deploying and monitoring rails

Deploying and Monitoring

Ruby on Rails A practical guide

Mathias Meyer and Jonathan Weiss, 25.05.2009

Peritor GmbH

Who are we?

Jonathan Weiss

• Consultant for Peritor GmbH in Berlin

• Specialized in Rails, Scaling, Deployment, and Code Review

• Webistrano - Rails deployment tool

• FreeBSD Rubygems and Ruby on Rails maintainer

http://www.peritor.com

http://blog.innerewut.de

Who are we?

Mathias Meyer

• Consultant for Peritor GmbH in Berlin

• Specialized in Rails, Performance/Database Tuning, Deployment, and Refactoring

• Maintainer of Macistrano – Webistrano-Client for Mac OS X (and soon the iPhone), run_later and acts_as_solr

http://www.paperplanes.de

Agenda

Infrastructure Deployment Monitoring Q & A Practical Session

Infrastructure Infrastructure

Simple Rails Setup

One Rails instance handles all requests

Rails is single-threaded: There is only one concurrent request

Rails Setup

Typical Rails Setup

• A load-balancer distributes the incoming requests

• Some load-balancers will deliver static requests themselves

• Several Rails instances handle all requests

• Number of concurrent requests equals number of Rails instances

Rails Setup Options

Deployment Questions

Mongrel?

Apache?

FastCGI?

mod_rails?

Nginx?

Lighttpd?

Pound? mod_proxy_balancer?

HA-Proxy?

Phusion Passenger?

Load-balancer? Proxy?

Rails Application Server?

Swiftiply? Reverse Proxy?

What we are going to cover today

Rails Application Server

• FastCGI

• Mongrel

• mod_rails / Phussion Passenger

• JRuby + Glassfish & Co.

Proxy/Web Server

• Apache2

• Nginx

• Lighttpd

• HA-Proxy

FastCGI

• Protocol to communicate with long-running CGI applications

• Usage of either mod_fcgi with Apache 1.3 or mod_fcgi with Lighttpd

• Proxy local and remote FastCGI instances

• Oldest way of deploying Rails

• Deprecated and unstable

• Hard to debug (FastCGI protocol)

FastCGI

Mongrel

• Developed by Zed Shaw as an alternative to FastCGI

• Complete HTTP-Server that can load arbitrary Ruby-servlets

• Built-in Rails support

Mongrel

Apache 2.2 – mod_proxy_balancer Lighttpd Nginx HA-Proxy Pound

Mongrel Cluster

Utility to manage several Mongrel instances

Mongrel Cluster

Control Mongrels

Mongrel and Apache 2.2

Define Mongrel Cluster in Apache

Simple Mongrel and Apache 2.2

Redirect all traffic to the Mongel cluster

A more complex example

• Redirect dynamic requests

• Serve static content

• Support cached pages

• Support maintenance page

• Enable client-side caching of images, stylesheets, and JavaScript

• Compress output if supported

Mongrel

• Very robust

• Strict HTTP parser

• Easy to debug (HTTP!)

• Used to be defacto deployment setup with Apache 2.2 and mod_proxy_balancer

• Can be a bit difficult to setup (mongrel_cluster, ports, Apache)

• Not so easy on mass/virtual hosting

mod_rails

mod_rails a.k.a Phusion Passenger

• Module for Apache 2.2 (and Nginx)

• Allows Apache to control Rails instances

• Apache starts and stops application instances depending on the application load

• Able to run any Rack-compatible Ruby application (Merb, Sinatra & Co.)

• Only manages Rails on one host - no remote instances

• Combine with HTTP-Proxy / balancing solution

Install Phusion Passenger

Install Apache module

Load and activate in Apache

Install Phusion Passenger

Install Passenger with nginx (installs custom nginx)

Configure nginx

Customized Phusion Passenger

Control Rails instance number

Control Phusion Passenger

Restart after deployment:

