✨(buildpack) add PaaS deployment support, tested with Scalingo

[sylvinus]

This PR adds a new deployment option for Heroku-like platforms based on buildpacks, like Scalingo.

To deploy there, create a new app on one of these platforms, configure Postgres and Redis addons, and then add these configuration variables:

AWS_S3_ACCESS_KEY_ID=xxx-secret
AWS_S3_ENDPOINT_URL=https://s3.fr-par.scw.cloud
AWS_S3_REGION_NAME=fr-par
AWS_S3_SECRET_ACCESS_KEY=xxx-secret
AWS_STORAGE_BUCKET_NAME=xxx-bucket-name
BUILDPACK_URL=https://github.com/suitenumerique/buildpack#main
COLLABORATION_API_URL=http://localhost:4444/
COLLABORATION_SERVER_SECRET=xxx-collaboration-secret
DATABASE_URL=xxx-postgres-url
DATA_DIR=/app/data
DJANGO_ALLOWED_HOSTS=xxx-hostname
DJANGO_CONFIGURATION=Production
DJANGO_SECRET_KEY=xxx-django-secret
DJANGO_SETTINGS_MODULE=impress.settings
DJANGO_STATIC_ROOT=/app/static_app/
FRONTEND_THEME=dsfr
LASUITE_BACKEND_DIR=.
LASUITE_NGINX_DIR=./
LASUITE_SCRIPT_POSTCOMPILE=bin/buildpack_postcompile.sh
LASUITE_SCRIPT_POSTFRONTEND=bin/buildpack_postfrontend.sh
LOGIN_REDIRECT_URL=/
LOGIN_REDIRECT_URL_FAILURE=/
LOGOUT_REDIRECT_URL=/
MEDIA_BASE_URL=xxx-https-url
NEXT_PUBLIC_SW_DEACTIVATED=true
OIDC_OP_AUTHORIZATION_ENDPOINT=https://docs-hwenen.us1.zitadel.cloud/oauth/v2/authorize
OIDC_OP_JWKS_ENDPOINT=https://docs-hwenen.us1.zitadel.cloud/oauth/v2/keys
OIDC_OP_TOKEN_ENDPOINT=https://docs-hwenen.us1.zitadel.cloud/oauth/v2/token
OIDC_OP_USER_ENDPOINT=https://docs-hwenen.us1.zitadel.cloud/oidc/v1/userinfo
OIDC_RP_CLIENT_ID=xxx-oidc-id
OIDC_RP_CLIENT_SECRET=xxx-oidc-secret
REDIS_URL=xxx-redis-url
Y_PROVIDER_API_BASE_URL=http://localhost:4444/api/
Y_PROVIDER_API_KEY=xxx-yprovider-api-key

(Note that I'm using Scaleway's object storage and Zitadel's OIDC provider, you are free to use other services)

I'm still debugging a websocket issue but this should mostly work, testers welcome!

A few interesting links:

• Buildpack for La Suite, supporting Docs and others apps from La Suite.
• Buildpack spec, although we only support "old-style" buildpacks for now
• 12-factor apps
• Heroku, Scalingo, there might be more?

[sylvinus]

TODO: we should not hardcode the node binary path here.

[sylvinus]

FYI the same support was merged in Drive: suitenumerique/drive@dd6f0be