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| 1 | +// This example requires the following input to succeed: |
| 2 | +// { "command": "do something" } |
| 3 | + |
| 4 | +use lambda_runtime::{service_fn, tracing, Diagnostic, Error, LambdaEvent}; |
| 5 | +use serde::{Deserialize, Serialize}; |
| 6 | + |
| 7 | +#[derive(Deserialize)] |
| 8 | +struct Request { |
| 9 | + #[serde(default, rename = "command")] |
| 10 | + _command: String, |
| 11 | + sleep: u32, |
| 12 | +} |
| 13 | + |
| 14 | +#[derive(Serialize, Debug, PartialEq)] |
| 15 | +struct Response { |
| 16 | + from: String, |
| 17 | +} |
| 18 | + |
| 19 | +#[derive(Debug)] |
| 20 | +struct HandlerError(String); |
| 21 | + |
| 22 | +impl std::fmt::Display for HandlerError { |
| 23 | + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| 24 | + write!(f, "{}", self.0) |
| 25 | + } |
| 26 | +} |
| 27 | + |
| 28 | +impl From<HandlerError> for Diagnostic { |
| 29 | + fn from(e: HandlerError) -> Diagnostic { |
| 30 | + Diagnostic { |
| 31 | + error_type: "HandlerError".into(), |
| 32 | + error_message: e.0, |
| 33 | + } |
| 34 | + } |
| 35 | +} |
| 36 | + |
| 37 | + |
| 38 | +/** |
| 39 | + * Cross-wiring protection: duplicate request-id after timeout. |
| 40 | +
|
| 41 | + Timeline: |
| 42 | + t=0: Invoke A starts, handler sleeps 7s |
| 43 | + t=5: A times out (timeout=5s). Batch 1 completes with timeout error. |
| 44 | + t=5: Invoke B starts (same request-id), handler sleeps 4s |
| 45 | + t=7: A's handler wakes up, posts stale /response/{same-id} |
| 46 | + t=9: B's handler wakes up, posts correct /response/{same-id} |
| 47 | +
|
| 48 | + With invocation-id: A's stale post at t=7 gets 410 Gone. B responds at t=9 correctly. |
| 49 | + Without: A's stale response at t=7 is accepted for B (cross-wired). |
| 50 | + */ |
| 51 | + |
| 52 | +#[tokio::main] |
| 53 | +async fn main() -> Result<(), Error> { |
| 54 | + // required to enable CloudWatch error logging by the runtime |
| 55 | + tracing::init_default_subscriber(); |
| 56 | + let max_concurrency = std::env::var("AWS_LAMBDA_MAX_CONCURRENCY").unwrap_or_else(|_| "not set".to_string()); |
| 57 | + tracing::info!(AWS_LAMBDA_MAX_CONCURRENCY = %max_concurrency, "starting concurrent handler"); |
| 58 | + |
| 59 | + let func = service_fn(my_handler); |
| 60 | + if let Err(err) = lambda_runtime::run_concurrent(func).await { |
| 61 | + tracing::error!(error = %err, "run error"); |
| 62 | + return Err(err); |
| 63 | + } |
| 64 | + Ok(()) |
| 65 | +} |
| 66 | + |
| 67 | +pub(crate) async fn my_handler(event: LambdaEvent<Request>) -> Result<Response, HandlerError> { |
| 68 | + if event.payload.sleep > 0 { |
| 69 | + tokio::time::sleep(tokio::time::Duration::from_secs(event.payload.sleep.into())).await; |
| 70 | + } |
| 71 | + |
| 72 | + Ok(Response { |
| 73 | + from: event.payload._command, |
| 74 | + }) |
| 75 | +} |
| 76 | + |
| 77 | +#[cfg(test)] |
| 78 | +mod tests { |
| 79 | + use super::*; |
| 80 | + use lambda_runtime::{Context, LambdaEvent}; |
| 81 | + |
| 82 | + #[tokio::test] |
| 83 | + async fn handler_echoes_marker() { |
| 84 | + let event = LambdaEvent { |
| 85 | + payload: Request { |
| 86 | + _command: "invoke-B".into(), |
| 87 | + sleep: 0, |
| 88 | + }, |
| 89 | + context: Context::default(), |
| 90 | + }; |
| 91 | + |
| 92 | + let result = my_handler(event).await.unwrap(); |
| 93 | + |
| 94 | + assert_eq!(result, Response { from: "invoke-B".into() }); |
| 95 | + } |
| 96 | + |
| 97 | + #[test] |
| 98 | + fn request_defaults_missing_command() { |
| 99 | + let request: Request = serde_json::from_str(r#"{"sleep": 0}"#).unwrap(); |
| 100 | + |
| 101 | + assert_eq!(request._command, ""); |
| 102 | + } |
| 103 | +} |
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