Domain 3: Deployment, Provision and Automation Flashcards
(14 cards)
Bastion Host Tips
Connect to Private Instances. A bastion host enables you to connect to private instances in your VPC from an unstrusted network using SSH or RDP.
. A bastion host is in a public subnet and is reachable from the internet.
. You need to configure the security group associated with the private subnet to enable SSH / RDP access from the bastion
EC2 Image Builder
. Automates the process of creating and maintaining AMI and Container Images.
. Select a base OS image, customize by adding software, test, and distribute to your chosen region.
Load Balancers
.Application Load Balancers: HTTP/HTTPS. Intelligent load balancing. Route requests to a specific web server based on the type of the request.
. Network load balancer: It provides high-performance balancing TCP traffic.
. Classic load balancer: The legacy option that supports both HTTP/HTTPS and TCP.
. Gateway Load Balancer: Provides load balancing for third-party virtual appliances, like firewalls, intrusion detection and Prevention Systems.
. X-Forwarded-For: if you need the IPV4 address of your and user, look for the X-Forwarded-For header.
Elastic Load Balancer CloudWatch Metrics
HealthyHostCount
UnhealthyHostCount
Request count
TargetResponseTime
HTTP Status Codes
Access Logs load balancer.
Access Logs for load balancer are not enabled by default, we need to activate them.
. They are encrypted by default and stored in a S3 bucket and decrypted when we access them.
Sticky sessions
. Sticky sessions override the algorithm and are really useful cause it uses a cookie to identify a session and send the requests to the same session for the same target.
. It really usefu ,for applications that cache information locally on the web
server.
. It’s common for shopping carts, online forms, a learning website which we don’t want to log out our customers halfway through a task.
Load Balancing based On IP Addresses
Elastic Load Balancer allows you to balance traffic to targets based on IP addresses.
. Register Targets: when we register our EC2 targets, we can use their instance ID or private IP Address.
. Use Cases: EC2 instances that have multiple IP addresses, and resources that are accessed using an IP, example: RDS.
Troubleshooting cloudformation
.Insufficient permissions: add permissions for the resources you are trying to create, delete or modify.
. Resource Limit Exceeded: Request a limit increase or delete unnecessary resources and retry.
. Update_ROLLBACK_FAILED: Fix the error causing the failure and retry.
CloudFormation StackSets
It can Create, delete and Update cloudformation stacks across multiple AWS accounts and regions using a single operation.
. Resource Access Manager: allow you to share resources with other accounts, example: EC2 instances, S3 Buckets, and EC2 Image Builder.
. Cross-Account Roles: For the administrator account, use AWSCloudFormationStackSetAdministratorRole, which is allowed to assume AWSCloudFormationStackSetExecutionRole to provision resources in the target accounts.
CloudFormation Best Practices
IAM: Control access to cloudformation using IAM.
Service Limits: If you hit a limit, Cloudformation will fail to create a stack, nowadays we can deploy 20 instances per region using a cloudformation template.
Avoid Manual Updates: Manual updates cause errors when you try to update or delete the stack.
Use a stack policy: Protect critical stack resources from unintentional updates and mistakes caused by human error.
Blue/Green deployment
. Low risk deployment strategy: Blue is the current version of the application, green is the new version.
. Enables testing: After testing is complete, live traffic can be directed to the new version.
. Rollback is easy and fast: If something goes wrong after the new version is being used in production, simply redirect all traffic to the original environment.
Rolling Deployment
. Batches: Deploy new application versions and other changes in batches.
. Cost effective: You can set the batch size and the minimum number of servers to keep in service.
. Complexity: Mixed environment. Rolling back involves a redeployment.
Canary Deployments
An early warning system that can indicate that something is wrong in your application.
. It can deploy the new version to a small number of servers.
. Direct a small proportion of customer traffic to the new version ex: 10%.
. Enables canary testing: testing your application with a small proportion of real customers before roll out to everybody.
