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Vivesh
Vivesh

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Cloud Migration Strategies

#cloud #migration #devops #discuss

Introduction to Cloud Migration

_Cloud migration is the process of moving applications, data, and workloads from an on-premise environment to the cloud. A well-planned migration ensures minimal disruption, maximized performance, and optimized costs.

_

Common Cloud Migration Strategies (6 R's)

  1. Rehosting ("Lift and Shift"):

    • Directly moving applications to the cloud without significant changes.
    • Best for legacy systems with minimal modification needs.

  2. Replatforming ("Lift, Tinker, and Shift"):

    • Making minor optimizations to leverage cloud benefits without major architecture changes.
    • Example: Switching databases to a cloud-managed version.

  3. Repurchasing:

    • Replacing the existing application with a cloud-native SaaS solution.
    • Example: Moving from a self-hosted CRM to Salesforce.

  4. Refactoring/Re-architecting:

    • Redesigning applications to take full advantage of cloud-native features (e.g., serverless computing, microservices).
    • Best for modernizing applications for scalability and performance.

  5. Retiring:

    • Decommissioning outdated or unnecessary systems instead of migrating them.

  6. Retaining:

    • Keeping certain applications on-premise for compliance or technical reasons.

Cloud Migration Plan for an On-Premise Application

1. Assess Current Environment

  • Inventory existing infrastructure, applications, and dependencies.
  • Evaluate application performance, scalability, and resource requirements.
  • Identify applications and data suitable for migration.

2. Define Migration Goals

  • Key Objectives:
    • Improve scalability and performance.
    • Reduce infrastructure maintenance costs.
    • Increase availability and disaster recovery capabilities.
    • Enhance security and compliance.

3. Choose a Cloud Provider

  • AWS, Azure, or Google Cloud Platform based on:
    • Budget.
    • Specific features (e.g., serverless, managed services).
    • Compliance requirements (e.g., GDPR, HIPAA).

4. Select a Migration Strategy

  • For this plan, we'll use a Replatforming strategy:
    • Move the on-premise application to a cloud VM (e.g., AWS EC2).
    • Transition the database to a managed service (e.g., Amazon RDS).

5. Migration Plan Steps

Step 1: Pre-Migration Preparation

  • Analyze application dependencies and identify services to move.
  • Create a migration timeline to minimize downtime.
  • Back up all application data to ensure data safety.

Step 2: Set Up the Cloud Environment

  • Provision Resources:
    • Create a Virtual Private Cloud (VPC) with public and private subnets.
    • Launch EC2 instances for the application.
    • Configure a load balancer for high availability.
  • Database Migration:
    • Set up Amazon RDS for the database.
    • Use AWS Database Migration Service (DMS) to migrate data from on-premise to RDS.

Step 3: Configure Networking and Security

  • Set up security groups and firewalls to restrict access.
  • Use IAM roles and policies to manage permissions.
  • Configure a VPN or Direct Connect for secure communication between on-premise and cloud environments during migration.

Step 4: Data Migration

  • Migrate static files to Amazon S3.
  • Use AWS Snowball for large datasets or AWS DataSync for continuous file synchronization.

Step 5: Application Migration

  • Package the application into containers (if applicable) for easy deployment.
  • Use AWS Elastic Beanstalk or Kubernetes for deployment orchestration.
  • Test the application in the cloud environment.

Step 6: Testing and Optimization

  • Test application performance, latency, and functionality.
  • Optimize instance types, storage, and autoscaling policies to reduce costs.

Step 7: Cutover and Go Live

  • Schedule a maintenance window for the final cutover.
  • Redirect DNS (using Amazon Route 53) to point traffic to the cloud-hosted application.

Step 8: Post-Migration Review

  • Monitor the application using Amazon CloudWatch or another monitoring tool.
  • Address any performance issues or bottlenecks.
  • Optimize resources to ensure cost efficiency.

Example AWS Architecture for the Migrated Application

  1. Compute:

    • EC2 instances in an Auto Scaling group.

  2. Database:

    • Amazon RDS with Multi-AZ deployment for high availability.

  3. Storage:

    • Amazon S3 for static content and backups.

  4. Networking:

    • VPC with public and private subnets.
    • Elastic Load Balancer for distributing traffic.

  5. Monitoring:

    • Amazon CloudWatch for metrics and alerts.

