Rolling Back

We'll see how to enable rollbacks using our current scheme for deployment. This will let you rollback to your previous code if you spot issues in your latest deployment.

Changes/New Functions

Here are a list of changes and new imports/functions in fabfile.py:

import os
from StringIO import StringIO
from tempfile import NamedTemporaryFile
# add "upload_template"
from fabric.contrib.files import exists, upload_template

# ...

last_release_file       = '/home/serial/serialapp.com/LAST_RELEASE'
current_release_file    = '/home/serial/serialapp.com/CURRENT_RELEASE' 

# ...

@task
def rollback():
    last_release = get_last_release()
    current_release = get_current_release()

    rollback_release(last_release)

    write_last_release(current_release)
    write_current_release(last_release)

def get_last_release():
    fd = StringIO()
    get(last_release_file, fd)
    return fd.getvalue()

def get_current_release():
    fd = StringIO()
    get(current_release_file, fd)
    return fd.getvalue()

def write_last_release(last_release):
    last_release_tmp = NamedTemporaryFile(delete=False)
    last_release_tmp.write('%(release)s')
    last_release_tmp.close()

    upload_template(last_release_tmp.name, last_release_file, {'release':last_release}, backup=False)
    os.remove(last_release_tmp.name)

def write_current_release(current_release):
    current_release_tmp = NamedTemporaryFile(delete=False)
    current_release_tmp.write('%(release)s')
    current_release_tmp.close()

    upload_template(current_release_tmp.name, current_release_file, {'release':current_release}, backup=False)
    os.remove(current_release_tmp.name)

def rollback_release(to_release):
    release_into = "%s/%s" % (release_dir, to_release)
    run("ln -nfs %s %s" % (release_into, current_release))
    run('sudo service php5-fpm reload')

# ...

def swap_symlinks():
    # ...

    # Put current_release as last release
    write_last_release(get_current_release())

    # Put new current_release
    write_current_release(next_release)

    # ...

Complete Fabfile

Here's the complete Fabfile with all changes:

from  __future__ import with_statement
import os
from time import time
from StringIO import StringIO
from tempfile import NamedTemporaryFile

from fabric.api import local, env, run, cd, get
from fabric.decorators import task
from fabric.contrib.files import exists, upload_template

env.use_ssh_config = True
env.hosts = ['serial-app']
# env.hosts = ['45.55.209.211']
# env.user = 'serial'
# env.key_filename = '~/.ssh/id_series'

git_repo        = 'git@github.com:Servers-for-Hackers/serialapp.git'
git_branch      = 'master'
release_dir     = '/home/serial/serialapp.com/releases'
current_release = '/home/serial/serialapp.com/current'
repo_dir        = '/home/serial/serialapp.com/repo'
last_release_file       = '/home/serial/serialapp.com/LAST_RELEASE'
current_release_file    = '/home/serial/serialapp.com/CURRENT_RELEASE'
persist_dir     = '/home/serial/serialapp.com/persist'
next_release    = "%(time).0f" % {'time': time()}

@task
def deploy():
    init()
    update_git()
    create_release()
    build_site()
    swap_symlinks()

@task
def rollback():
    last_release = get_last_release()
    current_release = get_current_release()

    rollback_release(last_release)

    write_last_release(current_release)
    write_current_release(last_release)

def get_last_release():
    fd = StringIO()
    get(last_release_file, fd)
    return fd.getvalue()

def get_current_release():
    fd = StringIO()
    get(current_release_file, fd)
    return fd.getvalue()

def write_last_release(last_release):
    last_release_tmp = NamedTemporaryFile(delete=False)
    last_release_tmp.write('%(release)s')
    last_release_tmp.close()

    upload_template(last_release_tmp.name, last_release_file, {'release':last_release}, backup=False)
    os.remove(last_release_tmp.name)

def write_current_release(current_release):
    current_release_tmp = NamedTemporaryFile(delete=False)
    current_release_tmp.write('%(release)s')
    current_release_tmp.close()

    upload_template(current_release_tmp.name, current_release_file, {'release':current_release}, backup=False)
    os.remove(current_release_tmp.name)

def rollback_release(to_release):
    release_into = "%s/%s" % (release_dir, to_release)
    run("ln -nfs %s %s" % (release_into, current_release))
    run('sudo service php5-fpm reload')

def init():
    if not exists(release_dir):
        run("mkdir -p %s" % release_dir)

    if not exists(repo_dir):
        run("git clone -b %s %s %s" % (git_branch, git_repo, repo_dir))

    if not exists("%s/storage" % persist_dir):
        run("mkdir -p %s/storage" % persist_dir)
        run("mkdir -p %s/storage/app" % persist_dir)
        run("mkdir -p %s/storage/framework" % persist_dir)
        run("mkdir -p %s/storage/framework/cache" % persist_dir)
        run("mkdir -p %s/storage/framework/session" % persist_dir)
        run("mkdir -p %s/storage/framework/views" % persist_dir)
        run("mkdir -p %s/storage/logs" % persist_dir)

def update_git():
    with cd(repo_dir):
        run("git checkout %s" % git_branch)
        run("git pull origin %s" % git_branch)

def create_release():
    release_into = "%s/%s" % (release_dir, next_release)
    run("mkdir -p %s" % release_into)
    with cd(repo_dir):
        run("git archive --worktree-attributes %s | tar -x -C %s" % (git_branch, release_into))

def build_site():
    with cd("%s/%s" % (release_dir, next_release)):
        run("composer install")

def swap_symlinks():
    # Build release directory
    release_into = "%s/%s" % (release_dir, next_release)

    # Symlink new .env and existing storage
    run("ln -nfs %s/.env %s/.env" % (persist_dir, release_into))
    run("rm -rf %s/storage" % release_into)
    run("ln -nfs %s/storage %s/storage" % (persist_dir, release_into))

    # Put site live
    run("ln -nfs %s %s" % (release_into, current_release))

    # Put current_release as last release
    write_last_release(get_current_release())

    # Put new current_release
    write_current_release(next_release)


    # Reload PHP-FPM gracefully
    run('sudo service php5-fpm reload')

Usage

Here's what that looks like when using it:

# On local computer

## Go to serialapp code in local development
cd ~/Sites/serialapp

## Source the virtualenv with fabric
## if needed
source .venv/bin/activate

## List tasks available
fabric -l

## Run our "deploy" task
fabric deploy

## Rollback
fabric rollback