Welcome!

PHP Authors: Liz McMillan, Carmen Gonzalez, Hovhannes Avoyan, Lori MacVittie, Trevor Parsons

Blog Feed Post

How to Proxyfy Apache

INTRODUCTION

There are a variety of ways to implement proxying capabilities for web servers. As Apache is the most popular web server, we will try to implement proxying on it. Everyone who knows Apache well, probably knows that Apache implements proxying capability for AJP13 , FTP, CONNECT , HTTP/1.x.

The choice of reverse proxy server is fully dependent on what is actually trying to be hidden behind it. Each proxy mechanism has its own benefits and bottlenecks. Only for Apache, there are several ways to hide application servers (mod_proxy, mod_passenger, mod_wsgi, mod_jk). While mod_passenger and mod_wsgi are good for ruby and python servers respectively, these are a little bit outside the proxying idea. In this article I would like to discuss mod_proxy and mod_jk.

HOW TO

Now let’s think about what we have and what we want to put under proxy. The most common case is to put a pool of Tomcat servers behind Apache. Tomcat servers by default listen to 8080 for HTTP and 8009 for AJP. Now, we want to have Apache listen to 80 for incoming HTTP requests and 443 for HTTPS. People who have configured Tomcat for SSL will undoubtedly agree with me that SSL on Tomcat is quite annoying, so it’s better to implement SSL on the Apache side rather than playing with Tomcat’s keystores.

 

Okay, now we have two Tomcat servers on 2 different servers with our application installed, and both are on 8080 and an 8009 HTTP/AJP respectively. And one Apache on a third which will do HTTP on 80 , HTTPS on 443 for us and process requests to downstream Tomcat servers.

Situation 1 with mod_proxy and mod_proxy_http:

 

OK, here’s what this means:

 

User opens http://www.yourdomain.com in their browser

  1. Request comes to Apache
  2. Apache proxies it via HTTP to downstream Tomcat to port 8080
  3. Tomcat sends response to Apache via HTTP
  4. Apache delivers content to User’s browser

Well, so what are the pros and cons of this situation? We will provide some comparison tables below, but in general:

Pros:

  1. Easy and quick to configure
  2. Works for all downstream application servers

Cons:

  1. We do not have sticky sessions: if a user logs in to Tomcat1 and sends another request it will most likely go to Tomcat2 and the user will get a session expired error.
  2. mod_proxy does not support failover detection, so it will continue to send requests to downstream Tomcat even if it is down.
  3. Some Java applications exhibit unpredictable behavior when they are under a proxy environment. (From my experience, Atlassian Bamboo and Fisheye server’s progress bars stalled on several pages, but this was corrected by moving to JK; I have heard about other strange problems as well. )

Now let’s see Situation 2, where we use JK for downstream servers:

A REAL LIFE EXAMPLE

At first sight we can see that nothing has been changed, but this is only at first sight. The main difference here is that now Apache is talking to the Tomcats via AJP 13 and not HTTP protocol. So the process of opening the web site is the following:

  1. User opens http://www.yourdomain.com in their browser
  2. Request comes to Apache
  3. Apache proxies it via AJP 13 to downstream Tomcat to the port 8009
  4. Tomcat sends response to Apache via AJP
  5. Apache receives AJP and delivers content to Users browser via HTTP

It seems there is a little overhead with jumping around on HTTP and AJP, but there are benefits as well. Let’s see the Good and Bad sides of JK balancing:

Pros:

  1. After a little tweaking we can have sticky sessions just by adding sticky_session=True on Apache and jvmRoute=”NODENAME” on the Tomcat sides. After this, users who are logged in to Tomcat1 will never be dropped to Tomcat2 until Tomcat1 is alive. (Actually you can Use Membase or Memcached as session store so users will never lose their session until it expires normally)
  2. We have node failure detection, so if Tomcat1 fails, Apache will not send requests to it until it detects that it is back.
  3. JK configuration is much more advanced than that of mod_proxy and allows lots of tweaking, which will result in better performance and make the environment work just as you need it to.
  4. JK has a web admin tool that allows you to decommission, suspend and play with the LB factor in real time.

Cons:

  1. So far I have found only one bad thing: it is a little harder to configure, so it required some administrator skills.

At this moment you may be asking “Why do I need this? I have a single Tomcat server and it’s working fine”.  As a matter of fact, you need to build a network which can handle your current load, be scalable and which will not affect the normal behavior of your websites. From this point of view, the choice of reverse proxy solution is quite reasonable.

Here is a real life example of one of our client server architectures, which I think is a good one :)

 

In general, the process is as follows:

  1. User does DNS request, gets ip address of one of the Varnish servers and the Static content server/s (NGINX).
  2. NGINX delivers content directly.
  3. Varnish caches whatever needs to be cached and sends request downstream to one of the Apaches.
  4. Apache gets JSESSIONID and forwards request via JK to the required Tomcat server or does balance if user does not have cookie.
  5. Tomcat servers keep sessions in local RAM and copy in Membase cluster (so even if one Tomcat fails another can retrieve its session from Membase ). Membase is clustered memcache so it is fault tolerant by nature (we will have a closer look at Membase in another article).
  6. Tomcat does needed application logic, (retrieves information from Hadoop/HBase database, etc.) and responds to Apache.
  7. Apache sends response back to Varnish.
  8. Varnish updates cache if needed and does delivery to client.

This is a real live working scenario, and it proved itself to be fault tolerant and extremely fast.

