automated deployment

Automated DeploymentBuilding a simple automated deployment platform with PHP and Linux

Michael Peacock@michaelpeacockmichaelpeacock.co.uk

whois?

• Senior / Lead Web Developer• Zend Certified Engineer• Published Author– PHP 5 Social Networking, PHP 5 E-Commerce

development & more

Deployment: (an) old style approach

• Take website offline / put into maintenance mode

• Backup everything• Upload new files - FTP• Upgrade database• Put online, and hope for the best

• Do it twice: once for staging and once for deployment

http://xkcd.com/303/

The problem

• Down time for upgrades• Manual process– FTP takes time; – forgot to CHMOD? – Clients want to see progress now!– Bugs and issues can lie dormant for some time

What about...

• Many existing solutions are geared towards large projects

• What about...– the little guy;– the small agency– the web app start up on an entry level VPS?

What's in store?

A few simple techniques, scripts and ideas that we currently use to make deployment easy

Deployment: the basics

• Get your latest code from version control, and stick it online

• Keep a central record of all the CHMOD / CHOWNing that you need to do

• Swap around your database connection details and other suitable configuration files

SVN Export

• Start with a simple svn export

– Store the date/time in a variable – Create two folders, named with the current

date/time. One within the web root, one outside of it

– Two exports: public and private (or one export, and some moving around of folders – up to you!)

#!/bin/bashDATE=`date +%H-%M-%e-%m-%y`mkdir /var/www/staging/$DATE/mkdir /var/www/staging-private/$DATE/

svn export --quiet --username phpne --password PhpN3 httP://localhost/svn/project/trunk /var/www/staging/$DATE/

svn export --quiet --username phpne --password PhpN3 http://localhost/svn/project/private /var/www/staging-private/$DATE/

SVN Export

Keep your servers svn client happy! It will ask what to do with the svn password, and nobody will listen – so tell it!

sudo nano /var/www/.subversion/servers

store-plaintext-passwords = no

AUTONOMYln –s /staging /live

Autonomy

• When the latest code is checked out, tests have been run, uploads imported, configuration changed and database patched we need to swap this into place instantly

• The answer: symlinks

#!/bin/bashDATE=`date +%H-%M-%e-%m-%y`

...

rm /home/user/public_html/

ln –s /var/www/staging/$DATE/ /home/user/public_html/

Sadly, you can’t edit a symlink, hence rm

My user profile pictures aren’t in version control…

User contributed files

• Store them elsewhere?– On a content delivery network?– On a sub-domain– Symlink them

• Copy them in post svn export?– A bit nasty and takes time, and what about new

user uploads during the copying process?

THE DATABASE

• Photo of database table not found, or mysql gone away error message

http://www.flickr.com/photos/meandmybadself/165846637/

Database changes: patches

For database changes to apply on deploy, you need some deploy aware code in your project.

• Multi-query patch processing

• Schema compare; its easy to forget a database patch!

• Backup database before applying patches

public function updateDatabase( $patchID, $some=false ) {

// look for the next patch if( file_exists( FRAMEWORK_PATH . '../database/patches/' . ++$patchID . '.php' ) ) {

$sql = file_get_contents( FRAMEWORK_PATH . '../database/patches/' . $patchID . '.php' );

// apply the changes from the patch mysqli_multi_query( $sql ); // lather, rinse and repeat$this->updateDatabase( $patchID, true );

} else if( $some ) {

// All done? Update patch ID in databasemysqli_query(“UPDATE settings SET `value`=” . $patchID-1 .

