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Splunk VS ELK/Elastic Stack

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  • | 1710 Ratings |
  • Last Updated September 01, 2017

Log management solutions play a pivotal role in an organization’s security framework. Without these solutions, enterprise can face security comprises or data breaches due to low visibility of actions and events happening in the infrastructure. The tools available for logging are in abundance. How can you choose the appropriate tool? Which is the best amongst the leading two log management tools solutions - Splunk or ELK (Elastic Stack)? Let’s stack up their comparison to choose the best tool.

What is Splunk?

Splunk is also termed as “Google for log files”. All the log data generated by any device or system in an IT environment is gathered and given as input to Splunk. Splunk refines it and generates powerful insight to the log data through alerts, charts, graphs etc. 

Three key components in Splunk are its forwarder, indexer and search head. Forwarder pushed data to remote indexer. Indexer responds to search queries. Search head is the front end web interface where these 3 components can be combined.

Splunk(Reference : https://www.splunk.com)

What is ELK?

ELK stands for Elasticsearch, Logstash, and Kibana. ELK consists of different software tools like Elasticsearch (log searching tool), logstash (data router and data processing tool) and Kibana(data visualization tool). Altogether, these 3 tools make up a full analytical tool. 

  • Elasticsearch - a NoSQL database which uses Lucene search engine
  • Logstash - It is a transportation pipeline used to populate Elasticsearch with data
  • Kibana - It is a dashboard working on top of Elasticsearch and provide data analysis through visualizations and dashboards.

Elastic Stack(Reference : https://www.elastic.co)

Let us summarize all the technical information we learnt in below table.

Technology splunk
Data Collection Splunk Forwarder Logstash/FileBeat
Transport Splunk TCP, HTTPS Elastic Transport, HTTPS
Index Storage Flat Files Flat Files
Indexing Technology Proprietary, C++ Bases, Schema on read Apache Lucene, Java Based, Schema on write
Search Technology Custom MapReduce Apache Lucene
Search Interface Splunk Search Head Kibana
Search Language SPL(Splunk Processing Language) Apache Lucene
Search Interface – REST API? Yes Yes

Splunk Vs. ELK

Pricing

Splunk: Splunk is a proprietary software with a price tag. It is a bit costly but has excellent benefits. For basic logging, you can always use Splunk light.

ELK: ELK is open source, so it is free. 

But to own a software, you need to consider many other costs along with software cost. Below are few costs which you should keep in mind while owning any software.

  • Infrastructure Cost: Splunk and ELK both are having similar hardware infrastructure.
  • Solution Implementation Cost: As Splunk is having a price tag attached to it, it comes with some consulting hours to implement the solution. Whereas for ELK, you need to pay extra for same.
  • Maintenance Cost: In Splunk, support hours are also included while purchasing. But in ELK, you don’t have any support. So you need to pay some extra bucks for their professional services.
  • Plugins and Add-ons Cost: To extend the functionalities, Splunk and ELK both support plugin/add-on based solutions. Few of them can be free and few can be expensive.

Features and Implementation

Loading Data

Splunk can accept any data in any format i.e. csv or json or any other log format. In case of ELK, logstash is responsible for data processing. Logstash doesn’t support all the data types. Plugins are required to work with those data types in logstash. But with logstash, it is difficult to debug with errors as it uses non-standard configuration language. 

Moreover for ELK, we need to identify and configure data fields before injecting into system. Whereas for Splunk, we can inject the data as it is and as it comes with some pre-configurations. Also in case of GUI also, splunk has an upper-hand over ELK due to its user friendly and intuitive nature.

Visualizations

Splunk UI has flexible controls to edit and add new components to your dashboards. It also allows different customized view for different users by configuring dashboards controls differently for them. Along with all these features, it also supports visualizations on mobile device having Splunk application.

ELK has Kibana tool for visualizations. Kibana has all the features to build the dashboards pretty quickly using its own built-in aggregators. But one thing we need to make sure is the data types. If they are incorrect, aggregator functions won’t work. Filtering data is much easier and advanced in ELK stack. Although Kibana doesn’t provide user management, we can have this functionality by using out of the box ELK hosted solutions.

Log Search Capabilities

For any log management software, search capabilities is the most important feature. Splunk uses its own Splunk Search Processing Language (SPL) to make search queries. Whereas ELK uses Lucene query language for search queries. 

Lucene is similar with other scripting languages so it will be easy to learn. In case of SPL, it is proprietary and needs to be learnt to work on it.  The key difference between SPL and Lucene is SPL supports search pipeline which Lucene doesn’t support. Search pipeline is one command’s output is input for the next one. Lucene is straightforward and used to generate output of one command without any transformations.

Release rate of new updates

Both software tools provide periodic updates by fixing bugs and enhancing their software with new features. Splunk is available right now with 7.1 version whereas ELK is available at 6.4 version. 

Splunk is generally having quarterly release cycle. On the other side ELK releases their new updates much faster than prior. This arise questions in my mind to think about the quality of ELK’s build releases.

Companies who work with these tools

There are very hifi companies using Splunk for their log management. Splunk is offering their services to approximately 12000 customers. 89 amongst them are in Fortune 100 list. Below are few companies using Splunk.

Splunk Companies

ELK is also having same impressive companies list. Below are the top customers served by ELK.

ELK

Community Support and Documentation

Splunk has a great customer base so its community is also large. On those communities, you will be able to find all your answers. Furthermore, Splunk is also having a developer community. So a Splunk licence can give you access to these communities as well as their enterprise support.

ELK is an open source software. But they offer paid support. So it is a “freemium” model of software. There are so many open source communities for ELK which provides support and answers to your questions. But there is a drawback of data confidentiality/security. 

API and Extensibility

Splunk provide a RESTful API with over  200 endpoints to access each and every feature residing in the product. Also this API is well-documented which makes the work easier and faster. It also offers product SDKs for many popular languages. 

ELK Stack has Elasticsearch which was designed as a distributed search and analytics engine using standard RESTful APIs and JSON. ELK offers pre-built clients for creating customized apps in various languages like Python, Java, .NET and more.

Integration and Plugins

Splunk was proved to be better when it comes to set-up the integrations with other tools. Splunk offers almost 1000 add-ons and apps which are divided into 6 different categories: 

  • DevOps
  • IT operations
  • Security/fraud/compliance
  • Business analytics
  • IoT/industrial data
  • Utilities

Although ELK also supports plethora of plugins. But it doesn’t have much integrations like Splunk. Logstash responsible for data loading is only having 160 integrations as of now.

Learning Curve

Learning curve for both tools are steep. As for both the products we need knowledge about Regex, scripting languages and TCP/IP. But compared to Splunk, ELK’s curve is flat as there are lots of materials available online due to ELK being an open source platform. Splunk offers trial period with its extensive and useful documentation. Although, its advances courses are pricy.

Below is the summarized table comparing features between Splunk and ELK.

Feature Splunk ELK
Searching Integration Needed
Analysis Integration Needed
Visualization Integration Needed
On Premise Setup
Inject any data type Plug in Needed
Customer Support
Documentation and Community
Plugins and Integration
SaaS Setup

Final Thoughts

Although Splunk and ELK are great tools for log management, choice for any tools must depend on customer’s specific needs, infrastructure size and cost. For any small or medium enterprise having low budget should go for ELK while a large enterprise should choose Splunk over ELK.

If Splunk interests you, then go and check out our Splunk online training which comes with lifetime access to videos and training materials.

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