bash wrapper around doctl digital ocean cli, can be used to backup & resize a droplet

resize-droplet.bash

#!/usr/bin/env bash

# Note if you try to resize to the same size, it just takes a backup.

# One use is to setup as a crontab configured to auto scale down your
# servers at 3am (in-case you forget, saving you money).

# Dependencies:
#   doctl (DO cli)
#   jq (a great json manipulating cli tool)
#   backup-remote-machine (my funky bash script, it's optional)

if [[ $# != 2 ]]; then
  echo "usage: <droplet name> <size slug>"
  echo "       resize-droplet ubuntu-s-1vcpu-1gb-lon1-ansible-01 s-8vcpu-32gb"
  echo "       resize-droplet ubuntu-s-1vcpu-1gb-lon1-ansible-01 s-1vcpu-1gb"
  exit 1
fi

# Config
log_file="/tmp/resize-droplet.log"
ssh_username="bamarch"

main(){

  # Gather information
  droplet_name="$1"
  target_size_slug="$2"

  droplet_id=$(fetch-droplet-info-by-name "$droplet_name" "ID")
  echo "Found ID $droplet_id for $droplet_name." >> "$log_file" 2>&1

  droplet_ipv4=$(fetch-droplet-info-by-name "$droplet_name" "PublicIPv4")
  echo "Found IP $droplet_ipv4 for $droplet_name." >> "$log_file" 2>&1

  # Backup the droplet locally (could be skipped)
  backup-remote-machine "$droplet_ipv4" >> "$log_file" 2>&1
  if [[ $? != 0 ]]; then
    echo "Backup failure, exiting!" >> "$log_file" 2>&1
  fi

  # Go no further if the droplet doesn't need resizing
  current_size_slug=$(fetch-droplet-info-by-id $droplet_id '.[] .size_slug')
  echo "Current size slug: $current_size_slug. Target size slug: $target_size_slug"  >> "$log_file" 2>&1
   if [[ "$target_size_slug" = "$current_size_slug" ]]; then
    echo "Will not proceed further, size slugs match, no resize is required." >> "$log_file" 2>&1
    exit 0
  fi

  # Shutdown the server before resizing
  # (requires passwordless sudo - make sure you have a good RSA key, and disable password auth for ssh login)
  ssh "${ssh_username}@${droplet_ipv4}" 'sudo shutdown now'
  echo "Attempting to switch off droplet..."  >> "$log_file" 2>&1
  counter=0
  until [[ $(fetch-droplet-info-by-name "$droplet_name" "Status") = "off" ]]; do
    let "counter++"
    if [[ $counter = 20 ]]; then
      echo "Timed out waiting for droplet to switch off" >> "$log_file" 2>&1
      exit 1
    fi
    echo "Attempt #$counter: Droplet is $(fetch-droplet-info-by-name "$droplet_name" "Status")" >> "$log_file" 2>&1
    echo "Waiting for droplet to switch off..." >> "$log_file" 2>&1
    sleep 1
  done
  echo "Droplet is off."  >> "$log_file" 2>&1


  # Resize the droplet
  echo "Resizing $droplet_name to $target_size_slug" >> "$log_file" 2>&1
  resize_action_id=$(droplet-action-resize "$droplet_id" "$target_size_slug")
  if [[ -n $resize_action_id ]]; then
    echo "Resize action id is $resize_action_id" >> "$log_file" 2>&1
  else
    echo "Error unable to parse resize action id" >> "$log_file" 2>&1
    exit 1
  fi

  # Wait
  echo "Waiting for droplet to resize..."  >> "$log_file" 2>&1
  counter=0
  until [[ $(fetch-droplet-action-resize-status "$droplet_id" "$resize_action_id") = "completed" ]]; do
    let "counter++"
    if [[ $counter = 3600 ]]; then
      echo "Timed out waiting for droplet to be ready" >> "$log_file" 2>&1
      exit 1
    fi
    current_status=$(fetch-droplet-action-resize-status "$droplet_id" "$resize_action_id")
    if [[ $current_status != "in-progress" && $current_status != "completed" ]]; then
      echo "Unexpected action status: $current_status" >> "$log_file" 2>&1
      exit 1
    fi
    echo "Current resize status is: $current_status"
    echo "Loop #$counter: Waiting for droplet to be ready..." >> "$log_file" 2>&1
    sleep 1
  done
  echo "Action $resize_action_id was completed, droplet is resized"  >> "$log_file" 2>&1

  # Everything went well, power the droplet back on
  droplet-power-on "$droplet_id"
}

fetch-droplet-info-by-name() {
  # e.g. fetch-droplet-info-by-name $droplet-name 'ID'
  #      fetch-droplet-info-by-name $droplet-name 'PublicIPv4'
  # Whitespace after the name is important to prevent matching substrings
  doctl compute droplet list --no-header --format="Name,$2" |\
  tee -a "$log_file" |\
  grep "^$1 " |\
  awk '{print $2}'
}

fetch-droplet-info-by-id() {
   # e.g. fetch-droplet-info-by-id $droplet_id '.[] .size_slug'
   #      fetch-droplet-info-by-id $droplet_id '.[] .networks .v4[] .ip_address'
  doctl compute droplet get "$1" --output='json' |\
  tee -a "$log_file" |\
  jq --raw-output "$2"
}

droplet-action-resize() {
  # e.g. droplet-action-resize "$droplet_id" "$target_size_slug"
  doctl compute droplet-action resize "$1" --size="$2" --output='json' |\
  tee -a "$log_file" |\
  jq --raw-output '.[] .id'
}

fetch-droplet-action-resize-status() {
  # e.g. fetch-droplet-action-resize-status "$droplet_id" "$resize_action_id"
  doctl compute droplet-action get "$1" --action-id "$2" --output='json' |\
  jq --raw-output '.[] .status'
}

droplet-power-on() {
  # e.g. droplet-power-on "$droplet_id"
  doctl compute droplet-action power-on "$1" |\
  tee -a "$log_file"
}

#-------------------------------
# Call main method with all args
main "$@"