Bash script to automate the renewal of LetsEncrypt certificates using DNS authentication with Route53 and then updating the load balancers

update_elb_certificate_letsencrypt_route53.sh

#!/usr/bin/bash

# pre-requisites:
# apt install python3-pip awscli
# pip3 install certbot certbot-dns-route53 awscli
# mkdir .certbot/{config,work,logs}
# IAM policy attached to EC2 instance with:
#  - route53:ListHostedZones
#  - route53:GetChange
#  - route53:ChangeResourceRecordSets
#  - acm:ListCertificates
#  - acm:ImportCertificate
#  - acm:AddTagsToCertificate
#  - elasticloadbalancing:SetLoadBalancerListenerSSLCertificate

# USAGE ./update_certificates.sh -d DOMAINTOGETCERTFOR -l LOADBALANCERTOUPDATE
#  e.g. ./update_certificates.sh -d *.example.com -l production-public-lb

while getopts d:l: option
do
	case "${option}"
	in
	d) DOMAIN=${OPTARG};;
	l) LOADBALANCER=${OPTARG};;
	esac
done

if [ -z "$DOMAIN" ] || [ -z "$LOADBALANCER" ];
then
	echo "Error: Domain or LoadBalancer variable not set. Exiting"
	echo "USAGE ./update_certificates.sh -d DOMAINTOGETCERTFOR -l LOADBALANCERTOUPDATE"
	echo "  e.g. ./update_certificates.sh -d *.example.com -l production-public-lb"

	exit 1
fi

echo "$(date) Getting certificate for domain - $DOMAIN, and updating load balancer - $LOADBALANCER"

SHORTDOMAIN=$DOMAIN
if [[ "$DOMAIN" == *"*"* ]]
then
	echo "Wildcard domain supplied - $DOMAIN"
	SHORTDOMAIN=$(echo $DOMAIN | cut -d'.' -f2-)
	echo "Without wildcard is $SHORTDOMAIN"
fi

# Get the certificates
.local/bin/certbot certonly \
	--config-dir .certbot/config \
	--work-dir .certbot/work \
	--logs-dir .certbot/logs \
	-n --agree-tos \
	--email ops@example.com \
	--dns-route53 -d $DOMAIN \

MD5SUM_CERT=$(md5sum .certbot/config/live/$SHORTDOMAIN/cert.pem | cut -d' ' -f1)
MD5SUM_KEY=$(md5sum .certbot/config/live/$SHORTDOMAIN/privkey.pem | cut -d' ' -f1)
TIMENOW=$(date +%s)

echo "Checking if certificate is already in AWS Certificate Manager..."
for acmCertificate in $(/home/ubuntu/.local/bin/aws acm list-certificates | jq -r .CertificateSummaryList[].CertificateArn)
do
	echo "Checking certificate with ARN: $acmCertificate"
	ACM_CERT_MD5SUM=$(/home/ubuntu/.local/bin/aws acm list-tags-for-certificate --certificate-arn $acmCertificate | jq -r '.Tags[] | select(.Key | contains("Md5SumCert")) | .Value')

        if [[ "$MD5SUM_CERT" == "$ACM_CERT_MD5SUM" ]]
        then
		echo "$(date) Found certificate with matching hash! No need to import."
		CERTIFICATE_ARN=$acmCertificate
		break
        fi
done

if [ -z "$CERTIFICATE_ARN" ]
then
	echo "No matches found. Importing certificate to AWS Certificate Manager..."
	CERTIFICATE_ARN=$(/home/ubuntu/.local/bin/aws acm import-certificate \
		--certificate file://.certbot/config/live/$SHORTDOMAIN/cert.pem \
		--private-key file://.certbot/config/live/$SHORTDOMAIN/privkey.pem \
		--certificate-chain file://.certbot/config/live/$SHORTDOMAIN/chain.pem \
		--tags Key=Name,Value=tj_co_wld_$TIMENOW Key=Md5SumCert,Value=$MD5SUM_CERT Key=Md5SumKey,Value=$MD5SUM_KEY \
		| jq -r .CertificateArn)
fi

ELB_NAME=$LOADBALANCER

echo "$(date) Updating SSL certificate of $ELB_NAME load balancter to be $CERTIFICATE_ARN"

# Switch LoadBalancers to use the new certificate
/home/ubuntu/.local/bin/aws elb set-load-balancer-listener-ssl-certificate \
	--load-balancer-name $ELB_NAME \
	--load-balancer-port 443 \
	--ssl-certificate-id $CERTIFICATE_ARN