DevOps Classroom Series – 18/Jan/2021

Revision of last six sessions

• To deploy applications in various test and prod environments
  • We need to have or create servers
  • Once the server is available we need to execute set of steps to configure the application
• Configuration Management is all about automating set of steps to configure the application in an environment
• Set of steps automation
  • Scripting
    • This is procedural (we have to specify how and what has to be done)
    • Executing same script multiple times on same machine for different versions of the deployment might not give same results
  • Configuration Management
    • This is declarative (we have to specify what has to be done)
    • Executing same script multiple times on same machine for different versions of the deployment will give same result (idempotance is supported in CM)
• Architecture of Configuration Management
  • We will have nodes which are servers where the application has to be deployed
  • We will have a server for configuration management
• We have two possibilities in CM
  • PUSH based CM
    • Example: Ansible, Salt Stack
  • PULL based CM
    • Example: Chef, Puppet
• Since Chef is a PULL Based CM, we need to install agents on nodes (bootstrapping)
• We can install chef server on a linux machine or go with hosted chef Refer Here
• we have learnt how to bootstrap nodes using chef dk (knife), upload cookbooks (berkshelf)
• We have started looking at hosted chef server and came to following conclusion
• We have to learn the chef cookbook development workflow
  • Gather all the steps required to manually configure the application
  • Take each step and try to find the equivalent chef resource to perform the step
  • organize the steps in the recipes
  • Test the developed recipes using test kitchen
• Test Kitchen helps in creating linux/windows machines in
  • AWS
  • Azure
  • Docker
  • Virtual Machines in vmware, virtual box or hyperv using Vagrant Refer Here

Test Kitchen Configuration

• Lets take the the following scenario
• Linux Apache Server and mysql (LAMP Stack)
  • Ubuntu Refer Here
  • Centos 7 Refer Here
• Steps:
  • Try executing manual steps on a machine to verify if they are working or not
  • Now create a chef cookbook

  chef generate cookbook -b mylamp
  

  • Now try configuring test kitchen to test your recipes in desired environments
  • In this case lets try to configure test kitchen to create an ubuntu instance in aws Refer Here