Overview

This script automates the process of mapping a custom domain to an IBM Cloud Code Engine application using Certbot and the multi-dns plugin to generate a TLS certificate and store it as a Code Engine Secret.

Prerequisites

• Python 3.x
• Required Python packages installed (see requirements.txt)
• IBM Cloud API Key: Instructions
• API Key for your DNS Provider: See the list of providers and associated Environment variables here
• CNAME record pointing your custom domain to your IBM Cloud Code Engine default hostname. Ex: custom.gh40.xyz points to my apps default URL at rst-custom-test.17rgnniognng.us-south.codeengine.appdomain.cloud

Usage

Step 1: Grab the code

First grab a copy of the repository:

git clone https://github.com/greyhoundforty/code-engine-certbot.git
cd code-engine-certbot

If you use mise you should see that it has created the venv for you once you change into the directory. The mise.toml file includes a few tasks as well that you can use to install the required packages and run the script.

Step 2: Install the required packages

Next we need to install the required python packages. I recommend a virtualenv so as not to pollute your system python. You can do this by running the following commands:

python -v venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Step 3: Export the required environment variables

The script requires 2 variables to be set in the environment: IBM_CLOUD_API_KEY and <DNS_PROVIDER_ENVIRONMENT_VAR>. The IBM Cloud API Key is used to interact with the IBM Cloud Code Engine API. The <DNS_PROVIDER_ENVIRONMENT_VAR> is used to interact with the DNS provider's API to create the required DNS records for the Let's Encrypt DNS challenge.

In this case <DNS_PROVIDER_ENVIRONMENT_VAR> is a placeholder and should be replaced with the appropriate environment variable for your DNS provider. For example, if you are using Cloudflare, you would run export CLOUDFLARE_DNS_API_TOKEN=<your token>, for DigitalOcean you would run export DO_AUTH_TOKEN=<your token>, etc.

export IBM_CLOUD_API_KEY=<ibm-cloud-api-key>
export <DNS_PROVIDER_ENVIRONMENT_VAR>=<dns-provider-api-key>

Step 4: Run the script

With the environment variables set, we can now run the script. The script takes the following arguments:

• --region: The IBM Cloud region where your Code Engine project is located.
• --project-name: The name of the Code Engine project.
• --app-name: The name of the Code Engine application.
• --custom-domain: The custom domain you want to map to the Code Engine application.
• --dns-provider: The DNS provider you are using. List of DNS providers
• --certbot-email: The email address to use for the Let's Encrypt certificate.

python ce_tls_app.py --region <ibmcloud-region> \
    --project-name <code-engine-project-name> \
    --app-name <application-name> \
    --custom-domain <custom-domain> \
    --dns-provider <dns-provider> \
    --certbot-email <certbot-email>

Demo