Daily Email

Pluggable sections

Each section is a plugin: one Python file with a run(options, today) function that fetches whatever it needs and returns an HTML snippet. The digest doesn't know anything about what a plugin does, so the email can hold any mix of sources.

• Adding a source means adding one plugin file and a config entry.
• Plugins can skip a day by returning nothing, so a section only appears when it has something to say.
• Failures stay contained. If a plugin crashes, its section shows the error, the rest of the email still sends, and the subject line flags it.

The plugins I run today are homework from Canvas, fantasy football lineup alerts from Sleeper, the weather, countdowns, and a daily quote. The example below shows that setup.

How it runs

An EventBridge schedule triggers a Python Lambda function every morning. The function loads the current config, runs each enabled plugin in order, puts their HTML into one email template, and sends it through SES. The whole stack is defined in an AWS SAM template, so deploying is sam build && sam deploy.

Each run is independent of which plugins exist: the function reads the list of enabled plugins from the config at send time, so turning a section on or off never needs a redeploy.

Settings without redeploying

Every email ends with a link to a settings page, served by a second Lambda function through a function URL. From there you can turn sections on and off, reorder them, change their options, or send a test email right away. Each plugin declares its own settings fields, and the form is generated from them, so a new plugin gets a settings UI for free.

• The links are HMAC-signed and expire after 7 days, so the page needs no login.
• The live config is stored in an S3 bucket with versioning on, so a bad save can be rolled back.

Screenshots use sample data in place of my real accounts.