populate-lambda-mock-env-vars.ts

import { $TSContext, pathManager, stateManager } from '@aws-amplify/amplify-cli-core';
import * as path from 'path';
import * as dotenv from 'dotenv';
import { loadConfigurationForEnv, resolveAppId } from '@aws-amplify/amplify-provider-awscloudformation';
import { ProcessedLambdaFunction } from '../../CFNParser/stack/types';

/**
 * Appends default labmda environment variables to the environment property of the processedLambda
 * (see https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html#configuration-envvars-runtime)
 * Some values are stubbed properly and others have static default values
 */
export const populateLambdaMockEnvVars = async (context: $TSContext, processedLambda: ProcessedLambdaFunction): Promise<void> => {
  // eslint-disable-next-line no-param-reassign
  processedLambda.environment = (
    await Promise.all(
      [getAwsCredentials, getStaticDefaults, getDynamicDefaults, getDotEnvValues].map((envVarGetter) =>
        envVarGetter(processedLambda, context),
      ),
    )
  ).reduce((acc, it) => ({ ...acc, ...it }), processedLambda.environment);
};

// eslint-disable-next-line @typescript-eslint/no-shadow
const getAwsCredentials = async (__, context: $TSContext): Promise<Record<string, string>> => {
  const env = stateManager.getLocalEnvInfo().envName;
  let appId: string | undefined;
  try {
    appId = resolveAppId(context);
  } catch {
    // swallow no appId found as it's not necessary for mocking
  }
  const awsConfigInfo = await loadConfigurationForEnv(context, env, appId);
  return {
    AWS_ACCESS_KEY_ID: awsConfigInfo.accessKeyId,
    AWS_SECRET_ACCESS_KEY: awsConfigInfo.secretAccessKey,
    AWS_SESSION_TOKEN: awsConfigInfo.sessionToken,
  };
};

const getStaticDefaults = (): Record<string, string> => ({
  // eslint-disable-next-line spellcheck/spell-checker
  _X_AMZN_TRACE_ID: 'amplify-mock-x-amzn-trace-id',
  AWS_EXECUTION_ENV: 'AWS_Lambda_amplify-mock', // we could do some work to resolve the actual runtime here, but there doesn't seem to be a need at this point
  AWS_LAMBDA_FUNCTION_MEMORY_SIZE: '128', // the default
  AWS_LAMBDA_FUNCTION_VERSION: '1',
  AWS_LAMBDA_INITIALIZATION_TYPE: 'on-demand',
  AWS_LAMBDA_LOG_GROUP_NAME: 'amplify-mock-aws-lambda-log-group-name',
  AWS_LAMBDA_LOG_STREAM_NAME: 'amplify-mock-aws-lambda-log-stream-name',
  TZ: 'UTC',
});

const getDynamicDefaults = (processedLambda: ProcessedLambdaFunction): Record<string, string> => {
  const region = stateManager.getMeta()?.providers?.awscloudformation?.Region || 'us-test-1';
  // This isn't exactly in parity with what the path will be when deployed but we don't have a good mechanism for getting a better value
  const lambdaPath = path.join(pathManager.getBackendDirPath(), 'function', processedLambda.name);

  return {
    _HANDLER: processedLambda.handler,
    AWS_REGION: region,
    AWS_LAMBDA_FUNCTION_NAME: processedLambda.name,
    LAMBDA_TASK_ROOT: lambdaPath,
    LAMBDA_RUNTIME_DIR: lambdaPath,
  };
};

const getDotEnvValues = (processedLambda: ProcessedLambdaFunction): Record<string, string> => {
  try {
    const result = dotenv.config({ path: path.join(pathManager.getBackendDirPath(), 'function', processedLambda.name, '.env') });
    if (result.error) {
      throw result.error;
    }
    return result.parsed;
  } catch {
    // if there's no .env file, carry on without it
  }
  return undefined;
};