DevOps Classroomnotes 29/Mar/2023

Multi user

• Lets create a simple terraform template to create vpc Refer Here for the changes
• Execute this from two different machines.
• Consider both of them are working for same purpose
• User 1:
  
• User 2:
  
• Execution Create two different resources, which is not desired
  
• As of now state is stored locally i.e. when user1 executes it is stored in user1 system and same for user2
  
• To solve this problem we need to store the state in some common place
  
• The location of state file in terraform is defined by backend.

Terraform Backends

• Backend defines where the state has to be stored
• Refer Here for offical docs and Refer Here for configuring backend
• There are two types of backends
  • local-backend:
    • This is default backend
  • remote-backend
• Refer Here for available backends
• As common state for terraform for multiple users will have concurrency problem, Terraform backends need locking and unlocking
• S3 bucket can be used as terraform backend, S3 buckend doesnot support locking, if you need locking add dynamo db details

Remote Backends with S3

• Refer Here for official docs
• Create an s3 bucket
  
• Create a dynamo DB table with any name and partition key LockID
  
• Refer Here for the changes done to add s3 backend
• Perform init on both user machines
  
• Now lets user1 apply the changes
  
• Now while user1 is still applying let user 2 also apply
  
• Let user1 finish applying and create the resources
  
• Now let user2 try applying
  
  
• Exercise: Configure Azurerm backend Refer Here which has inbuilt locking facility

Next Steps

• Provisioning
• Immutable Infrastructure