“ WHERE `key`=‘database-patch-id’ ” );exit();

} }

Apply your database patches

$testTables = array();mysqli_select_db( $config['patched_db'] );$result = mysql_query("SHOW TABLES");while( $row = mysql_fetch_row($result) ) {

$testTables[ $row[0] ] = array();}foreach( $testTables as $table => $fields ){

$result = mysql_query("SHOW COLUMNS FROM " . $table );

while( $row = mysql_fetch_assoc( $result ) ) {

$tables[ $table ][ $row['Field'] ] = $row;}

}

Turn your database schema into an array

Compare your patched database to what you expected

http://joefreeman.co.uk/blog/2009/07/php-script-to-compare-mysql-database-schemas/

Databases: Test Database

• If you are applying changes to your database structure, you will need another test database

• Changes are first applied to the test database– Comparisons run against it– Unit testing run against code working with that

database• When all is clear, the live database can be

patched and upgraded

Ask the audience

• Database integration, patching, testing and deployment is probably the weakest link in this deployment chain

Unit testing

• While its good practice to only commit code which passes unit tests, sometimes a commit can break existing code if you are a lazy svn updater

• Run the unit tests against sandboxed code before pushing the deployment live

• Did the deployment fail?

Unit testing

• Both PHPUnit and PHP SimpleTest have command line interface

• Options:– Parse the output and look for errors; then

continue once its done– Store a report, and require manual approval

before continuing with deployment

phpunit –testdox-text somefile.txt MyTests

*this isn’t a stage I’ve actually implemented in our deployment pipeline, just something I’m working on

The problem with including Unit Tests

• Running unit tests take time

• We need to log deployment attempts, and try and deploy them once the tests have been run

• We need a central deployment system

• Photo of USB “kill switch”

http://www.flickr.com/photos/stevendepolo/3517227492/

Triggering deployment: PHP

echo shell_exec( ‘/var/deploy/deploy.sh ’ . $project . ‘ ‘ . $environment );

What about root?

Deployment script requires root access? Update sudoers file

PHP Deploy as Root

• Edit the sudoers file– Sudo visudo

• Create an alias for your deployment scripts– Cmnd_Alias DPLY = /var/deploy/script1,

/var/deploy/script2• Let the webserver execute as root, without

requiring a password– www-data ALL=(ALL) NOPASSWD: DPLY

Automating deployment

• Cron

• Postcommit hooks– Do this for your bleeding edge staging area; its

good to continually test code in its live server environment

• Scheduled deployments

Deployment Infrastructure

• Deploying projects across multiple servers?

– Send your commands over SSH to a remote server

– Implement a skeleton deployment system on each server, called from a central deployment area

Build a deployment platform

• Projects• Deployment areas:– Bleeding– Staging– Production

• Configurations, reports and deployment schedules

Recap

1. Export your repository2. Apply your permission changes3. Swap in/out the appropriate configuration files4. Backup your (test) database5. Patch your database6. Unit test validation7. Swap in/out your configuration files8. Pull in user contributed files9. Backup your environment database10. Patch your live database11. Update your symlinks

Rolling back

Shit! That last deployment didn’t go as planned!

• Symlinks let you keep copies• Database backup before patches were applied –

just incase• Database patch rollback files – allows you to keep

new data but undo structural changes• Make an undo button in your deployment platform;

if you don’t you will need it – if you do, you wont*!

* OK, I lied, you probably will at some point

CAVEATS

Queue cheesy stock photo of confused bean figure

Caveats

Some useful pointers when having multiple versions online (bleeding, staging and production)

• Keep robots out (robots.txt meta_robots)– You don’t want search engines taking your users to the

staging environment, nor do you want to be peanalised for duplicate content

• Keep unwanted users out (.htaccess or limited user database)

• Make it clear that the environment is non-production – in case a production user stumbles upon staging!

Conclusion

• Deployment needs to take into account a lot of things

• Small and simple home-brew scripts, processes and techniques should help you out

• Look at pulling them together into a simple web-based deployment centre

Deploy your projects quickly!@michaelpeacock

mkpeacock@gmail.com

michaelpeacock.co.uk

http://slidesha.re/phpdeploy

http://www.flickr.com/photos/jurvetson/4853963652/sizes/m/in/photostream/