lambda-extension 0.8.0

AWS Lambda Extension API
Documentation 
use crate::{Error, LogBuffering};
use http::{Method, Request};
use hyper::Body;
use lambda_runtime_api_client::build_request;
use serde::Serialize;

const EXTENSION_NAME_HEADER: &str = "Lambda-Extension-Name";
pub(crate) const EXTENSION_ID_HEADER: &str = "Lambda-Extension-Identifier";
const EXTENSION_ERROR_TYPE_HEADER: &str = "Lambda-Extension-Function-Error-Type";

pub(crate) fn next_event_request(extension_id: &str) -> Result<Request<Body>, Error> {
    let req = build_request()
        .method(Method::GET)
        .header(EXTENSION_ID_HEADER, extension_id)
        .uri("/2020-01-01/extension/event/next")
        .body(Body::empty())?;
    Ok(req)
}

pub(crate) fn register_request(extension_name: &str, events: &[&str]) -> Result<Request<Body>, Error> {
    let events = serde_json::json!({ "events": events });

    let req = build_request()
        .method(Method::POST)
        .uri("/2020-01-01/extension/register")
        .header(EXTENSION_NAME_HEADER, extension_name)
        .body(Body::from(serde_json::to_string(&events)?))?;

    Ok(req)
}

pub(crate) enum Api {
    LogsApi,
    TelemetryApi,
}

impl Api {
    pub(crate) fn schema_version(&self) -> &str {
        match *self {
            Api::LogsApi => "2021-03-18",
            Api::TelemetryApi => "2022-07-01",
        }
    }

    pub(crate) fn uri(&self) -> &str {
        match *self {
            Api::LogsApi => "/2020-08-15/logs",
            Api::TelemetryApi => "/2022-07-01/telemetry",
        }
    }
}

pub(crate) fn subscribe_request(
    api: Api,
    extension_id: &str,
    types: Option<&[&str]>,
    buffering: Option<LogBuffering>,
    port_number: u16,
) -> Result<Request<Body>, Error> {
    let types = types.unwrap_or(&["platform", "function"]);

    let data = serde_json::json!({
        "schemaVersion": api.schema_version(),
        "types": types,
        "buffering": buffering.unwrap_or_default(),
        "destination": {
            "protocol": "HTTP",
            "URI": format!("http://sandbox.localdomain:{}", port_number),
        }
    });

    let req = build_request()
        .method(Method::PUT)
        .uri(api.uri())
        .header(EXTENSION_ID_HEADER, extension_id)
        .body(Body::from(serde_json::to_string(&data)?))?;

    Ok(req)
}

/// Payload to send error information to the Extensions API.
#[derive(Debug, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct ErrorRequest<'a> {
    /// Human readable error description
    pub error_message: &'a str,
    /// The type of error to categorize
    pub error_type: &'a str,
    /// The error backtrace
    pub stack_trace: Vec<&'a str>,
}

/// Create a new init error request to send to the Extensions API
pub fn init_error<'a>(
    extension_id: &str,
    error_type: &str,
    request: Option<ErrorRequest<'a>>,
) -> Result<Request<Body>, Error> {
    error_request("init", extension_id, error_type, request)
}

/// Create a new exit error request to send to the Extensions API
pub fn exit_error<'a>(
    extension_id: &str,
    error_type: &str,
    request: Option<ErrorRequest<'a>>,
) -> Result<Request<Body>, Error> {
    error_request("exit", extension_id, error_type, request)
}

fn error_request<'a>(
    error_type: &str,
    extension_id: &str,
    error_str: &str,
    request: Option<ErrorRequest<'a>>,
) -> Result<Request<Body>, Error> {
    let uri = format!("/2020-01-01/extension/{}/error", error_type);

    let body = match request {
        None => Body::empty(),
        Some(err) => Body::from(serde_json::to_string(&err)?),
    };

    let req = build_request()
        .method(Method::POST)
        .uri(uri)
        .header(EXTENSION_ID_HEADER, extension_id)
        .header(EXTENSION_ERROR_TYPE_HEADER, error_str)
        .body(body)?;
    Ok(req)
}