Welcome!

Blog Feed Post

Node.Js server monitoring, part 2

node-js-monitorLast time we mentioned two fundamental principles while monitoring any object:

1. The monitor should collect as much important information as possible that will allow to accurately evaluate the health state of an object.
2. The monitor should have little to no effect on the activity of the object.

Sure, these two principles work against each other in most of cases, but with Node.js they work together quite nicely because Node.js is based on event-driven technology and doesn’t use the traditional threads-driven approach. This technology allows to register many listeners for one event and process them in parallel almost independently. To avoid even a small effect on the production server, it was decided to separate the monitor into two parts – the first is the javascript module-plugin that listens to all server events and accumulates necessary information and the second is the Linux shell script that periodically runs the monitor-plugin by using the REST technique for collecting, processing, and sending information to the Monitis main server.

Normally, it is necessary to add couple lines in your existing Node.js server code to activate the monitor-plugin:

var monitor = require('monitor');// insert monitor module-plugin
....

var server = … // the definition of current Node.js server

….

monitor.Monitor(server); //add server to monitor

Now the monitor will begin collecting and measuring data. The monitor-plugin has an embedded simple HTTP server that sends accumulated data by request and should correspond (in current implementation) to the following pattern

http://127.0.0.1:10010/node_monitor?action=getdata&access_code=

where
10010 – the listen port of monitor-plugin (configurable)
‘node_monitor’ – the pathname keyword
‘action=getdata’ – command for getting collected data
‘access_code’ – the specially generated access code that changes for every session

Please notice that monitis-plugin server (in current implementation) listens the localhost only. This and usage of the security access code for every session gives enough security while monitoring. More detailed information can be found along with implemented code in the github repository.

Server monitoring metrics

There are a largely standard set of metrics which can be used to monitor the underlying health of any server.

* CPU Usage describes the level of utilisation of the system CPU(s) and is usually broken down into three states.
o IO Wait – indicates the proportion of CPU cycles spent waiting for IO (disk or network) events. If you experience large IO Wait proportions, it can indicate that your disks are causing a performance bottleneck.
o System – indicates the proportion of CPU cycles spent performing kernel-level processing. Generally you will find only a small proportion of your CPU cycles are spent on system tasks, Hence if you see spikes it could indicate a problem.
o User – indicates the proportion of CPU cycles spent performing user instigated processing. This is where you should see the bulk of your CPU cycles consumed; it includes activities such as web serving, application execution, and every other process not owned by the kernel.
o Idle – indicates the spare CPU capacity you have – all the cycles where the CPU is, quite literally, doing nothing.
* Load Average is a metric that indicates the level of load that a server is under at a given point in time. Usually evaluated as number of requests per second.
* RAM usage by server is broken down usually into the following parts.
o Free – the amount of unallocated RAM available. Linux systems tend to keep this as low as possible; and do not free up the system’s physical RAM until it is requested by another process.
o Inactive – RAM that is in-use for buffers and page caching, but hasn’t been used recently so will be reclaimed first for use by a running process.
o Active – RAM that has been used recently and will not be reclaimed unless we have insufficient Inactive RAM to claim from. In Linux systems this is generally the one to keep an eye on. Sudden, rapid increases signal a memory hungry process that will soon cause VM swapping to occur.
* The server uptime is a metric showing the elapsed time since the last reboot. Non-linear behavior of the server uptime line indicates that the server was rebooted somehow.
* Throughput – the amount of data traffic passing through the servers’ network interface is fundamentally important. It is usually broken down into inbound and outbound throughput and normally measured as average values for some period by kbit or kbyte per sec.
* Server Response time is defined as the duration from receiving a request to sending a response. Normally, it should not exceed reasonable timeout (usually this depends on the complexity of processing) but should be as little as possible. Usually, the average and peak response time is evaluated for some time period.
* The count of successfully processed requests is evaluated as the percentage of responses with 2xx status codes (success) to requests during observing time. This value should be as close as possible to 100%.

We have used part of these metrics and added some specific statistics that are important for our task (e.g. client platform, detailed info for response codes, etc.)

Test results

The results below were obtained on a Node.js server equipped with the monitor described above on a Debian6-x64. The server listens on HTTP (81) and HTTPS (443) ports and does not have a large load.


By double-clicking on a line you can view a specific part of the monitoring data.

The data can be shown in graphical view too.



In conclusion, the monitoring system has successfully tracked the metrics and found the Node.Js server to be in a good health state.

Share Now:del.icio.usDiggFacebookLinkedInBlinkListDZoneGoogle BookmarksRedditStumbleUponTwitterRSS

Read the original blog entry...

