cf-bg-restart.sh

#!/bin/bash

# cf-bg-restart.sh - Zero-downtime application restarting and restaging, inspired by bg-restage: https://github.com/orange-cloudfoundry/cf-plugin-bg-restage
# Copyright (C) 2018  Rakuten, Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Dependencies: cf, jq >= 1.5

set -euo pipefail

show_usage () {
    cat << EOF
Usage: $(basename "$0") [OPTION]... APP_NAME

  -S                enable ssh
  -r                restage
  -s STACK          override stack (must be used with -r)
  -b BUILDPACK      override buildpack (must be used with -r)
  -h                display this help and exit

Examples:
  $(basename "$0") myapp
EOF
}

# Process command line options
opt_ssh="false"
opt_restage="false"
opt_stack=""
opt_buildpack=""
while getopts "Srs:b:h" opt; do
    case $opt in
        S)  opt_ssh="true"
            ;;
        r)  opt_restage="true"
            ;;
        s)  opt_stack=$OPTARG
            ;;
        b)  opt_buildpack=$OPTARG
            ;;
        h)
            show_usage
            exit 0
            ;;
        ?)
            show_usage >&2
            exit 1
            ;;
    esac
done
shift $(($OPTIND - 1))

if [[ $# -ne 1 ]] || { [[ -n $opt_stack || -n $opt_buildpack ]] && ! $opt_restage; }; then
    show_usage >&2
    exit 1
fi

cf_push_opts=()
if $opt_restage; then
    [[ -n $opt_stack ]] && cf_push_opts+=(-s "$opt_stack")
    [[ -n $opt_buildpack ]] && cf_push_opts+=(-b "$opt_buildpack")
fi

log_info () { sed <<< "$@" 's/^/[INFO] /'; }
log_error () { sed <<< "$@" 's/^/[ERROR] /'; }

APP_NAME="$1"
APP_OLD="${APP_NAME}-venerable"

# Unfortunately cf cli doesn't provide a programmatic way to determine the currently targeted space
if [[ $(cf app "$APP_NAME" --guid 2>&1 1>/dev/null) =~ App\ \'?$APP_NAME\'?\ not\ found ]]; then
  log_error "App $APP_NAME not found"
  exit 1
elif [[ $(cf curl /v3/apps/$(cf app "$APP_NAME" --guid) | jq -er '.state') != "STARTED" ]]; then
  log_error "App $APP_NAME is found but not started"
  exit 1
else
  APP_GUID=$(cf app "$APP_NAME" --guid)
  DROPLET_GUID=$(cf curl "/v3/apps/$APP_GUID/relationships/current_droplet" | jq -er '.data.guid')

  # Create temporary directories and files
  export TMPDIR=$(mktemp -d)
  manifest_file=$(mktemp)
  empty_dir=$(mktemp -d)

  # Get manifest
  log_info "Getting manifest ..."
  cf create-app-manifest "$APP_NAME" -p "$manifest_file"

  # Rename App
  log_info "Renaming app ..."
  cf rename "$APP_NAME" "$APP_OLD"

  # Push empty app
  log_info "Pushing an empty app ..."
  touch "$empty_dir/.empty"
  cf push -f "$manifest_file" -p "$empty_dir" --no-start "${cf_push_opts[@]+"${cf_push_opts[@]}"}" > /dev/null
  new_app_guid=$(cf app "$APP_NAME" --guid)

  # Enable SSH
  if $opt_ssh; then
    log_info "Enabling SSH ..."
    cf enable-ssh "$APP_NAME"
  fi

  # Copy app bits
  log_info "Copying the app bits ..."
  cf copy-source --no-restart "$APP_OLD" "$APP_NAME"
 
  # Copy droplet
  if ! $opt_restage; then
    log_info "Copying the droplet ..."
    new_droplet_guid=$(cf curl -X POST "/v3/droplets?source_guid=$DROPLET_GUID" -d "{\"relationships\": {\"app\": {\"data\": {\"guid\": \"$new_app_guid\"}}}}" | jq -er '.guid')
    while sleep 1; do
      [[ $(cf curl "/v3/droplets/$new_droplet_guid" | jq -r '.state') == "STAGED" ]] && break
    done
    log_info "Setting the droplet as current ..."
    cf curl -X PATCH "/v3/apps/$new_app_guid/relationships/current_droplet" -d "{\"data\": {\"guid\": \"$new_droplet_guid\"}}" > /dev/null
  fi

  # Start the app
  log_info "Starting the app ..."
  cf start "$APP_NAME"

  # Clean up
  log_info "Deleting the old app ..."
  cf delete -f "$APP_OLD"
  log_info "Deleting temporary files ..."
  rm -r "$TMPDIR"
fi