# Kendra Fallback Function

Provides a Lambda Hook for the no_hits question to search a set of Kendra indexes
as a fallback mechanism to provide answers.

Kendra provides a number of innovative features. This Kendra Fallback function performs a query against a
set of Kendra indexes and will return the first answer that Kendra identifies. Kendra can return multiple
answers however to keep responses limited in scope the first answer is provided through QnABot. Links to
documents stored in S3 buckets that Kendra indexes are also provided. The security of the S3 bucket governs
whether this link is usable. In addition Kendra can return discovered text with links to these documents as well.
This function returns a default of four discovered texts/links. The maximum number of returned links is
configurable.

## Configure Kendra Fallback using the following settings in Content designer Setting page

### ALT\_SEARCH\_KENDRA\_INDEXES

**Required** - A String value that specifies an array of
Kendra indexes to search.
The value of ALT\_SEARCH\_KENDRA\_INDEXES should be either a single index id, or an array of index ids, for example:

```bash
"857710ab-example-do-not-copy" OR ["857710ab-example1-do-not-copy","857710ab-example2-do-not-copy"]
```

#### ALT\_SEARCH\_KENDRA\_MAX\_DOCUMENT\_COUNT

Number - Overrides the maximum number of discovered text links
to display in markdown result. Default is 4.

#### ALT_SEARCH_KENDRA_S3_SIGNED_URLS  
  
If set **true** then if S3 document URL is in the search result, convert to a signed URL.
IMPORTANT: S3 Bucket names must start with qna (e.g. qnabot-mydocs), otherwise make sure IAM Role *...ESProxyLambdaRole...* (used by the Query function) has been granted S3:GetObject access to S3 objects in the Kendra index (otherwise the signed URLS will not have access)

#### ALT\_SEARCH\_KENDRA\_S3\_SIGNED\_URL\_EXPIRE\_SECS  
  
Value determines the expiration of the S3 URL - default 300 seconds.

## Installation

### Step 1

Set the ALT\_SEARCH\_KENDRA\_INDEXES setting in QnABot Designer UI Settings page

### Step 2

Using QnABot Designer UI, use the import menu and expand the Examples/Extensions block. Then look
for the extension named KendraFallback. Load this extension.

### Step 3

Once loaded you will update the question with the qid  "KendraFallback" changing its question from
"no_hits_alternative" to "no_hits".

### Step 4

If you have previously loaded the QnAUtility.json from Examples/Extensions you need to either remove
the question with the ID "CustomNoMatches" or change the question for this ID from "no_hits" to "no_hits_original"

Once the new question, "KendraFallback" is configured as the response for "no_hits", the Kendra index will be
searched for an answer whenever a curated answer can not be found. Once setup, Kendra provides a fallback
mechanism prior to telling the user an answer could not be found.