AWS : EC2 Instances Pricing

https://aws.amazon.com/ec2/pricing/on-demand/

AWS : IGW vs NATGW

https://medium.com/awesome-cloud/aws-vpc-difference-between-internet-gateway-and-nat-gateway-c9177e710af6

Internet Gateway (IGW) allows instances with public IPs to access the internet.
NAT Gateway (NGW) allows instances with no public IPs to access the internet.

IGW allows Outside traffic to go in

NAT-GW does not allow Outside traffic to come in, It only allows from inside to Outside

Ansible : Ansible Playbook: Ansible Tower

https://www.youtube.com/watch?v=EcnqJbxBcM0

https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html

Ansible :

• Configuration Management 
• YAML Based
• Push Based Approach
• Agentless Architecture - No agent on Target VMS - Simple SSH to Target VM

2 Parts on Local Machine/Server

1) Ansible Inventory : Client Manifest - Details of Group/Target Client VMs

2) Ansible Playbook : YAML - Job - Sections in Ansible - Yaml Configurations

The default location for inventory is a file called /etc/ansible/hosts. 

You can specify a different inventory file at the command line using the -i <path> option.

Michael DeHaan - Author of Ansible

Ansible was acquired by Redhat

Redhat was acquired by IBM

Ansible has a UI Centric version as well - Ansible Tower

Ansible Tower - Restful UI Web based 

Microservices: Spring Boot: Netflix : Components

https://www.optisolbusiness.com/insight/micro-services-architecture-spring-boot-and-netflix-infrastructure

Convert Certificates into formats

https://knowledge.digicert.com/solution/SO26449.html

Best Certificate Viewer Tool : SSL Viewer : Keystore Explorer : keystore-explorer.org

 

https://keystore-explorer.org

AWS: Cloudformation : How to update Stack by a new resource

 LEARN  From Here  ->  https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/gettingstarted.templatebasics.html

https://aws.amazon.com/premiumsupport/knowledge-center/cloudformation-custom-name/

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks.html

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-whatis-howdoesitwork.html

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-template-resource-type-ref.html

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-elasticloadbalancingv2-targetgroup.html

Update requires: No interruption

docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-get-template.html#using-cfn-updating-stacks-get-stack.CON

When updating a stack, AWS CloudFormation might interrupt resources or replace updated resources, depending on which properties you update. For more information about resource update behaviors, see Update behaviors of stack resources.

Update methods

AWS CloudFormation provides two methods for updating stacks: direct update or creating and executing change sets. When you directly update a stack, you submit changes and AWS CloudFormation immediately deploys them. Use direct updates when you want to quickly deploy your updates.

With change sets, you can preview the changes AWS CloudFormation will make to your stack, and then decide whether to apply those changes. Change sets are JSON-formatted documents that summarize the changes AWS CloudFormation will make to a stack. Use change sets when you want to ensure that AWS CloudFormation doesn't make unintentional changes or when you want to consider several options. For example, you can use a change set to verify that AWS CloudFormation won't replace your stack's database instances during an update.

Drift detection operations