serverless-offline/src/events/http/lambda-events/LambdaProxyIntegrationEventV2.js

Emulate AWS λ and API Gateway locally when developing your Serverless project

import { Buffer } from "node:buffer"
import { env } from "node:process"
import { decodeJwt } from "jose"
import { log } from "../../../utils/log.js"
import {
  detectEncoding,
  formatToClfTime,
  lowerCaseKeys,
  nullIfEmpty,
  parseHeaders,
  parseQueryStringParametersForPayloadV2,
} from "../../../utils/index.js"

const { isArray } = Array
const { parse } = JSON
const { assign, entries } = Object

// https://www.serverless.com/framework/docs/providers/aws/events/http-api/
// https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html
export default class LambdaProxyIntegrationEventV2 {
  #additionalRequestContext = null

  #routeKey = null

  #request = null

  #stage = null

  constructor(request, stage, routeKey, additionalRequestContext) {
    this.#additionalRequestContext = additionalRequestContext || {}
    this.#routeKey = routeKey
    this.#request = request
    this.#stage = stage
  }

  create() {
    const authContext =
      (this.#request.auth &&
        this.#request.auth.credentials &&
        this.#request.auth.credentials.context) ||
      {}

    // AWS adds the lambda key to the auth context object
    const lambdaAuthContext = { lambda: authContext }

    let authAuthorizer

    if (env.AUTHORIZER) {
      try {
        authAuthorizer = parse(env.AUTHORIZER)
      } catch {
        log.error(
          "Could not parse process.env.AUTHORIZER, make sure it is correct JSON",
        )
      }
    }

    let body = this.#request.payload
    let isBase64Encoded = false

    const { rawHeaders } = this.#request.raw.req

    // NOTE FIXME request.raw.req.rawHeaders can only be null for testing (hapi shot inject())
    const headers = lowerCaseKeys(parseHeaders(rawHeaders || [])) || {}

    if (headers["sls-offline-authorizer-override"]) {
      try {
        authAuthorizer = parse(headers["sls-offline-authorizer-override"])
      } catch {
        log.error(
          "Could not parse header sls-offline-authorizer-override, make sure it is correct JSON",
        )
      }
    }

    if (body) {
      if (
        this.#request.raw.req.payload &&
        detectEncoding(this.#request) === "binary"
      ) {
        body = Buffer.from(this.#request.raw.req.payload).toString("base64")
        headers["content-length"] = String(Buffer.byteLength(body, "base64"))
        isBase64Encoded = true
      }

      if (typeof body !== "string") {
        // this.#request.payload is NOT the same as the rawPayload
        body = this.#request.rawPayload
      }

      if (
        !headers["content-length"] &&
        (typeof body === "string" ||
          body instanceof Buffer ||
          body instanceof ArrayBuffer)
      ) {
        headers["content-length"] = String(Buffer.byteLength(body))
      }

      // Set a default Content-Type if not provided.
      if (!headers["content-type"]) {
        headers["content-type"] = "application/json"
      }
    } else if (body === undefined || body === "") {
      body = null
    }

    // clone own props
    const pathParams = { ...this.#request.params }

    let token = headers.Authorization || headers.authorization

    if (token && token.split(" ")[0] === "Bearer") {
      ;[, token] = token.split(" ")
    }

    let claims
    let scopes

    if (token) {
      try {
        claims = decodeJwt(token)
        if (claims.scp || claims.scope) {
          scopes = claims.scp || claims.scope.split(" ")
          // In AWS HTTP Api the scope property is removed from the decoded JWT
          // I'm leaving this property because I'm not sure how all of the authorizers
          // for AWS REST Api handle JWT.
          // claims = { ...claims }
          // delete claims.scope
        }
      } catch {
        // Do nothing
      }
    }

    const {
      headers: _headers,
      info: { received, remoteAddress },
      method,
    } = this.#request

    const httpMethod = method.toUpperCase()
    const requestTime = formatToClfTime(received)
    const requestTimeEpoch = received

    const cookies = this.#request.state
      ? entries(this.#request.state).flatMap(([key, value]) => {
          if (isArray(value)) {
            return value.map((v) => `${key}=${v}`)
          }
          return `${key}=${value}`
        })
      : undefined

    return {
      body,
      cookies,
      headers,
      isBase64Encoded,
      pathParameters: nullIfEmpty(pathParams),
      queryStringParameters: this.#request.url.search
        ? parseQueryStringParametersForPayloadV2(this.#request.url.searchParams)
        : null,
      rawPath: this.#request.url.pathname,
      rawQueryString: this.#request.url.searchParams.toString(),
      requestContext: {
        accountId: "offlineContext_accountId",
        apiId: "offlineContext_apiId",
        authorizer:
          authAuthorizer ||
          assign(lambdaAuthContext, {
            jwt: {
              claims,
              scopes,
            },
          }),
        domainName: "offlineContext_domainName",
        domainPrefix: "offlineContext_domainPrefix",
        http: {
          method: httpMethod,
          path: this.#request.url.pathname,
          protocol: "HTTP/1.1",
          sourceIp: remoteAddress,
          userAgent: _headers["user-agent"] || "",
        },
        operationName: this.#additionalRequestContext.operationName,
        requestId: "offlineContext_resourceId",
        routeKey: this.#routeKey,
        stage: this.#stage,
        time: requestTime,
        timeEpoch: requestTimeEpoch,
      },
      routeKey: this.#routeKey,
      stageVariables: null,
      version: "2.0",
    }
  }
}