DevOps Classroom Series – 11/Sept/2020

Installing Chef Server

• For Steps Refer Here
• Installing Chef Server Youtube Video

Enterprise Scenario

• Lets have a look at our team again

• Refer Here for understanding teams

• QT HMS Application Architecture

• QA Process of QT-HMS

  1. Component Env => Automated Unit Tests
  2. System ENV => Automated Functional Tests/Manual Test Engineer
  3. Stress ENV => Automated Stress Tests using Load runner/JMeter
  4. Pre-Staging (UAT) => Manual Tests Before production
  5. Production/Live => Customers

• Chef Workflow

  1. Create cookbooks for
     • loadbalancer
     • appserver-1 (tomcat based app component)
     • appserver-2 (nodejs based app component)
     • redisserver
     • database
  2. Boot strap nodes
     • bootstrap nodes of all environments
     • edit run list of each node
     • Apply run list
  3. Wait for convergence

• Challenges/Problems

  • Chef server always applies latest cookbook to node while convergence. To solve this we need to put restrictions on version of cookbook. This is where Chef environment comes into play
  • For every node we have to create a run_list and this is redundant job. if the run_list changes then apply changes to all the nodes applicable. It would be better if we can create some optimization over here. This can be achieved using Chef roles
  • Consider this scenario:
    • tomcat app in the dev might require java 11 and in all other environments it might be java 8
    • for one app server in the production we might need java 8 and for other server we might need java 9
    • so we need to learn how to apply attributes at different levels (environment, roles)
    • This is where chef attribute precedence comes into play
  • We need some kind of approach to hide sensitive content (like passwords). This is where chef data bags come into play

• Lab Setup:

  • Lets manage 3 environments
    • QA
    • UAT
    • PROD
  • In QA lets use same machine for app server and db server
  • UAT & PROD will have two servers each
  • Lets create two cookbooks
    • qthms-app
    • qthms-db
  • Create 3 ubuntu & 2 redhat servers and ensure they are bootstrapped. (Exercise)
  • Lets create qthms-app Refer Here