Cloudformation

Cloudformation 

Gives you the ablity to create a complete AWS environment which consists of different services with the help of a template. We can go head and describe complete environment into the json template and use this template to create the resource when we want for this, using this template we can create the resources whenever we need we can use it.

Concepts of Cloudformation

1) Template - Collection of AWS resources with its attributes.
When we feed this template to cloud formation engine AWS created all the resources in the template which is known as Stack.

To delete all the resources we can simply delte the stack to delete all resources.

2) Stack - Resources created by cloudformation engine with the help of template.

3) Change sets

How to Write a template

We ca

If we want to creat a template from an already created environment then we can use cloudformer. it will ask username nad passoerd (anything) it will create one ec2 instance and cloudformeer installed on the ec2. you can use it via browser it will point to one of region which we choose and all the resources from the region will be created in the template.

About Cloudformation

1) We can use any JSON editor to create template
2) Cloudformation is a IASS (Infratructe as Service)
3) With the help of cloudformation we can quickly replicate the infrastructure
4) Ref: in cloudformation template is we are referring to that resource to create.
5) While creating stack we can either upload template either from Desktop or from S3. 
6) Rollback on failure is b deafult set to false.
7) Stack Policy -  Once you create a stack we can go ahead and update stack. Some time we don't want to update some resources in that case we can use stack policy.
8) Chnage Set - Will Display what are the changes will happen to your stack. We can check this and update the stack.