refactor configureAWS to not assume presence of ~/.aws/ ini files

src/configureAWS.ts

@@ -1,13 +1,30 @@
-import * as aws from 'aws-sdk'
+import * as fs from 'fs';
+import * as path from 'path';
+import * as aws from 'aws-sdk';
 
+import { logger } from './logger';
 import { AWSRegion } from './aws-regions';
 
 async function configureAWS(profile?: string, region?: AWSRegion) {
   process.env.AWS_SDK_LOAD_CONFIG = 'true'; // see https://github.com/aws/aws-sdk-js/pull/1391
-  const credentials = new aws.SharedIniFileCredentials({profile});
-  await credentials.refreshPromise()
-  aws.config.credentials = credentials;
+
+  if (process.env.AWS_ACCESS_KEY_ID && ! profile) {
+    logger.debug(`Using AWS env vars. AWS_ACCESS_KEY_ID: ${process.env.AWS_ACCESS_KEY_ID}.`);
+  } else if (process.env.HOME && fs.existsSync(path.join(process.env.HOME as string, '.aws'))) {
+    logger.debug(`Using AWS ~/.aws/{config,credentials} file: profile: ${profile}.`);
+    // note, profile might be undefined here and that's fine.
+    const credentials = new aws.SharedIniFileCredentials({profile});
+    await credentials.refreshPromise();
+    aws.config.credentials = credentials;
+  } else if (profile || process.env.AWS_PROFILE) {
+    throw new Error('AWS profile provided but ~/.aws/{config,credentials} not found.')
+  } else {
+    logger.debug('Using AWS ec2 instance profile.');
+  }
+
+
   if (typeof region === 'string') {
+    logger.debug(`Setting AWS region: ${region}.`);
     aws.config.update({region});
   }
 }