Add script + doc note to access cluster via bastion host

Signed-off-by: Mikayla Thompson <thomika@amazon.com>

deployment/cdk/opensearch-service-migration/README.md

@@ -158,6 +158,17 @@ echo $FETCH_MIGRATION_COMMAND
 
 The pipeline configuration file can be viewed (and updated) via AWS Secrets Manager.
 
+## Accessing the Migration Analytics Domain
+
+The analytics domain receives metrics and events from the Capture Proxy and Replayer (if configured) and allows a user to visualize the progress and success of their migration.
+The domain & dashboard are only accessible from within the VPC, but a BastionHost is set up within the VPC that allows a user to use Session Manager to make the dashboard avaiable locally via port forwarding.
+
+Run the `accessAnalyticsDashboard` script, and then open https://localhost:8157/_dashboards to view your dashboard.
+```shell
+# ./accessAnalyticsDashboard.sh STAGE REGION
+./accessAnalyticsDashboard.sh dev us-east-1
+```
+
 
 ## Tearing down CDK
 To remove all the CDK stack(s) which get created during a deployment we can execute a command similar to below

deployment/cdk/opensearch-service-migration/accessAnalyticsDashboard.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Example usage: ./accessAnalyticsDashboard.sh dev us-east-1
+
+stage=$1
+region=$2
+
+export AWS_DEFAULT_REGION=$region
+
+bastion_id=$(aws ec2 describe-instances --filter Name=tag-key,Values=migration_deployment --filter Name=tag:Name,Values=BastionHost --filter Name=tag:aws:cloudformation:stack-name,Values=OSMigrations-${stage}-${region}-MigrationAnalytics | jq --raw-output '.Reservations[0].Instances[0].InstanceId')
+
+domain_endpoint=$(aws opensearch describe-domains --domain-names migration-analytics-domain | jq --raw-output '.DomainStatusList[0].Endpoints.vpc')
+
+JSON_STRING=$( jq -n -c\
+                  --arg port "443" \
+                  --arg localPort "8157" \
+                  --arg host "$domain_endpoint" \
+                  '{portNumber: [$port], localPortNumber: [$localPort], host: [$host]}' )
+
+echo "Access the Analytics Dashboard at https://localhost:8157/_dashboards"
+
+aws ssm start-session --target $bastion_id --document-name AWS-StartPortForwardingSessionToRemoteHost --parameters "${JSON_STRING}"