I know that after reading this article a lot of people will ask, “why is Apache needed when Varnish can do session stickiness, etc. …”

But the idea here is to use the best possible software for each particular role, software which has real and approved redundancy and reasonable layers of architecture which can help us to easily and quickly detect problems and fix them as they appear. Also, if we keep in mind that the client uses not only HTTP, but also HTTPS, I did not see any webserver which worked with SSL as smoothly as Apache did. Even if we do not have SSL initially, we will have it soon, and I do not believe that any web project can go far without SSL.

Following is a little comparison of JK and mod_proxy, so you can see more closely what these tools are.

 

Features mod_proxy Weight mod_jk Weight
Load balancing Basic 5 Advanced 10
Node failure detection mod_proxy_balancer has to be present in the server 7 Advanced 10
Backend SSL supported (mod_ssl required) 5 not supported 0
Session stickiness not supported 0 Supported via JVM Route 10
Protocols HTTP, HTTPS 10 AJP 13 8
Node decommissioning Manual needs Apache reload 3 Online via web admin 10
Web admin interface Not present 0 Advanced with RO and RW support 10
Large AJP packet sizes 8K 5 Larger than 8K 10
Compatibility with other app. servers Works with all HTTP application servers 10 AJP Compatible (Tomcat, Glassfish, etc. …) 5
Configuration Compatible with Apache Httpd configuration file 10 Need separate JK Workers file in .properties format 8
Summary 55 81

 

So now let’s do some stress tests on both mod_jk and mod_proxy. The Installation schema is as described above (one load balancer, two application servers.) On both Apache server hosts, monitoring software from Monitis.com is installed which will check the servers’ health in real time.

We have used Amazon EC2 medium instances for this test. Here are the load test results in both graphical and plain text mode.

Monitoring is implemented using Monitis M3 monitors.

There are 2 monitors used:

apache_monitor – used for apache server’s health check.

http_load monitor - used to check the load time difference during Apache benchmarking.

 

The mentioned monitors provide useful information which helps to find relationships between various metrics.

mod_proxy:

The graphic below depicts Apache worker’s status while busy (upper line) and idle (lower line) while benchmarking using

mod_proxy balancer.

This graph shows Apache busy and idle worker processes on the Apache web server, so we can see that of 150 enabled processes, almost all are busy during the stress test.

 

Http content load time (time connect, time transfer, time total)

Following is data provided by siege after benchmarking 7 times (using mod_proxy), each time increasing the concurrent users’ number by 100:

 

Concurrent conns. Trans Elap Time Data Trans Resp Time Trans Rate Throughput Concurrent Failed
100 112173 359.18 206 0.32 312.30 0.57 99.93 0
200 181578 360.01 333 0.40 504.37 0.92 199.72 3
300 179025 360.00 329 0.60 497.29 0.91 299.37 5
400 177681 360.00 326 0.81 493.56 0.91 397.44 40
500 166401 359.99 305 1.07 462.24 0.85 494.52 130
600 160853 359.99 295 1.31 446.83 0.82 584.32 444

 

mod_jk:

The graphic below represents Apache worker’s busy (upper line) and idle (lower line) status while benchmarking using

mod_jk.


This graph shows Apache busy and idle worker processes on the Apache webserver, so we can see that of 150 enabled processes, almost all are busy during the stress test.

Http content load time (time connect, time transfer, time total)

Following is data provided by siege after benchmarking 7 times (using mod_jk), each time increasing the concurrent users number by 100:

 

Concurrent conns. Trans Elap time Data Trans Resp Time Trans time Throughput Concurrent Failed
100 106919 359.60 198 0.34 297.33 0.55 99.93 0
200 186123 360.01 345 0.39 516.99 0.96 199.76 0
300 183017 360.00 339 0.59 508.38 0.94 299.29 8
400 179891 360.00 333 0.80 499.70 0.93 397.34 49
500 169284 359.99 313 1.05 470.25 0.87 494.55 124
600 182954 359.99 339 1.16 508.22 0.94 590.32 258

 

 

CONCLUSION

Both mentioned modules, mod_proxy and mod_jk, are used as balancers for backend application servers such as Tomcat and GlassFish. What are the most important features in load balancing? I assumed node failure detection at first, and ease of session stability and load balancing configuration, without requiring any other extra tools or packages. Do not forget about performance, as well.

So what do we have? The resulting tables show that when advanced load balancing or node failure detection is needed, mod_jk is preferable. However, it cannot provide flexibility such as mod_proxy does when configuring (mod_proxy configuration is as easy as Apache configuration and there is no need for separate files like workers.properties) nor for compatibility needs with servers, other than AJP compatibility.

Now a little bit about performance. While the concurrent users count is not so high (in our case: 400), both servers’ behavior is similar, and it seems mod_proxy is able to provide better performance, but things changed as the number of concurrent users grew.

Take a look at this table:

 

Concurrent users Failed requests(10 Seconds Timeout)
mod_jk 590.32 258
mod_proxy 584.32 444

As you see, with an almost equal number of connections, mod_proxy fails approximately 59% more often.

If you have a small project, or need to hide a variety of application servers (Tomcat+Rails+Django), and if you need an easily configurable and fast SSL solution and your server load is not heavy, then use mod_proxy.

But if your goal is to loadbalance Java applications servers, then JK is definitely the better solution.

Share Now:del.icio.usDiggFacebookLinkedInBlinkListDZoneGoogle BookmarksRedditStumbleUponTwitterRSS

Read the original blog entry...

More Stories By Hovhannes Avoyan

Hovhannes Avoyan is the CEO of PicsArt, Inc.,

@ThingsExpo Stories
DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of the 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great deals to gre...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and shared the must-have mindsets for removing complexity from the develop...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.