145 lines
4 KiB
Bash
Executable file
145 lines
4 KiB
Bash
Executable file
#!/bin/bash
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# Configure systemd-resolved it to forward requests for a specific domain to Consul. This script has been tested
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# with the following operating systems:
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#
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# 1. Ubuntu 18.04
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# See https://learn.hashicorp.com/consul/security-networking/forwarding#systemd-resolved-setup for more details
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# Github Issue: https://github.com/hashicorp/consul/issues/4155
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set -e
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readonly DEFAULT_CONSUL_DOMAIN="consul"
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readonly DEFAULT_CONSUL_IP="127.0.0.1"
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readonly DEFAULT_CONSUL_DNS_PORT=8600
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readonly SYSTEMD_RESVOLDED_CONFIG_FILE="/etc/systemd/resolved.conf"
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readonly SCRIPT_NAME="$(basename "$0")"
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function print_usage {
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echo
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echo "Usage: setup-systemd-resolved [OPTIONS]"
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echo
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echo "Configure systemd-resolved to forward requests for a specific domain to Consul. This script has been tested with Ubuntu 18.04."
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echo
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echo "Options:"
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echo
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echo -e " --consul-domain\tThe domain name to point to Consul. Optional. Default: $DEFAULT_CONSUL_DOMAIN."
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echo -e " --consul-ip\t\tThe IP address to use for Consul. Optional. Default: $DEFAULT_CONSUL_IP."
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echo -e " --consul-dns-port\tThe port Consul uses for DNS. Optional. Default: $DEFAULT_CONSUL_DNS_PORT."
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echo
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echo "Example:"
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echo
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echo " setup-systemd-resolved"
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}
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function log {
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local -r level="$1"
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local -r message="$2"
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local -r timestamp=$(date +"%Y-%m-%d %H:%M:%S")
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>&2 echo -e "${timestamp} [${level}] [$SCRIPT_NAME] ${message}"
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}
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function log_info {
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local -r message="$1"
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log "INFO" "$message"
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}
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function log_warn {
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local -r message="$1"
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log "WARN" "$message"
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}
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function log_error {
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local -r message="$1"
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log "ERROR" "$message"
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}
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function assert_not_empty {
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local -r arg_name="$1"
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local -r arg_value="$2"
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if [[ -z "$arg_value" ]]; then
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log_error "The value for '$arg_name' cannot be empty"
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print_usage
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exit 1
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fi
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}
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function install_dependencies {
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local -r consul_ip="$1"
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log_info "Installing dependencies"
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sudo apt-get update -y
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echo iptables-persistent iptables-persistent/autosave_v4 boolean true | sudo debconf-set-selections
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echo iptables-persistent iptables-persistent/autosave_v6 boolean true | sudo debconf-set-selections
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sudo apt-get install -y iptables-persistent
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}
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function configure_systemd_resolved {
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local -r consul_domain="$1"
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local -r consul_ip="$2"
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local -r consul_port="$3"
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UBUNTU_VERSION=`lsb_release -s -r`
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if [ "$UBUNTU_VERSION" == "18.04" ]; then
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log_info "Configuring systemd-resolved to forward lookups of the '$consul_domain' domain to $consul_ip:$consul_port in $CONSUL_DNS_MASQ_CONFIG_FILE"
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sudo iptables -t nat -A OUTPUT -d localhost -p udp -m udp --dport 53 -j REDIRECT --to-ports $consul_port
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sudo iptables -t nat -A OUTPUT -d localhost -p tcp -m tcp --dport 53 -j REDIRECT --to-ports $consul_port
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sudo iptables-save | sudo tee /etc/iptables/rules.v4
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sudo ip6tables-save | sudo tee /etc/iptables/rules.v6
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sudo sed -i "s/#DNS=/DNS=${consul_ip}/g" "$SYSTEMD_RESVOLDED_CONFIG_FILE"
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sudo sed -i "s/#Domains=/Domains=~${consul_domain}/g" "$SYSTEMD_RESVOLDED_CONFIG_FILE"
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else
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log_error "Cannot install on this OS."
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exit 1
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fi
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}
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function install {
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local consul_domain="$DEFAULT_CONSUL_DOMAIN"
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local consul_ip="$DEFAULT_CONSUL_IP"
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local consul_dns_port="$DEFAULT_CONSUL_DNS_PORT"
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while [[ $# > 0 ]]; do
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local key="$1"
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case "$key" in
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--consul-domain)
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assert_not_empty "$key" "$2"
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consul_domain="$2"
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shift
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;;
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--consul-ip)
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assert_not_empty "$key" "$2"
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consul_ip="$2"
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shift
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;;
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--consul-dns-port)
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assert_not_empty "$key" "$2"
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consul_dns_port="$2"
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shift
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;;
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--help)
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print_usage
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exit
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;;
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*)
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log_error "Unrecognized argument: $key"
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print_usage
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exit 1
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;;
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esac
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shift
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done
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log_info "Configuring systemd-resolved"
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install_dependencies
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configure_systemd_resolved "$consul_domain" "$consul_ip" "$consul_dns_port"
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log_info "systemd-resolved configured!"
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}
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install "$@"
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