Functions: Clean up AWS APIs example(s) (#2878)

* Functions / AWS APIs: Fix JSON formatting

* Functions / AWS APIs: Clean up code example

Author: tysonmote

src/connections/functions/aws-apis.md

@@ -13,41 +13,41 @@ To set up your functions to call AWS APIs:
     2. Create an IAM role in your AWS account with the [minimum set of necessary permissions](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#grant-least-privilege){:target="_blank"}.
     3. Add a trust relationship to your role with the following policy, filling in the principal account ID and external ID from step 1.1:
       ```json
-      {
-        "Version": "2012-10-17",
-        "Statement": [
-          {
-            "Effect": "Allow",
-            "Principal": {
-              "AWS": "<PRINCIPAL_ACCOUNT_ID>"
-            },
-            "Action": "sts:AssumeRole",
-            "Condition": {
-              "StringEquals": {
-                "sts:ExternalId": "<EXTERNAL_ID>"
+        {
+          "Version": "2012-10-17",
+          "Statement": [
+            {
+              "Effect": "Allow",
+              "Principal": {
+                "AWS": "<PRINCIPAL_ACCOUNT_ID>"
+              },
+              "Action": "sts:AssumeRole",
+              "Condition": {
+                "StringEquals": {
+                  "sts:ExternalId": "<EXTERNAL_ID>"
+                }
               }
             }
-          }
-        ]
-      }
+          ]
+        }
       ```
 
 2. Create your function.
   <br> Now that you have an IAM role in your AWS account, you can create your source or destination function. Segment recommends you to use function settings to make the IAM role configurable. This allows you to use different roles for different instances of your function and to securely store your external ID value by making it a "sensitive" setting. Here are the required settings:
   * **IAM Role ARN**: A string setting that is the ARN for the IAM role above. For example, `arn:aws:iam::1234567890:role/my-secure-role`.
   * **IAM Role External ID**: A sensitive string setting that is the external ID for your IAM role.
 
-    Below is an example destination function that uploads each event received to an S3 bucket (configured using an additional "S3 Bucket" setting). It uses the built-in local cache to retain S3 clients between requests to minimize processing time and to allow different instances of the function to use different IAM roles.
+    Below is an example destination function that uploads each event received to an S3 bucket (configured using additional "S3 Bucket" and "S3 Bucket Region" settings). It uses the built-in local cache to retain S3 clients between requests to minimize processing time and to allow different instances of the function to use different IAM roles.
 
     ```javascript
     async function getS3(settings) {
       const ttl = 30 * 60 * 1000; // 30 minutes
-      const key = settings.iamRoleArn + settings.iamRoleExternalId;
+      const key = [settings.iamRoleArn, settings.s3Bucket].join();
 
       return cache.load(key, ttl, async () => {
         const sts = new AWS.STS();
 
-        const creds = await sts
+        const opts = await sts
           .assumeRole({
             RoleArn: settings.iamRoleArn,
             ExternalId: settings.iamRoleExternalId,
@@ -56,16 +56,14 @@ To set up your functions to call AWS APIs:
           .promise()
           .then(data => {
             return {
+              region: settings.s3BucketRegion,
               accessKeyId: data.Credentials.AccessKeyId,
               secretAccessKey: data.Credentials.SecretAccessKey,
               sessionToken: data.Credentials.SessionToken
             };
-          })
-          .catch(err => {
-            throw err;
           });
 
-        return new AWS.S3(creds);
+        return new AWS.S3();
       });
     }
 
@@ -81,9 +79,6 @@ To set up your functions to call AWS APIs:
         .promise()
         .then(data => {
           console.log(data);
-        })
-        .catch(err => {
-          throw err;
         });
     }
     ```