Configuration Management Systems enables to manage large-scale server infrastructure efficiently. These tools are also designed to ensure reliability and compliance while minimizing the complexity of configuring distributed infrastructure resources. The usage of the Configuration Management System is ever increasing due to its ease of usage and efficiency. The Gartner report mentions “by 2020, 50% of global enterprises will have implemented at least one application release automation solution, up from less than 15% today.”Here, we are going to explain the importance of Configuration Management Systems and the pros, cons and quick comparison of Ansible, Puppet and Chef.
The need for Configuration Management Systems
Organizations use replicated servers with the same services and configuration to achieve load balancing and scalability. But with this set-up, any updates or configuration changes are also needed to be replicated in all the servers. Even though these can be automated using shell scripts and SSH access to the client nodes, often we require robust methods to manage and audit servers effectively. In situations like these, a Configuration Management System comes in handy.
The configuration management systems can control various attributes like Users, Softwares and Services, Firewall etc in the Client nodes. These systems also include automated provisioning of servers and configurations saved in a high-level language.
To get the most out of it, the Configuration Management Systems need to be planned prior to the initialization of the systems.
Management Systems requirements
A management system should meet the following qualities:
1. A Centralized Catalogue for services and client nodes.
2. Able to Replicate configurations and services across all or a list of servers, according to your need.
3. Idempotent at most cases ( ie., even if a catalogue run repeatedly, the result should be same ).
4. Manage Entire client setup from one interface.
5. Audit the client node attributes.
6. Reduce service Downtime
7. Can be Scalable with little configuration changes.
8. Catalogues should include every configuration and changes that are made in time. So after a catastrophic event, systems could be rebuilt without any further manual intervention.
There are many software packages available in the market, but we will be covering Open Source versions of Ansible, Puppet, and Chef in a Linux environment.
Puppet is the oldest of the three management system, which has its initial release in 2005. It uses Ruby DSL or its own declarative language to describe system configuration. This causes some controversies since the Language is not entirely Open Source.
Puppet offers two flavours , Open source Puppet and Puppet Enterprise. Open Source version supports only Pull model, but Enterprise puppet has Push model also.
Puppet Client sends current configurations ( like service status, service configurations ) to the Puppet Master. The master compiles the catalog for the client to ensure the result is achieved. Once the configuration is completed, Agent report back to the Master and data is updated in the Dashboard.
The Chef started in 2009, it also follows Open Source model along with an Enterprise edition. The Chef works on a client-server architecture. The Chef client updates current client status and values to the Chef server at regular intervals. The server indexes these attributes. When clients query this information, Chef server provides catalogs according to each client requirement. Then, these patterns are defined using Ruby as its reference language.
Ansible is a newcomer to this arena, released in 2012, Ansible is managed and commercially supported by Redhat. It’s also minimal in nature rather than Puppet or Chef.
Ansible saves catalog to the server node. Then, run the catalog over SSH service in each client node. It does not depend on any other services.
|Client Agent||Required||Not needed||Required|
|Learning Curve||Required||Lot easier||Required|
|Language knowledge required||Custom DSL(Ruby)||YAML(Python)||DSL(Ruby)|
|Runtime required||Open source version only support pull modelwhich require time||Push mode, which is instantaneous||Pull model, which require time|
Incorrect configurations: You should make sure the catalogs are configured correctly and are well tested. Any configuration will be replicated in all servers, so this itself can cause server failures.
Configuration Drift: If different systems are incorrectly running with a slightly different application version or configuration change, Configuration Drift happens. A good Configuration Management System can track this difference systematically.
Like any other competitive platform, each system has its own pros and cons. They are capable for most situations but vary in uniqueness when it comes to mode of operation method and other functions. For example, Chef and Puppet use Pull model and good for continuous development whereas Ansible is easier for configuring and scaling.
While choosing Configuration management Systems you need to choose a system that goes according to your task flow, internal server setup, features, and support needs. But a close look at each system reveals us a conclusion, Ansible has a little edge over Puppet and Chef for its simplicity and minimalistic approach. After all, when it comes to securing a server from harm, a minimalistic approach causes less amount of headaches than a complex system.
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