Phusion Passenger

One machine

Phusion Passenger

One machine Multiple machines

Phusion Passenger

• Ready for production

• Makes setup easier – on the single machine level

• Multiple servers still require load balancer

• Suitable for mass-hosting

• upcoming standard way of deploying Rails

• Ruby Runtime on the Java Virtual Machine

• Implemented in Java and Ruby

• Compiles Ruby into Java-bytecode

• Integrates with Java code and libraries

• Java’s promises of native threads and JIT

• Allows for Ruby/Rails applications to be packaged as WAR files

• WAR files deployable on any J2EE-container: Glassfish, JBoss, Tomcat, Jetty, …

JRuby on Rails

JRuby on Glassfish

One machine

JRuby on Glassfish

One machine Multiple machines

Setup JRuby on Glassfish

1. Download JRuby and Glassfish

2. From http://blog.headius.com/2008/08/zero-to-production-in-15-minutes.html

Warble Configuration

Define min/max Rails runtimes

Glassfish for development

Shrunk-down version of Glassfish v3 - packaged as a gem

Can run any Rack-based application

Installation:

• $ jruby -S gem install glassfish

• $ glassfish

• There is no Step 3

Rails Setup

Proxy Options

Proxy Requirements

• Hide cluster backend from the user

• Load-balancer backend instances

• Recognize down hosts

• Fair scheduler

• (Deliver static content)

Apache 2.2

• Apache 2.2 introduced mod_proxy_balancer

• mod_proxy_balancer can speak to multiple backends and balance requests

• Apache can acts as a pure proxy or can also serve static files

Apache 2.2

• Stable, robust, and mature

• Many people know how to work with Apache

• Integrates well with other modules (SVN, DAV, Auth, …)

• Apache can be complicated to configure

• The stock Apache is quite resource-hungry compared to pure proxy solutions

Nginx – From Russia with love

• Nginx - popular Russian webserver with good proxy support

• Can load-balance multiple backends and deliver static content

• Quite popular with Mongrel as the Rails backend

• Recent Passenger support

Nginx Configuration

Simple proxy example

Get complete version here:

http://brainspl.at/nginx.conf.txt

• Stable, robust, and fast

• Uses fewer resources (CPU and RAM) than Apache for proxy-mode and static files

• Simpler configuration file

• Can directly talk to memcached - SSI

• More documentation would be nice

• No equivalent for many Apache modules

Lighttpd

• Lightweight and fast webserver

• Balancing proxy support

• Good FastCGI support

• Used to be popular – until Mongrel came around

Lighttpd Configuration

Lighttpd

• Fast and lightweight

• Uses fewer resources (CPU and RAM) than Apache for proxy-mode and static files

• Simpler configuration file

• Unstable for some people

• Slow development cycle

• More documentation would be nice

• Configuration file can be too simple (virtual host aliasing)

• No equivalent for many Apache modules

• (No Passenger support)

HA-Proxy

• HAProxy – reliable, high performance TCP/HTTP load balancer

• Proxying and content inspection

• No content serving, just a proxy

• Mature proxy module (fair scheduler)

• ACL support

See also similar Pound and Pen

HAProxy

• Mature, stable, robust, and fast

• TCP and HTTP balancing

• Few Rails examples

• Usually not needed in a Rails setup

Recommended Setups

Small Site

Recommendation

Apache 2.2 with mod_rails / Phusion Passenger

Medium Site

Recommendation

• Apache/Nginx as the frontend proxy

• Passenger/mod_rails as the backend

• Deliver static files with Apache

Large Rails Setup

Recommendation

• Redundant load-balancer

• Redundant proxy / web

• Passenger/mod_rails

Heavy Static Files

Recommendation

• Deliver static assets through separate web server farm

• Passenger/mod_rails

Java Shop

Recommendation

• Deliver a Rails-WAR file and you are done

• Integrate with existing Java landscape and infrastructure

Application Server Handler

Rack Handler

Rack Middleware

• Authentication (HTTP, OpenID)

• Sessions

• Routing

• Caching

• Logging

• Debugging

Support

Frameworks

• Rails

• Merb

• Camping

• Sinatra

• Mack

• Maveric

• Halcyon

• Ramaze

• Rum

• Vintage

• Waves

Web Server

• CGI

• FastCGI

• Mongrel

• Phusion Passenger

• JRuby Servlets

• WEBrick

• Ebb

• Thin

• LiteSpeed

• Swiftcore

• Unicorn

Remarks

Ruby Enterprise Edition

• Copy-On-Write patches to Ruby 1.8

• Saves memory when spawning several Rails instances

• Used by Phusion Passenger if available

Thin, Ebb, Evented Mongrel & Co.

