Hockey Reminder Lambda (Rust)

This project is an AWS Lambda function written in Rust that posts upcoming hockey game information to Discord. It can:

• Generate and post a DaySmart “next game” reminder message
• Optionally generate and post a BenchApp-compatible CSV (from an iCal feed) as a Discord attachment

The function is configured entirely via the invocation request payload (no environment variables required).

Quick links

• Official AWS docs for Rust on Lambda (read this first): https://docs.aws.amazon.com/lambda/latest/dg/lambda-rust.html
• How to set up a Discord webhook: https://support.discord.com/hc/en-us/articles/228383668-Intro-to-Webhooks

Request and response schema

The handler expects the following JSON payload:

• mode: "test" | "production"
  • Chooses which Discord webhook to use.
• discord_hook_url: string
  • Webhook for production mode.
• test_discord_hook_url: string (optional)
  • Webhook for test mode. If omitted, test mode falls back to discord_hook_url.
• ical_url: string (optional)
  • If present and the ical workflow is selected, the iCal feed is fetched and converted to a BenchApp CSV.
• team_id: string
  • Your team identifier for DaySmart.
• company: string
  • Your company/organization identifier for DaySmart.
• workflows: array (optional)
  • Supported values: "daysmart", "ical".
  • If omitted or empty, the function defaults to ["daysmart"].

The function returns:

• { "message": string }
  • A human-readable summary of what was done.

Example minimal payload (defaults to DaySmart workflow):

{ "mode": "test", "discord_hook_url": "https://discord.com/api/webhooks/.../prod", "team_id": "12345", "company": "acme" }

Example with explicit workflows and iCal:

{ "mode": "production", "discord_hook_url": "https://discord.com/api/webhooks/.../prod", "test_discord_hook_url": "https://discord.com/api/webhooks/.../test", "ical_url": "https://example.com/schedule.ics", "team_id": "12345", "company": "acme", "workflows": ["daysmart", "ical"] }

Behavioral notes:

• If there are no upcoming games, the function skips posting to Discord and returns a summary indicating it skipped.
• If "ical" is requested but ical_url is not provided, the ical workflow is silently skipped.

Build and deploy to AWS Lambda

You can deploy this Lambda using either:

• Manual build + zip upload (uses the custom runtime for Rust, Provided.al2)
• cargo-lambda (recommended for convenience)

The official guide (linked above) explains both in detail. Below are concise steps adapted to this project.

1) Prerequisites

• Rust toolchain installed
• AWS account and credentials configured (AWS CLI or your preferred method)
• A Discord Webhook URL for production mode (optionally provide a separate test webhook) — see: https://support.discord.com/hc/en-us/articles/228383668-Intro-to-Webhooks
• Outbound internet access for the Lambda function (Discord webhooks require internet). If your Lambda runs in a VPC, ensure proper NAT/egress is configured.

Option A: Manual build and upload (x86_64)

1. Build a Linux-compatible binary in release mode:

   • For x86_64: rustup target add x86_64-unknown-linux-gnu cargo build --release --target x86_64-unknown-linux-gnu

   • For better compatibility with Amazon Linux 2, you can also build in a container or use musl/zig. See the AWS docs for details and alternatives.

2. Prepare the bootstrap file expected by the custom runtime:

   • The release binary is typically at target/x86_64-unknown-linux-gnu/release/hockey_reminder_lambda_rust

   • Copy or rename it to a file named bootstrap and zip it:

     cd target/x86_64-unknown-linux-gnu/release copy hockey_reminder_lambda_rust bootstrap tar -a -c -f bootstrap.zip bootstrap

   Notes:

   • On Linux/macOS you can use cp and zip. On Windows, the above PowerShell example uses copy and tar with -a to create a .zip.

3. Create the Lambda function (once):

   • Runtime: Provide your own bootstrap on Amazon Linux 2 (Provided.al2)
   • Architecture: x86_64 (to match the build target)
   • Upload code: Use the bootstrap.zip created above

   You can do this in the AWS Console or with the AWS CLI, e.g.:

   aws lambda create-function ^ --function-name hockey-reminder ^ --runtime provided.al2 ^ --role arn:aws:iam::123456789012:role/your-lambda-execution-role ^ --handler bootstrap ^ --architectures x86_64 ^ --zip-file fileb://bootstrap.zip

4. Update code on subsequent deployments:

   aws lambda update-function-code ^ --function-name hockey-reminder ^ --zip-file fileb://bootstrap.zip

5. Test the function (Console or CLI):

• Use a test event with the Request payload described above.
• Check the CloudWatch Logs for details (the project uses structured logging with tracing).

Option B: cargo-lambda (recommended)

cargo-lambda wraps the best practices for building and deploying Rust Lambdas.

1. Install cargo-lambda:

   cargo install cargo-lambda

2. Build for Lambda:

   cargo lambda build --release

   This produces an artifact suitable for upload in target/lambda/hockey_reminder_lambda_rust/bootstrap

3. Deploy:

   cargo lambda deploy hockey-reminder

   You can pass flags to set runtime/arch/role on first deploy; consult: https://www.cargo-lambda.info/

4. Invoke for testing:

   cargo lambda invoke hockey-reminder --data-file event.json --remote

   Where event.json contains one of the example payloads above.

Local testing

Run the Rust tests:

cargo test

Note: The function’s external calls (Discord, DaySmart, iCal fetching) are exercised indirectly via unit tests that focus on serialization and internal logic. Integration tests against real services are not included.

Operational considerations

• Networking: Discord webhook delivery requires outbound internet. If the Lambda runs in a VPC, configure NAT Gateway or VPC endpoints accordingly.
• Logging/Observability: Output goes to CloudWatch Logs. You can add subscriptions or log retention policies per your standards.
• Time windows: DaySmart message looks up the next game within 5 days of the invocation time (UTC now).
• Idempotency: The function does not persist state; repeated invocations within the same window will re-post unless there are no upcoming games.

Repository layout

• src/handler.rs — Lambda handler with request/response types and workflow orchestration
• src/daysmart.rs — DaySmart integration and message generation
• src/ical.rs — BenchApp CSV generator from an iCal feed
• src/discord.rs — Minimal Discord webhook client
• src/main.rs — Binary entry point that wires Lambda runtime to the handler
• tests/* — Unit tests

License

MIT (or your project’s chosen license).