Base code for python3, flask, zappa

• python3
• flask
• postgres
• sqlalchemy
• flask-migrate
• bulma css
• zappa (serverless deployment on aws)
• flask-s3 (static files from aws s3)

0. Clone: git clone https://github.com/tonyin/flask-base.git
1. Set up virtualenv: python3 -m venv venv && . venv/bin/activate
2. Install libs: pip install -r requirements.txt
3. Create a config.env with required values (see config.py): touch config.env
4. Run: ./run.py

We use three environments:

1. Development: Local machine and server development environment
2. Production: What everyone sees

In order for zappa deploy and other AWS command-line functions to work, you need to add your AWS credentials to a known location, usually somewhere like ~/.aws/credentials. A sample credentials file would look something like this:

[app-name]
aws_access_key_id = some20characterstring
aws_secret_access_key = SomeOtherLonger40characterstring

profile_name: Use the app-name that holds your AWS credentials

The first time, zappa deploy development

Thereafter, zappa update development

1. Create a new AWS user to get security credentials. For permissions, add Lambda, API Gateway, RDS, IAM, and CloudFormation policies. At time of writing, CloudFormation requires a manual "inline" policy (as opposed to AWS-managed)
2. Create a public S3 bucket for your app to use for static assets
3. Create a PostgreSQL db. Your DATABASE_URL will be in the form postgresql://user:pass@endpoint.rds.amazonaws.com/dbname. If you plan to access the db remotely, use a dedicated security group and whitelist the IPs that you will use
4. Assign a VPC, subnets, and security group to your Lambda handler to enable proper permissions

1. Upload Flask static assets with the upload_assets.py script, which should run automatically with no additional commands if the environment variables are set correctly
2. Navigate to your .css files and set the Content-Type metadata to text/css. Unfortunately this step must be done each time you upload, as there is no programmatic way to set the file metadata currently.

1. zappa deploy production
2. The first deployment requires extra steps. In addition to the environment variables passed via zappa_settings.json, navigate to your app's Lambda function and add the following variables:
   • DATABASE_URL
   • SECRET_KEY
   • MAIL_USERNAME
   • MAIL_PASSWORD
3. To update, zappa update
4. To view logs, zappa tail --since 1h

0. Initialize: flask db init
1. Migrate: flask db migrate
2. Review code changes: flask db edit
3. Upgrade: flask db upgrade

Custom css and js modules can be defined in app/static/css/app.css and app/static/js/app.js respectively. We already load in bulma, jquery, and fontawesome.

Lambda has a timeout of 30s, so longer-running tasks cannot be synchronously executed. To get around this, we asynchronously execute tasks with zappa's @task decorator. For an example, see the email.py function.

• explore flask
• official flask
• hack4impact/flask-base