Certbot renewal hook scripts

These scripts help automate Let's Encrypt domain renewal. The certbot
renew command offers --manual-authenticate-hook and
--manual-cleanup-hook to automate the process of renewal. For DNS domain
validation the authenticate script will be called with CERTBOT_DOMAIN
and CERTBOT_VALIDATION values filled in. We then add a TXT record to the
domain with the supplied value and enter into a loop checking for
propagation. If propagated the hook returns to certbot which renews the
cert. Cleanup consists of removing the TXT record.

diff --git a/bin/certbot_authentication.sh b/bin/certbot_authentication.sh
new file mode 100755 (executable)
index 0000000..b026810
--- /dev/null
+++ b/bin/certbot_authentication.sh
@@ -0,0 +1,88 @@
+#!/bin/bash
+################################################################################
+#
+# File:         certbot_authentication.sh
+# Revision:     1.0
+# Description:  Perform domain validation by creating a TXT record on the domain
+#               from certbot. This script is designed to work with 
+#               Dreamhost.com's API and certbot running on Ubuntu 20.04. Note
+#               that it has not been extended to handle multiple domains.
+#
+#               Domain validation is the process of validating you have control
+#               over a domain. Services like Let's Encrypt can then issue you
+#               domain validated TLS certificates for use to secure websites.
+#
+# See also:     https://help.dreamhost.com/hc/en-us/articles/217555707-DNS-API-commands
+#
+# Crontab:      0 0 1 * * certbot renew --manual-auth-hook /path/to/certbot_authentication.sh --manual-cleanup-hook /path/to/certbot_cleanup.sh
+#
+# Author:       Andrew@DeFaria.com
+# Created:      Fri 04 Jun 2021 11:20:16 PDT
+# Modified:
+# Language:     Bash
+#
+# (c) Copyright 2021, ClearSCM, Inc., all rights reserved
+#
+################################################################################
+# The following are environment variables that certbot passes to us
+#
+# CERTBOT_DOMAIN:     Domain being authenticated. For example,
+#                     _acme-challenge.example.com for a wildcart cert or
+#                     _acme-challenge.subdomain.example.com for a subdomain
+#                     Note: Pass in $1 for testing or use the default of
+#                     CERTBOT_DOMAIN
+domain=${1:-CERTBOT_DOMAIN}
+
+# CERTBOT_VALIDATION: The validation string. Pass in $2 or use the default of
+#                     CERTBOT_VALIDATION
+value=${2:-CERTBOT_VALIDATION}
+
+# Dreamhost key - generate at https://panel.dreamhost.com/?tree=home.api
+key=KHY6UJQXD9MEJZHR
+
+# URL where the REST endpoint is
+url="https://api.dreamhost.com/?key=$key"
+
+# Add a TXT record to domain
+function addTXT {
+  echo "Adding TXT record $domain = $value)"
+  cmd="$url&unique_id=$(uuidgen)&cmd=dns-add_record&record=$domain&type=TXT&value=$value"
+
+  response=$(wget -O- -q "$cmd")
+
+  echo "$response"
+} # addTXT
+
+# Verifies that the TXT record has propogated. Note that this cannot be
+# likewise used for removal of the TXT record, which also needs to propagate.
+# However, we are not concerned with when the removal is propagated, it can
+# do so on its own time
+function verifyPropagation {
+  # We will try 4 times waiting 5 minutes in between
+  max_attempts=4
+  time_between_attempts=300
+
+  # Obviously it's not propagated immediately so first wait
+  attempt=0
+  while [ $attempt -lt 4 ]; do
+    echo "Waiting 5 minutes for TXT record $domain to propagate..."
+    sleep $time_between_attempts
+
+    ((attempt++))
+    echo "Attempt #$attempt: Validating of propagation of TXT record $domain"
+    TXT=$(nslookup -type=TXT $domain | grep -v "can't find" | grep $domain)
+
+    if [ -n "$TXT" ]; then
+      echo "TXT record $name.$domain propagated"
+      return
+    else
+      echo "TXT record $name.$domain not propagated yet"
+    fi
+  done
+
+  echo "ERROR: Unable to validate propagation"
+  exit 1
+} # verifyPropagation
+
+addTXT
+verifyPropagation

diff --git a/bin/certbot_cleanup.sh b/bin/certbot_cleanup.sh
new file mode 100755 (executable)
index 0000000..a337cf5
--- /dev/null
+++ b/bin/certbot_cleanup.sh
@@ -0,0 +1,57 @@
+#!/bin/bash
+################################################################################
+#
+# File:         certbot_cleanup.sh
+# Revision:     1.0
+# Description:  Perform cleanup after domain validation by removing the TXT
+#               record on the domain created by certbot_authentication.sh
+#
+#               Domain validation is the process of validating you have control
+#               over a domain. Services like Let's Encrypt can then issue you
+#               domain validated TLS certificates for use to secure websites.
+#
+# See also:     https://help.dreamhost.com/hc/en-us/articles/217555707-DNS-API-commands
+#
+# Crontab:      0 0 1 * * certbot renew --manual-auth-hook /path/to/certbot_authentication.sh --manual-cleanup-hook /path/to/certbot_cleanup.sh
+#
+# Author:       Andrew@DeFaria.com
+# Created:      Fri 04 Jun 2021 11:20:16 PDT
+# Modified:
+# Language:     Bash
+#
+# (c) Copyright 2021, ClearSCM, Inc., all rights reserved
+#
+################################################################################
+# The following are environment variables that certbot passes to us
+#
+# CERTBOT_DOMAIN:     Domain being authenticated. For example,
+#                     _acme-challenge.example.com for a wildcart cert or
+#                     _acme-challenge.subdomain.example.com for a subdomain
+#                     Note: Pass in $1 for testing or use the default of
+#                     CERTBOT_DOMAIN
+domain=${1:-CERTBOT_DOMAIN}
+
+# CERTBOT_VALIDATION: The validation string. Pass in $2 or use the default of
+#                     CERTBOT_VALIDATION
+value=${2:-CERTBOT_VALIDATION}
+
+# Dreamhost key - generate at https://panel.dreamhost.com/?tree=home.api 
+key=KHY6UJQXD9MEJZHR
+
+# URL where the REST endpoint is
+url="https://api.dreamhost.com/?key=$key"
+
+# Remove a TXT record. Oddly you must also specify the value.
+function removeTXT {
+  echo "Removing TXT record $CERTBOT_DOMAIN_DOMAIN = $CERTBOT_VALIDATION"
+  cmd="$url&unique_id=$(uuidgen)&cmd=dns-remove_record&record=$CERTBOT_DOMAIN&type=TXT&value=$CERTBOT_VALIDATION"
+
+  response=$(wget -O- -q "$cmd")
+
+  echo "$response"
+} # removeTXT
+
+removeTXT
+
+# Removal is instanteous but propagation will take some time. No need to wait
+# around though...
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