2 Copy example code into Workers app

3 Save and deploy example app

4 Get HTML code using WYSIWYG HTML Editor
I used a Blogger HTML Editor to create a page then toggle it to HTML view to get code. Then copy it back to Workers app code area between <body> and </body>

const html = `<!DOCTYPE html><body>"copy your html code here"</body>`
async function handleRequest(request) {  return new Response(html, {    headers: {      "content-type": "text/html;charset=UTF-8",    },  })}
addEventListener("fetch", event => {  return event.respondWith(handleRequest(event.request))})

YouTube video:

Using your own domain for your Workers

1 Create a sub-domain name

As mentioned earlier, domain names, such as 51sec,org must be hosted on or pointing to CloudFlare, and other DNS registrars will result in various weird errors.

Domain hosting or pointing to CloudFlare is easy, create a dns A record and point to any valid ip address.

After a new DNS record is added, this A record name will be used for our Workers App's sub-domain. When adding this A record, name is the subdomain to be customized (such as proxy.51sec.org). The value of IPv4 address does not matter, but the key is to enable the Proxied.

2 Associated domain names to Workers

After you create Workers switch to your domain's Workers tab for the domain name (note that the domain name is here, where in Workers you won't find a place to associate it with your domain and then add the association to Add route

3 Create a Workers Route

Route fills in the subdomain with /*, (proxy.51sec.org/*) ,Worker selects the worker application we created before, who needs to customize the domain name access, so you need to create a Worker and then associate , to represent access to the Worker service through this custom domain name: proxy.51sec.org/*

When you’re done, you can access the Worker service through a custom domain name, such as https://proxy.51sec.org/

API to Set Up DDNS

CloudFlare DDNS

CloudFlare itself does not have official DDNS support, but it can be implemented using CloudFlare API. GitHub Project Cloudflare-ddns provides a nice script to update your CloudFlare DNS IP using API. I have forked it to my repository to use.

Example : Ubuntu 18.04

Sudo -i

apt-get update -y & apt-get upgrade -y

First clone code from GitHub

git clone https://github.com/51sec/cloudflare-ddns.git

Enter the catalog

cd cloudflare-ddns/

Installation Pip

apt-get install python-pip

Installation dependencies

pip install -r requirements.txt

Rename the config.yaml.template file

mv config.yaml.template config.yaml

Modify config.yaml

nano config.yaml

It's almost like this:

%YAML 1.2
# CloudFlare DDNS updater script config.
---

# CloudFlare API key
# You can find this under Account > My account after logging into CloudFlare.
cf_key: 'cloudflare API Key'

# Email address for your CloudFlare account.
cf_email: 'CloudFlare log in email'

# Domain you're using CloudFlare to manage.
# If the host name you're updating is "ddns.domain.com", make this "domain.com".
cf_domain: 'root domain'

# The subdomain you're using for your DDNS A record.
# If the host name you're updating is "ddns.domain.com", make this "ddns".
# However, if you're updating the A record for the naked domain (that is, just
# "domain.com" without a subdomain), then set cf_subdomain to an empty value.
cf_subdomain: 'sub domain'

# CloudFlare service mode. This enables/disables CF's traffic acceleration.
# Enabled (orange cloud) is 1. Disabled (grey cloud) is 0.
cf_service_mode: 0

# If set to true, prints a message only when the record changes or when
# there's an error.  If set to 'false', prints a message every time even if
# the record didn't change.
quiet: false

# If set to true then we call the ec2metadata service for the instance
# public ip address rather than an external service.
aws_use_ec2metadata: false

# If set to true dig will be used to fetch the public IP which is better
# but not available on all systems.
use_dig: false

Get API key

Create subdomain

Run script

python cloudflare_ddns.py config.yaml

Add a scheduled task

crontab -e

Fill in the following

# Every 15 minutes, check the current public IP, and update the A record on CloudFlare.
*/15 * * * * /root/cloudflare-ddns/cloudflare_ddns.py /root/cloudflare-ddns/config.yaml >> /var/log/cloudflare_ddns.log

After scheduled job configuration completed, the IP will be updated to Cloudflare every 15 minutes

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December 15, 2020 at 10:38PM Cloud

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