[Feature] Add Airflow deployment via Helm with git-sync DAGs integration managed by Argo CD

[bwalsh]

User Story

As a platform engineer, I want to deploy Apache Airflow on Kubernetes using Helm, with DAGs automatically synchronized from a Git repository via git-sync, and all deployments and updates managed through Argo CD, so that our workflow automation is robust, reproducible, and GitOps-native.

Definition of Done

• An Airflow Helm release can be installed via calypr/argo-helm with support for:
  • Helm configuration values and templates for Airflow core components (webserver, scheduler, workers, database, etc.)
  • Integration of a git-sync sidecar (or initContainer) that automatically pulls DAGs from a configurable Git repository
  • DAG synchronization volume mounted into necessary Airflow components
  • All credentials and sensitive values (e.g., Git SSH key, database password) fetched securely via Kubernetes Secrets
  • Support for configuration and deployment via Argo CD Applications
  • Documentation on configuring DAG repo, secrets, and upgrade workflow
• Helm values and README updated to document Airflow and GitOps options

Acceptance Tests

• Successful installation of Airflow using the provided Helm chart, including DAG synchronization from a target Git repo
• DAGs become available and executable in Airflow within minutes of being updated in the Git repo
• Airflow and DAG synchronization can be fully managed via Argo CD Application(s)
• Changing the Git repo or branch for DAGs reflects in the Airflow deployment without manual intervention
• All sensitive values are stored in Kubernetes Secrets and not in plaintext config
• All steps are clearly documented for platform users

[bwalsh]

https://medium.com/ankercloud-engineering/airflow-on-argo-cd-a-step-by-step-gitops-guide-with-git-sync-for-dags-464bd0d7e2f5