Add sample for Route53 DNS failover (#221)

* Add sample for Route53 DNS failover

* Add readme and make small fixes

* Add makefile

* minor changes to enable running under MacOS/M1

---------

Co-authored-by: Waldemar Hummer <[email protected]>

Author: viren-nadkarni

route53-dns-failover/Makefile

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+.PHONY: run
+
+run:
+	bash run_demo.sh

route53-dns-failover/README.md

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+This sample demonstrates the Route53 DNS failover based on health check in LocalStack.
+
+We suggest taking a look at [run_demo.sh](run_demo.sh) script to understand the setup.
+
+To run the demo:
+
+```
+$ LOCALSTACK_API_KEY=<your-api-key> docker-compose up -d
+```
+
+```
+$ make run
+```

route53-dns-failover/docker-compose.yml

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+version: "3.8"
+
+services:
+  localstack:
+    container_name: "${LOCALSTACK_DOCKER_NAME-localstack_main}"
+    image: localstack/localstack-pro:2.1.0
+    networks:
+      sweet_mahavira:
+    ports:
+      - "127.0.0.1:53:53"
+      - "127.0.0.1:53:53/udp"
+      - "127.0.0.1:4566:443"
+      - "127.0.0.1:4510:4510"
+    environment:
+      - LOCALSTACK_API_KEY=${LOCALSTACK_API_KEY}
+    volumes:
+      - "/var/run/docker.sock:/var/run/docker.sock"
+
+  # alternative 1:
+  http_echo:
+    container_name: http_echo
+    image: ealen/echo-server
+    networks:
+      sweet_mahavira:
+    ports:
+     - 5678:80
+
+  # alternative 2:
+  # http_echo:
+  #   container_name: http_echo
+  #   image: mendhak/http-https-echo
+  #   networks:
+  #     sweet_mahavira:
+  #   ports:
+  #     - "127.0.0.1:8080:8080"
+
+networks:
+  sweet_mahavira:

route53-dns-failover/run_demo.sh

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+#!/usr/bin/env bash
+
+# This is a demo script that showcases Route53 DNS failover in LocalStack
+# Make sure the Docker Compose setup is running before executing this script
+
+set -eux
+
+HOSTED_ZONE_NAME=hello-localstack.com
+
+# Create a hosted zone
+HOSTED_ZONE_ID=$(awslocal route53 create-hosted-zone --name $HOSTED_ZONE_NAME --caller-reference foo | jq -r .HostedZone.Id)
+
+# Create a health check that runs against the `http_echo` container
+HEALTH_CHECK_ID=$(awslocal route53 create-health-check --caller-reference foobar --health-check-config '{
+    "FullyQualifiedDomainName": "http_echo",
+    "Port": 80,
+    "ResourcePath": "/",
+    "Type": "HTTP",
+    "RequestInterval": 10
+}' | jq -r .HealthCheck.Id)
+
+# Create RRSets
+awslocal route53 change-resource-record-sets --hosted-zone ${HOSTED_ZONE_ID#/hostedzone/} --change-batch '{
+"Changes": [
+    {
+        "Action": "CREATE",
+        "ResourceRecordSet": {
+            "Name": "target1.'$HOSTED_ZONE_NAME'",
+            "Type": "CNAME",
+            "TTL": 60,
+            "ResourceRecords": [{"Value": "target1.example.com"}]
+        }
+    },
+    {
+        "Action": "CREATE",
+        "ResourceRecordSet": {
+            "Name": "target2.'$HOSTED_ZONE_NAME'",
+            "Type": "CNAME",
+            "TTL": 60,
+            "ResourceRecords": [{"Value": "target2.example.com"}]
+        }
+    }
+]}'
+awslocal route53 change-resource-record-sets --hosted-zone-id ${HOSTED_ZONE_ID#/hostedzone/} --change-batch '{
+"Changes": [
+    {
+        "Action": "CREATE",
+        "ResourceRecordSet": {
+            "Name": "test.'$HOSTED_ZONE_NAME'",
+            "Type": "CNAME",
+            "SetIdentifier": "target1",
+            "AliasTarget": {
+                "HostedZoneId": "'${HOSTED_ZONE_ID#/hostedzone/}'",
+                "DNSName": "target1.'$HOSTED_ZONE_NAME'",
+                "EvaluateTargetHealth": true
+            },
+            "HealthCheckId": "'${HEALTH_CHECK_ID}'",
+            "Failover": "PRIMARY"
+        }
+    },
+    {
+        "Action": "CREATE",
+        "ResourceRecordSet": {
+            "Name": "test.'$HOSTED_ZONE_NAME'",
+            "Type": "CNAME",
+            "SetIdentifier": "target2",
+            "AliasTarget": {
+                "HostedZoneId": "'${HOSTED_ZONE_ID#/hostedzone/}'",
+                "DNSName": "target2.'$HOSTED_ZONE_NAME'",
+                "EvaluateTargetHealth": true
+            },
+            "Failover": "SECONDARY"
+        }
+    }
+]}'
+
+# Get the IP address of the LocalStack container on the Docker bridge
+LOCALSTACK_DNS_SERVER=$(docker inspect localstack_main | jq -r '.[0].NetworkSettings.Networks."route53-dns-failover_sweet_mahavira".IPAddress')
+LOCALSTACK_DNS_SERVER=localhost
+
+# This IP address is used to query the LocalStack DNS server
+# This should return `target1.example.com` as the healthcheck is currently passing
+dig @$LOCALSTACK_DNS_SERVER +noall +answer test.hello-localstack.com CNAME
+
+# Make the healthcheck fail by pointing it to a nonexistent host
+awslocal route53 update-health-check --health-check-id ${HEALTH_CHECK_ID} --fully-qualified-domain-name bad-host-p45e8eG94rK.com
+
+# Wait for the healthcheck to refresh
+sleep 12
+
+# This should return the failover `target2.example.com`
+dig @$LOCALSTACK_DNS_SERVER +noall +answer test.hello-localstack.com CNAME