Terraform Configuration

1. Providers and Variables 

provider "aws" {
  region = "us-east-1"  # Change as needed
}

variable "vpc_cidr" {
  default = "10.0.0.0/16"
}

variable "public_subnets" {
  default = ["10.0.1.0/24", "10.0.2.0/24"]
}

variable "private_subnets" {
  default = ["10.0.3.0/24", "10.0.4.0/24"]
}

variable "db_username" {
  default = "admin"  # Set your username
}

variable "db_password" {
  default = "yourpassword"  # Use secrets management for production
}

variable "instance_type" {
  default = "t3.micro"  # Modify as needed
}
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2. Networking: VPC, Subnets, Internet Gateway, and Security Groups 

resource "aws_vpc" "main" {
  cidr_block = var.vpc_cidr
}

resource "aws_subnet" "public" {
  count             = length(var.public_subnets)
  vpc_id            = aws_vpc.main.id
  cidr_block        = var.public_subnets[count.index]
  map_public_ip_on_launch = true
}

resource "aws_subnet" "private" {
  count      = length(var.private_subnets)
  vpc_id     = aws_vpc.main.id
  cidr_block = var.private_subnets[count.index]
}

resource "aws_internet_gateway" "igw" {
  vpc_id = aws_vpc.main.id
}

resource "aws_route_table" "public_rt" {
  vpc_id = aws_vpc.main.id
}

resource "aws_route" "default_route" {
  route_table_id         = aws_route_table.public_rt.id
  destination_cidr_block = "0.0.0.0/0"
  gateway_id             = aws_internet_gateway.igw.id
}

resource "aws_security_group" "web_sg" {
  vpc_id = aws_vpc.main.id

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port   = 443
    to_port     = 443
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

resource "aws_security_group" "db_sg" {
  vpc_id = aws_vpc.main.id

  ingress {
    from_port   = 3306
    to_port     = 3306
    protocol    = "tcp"
    security_groups = [aws_security_group.web_sg.id]
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }
}
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3. Compute: EC2 Instances with Auto Scaling 

resource "aws_launch_configuration" "app" {
  name          = "app-launch-configuration"
  image_id      = "ami-0c02fb55956c7d316"  # Amazon Linux 2
  instance_type = var.instance_type
  security_groups = [aws_security_group.web_sg.id]

  lifecycle {
    create_before_destroy = true
  }
}

resource "aws_autoscaling_group" "app_asg" {
  desired_capacity     = 2
  max_size             = 3
  min_size             = 1
  launch_configuration = aws_launch_configuration.app.id
  vpc_zone_identifier  = aws_subnet.public[*].id

  tag {
    key                 = "Name"
    value               = "app-instance"
    propagate_at_launch = true
  }
}
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4. Database: RDS Instance 

resource "aws_db_subnet_group" "db" {
  name       = "db-subnet-group"
  subnet_ids = aws_subnet.private[*].id
}

resource "aws_db_instance" "app_db" {
  allocated_storage    = 20
  engine               = "mysql"
  instance_class       = "db.t3.micro"
  name                 = "appdb"
  username             = var.db_username
  password             = var.db_password
  vpc_security_group_ids = [aws_security_group.db_sg.id]
  db_subnet_group_name = aws_db_subnet_group.db.name
  multi_az             = true
  skip_final_snapshot  = true
}
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5. Storage: S3 Bucket for Static Files 

resource "aws_s3_bucket" "static" {
  bucket = "app-static-files-${random_id.bucket_id.hex}"
  acl    = "public-read"

  tags = {
    Name = "StaticFilesBucket"
  }
}

resource "random_id" "bucket_id" {
  byte_length = 8
}
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6. Load Balancer 

resource "aws_lb" "app_lb" {
  name               = "app-load-balancer"
  internal           = false
  load_balancer_type = "application"
  security_groups    = [aws_security_group.web_sg.id]
  subnets            = aws_subnet.public[*].id
}

resource "aws_lb_target_group" "app_tg" {
  name     = "app-target-group"
  port     = 80
  protocol = "HTTP"
  vpc_id   = aws_vpc.main.id
}

resource "aws_lb_listener" "http_listener" {
  load_balancer_arn = aws_lb.app_lb.arn
  port              = 80
  protocol          = "HTTP"
  default_action {
    type             = "forward"
    target_group_arn = aws_lb_target_group.app_tg.arn
  }
}

resource "aws_autoscaling_attachment" "asg_attachment" {
  autoscaling_group_name = aws_autoscaling_group.app_asg.name
  target_group_arn       = aws_lb_target_group.app_tg.arn
}
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How to Deploy This Configuration

  1. Install Terraform on your local machine.
  2. Save the configuration in a .tf file (e.g., main.tf).
  3. Initialize Terraform: 
   terraform init
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  1. Validate the configuration: 
   terraform validate
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  1. Plan the deployment: 
   terraform plan
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  1. Deploy the resources: 
   terraform apply
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Summary

Migrating an on-premise application to the cloud requires careful planning, execution, and testing. By following a structured migration strategy like the one outlined above, organizations can achieve improved scalability, reliability, and cost savings while minimizing downtime and risks.

Happy Learning !!!

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LogicEra •

Cloud migration is more than just moving workloads—it's about unlocking agility, scalability, and long-term efficiency. At LogicEra, we specialize in end-to-end cloud migration services tailored to your business needs. From assessing your current infrastructure to selecting the right cloud strategy, managing secure data migration, and optimizing your applications for cloud performance, we ensure a smooth transition with minimal downtime.

Whether you’re looking to rehost, replatform, or refactor, our experts design a migration plan that maximizes performance while reducing costs and risks. Partner with LogicEra to modernize your IT environment and take full advantage of cloud-native technologies.