How to Install and Upgrade to PHP-FPM 5.6 on CentOS 6.x: An In-Depth Guide

Is your CentOS 6 server still running the ancient PHP 5.3 version that‘s been outdated for over 5 years now? If so, an upgrade should be a top priority – and here‘s why.

In this comprehensive guide, I‘ll provide extensive details on how to smoothly upgrade PHP-FPM to 5.6 on CentOS 6 for improved security, performance, and features support. I‘ll also dig deeper into why upgrading PHP matters, common issues you may face, and expert-level tips for optimized deployments.

Let‘s get started!

The Risks of Running Unsupported PHP 5.3

Before we dive into the how-to, it‘s important to understand the risks of relying on a PHP version from 2010 that lost official support in 2014. Here are some cold hard facts:

Over 35% of sites are still running PHP 5.3 or older according to W3Tech‘s data. This means a huge number of sites are potentially vulnerable.
PHP 5.3 has over 200 security fixes since it went unsupported, leaving these sites open to attack.
Specific exploits like CVE-2013-6420 allow remote code execution via deserialized objects – easily avoided by upgrading.
The average website gets attacked 44 times daily according to SiteLock. Outdated platforms give hackers an easy path in.

Simply put, using obsolete technology leaves you extremely vulnerable to compromise. Ensuring you run actively supported software is a must for security.

The Performance and Feature Benefits

Beyond closing security gaps, what other advantages does upgrading to PHP 5.6 offer?

2x higher throughput – PHP 5.6 can handle around 2x more requests per second versus 5.3 in benchmarks.
Lower memory usage – PHP 5.6 uses Zend OpCache for 50% less RAM consumption for better scalability.

Version	Requests/sec	Peak Memory Use
PHP 5.3	3700	155 MB
PHP 5.6	6300	73 MB

New language features – Constant arrays, anonymous classes, password hashing APIs, and more help you write better code.
Better compatibility – PHP 5.6 is required for latest versions of CMSs like WordPress, Drupal, Laravel and tools like Composer.

The bottom line is upgrading means faster performance, better code, and access to modern frameworks.

Step-by-Step Guide to Upgrading to PHP 5.6 on CentOS 6

Alright, let‘s dig into the nuts and bolts of how to upgrade your PHP install from 5.3 to 5.6 on CentOS 6 step-by-step:

1. Backup Existing Systems

As with any major software change, start by taking backups of your full systems:

Code repositories – Commit and push latest code changes first
Database – Use mysqldump or tools like Percona XtraBackup
Files – Archive sites directories, logs, and other data

Having backups ensures you can safely roll back in case of upgrade issues.

2. Add Required Repositories

CentOS 6 repositories only include older software versions. We need to add some additional repos providing PHP 5.6:

rpm -Uvh https://mirror.webtatic.com/yum/el6/latest.rpm
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

Webtatic and EPEL repos will allow installing the newer PHP from there.

3. Install PHP 5.6 with Yum

Now install PHP 5.6 and php-fpm for serving web requests:

yum install php-fpm php php-devel -y --enablerepo=remi-php56

This will compile the latest 5.6 version from source.

4. Install Required PHP Modules

Enable needed extensions like mcrypt, curl etc:

yum install php-mcrypt php-mbstring php-curl ... -y --enablerepo=remi-php56

5. Verify Upgrade Success

Check that PHP has been upgraded by running:

php -v

PHP 5.6.40 (cli) (built: Sep 29 2018 00:02:46) 
Copyright (c) 1997-2016 The PHP Group

The PHP 5.6 version indicates a successful upgrade!

6. Tweak Configuration

There are a few recommended post-upgrade tweaks:

Adjust opcache settings for optimal performance based on your traffic patterns.
Modify php-fpm config for high-load sites, like using socket over TCP.
Review and update any custom php.ini settings as needed.
Increase memory_limit if you see issues. The 5.6 engine uses a bit more RAM.

Properly configuring PHP 5.6 ensures you maximize performance benefits.

Post-Upgrade Best Practices

After upgrading, be sure to follow these additional best practices:

Monitor Impact on Applications

Closely track application behavior for a few days and watch for any degradations. Measure response times and error rates to detect problems early.

Perform Security Scans

Run website vulnerability scanners like Geekflare to uncover any fixed or new issues. Tighten down access, enable HSTS, and implement other security enhancements.

Consider Migrating to PHP 7.x

For large, high-traffic sites think about jumping straight to PHP 7.x for even more substantial performance and scalability gains.

Automate Deployments

Use Ansible, Puppet or other DevOps tools to script and automate PHP deployments across clusters of servers. This eases upgrading at scale.

Plan Zero-Downtime Maintenance

For mission-critical systems, plan a zero-downtime upgrade using load balancers and staged rollouts. This prevents application outages.

Troubleshooting Common Upgrade Problems

Despite best efforts, you may encounter issues during or after a PHP upgrade such as:

Version Mismatch

If php -v still shows 5.3, clear yum cache and reinstall php-fpm to sync versions:

yum clean all 
yum install php-fpm

Extension Conflicts

Disable old extensions in php.ini that conflict with built-ins like mysql, curl etc.

Code Warnings or Breakage

Update code as needed to resolve deprecation warnings or fatal errors from language changes.

Service Restart Failures

Double check php-fpm.conf and httpd.conf match working configs. Confirm OS user permissions.

Crashes and 500 Errors

Compare current php-fpm settings against a known good server to identify config differences causing crashes.

Carefully reviewing logs and configs can help uncover most upgrade issues. Consider staging rollouts to catch problems early.

Conclusion

I hope this guide has armed you with extensive knowledge to smoothly upgrade PHP on CentOS 6 from the insecure 5.3 branch to the supported 5.6 release.

Just remember to backup systems, closely monitor apps post-upgrade, and follow performance optimization and security best practices. Keeping your technology stack up-to-date is one of the most impactful things you can do ensure your systems run faster, safer and with access to modern features.

Now go forth and upgrade those PHP versions! Your apps will thank you. Let me know in the comments if you have any other tips or questions.