added function to get an AWS security token using STS

lib/get-aws-sts-token.js

@@ -0,0 +1,44 @@
+const { STSClient, GetSessionTokenCommand } = require('@aws-sdk/client-sts');
+const {makeAwsKey, noopLogger} = require('./utils');
+const debug = require('debug')('jambonz:speech-utils');
+const EXPIRY = 3600;
+
+async function getAwsAuthToken(
+  logger,
+  createHash, retrieveHash,
+  awsAccessKeyId, awsSecretAccessKey, awsRegion) {
+  logger = logger || noopLogger;
+  try {
+    const key = makeAwsKey(awsAccessKeyId);
+    const obj = await retrieveHash(key);
+    if (obj) return {...obj, servedFromCache: true};
+
+    /* access token not found in cache, so generate it using STS */
+    const stsClient = new STSClient({ region: awsRegion });
+    const params = {
+      accessKeyId: awsAccessKeyId,
+      secretAccessKey: awsSecretAccessKey,
+      DurationSeconds: EXPIRY
+    };
+    const command = new GetSessionTokenCommand(params);
+    const data = await stsClient.send(command);
+
+    const credentials = {
+      accessKeyId: data.Credentials.AccessKeyId,
+      secretAccessKey: data.Credentials.SecretAccessKey,
+      sessionToken: data.Credentials.SessionToken
+    };
+
+    /* expire 10 minutes before the hour, so we don't lose the use of it during a call */
+    createHash(key, credentials, EXPIRY - 600)
+      .catch((err) => logger.error(err, `Error saving hash for key ${key}`));
+
+    return {...credentials, servedFromCache: false};
+  } catch (err) {
+    debug(err, 'getAwsAuthToken: Error retrieving AWS auth token');
+    logger.error(err, 'getAwsAuthToken: Error retrieving AWS auth token');
+    throw err;
+  }
+}
+
+module.exports = getAwsAuthToken;

lib/utils.js

@@ -43,6 +43,12 @@ function makeIbmKey(apiKey) {
   return `ibm:${hash.digest('hex')}`;
 }
 
+function makeAwsKey(awsAccessKeyId) {
+  const hash = crypto.createHash('sha1');
+  hash.update(awsAccessKeyId);
+  return `aws:${hash.digest('hex')}`;
+}
+
 function makeNuanceKey(clientId, secret, scope) {
   const hash = crypto.createHash('sha1');
   hash.update(`${clientId}:${secret}:${scope}`);
@@ -110,6 +116,7 @@ module.exports = {
   makeSynthKey,
   makeNuanceKey,
   makeIbmKey,
+  makeAwsKey,
   getNuanceAccessToken,
   createNuanceClient,
   createKryptonClient,