Deploying a pelican site to Google Cloud Run with Dockerfile not working

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04-10-2024

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Pelican Blog on Google Cloud Run: Dockerfile Deployment Troubleshoot

Problem: You've built a fantastic Pelican blog and want to deploy it on Google Cloud Run, leveraging the power of Docker. However, your Dockerfile isn't playing nice, and the deployment is failing.

Simplified: Your Pelican blog won't deploy on Google Cloud Run because of a misconfigured Dockerfile.

This article guides you through the common pitfalls and provides a robust solution to successfully deploy your Pelican blog on Google Cloud Run with a well-crafted Dockerfile.

Scenario:

Imagine you have a Pelican blog project structured like this:

pelican-blog/
├── content/
│   ├── pages/
│   │   └── about.rst
│   ├── articles/
│   │   └── first-post.rst
│   └── index.rst
├── pelicanconf.py
├── fabfile.py
├── Dockerfile
└── requirements.txt

Your Dockerfile might look something like this:

FROM python:3.10-slim

WORKDIR /app

COPY . .

RUN pip install -r requirements.txt

CMD ["pelican", "content"]

However, when you try to deploy this image to Google Cloud Run, it either fails to build or runs into issues during execution.

Analysis & Solutions:

1. Missing Dependencies:

• Problem: Google Cloud Run environments may not have all the dependencies your Pelican blog requires, like image processing libraries (e.g., Pillow).
• Solution: Ensure your requirements.txt file includes all necessary packages.

2. Incorrect Entrypoint:

• Problem: CMD in your Dockerfile might not be sufficient for proper Pelican execution. It might be missing the necessary commands for content generation and serving.
• Solution: Use ENTRYPOINT to define the main command for your Docker image. This will ensure Pelican runs correctly in the Cloud Run environment.

3. Static Content Handling:

• Problem: Pelican generates static content (HTML, CSS, images). Google Cloud Run might not have a built-in way to serve this content.
• Solution: Use an HTTP server like nginx or gunicorn in your Dockerfile to serve the generated content.

Example Dockerfile (with fixes):

FROM python:3.10-slim

WORKDIR /app

COPY . .

RUN pip install -r requirements.txt

# Install nginx
RUN apt-get update && apt-get install -y nginx

# Copy Pelican output to nginx's document root
COPY output/ /var/www/html

# Define the main command (ENTRYPOINT)
ENTRYPOINT ["nginx", "-g", "daemon off;"]

# Run the Pelican command to generate the content (CMD)
CMD ["pelican", "content"]

Explanation:

• We install nginx to serve the static content generated by Pelican.
• We copy the output of the pelican command to nginx's document root.
• ENTRYPOINT runs nginx to serve the content.
• CMD executes the pelican command to generate the content on startup.

Additional Tips:

• Caching: Use RUN apt-get update && apt-get install -y nginx with --no-cache flag to improve build time.
• Debugging: Utilize docker build -t pelican-blog . and docker run -it pelican-blog bash to debug your Dockerfile locally.
• Environment Variables: Use environment variables in your pelicanconf.py to customize your blog's settings, like the site URL, for different environments.

Conclusion:

By understanding the common pitfalls and implementing the suggested fixes, you can successfully deploy your Pelican blog to Google Cloud Run using Docker. With a well-structured Dockerfile and an optimized build process, you can enjoy the benefits of a serverless platform while showcasing your writing to the world.

Resources:

• Pelican Documentation: https://docs.getpelican.com/
• Google Cloud Run Documentation: https://cloud.google.com/run
• Nginx Documentation: https://nginx.org/en/docs/