• Alternatives to Mongrel

• Claim to be faster, lighter, and what have you

• Rendering “Hello World” is usually not your bottleneck

Stick with stable and robust Mongrel, or better yet, with Passenger

Infrastructure Deployment

Deployment Options

What does Capistrano do?

Capistrano Deployment Cycle

Requirements

What doesn’t Capistrano do?

• Plan your initial server setup

• Configure basic services

Basic Ingredients

• The cap command

• Variables

• Roles

• Tasks

• Namespaces

Basic Ingredients - cap

Your one-stop deployment shop

Basic Ingredients - Variables

• Configure basic project information

• Override Capistrano’s default assumptions

• Once set, variables are available globally

• Defined using the set method

Basic Ingredients - Roles

• Define types of servers

• Default roles

• :www

• :app

• :db

• All can point to the same server

• But all three must be defined

• At least one database server needs to be primary

Basic Ingredients - Roles

Define custom roles as you please

Can be reused when defining tasks

Basic Ingredients - Tasks

• Define an atomic set of actions for Capistrano

• Can be called from the command line

• Or other tasks

Basic Ingredients - Tasks

To find all the tasks available in your project, use

Basic Ingredients - Namespaces

Group tasks together logically

Namespaces and tasks are separated with “:”

Get Your Capistrano On

Capfile, the place to include more recipes

config/deploy.rb, application specific configuration

Capistrano’s Defaults

• Your SCM is Subversion

• Deployment directory is /u/apps/#{application_name}

• User for SCM and SSH is the currently logged-in user

• Commands are run with sudo

• Capistrano expects a directory structure

• Can be created with cap deploy:setup

The Deployment Lifecycle

Check the prerequisites:

Set up your application for the first time

The initial deployment

1. Checks the revision from the local machine

2. Checks out the code on the remote machines

3. Sets a link called current pointing to the lates release

4. Runs the migrations

5. Fires up application servers

Subsequent deployments

1. Checks the revision from the local machine

2. Checks out the code on the remote machines

3. Updates current link

4. Restarts application servers

Common Capistrano Tasks

Deploy and run migrations

Run only the migrations

Restart application servers

Rollback to the previous release

Have Your Shell, and Eat It Too

Invoking any Command

Deployment Strategies

Direct checkout (from scratch) on the servers

Keep a cached copy of the current SCM head

Check out locally and transfer

Give it a little Spin

Capistrano expects a script called spin in script/process

For Passenger

Customizing Capistrano

Write your own Tasks

Namespace your Tasks

Callbacks

Execute a task before another runs

Execute a task after another has finished

Callbacks are run in the order they’re defined

Useful Variables

Transactions

The Rest

• Gem dependencies

• Support for deploying through gateway servers

• Parallel execution on multiple servers

• Server setup with deprec gem

Vlad the Deployer

• Simple, Rake-based deployment solution

• Comes with defaults for most popular SCM, app and web servers

Vlad the Deployer

Configure

Vlad the Deployer

Deployment

Vlad the Deployer

• Simple, sometimes too simple

• No callback mechanism, instead the Rake syntax must be used

• Very non-verbose output, using --trace recommended

• System Integration Framework

• Written in Ruby – inspired by Puppet

• Manage multiple nodes

• Configuration

• Packages

• Custom scripts and commands

Architecture

Recipes

Install and upgrade packages

Recipes

Create and update remote files

Recipes

Create and update remote files

chef-deploy

Enable

Use in recipe

Chef and chef-deploy

• In heavy development: sometimes unstable and hard to debug

• Be prepared to get your hands dirty

• Better suited for configuration than deployment

• Community recipes at http://github.com/opscode/cookbooks

One Click Deploy

Webistrano

• Web-UI to Capistrano

• Manages projects and their stages

• Alerting and Accounting

• Scriptable and extendable

• BSD License

http://labs.peritor.com/webistrano

Macistrano

• Mac-GUI to Webistrano

• Fire and monitor deployments from your desktop

http://github.com/mattmatt/macistrano

Infrastructure Practical Session

Practical Capistrano

EC2 Instances

• Users

• root / railswaycon

• deploy / railswaycon

• MySQL

• root / ‘’

• Apache Configuration

• /etc/apache2/sites-enabled/default

• Rails

• /srv/www

Git Repository

• git://github.com/mattmatt/railscasts.git

• Setup the servers

• Deploy!

