Deploying Django to AWS using CNC

We are going to deploy a django app with a postgres DB to ECS using the built-in ecs flavor of cnc. Read more about ecs deployment here.

Before starting, follow the steps at Getting Started. If you are using aws sso for your credentials locally, you'll need to set AWS_PROFILE=PROFILE_NAME in your environment.

repo setup

Following the instructions at the django tutorial we have set up our app. Here's an example: django.

As indicated in the tutorial, we update settings with the right configuration to talk to our database. For django with postgres this looks like:

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "NAME": os.environ.get("DB_NAME"),
        "USER": os.environ.get("DB_USER"),
        "PASSWORD": os.environ.get("DB_PASSWORD"),
        "HOST": os.environ.get("DB_HOST"),
        "PORT": "5432",
    }
}

The environment variables referenced will be automatically populated by cnc based on the configuration's resources. In your app, you'd want to handle setting these in development to the right values, having defaults that work locally when these are not set (e.g. in dev), or using an alternate settings.py with different values.

cnc.yml

You add this to cnc.yml. Read more about the file format here.

services:
  app:
    # activating the venv is due to using nixpacks, if you write your own dockerfile you don't need this part of the command
    command: ". /opt/venv/bin/activate && python manage.py runserver 0.0.0.0:$PORT"
    x-cnc:
      type: backend
    build:
      context: .
  db:
    x-cnc:
      type: database
      version: 15
    image: postgres

environments.yml

You add this to environments.yml. Read more about the file format here.

# name this whatever you want
name: django-app
provider: aws
flavor: ecs
version: 1

collections:
# eventually you would likely add a "prod" collection in another AWS account as well by adding another element here
- name: dev
  region: us-east-1
  base_domain: dev.mynextsite.com
  account_id: "123476727859"
  environments:
  - name: staging
    environment_variables:
    - name: FOO
      value: bar

See more about available options including environment variables in configuration.

add requirements file

You can either write your own Dockerfile and supply it under the build as dockerfile in the cnc.yml or you can use the built in support for nixpacks. As per nixpacks docs we are going to add a requirements.txt to configure as python build. Add the following to requirements.txt:

django
psycopg2

Provision your infra

run cnc provision apply. confirm with yes when requested by terraform, and then wait for the infra to provision. should take just a few minutes. the only thing this will create is the NS records zone for your base domain. you only need to do this once per collection, and then can add as many environments as you like under that domain without waiting for this again or touching DNS settings again.
run cnc info environments and grab the NS records to set for your DNS provider for the domain you set in base_domain above.
after applying those NS records to your provider, run cnc provision apply. confirm with yes when requested by terraform, and then wait for the infra to provision, should take longer than the first time perhaps 10 mins or so.

Deploy your app

run cnc update perform staging --service-tag app=v1. you can set v1 to whatever you want to use for the release tag, usually the git SHA is a good choice here, can get that with git rev-parse --short HEAD.
the first deploy will take the longest, once this runs once locally building the images will be faster due to docker cache in subsequent runs.
- 15 mins is normal for first time, 3ish mins after that
- you can also run this step from CI/CD e.g. github actions once it works for you and you want to automate it

visit the URL

run cnc info environments again, and visit the URL for your staging environment.

Next steps

add another environment
customize your terraform
add additional services
explore the toolbox