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A serverless full-stack application using only git, google drive, and public ci/cd runners

edersonbrilhante profile image Ederson Brilhante ・4 min read

TL;DR; How I built the Vilicus Service, a serverless full-stack application with backend workers and database only using git and ci/cd runners.


What is Vilicus?

Vilicus is an open-source tool that orchestrates security scans of container images(Docker/OCI) and centralizes all results into a database for further analysis and metrics.

Vilicus provides many alternatives to use it:

This article explains how it was possible to build the Free Online Service without using a traditional deployment.


Architecture

Architecture

The Frontend is hosted in GitHub Pages. This frontend is a landing page with a free service to scan or display the vulnerabilities in container images.

The results of container image scans are stored in a GitLab Repository.

When the user asks to show the results from an image, the frontend consumes the GitLab API to retrieve the file with vulns from this image. In case this image is not scanned yet, the user has the option to schedule a scan using a google form.

When this form is filled, the data is sent to a Google Spreadsheet.

A GitHub Workflow runs every 5 minutes to check if there are new answers in this Spreadsheet. For each new image in the Spreadsheet, this workflow triggers another Workflow to scan the image and save the result in the GitLab Repository.

Why store in GitLab?

GitLab provides bigger limits.

Here's a summary of differences in offering on public cloud and free tier:

Free users Max repo size (GB) Max file size (MB) Max API calls per hour (per client)
GitHub 3 2 100 5000
BitBucket 5 1 Unlimited (up to repo size) 5000
GitLab Unlimited 10 Unlimited (up to repo size) 36000

Google Drive

This choice was a "quick win". In a usual deployment, the backend could call an API passing secrets without the clients knowing the secrets.

But because I am using GitHub Pages I cannot use that(Well, I could do it in the javascript, but anyone using the Browser Inspect would see the secrets. So let's don't do it πŸ˜‰)

This makes the Google Spreadsheet perform as a Queue.

Google Form:
Form
Google Spreadsheet with answers:
Answers


GitHub Workflows

The Schedule Workflow runs at most every 5 minutes. This workflow executes the python script that checks if there are new rows in the Google Spreadsheet, and for each row is made an HTTP request to trigger the event repository_dispatch.

This makes the workflows perform as backend workers.

Schedule in workflow:

name: Schedule
on:
  schedule:
    - cron:  '*/5 * * * *'
...
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Event repository_dispatch in WorkFlow:

name: Report
on: [repository_dispatch]
...
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Screenshots:

Schedule History:
Schedules
Schedule WorkFlow:
Schedule
Scans History:
Scans
Report Workflow:
Report
Scan Report stored in GitLab:
Report File Example

Source Code:

Do you want to know more about GitHub Actions?


Github Pages

The Frontend is running in GitHub Pages.

By default an application running in GH Pages is hosted as http://<github-user>.github.io/<repository>.

But GitHub allows you to customize the domain, because that it's possible to access Vilicus using https://vilicus.edersonbrilhante.com.br instead of http://edersonbrilhante.github.io/vilicus.

GitHub Workflow to build the application and deploy it in GH Pages

Building the source code:

- name: Build
  run: |
    cd website
    npm install
    npm run-script build
  env:
    REACT_APP_GA_CODE: ${{ secrets.REACT_APP_GA_CODE }}
    REACT_APP_FORM_SCAN: ${{ secrets.REACT_APP_FORM_SCAN }}
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Deploying the build:

- name: Deploy
  uses: JamesIves/github-pages-deploy-action@releases/v3
  with:
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    BRANCH: gh-pages
    FOLDER: website/build
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Source Code:

Do you want to know more about GitHub Pages?


That’s it!

In case you have any questions, please leave a comment here or ping me on LinkedIn.

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