• Make memcached restart with every deploy

• (Usually not a good idea, but why not?)

• Make Apache recognize maintenance.html and display it if exists

Maintenance Page

• Create symbolic link to /etc/apache2/mods-available/rewrite.load in /etc/apache2/mods-enabled

• Update virtual host configuration with rewrite rules

• Run cap deploy:web:disable • Hook it into the deployment process

• Deploy a Rack-based application

• Install Sinatra locally and on the server

• git://github.com/mattmatt/railswaycon.git

• Create deployment configuration

• Create Apache configuration

Infrastructure Monitoring

The two questions of monitoring

1. Is everything still running?

2. What are the trends?

• Process-level monitoring

• Checks PID-files, ports, and permissions

• Reacts by executing a script and/or alerting

• Has a web GUI for administering nodes

Apache

Mongrel

• Ruby-based configuration

• Easily extendible

• Can work with event- and poll-based conditions

• Comes with less recipes than Monit

Mongrel

• Host-level monitoring

• Master periodically asks nodes for local data

• Checks system resources and records historical data

• Allows to recognize trends and make predictions

• Alerting support

Exception Monitoring

• Monitor errors raised by your application

• Usually notifying you by email

• Good old exception_notification Plugin

• Exceptions as a Service

Hoptoad

Exceptional

New Relic

• Rails Performance monitoring

• Live view into your application

Other Tools

• Nagios

• Big Brother

• New Relic RPM

• FiveRuns

• JMX

Infrastructure Advanced Deployment

Search

Full text search

Can become very slow on big data sets

Full Text Search Engine

Separate Service

• Creates full text index

• Application queries search daemon

• Index update through application or database

Possible Engines

• Ferret

• Sphinx

• Solr

• Lucene

• …

Search Slave

Database replication slave

• Has complete dataset

• Migrates slow search queries from master

• Can use different database table engine

Database Index

PostgreSQL Tsearch2

• Core since 8.3

• Allows to create full text index on multiple columns or arbitrary SQL expressions

MySQL MyISAM FULLTEXT index

• Only works with MySQL <= 5.0 and MyISAM tables

• Full text index on multiple columns

What to use?

Different characteristics

• Real-time updates and stale data

• Lost updates

• Performance

• Document content and format

• Complexity

Background Processing

Problem

Long running tasks

• Resizing uploaded images

• Mailing

• Computing an expensive operation

• Accessing slow back-ends

When running inside request-response-cycle

• Blocks user

• Blocks Rails instance

• Hard to monitor and debug

Solution

Asynchronous processing in the background

Message/Queue Scheduler

Background Processing

Options

Options for message bus:

• Database

• Amazon SQS

• Drb

• Memcache

• ActiveMQ

• …

Options for background process:

• (Ruby) Daemon

• Cron job with script/runner

• Forked process

• Delayed Job / BJ / (Backgroundrb)

• run_later

• ….

Database/Ruby daemon example

Cloud Infrastructure

Servers come and go

• You do not know your servers before deploying

• Restarting is the same as introducing a new machine

You can’t hardcode IPs

database.yml

Solution #1

Query and manually adjust

• Servers do not change that often

• New nodes probably need manual intervention

• Use AWS ElasticIPs to ease the pain

Set servers dynamically AWS Elastic IP

Solution #2

Use a central directory service

• A central place to manage your running instances

• Instances query the directory and react

Solution #2

Use a central directory service

• A central place to manage your running instances

• Instances query the directory and react

Central Directory

Different Implementations

• File on S3

• SimpleDB

• A complete service, capable of monitoring and controlling your instances

Peritor GmbH

Teutonenstraße 16 14129 Berlin

Telefon: +49 (0)30 69 20 09 84 0 Telefax: +49 (0)30 69 20 09 84 9

Internet: www.peritor.com E-Mail: kontakt@peritor.com

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