php at density and scale
DESCRIPTION
Mixing performance, configurability, density, and security at scale has, historically, been hard with PHP. Early approaches have involved CGIs, suhosin, or multiple Apache instances. Then came PHP-FPM. At Pantheon, we've taken PHP-FPM, integrated it with cgroups, namespaces, and systemd socket activation. We use it to deliver all of our goals at unheard-of densities: thousands and thousands of isolated pools per box. Watch how it's configured and see PHP-FPM pools start real-time to serve different Drupal sites as requests come into a server. All of our tools for this are open-source and usable on your own virtual machines and hardware.TRANSCRIPT
PHP at Density and ScaleHow Pantheon sees the future of computing.
About Me
● Four Kitchens● Drupal.org● Pressflow● Pantheon● systemd
Topics● Performance
○ Socket activation○ Automount/autofs○ cgroups○ “Customer Experience Monitor”○ Migration
● Security○ Users○ Namespaces○ Defense-in-depth○ Non-disruptive fixes
Traditional server sockets: overview
...
nginxTCP80Client
nginxTCP81If you want a service
available, the daemon has to be running.
Socket activation: overview
systemd
TCP80Client
TCP81
nginxfd=3
Only a socket in systemd has to run for service availability.
Socket activation: details
● systemd squats on all listeners○ Looks for incoming traffic with EPOLL○ Starts the services/containers on-demand○ Passes socket to daemon as fd=3
● Not a proxy (same performance)● No client awareness
Socket activation: Pantheon’s use
● nginx and PHP-FPM● MariaDB soon
○ Using an alternative now● Allows 90%+ containers to be idle● Makes bootup sensible● Reconfiguration pattern is stop, not restart
Socket Activation
Demo
Automount/autofs
● Like socket activation for file system mounts○ Kernel squats on mount path and looks for traffic○ Brings up file mount lazily
● Used for FuseDAV (Valhalla client)
Automount Demo
cgroups
● Many options○ Pantheon uses CPUShares and BlockIOWeight
● Keeps things fair under contention○ Kind of like adding purple ropes when people are
queueing
Contentionwith cgroups Demo
Customer Experience Monitor
● Runs a representative Drupal site on every container host
● Reports scores to the API and monitoring● Influences migration and container
placement
Migration
● At density, rebalancing is important● Keep state lightweight
○ No OS○ No runtime
● Mutiny: migration as replication + promotion
Isolation for security
● Users● Namespaces
Defense in depth● Application
○ Drupal● Runtime
○ nginx, PHP-FPM, FuseDAV● Container: “binding” certificate
○ Linux user, namespaces, etc.● Container host: “endpoint” certificate
○ Only trusted for the containers assigned● Platform: root certificate
Non-disruptive fixes
● Kernel upgrades via migration● Rolling daemon and library upgrades
○ Heartbleed
Heartbleed Fix Demo