Dynamic hostnames

packer/hab-base/image.json

@@ -26,15 +26,29 @@
     "ami_name": "hab-base-{{timestamp}}"
   }],
   "provisioners": [
+    { "type": "file", "source": "../shared/files/hostname-adjectives", "destination": "hostname-adjectives" },
+    { "type": "file", "source": "../shared/files/hostname-nouns", "destination": "hostname-nouns" },
+    { "type": "file", "source": "../shared/files/set_hostname.sh", "destination": "set_hostname.sh" },
     { "type": "file", "source": "../shared/files/set_host_type_prompt.sh", "destination": "set_host_type_prompt.sh" },
+    { "type": "file", "source": "../shared/files/set-hostname.service", "destination": "set-hostname.service" },
     {
       "type": "shell",
       "execute_command": "echo 'packer' | sudo -S sh -c '{{ .Vars }} {{ .Path }}'",
       "inline": [
         "apt-get update",
         "apt install -y unattended-upgrades python awscli jq",
+        "mv hostname-nouns /usr/share/dict",
+        "mv hostname-adjectives /usr/share/dict",
         "mv set_host_type_prompt.sh /usr/bin",
+        "mv set_hostname.sh /usr/bin",
+        "mv set-hostname.service /etc/systemd/system/default.target.wants",
+        "chown root:root /etc/systemd/system/default.target.wants/set-hostname.service",
+        "chown root:root /usr/share/dict/hostname-nouns",
+        "chown root:root /usr/share/dict/hostname-adjectives",
+        "chown root:root /usr/bin/set_hostname.sh",
+        "chown root:root /usr/bin/set_host_type_prompt.sh",
         "chmod +x /usr/bin/set_host_type_prompt.sh",
+        "chmod +x /usr/bin/set_hostname.sh",
         "echo \". /usr/bin/set_host_type_prompt.sh\" >> /home/ubuntu/.bashrc",
         "echo \". /usr/bin/set_host_type_prompt.sh\" >> /root/.bashrc"
       ]

packer/shared/files/hostname-adjectives

@@ -0,0 +1,93 @@
+admiring
+adoring
+affectionate
+agitated
+amazing
+angry
+awesome
+blissful
+boring
+brave
+clever
+cocky
+compassionate
+competent
+condescending
+confident
+cranky
+dazzling
+determined
+distracted
+dreamy
+eager
+ecstatic
+elastic
+elated
+elegant
+eloquent
+epic
+fervent
+festive
+flamboyant
+focused
+friendly
+frosty
+gallant
+gifted
+goofy
+gracious
+happy
+hardcore
+heuristic
+hopeful
+hungry
+infallible
+inspiring
+jolly
+jovial
+keen
+kind
+laughing
+loving
+lucid
+mystifying
+modest
+musing
+naughty
+nervous
+nifty
+nostalgic
+objective
+optimistic
+peaceful
+pedantic
+pensive
+practical
+priceless
+quirky
+quizzical
+relaxed
+reverent
+romantic
+sad
+serene
+sharp
+silly
+sleepy
+stoic
+stupefied
+suspicious
+tender
+thirsty
+trusting
+unruffled
+upbeat
+vibrant
+vigilant
+vigorous
+wizardly
+wonderful
+xenodochial
+youthful
+zealous
+zen

packer/shared/files/hostname-nouns

@@ -0,0 +1,33 @@
+ardent
+artificer
+balrog
+barbarian
+bard
+cleric
+druid
+dwarf
+elf
+ent
+fighter
+giant
+goblin
+halfling
+hobbit
+illusionist
+invoker
+mage
+monk
+mystic
+orc
+paladin
+psion
+ranger
+rogue
+seeker
+sorcerer
+thief
+troll
+vampire
+warlock
+werewolf
+wizard

packer/shared/files/set-hostname.service

@@ -0,0 +1,8 @@
+[Unit]
+Description=Set Hostname and DNS
+
+[Service]
+ExecStart=/bin/bash /usr/bin/set_hostname.sh
+
+[Install]
+WantedBy=default.target

packer/shared/files/set_hostname.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+EXISTING_IP=""
+NEW_HOSTNAME=""
+
+HOSTED_ZONE_ID="Z26OTGLBBCAHK4"
+HOSTED_ZONE_NAME="reticulum.io"
+
+if [[ ! -z "$(hostname | grep $HOSTED_ZONE_NAME)" ]] ; then
+  echo "Hostname already set, exiting."
+  exit 0
+fi
+
+PUBLIC_IP=$(curl -s http://169.254.169.254/latest/meta-data/public-ipv4)
+INSTANCE_ID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
+REGION=$(curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone | sed 's/[a-z]$//')
+
+attempt_generate_hostname() {
+  ADJECTIVE=$(cat /usr/share/dict/hostname-adjectives | shuf | head -n1)
+  NOUN=$(cat /usr/share/dict/hostname-nouns | shuf | head -n1)
+
+  NEW_HOSTNAME="${ADJECTIVE}-${NOUN}"
+  DNS_IP=$(dig $NEW_HOSTNAME A +short)
+
+  if [[ ! -z "$DNS_IP" ]] ; then
+    EXISTING_IP=$(aws ec2 --region $REGION describe-instances | grep $DNS_IP)
+  fi
+}
+
+attempt_generate_hostname
+
+while [[ ! -z $EXISTING_IP ]]
+do
+  attempt_generate_hostname
+done
+
+echo "Setting hostname to ${NEW_HOSTNAME} and registering ${PUBLIC_IP}"
+
+ROUTE53_RECORD="{ \"ChangeBatch\": { \"Changes\": [ { \"Action\": \"UPSERT\", \"ResourceRecordSet\": { \"Name\": \"${NEW_HOSTNAME}.${HOSTED_ZONE_NAME}.\", \"Type\": \"A\", \"TTL\": 900, \"ResourceRecords\": [ { \"Value\": \"$PUBLIC_IP\" } ] } } ] } }"
+
+aws route53 change-resource-record-sets --hosted-zone-id "$HOSTED_ZONE_ID" --cli-input-json "${ROUTE53_RECORD}"
+aws ec2 create-tags --region $REGION --resources "${INSTANCE_ID}" --tags "Key=Name,Value=${NEW_HOSTNAME}"
+sudo hostname "$NEW_HOSTNAME.$HOSTED_ZONE_NAME"