More Stories By Hovhannes Avoyan

Hovhannes Avoyan is the CEO of PicsArt, Inc.,

Latest Stories
"Storpool does only block-level storage so we do one thing extremely well. The growth in data is what drives the move to software-defined technologies in general and software-defined storage," explained Boyan Ivanov, CEO and co-founder at StorPool, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
ChatOps is an emerging topic that has led to the wide availability of integrations between group chat and various other tools/platforms. Currently, HipChat is an extremely powerful collaboration platform due to the various ChatOps integrations that are available. However, DevOps automation can involve orchestration and complex workflows. In his session at @DevOpsSummit at 20th Cloud Expo, Himanshu Chhetri, CTO at Addteq, will cover practical examples and use cases such as self-provisioning infra...
As DevOps methodologies expand their reach across the enterprise, organizations face the daunting challenge of adapting related cloud strategies to ensure optimal alignment, from managing complexity to ensuring proper governance. How can culture, automation, legacy apps and even budget be reexamined to enable this ongoing shift within the modern software factory? In her Day 2 Keynote at @DevOpsSummit at 21st Cloud Expo, Aruna Ravichandran, VP, DevOps Solutions Marketing, CA Technologies, was jo...
As Marc Andreessen says software is eating the world. Everything is rapidly moving toward being software-defined – from our phones and cars through our washing machines to the datacenter. However, there are larger challenges when implementing software defined on a larger scale - when building software defined infrastructure. In his session at 16th Cloud Expo, Boyan Ivanov, CEO of StorPool, provided some practical insights on what, how and why when implementing "software-defined" in the datacent...
Blockchain. A day doesn’t seem to go by without seeing articles and discussions about the technology. According to PwC executive Seamus Cushley, approximately $1.4B has been invested in blockchain just last year. In Gartner’s recent hype cycle for emerging technologies, blockchain is approaching the peak. It is considered by Gartner as one of the ‘Key platform-enabling technologies to track.’ While there is a lot of ‘hype vs reality’ discussions going on, there is no arguing that blockchain is b...
Blockchain is a shared, secure record of exchange that establishes trust, accountability and transparency across business networks. Supported by the Linux Foundation's open source, open-standards based Hyperledger Project, Blockchain has the potential to improve regulatory compliance, reduce cost as well as advance trade. Are you curious about how Blockchain is built for business? In her session at 21st Cloud Expo, René Bostic, Technical VP of the IBM Cloud Unit in North America, discussed the b...
You know you need the cloud, but you’re hesitant to simply dump everything at Amazon since you know that not all workloads are suitable for cloud. You know that you want the kind of ease of use and scalability that you get with public cloud, but your applications are architected in a way that makes the public cloud a non-starter. You’re looking at private cloud solutions based on hyperconverged infrastructure, but you’re concerned with the limits inherent in those technologies.
Is advanced scheduling in Kubernetes achievable?Yes, however, how do you properly accommodate every real-life scenario that a Kubernetes user might encounter? How do you leverage advanced scheduling techniques to shape and describe each scenario in easy-to-use rules and configurations? In his session at @DevOpsSummit at 21st Cloud Expo, Oleg Chunikhin, CTO at Kublr, answered these questions and demonstrated techniques for implementing advanced scheduling. For example, using spot instances and co...
The use of containers by developers -- and now increasingly IT operators -- has grown from infatuation to deep and abiding love. But as with any long-term affair, the honeymoon soon leads to needing to live well together ... and maybe even getting some relationship help along the way. And so it goes with container orchestration and automation solutions, which are rapidly emerging as the means to maintain the bliss between rapid container adoption and broad container use among multiple cloud host...
The cloud era has reached the stage where it is no longer a question of whether a company should migrate, but when. Enterprises have embraced the outsourcing of where their various applications are stored and who manages them, saving significant investment along the way. Plus, the cloud has become a defining competitive edge. Companies that fail to successfully adapt risk failure. The media, of course, continues to extol the virtues of the cloud, including how easy it is to get there. Migrating...
Imagine if you will, a retail floor so densely packed with sensors that they can pick up the movements of insects scurrying across a store aisle. Or a component of a piece of factory equipment so well-instrumented that its digital twin provides resolution down to the micrometer.
The need for greater agility and scalability necessitated the digital transformation in the form of following equation: monolithic to microservices to serverless architecture (FaaS). To keep up with the cut-throat competition, the organisations need to update their technology stack to make software development their differentiating factor. Thus microservices architecture emerged as a potential method to provide development teams with greater flexibility and other advantages, such as the abili...
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settle...
Product connectivity goes hand and hand these days with increased use of personal data. New IoT devices are becoming more personalized than ever before. In his session at 22nd Cloud Expo | DXWorld Expo, Nicolas Fierro, CEO of MIMIR Blockchain Solutions, will discuss how in order to protect your data and privacy, IoT applications need to embrace Blockchain technology for a new level of product security never before seen - or needed.