How to update your Reference Architecture to use the Gruntwork Service Catalog

#!/usr/bin/env bash
# Helper functions for implementing state migrations for updating terraform modules to newer versions.

function log {
  >&2 echo -e "$@"
}

# find_state_address uses the provided query string to identify the full resource address to use in the state file.
function find_state_address {
  local -r query="$1"

  log "Identifying real state address of $query"
  terragrunt state list \
    | grep -E "$query" || true
}

# strip_bash_color will strip out bash color/bold escape sequences.
function strip_bash_color {
  local -r input="$1"
  # Based on this stack overflow post: https://stackoverflow.com/questions/6534556/how-to-remove-and-all-of-the-escape-sequences-in-a-file-using-linux-shell-sc.
  # None of the sed calls worked to completely strip of the escape sequences by itself, but the following combination worked.
  echo "$input" | cat -v | sed 's/\^\[\[[10]m//g'
}

# Check that the given binary is available on the PATH. If it's not, exit with an error.
function assert_is_installed {
  local -r name="$1"
  local -r help_url="$2"

  if ! command -v "$name" > /dev/null; then
    log "ERROR: The command '$name' is required by this script but is not installed or in the system's PATH. Visit $help_url for instructions on how to install."
    exit 1
  fi
}

# Make sure that the hcledit utility is installed and available on the system.
function assert_hcledit_is_installed {
  assert_is_installed 'hcledit' 'https://github.com/minamijoyo/hcledit#install'
}

# Make sure that the jq utility is installed and available on the system.
function assert_jq_is_installed {
  assert_is_installed 'jq' 'https://stedolan.github.io/jq/download/'
}

# Move resources in a literal terraform state move. Unlike a simple terragrunt state mv call, this does error checking
# to make sure the given state actually exists.
function move_state {
  local -r original_addr="$1"
  local -r new_addr="$2"

  if [[ "$original_addr" == "$new_addr" ]]; then
    echo "Nothing to change. Skipping state migration."
    return
  fi

  if ! terragrunt state show "$original_addr" >/dev/null 2>&1; then
    echo "Original address $original_addr not found in state file. Nothing to change. Skipping state migration."
    return
  fi

  echo "Migrating state:"
  echo
  echo "    $original_addr =>"
  echo "      $new_addr"
  echo
  terragrunt state mv "$original_addr" "$new_addr"
}

# Move resources in terraform state using fuzzy matches.
function fuzzy_move_state {
  local -r original_addr_query="$1"
  local -r new_addr="$2"
  local -r friendly_name="$3"

  log "Checking if $friendly_name needs to be migrated"

  local original_addr
  original_addr="$(find_state_address "$original_addr_query")"

  if [[ -z "$original_addr" ]] || [[ "$original_addr" == "$new_addr" ]]; then
    echo "Nothing to change. Skipping state migration."
  else
    echo "Migrating state:"
    echo
    echo "    $original_addr =>"
    echo "      $new_addr"
    echo
    terragrunt state mv "$original_addr" "$new_addr"
  fi
}

# The following routine extracts a resource attribute.
function extract_attribute {
  local -r address="$1"
  local -r resource_basename="$2"
  local -r attribute="$3"

  local state
  state="$(terragrunt state show "$address")"
  local state_nocolor
  state_nocolor="$(strip_bash_color "$state")"

  echo "$state_nocolor" \
    | hcledit attribute get "$resource_basename"."$attribute" \
    | jq -r '.'
}

# Move resources in terraform state using an import call instead of state mv. This is useful when moving resources
# across aliased resources (e.g., aws_alb => aws_lb).
function fuzzy_import_move_state {
  local -r original_addr_query="$1"
  local -r new_addr="$2"
  local -r resource_basename="$3"
  local -r friendly_name="$4"

  log "Checking if $friendly_name needs to be migrated."
  local original_addr
  original_addr="$(find_state_address "$original_addr_query")"
  if [[ -z "$original_addr" ]]; then
    log "$friendly_name is already migrated. Skipping import."
    return
  fi

  log "$friendly_name needs to be migrated"

  log "Identifying $friendly_name ID to import into new resource."
  local resource_id
  resource_id="$(extract_attribute $original_addr $resource_basename "id")"

  if [[ -z "$resource_id" ]]; then
    log "ERROR: could not identify $friendly_name ID to import."
    exit 1
  fi

  log "Importing $friendly_name to new resource:"
  log
  log "    ID:           $resource_id"
  log "    ResourceAddr: $new_addr"
  terragrunt import "$new_addr" "$resource_id"

  log "Removing old $friendly_name state."
  terragrunt state rm "$original_addr"
}

# This function migrates the original list into a new map at the original address.
# First it moves each item in the list into a new map.
# Then it moves the new map back to the original address.
# The keys of the new map correspond to the value of the attribute that is passed into `attribute`.
# We look up this value in the function.
function move_state_list_to_map {
  local -r original_addr="$1"
  local -r attribute="$2"

  # Move the list to a temporary map
  local map_addr
  map_addr="$1_tmp"

  # Pull the full list of addresses in the original_addr (aws_ecr_repository.repos[0], aws_ecr_repository.repos[1], etc)
  local list_addresses
  list_addresses="$(find_state_address "$original_addr")"
  for addr in $list_addresses
  do
    # Extract the attribute that will be the new key in the map.
    local key
    key="$(extract_attribute "$addr" "resource.$original_addr" "$attribute")"
    echo "Migrating state:"
    echo
    echo "    $addr =>"
    echo "      $map_addr[$key]"
    echo
    # Move the resource to the new temporary map address.
    terragrunt state mv "$addr" "$map_addr[\"$key\"]"
  done

  # Move the temporary map back to the original address, now as a map
  terragrunt state mv "$map_addr" "$original_addr"
}

# This function migrates a list to a new list with a different name.
function fuzzy_move_list {
  local -r original_list="$1"
  local -r new_list="$2"
  local -r friendly_name="$3"

  log "Checking if $friendly_name needs to be migrated"

  if [[ -z "$original_list" ]] || [[ "$original_list" == "$new_list" ]]; then
    echo "Nothing to change. Skipping state migration."
  else
    local original_addrs
    original_addrs="$(find_state_address "$original_list")"
    for addr in $original_addrs
    do
      local new_addr
      new_addr="$(
        echo "$addr" \
          | sed "s/$original_list/$new_list/"
      )"
      echo "Migrating state:"
      echo
      echo "    $addr =>"
      echo "      $new_addr"
      echo
      terragrunt state mv "$addr" "$new_addr"
    done
  fi
}