This is a simple app which has dynamic configuration demo and provide basic configmap, secret, iam role usage and kubernetes deployment spec.
Codebase: Codebase will be same for across all deployments, however deployments can run multiple versions of the app in different environments (preprod/prod/staging/foo's local laptop/bar's staging cluster)
Dependencies: ./requirements.txt contains all required
dependencies. This project is developed using virtual environment in local, but inside container
there is not venv
Config: We identified configs as key-value pairs and secrets. KVs and Secrets are being managed by ConfigMap and Secrets respectively. Confd sidecar can be used to dynamically fetch config from consul and store in a local directory which you can mount as config volume. Config change doesn't require new deployment.
Backing Services: Services must be treated as resources and URLs and credentials must use config maps or secrets as necessary.
- Build is docker build phase, which
gets initialized when you push to github. Build is defined here:
./.drone.yml - Release and run phases are managed by argo. Click on 'Sync' on respective argo application to release and rollout deploy
Processes: Hola app runs as gunicorn process with 4 worker processes.
Port binding: Hosts the app on 5000
Concurrency: As a twelve factor application, hola doesn't manage any PID file and gunicorn runs as pid 0 process, so that we can easily orchestrate using kubernetes to manage log output stream, release, scaling
Disposability: Disposability is
delegated to gunicorn and supports these (signals)[http://docs.gunicorn.org/en/latest/signals.html].
However disposability is far vast topic more than just handling signals but hola being a simple
app there is not much to demonstrate.
Dev/prod parity: Same architecture for all environments, mostly configmaps and secret will differ.
Logs: As a 12factor app, the app should never manage log files
itself and send logs as unbuffered stream to stdout
Admin processes: Since we are running kubernetes, define
admin commands the app supports in entrypoint.sh and run them as Job in kubernetes.