Cloudformation Template for the following

• Simple
  • Create S3 bucket
  • Create an EC2 instance
  • Solution:

  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "This template is written for learning and it creates s3 bucket and ec2 instance",
      "Resources": {
          
          "mys3": {
              "Type": "AWS::S3::Bucket",
              "Properties": {
                  "AccessControl": "PublicRead",
                  "BucketName": "qts3forpracticemay"
              }
          },
          "myec2": {
              "Type": "AWS::EC2::Instance",
              "Properties": {
                  "ImageId": "ami-0470e33cd681b2476",
                  "InstanceType": "t2.micro"
              }
  
          }
          
      }
  
  }
  

  • The above template is not resuable bcoz of names directly used in properties (hard-coded)
  • We can eliminate hard coding by using parameters Refer Here
  • Lets add a parameter for s3 buckets name and ec2 instance type and Image-Id. Refer Here for parameters section.
  • Lets add the string parameters to the template

  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "This template is written for learning and it creates s3 bucket and ec2 instance",
      "Parameters": {
          "s3bucketname": {
              "Description": "The name of the bucket which you want to create",
              "Type": "String"
          },
          "ec2instancetype": {
              "Description": "Instance type of ec2",
              "Type": "String",
              "Default": "t2.micro"
          },
          "amiid": {
              "Description": "Image Id",
              "Type": "String",
              "Default": "ami-0470e33cd681b2476"
          }
      },
      "Resources": {
          "mys3": {
              "Type": "AWS::S3::Bucket",
              "Properties": {
                  "AccessControl": "PublicRead",
                  "BucketName": "qts3forpracticemay"
              }
          },
          "myec2": {
              "Type": "AWS::EC2::Instance",
              "Properties": {
                  "ImageId": "ami-0470e33cd681b2476",
                  "InstanceType": "t2.micro"
              }
          }
      }
  }
  

  • Lets add the references of the parameters in resources using Ref

  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "This template is written for learning and it creates s3 bucket and ec2 instance",
      "Parameters": {
          "s3bucketname": {
              "Description": "The name of the bucket which you want to create",
              "Type": "String"
          },
          "ec2instancetype": {
              "Description": "Instance type of ec2",
              "Type": "String",
              "Default": "t2.micro"
          },
          "amiid": {
              "Description": "Image Id",
              "Type": "String",
              "Default": "ami-0470e33cd681b2476"
          },
          "s3accesscontrol": {
              "Description": "S3 Access control",
              "Type": "String",
              "Default": "PublicRead"
          }
      },
      "Resources": {
          "mys3": {
              "Type": "AWS::S3::Bucket",
              "Properties": {
                  "AccessControl": {
                      "Ref": "s3accesscontrol"
                  },
                  "BucketName": {
                      "Ref": "s3bucketname"
                  }
              }
          },
          "myec2": {
              "Type": "AWS::EC2::Instance",
              "Properties": {
                  "ImageId": {
                      "Ref": "amiid"
                  },
                  "InstanceType": {
                      "Ref": "ec2instancetype"
                  }
              }
          }
      }
  }
  

  • Now if we create the stack from cf template the parameters section will be shown in the UI
  • Now lets restrict user from entering anything into parameters by using AllowedValues and using Regular expressions in parameter section AllowedPattern.

  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "This template is written for learning and it creates s3 bucket and ec2 instance",
      "Parameters": {
          "s3bucketname": {
              "Description": "The name of the bucket which you want to create",
              "Type": "String"
          },
          "ec2instancetype": {
              "Description": "Instance type of ec2",
              "Type": "String",
              "AllowedValues": [
                  "t2.micro",
                  "t2.nano",
                  "t2.small"
              ],
              "Default": "t2.micro"
          },
          "amiid": {
              "Description": "Image Id",
              "Type": "String",
              "Default": "ami-0470e33cd681b2476"
          },
          "s3accesscontrol": {
              "Description": "S3 Access control",
              "Type": "String",
              "AllowedValues": [
                  "Private",
                  "PublicRead",
                  "PublicReadWrite",
                  "AuthenticatedRead",
                  "LogDeliveryWrite",
                  " BucketOwnerRead",
                  "BucketOwnerFullControl"
              ],
              "Default": "PublicRead"
          }
      },
      "Resources": {
          "mys3": {
              "Type": "AWS::S3::Bucket",
              "Properties": {
                  "AccessControl": {
                      "Ref": "s3accesscontrol"
                  },
                  "BucketName": {
                      "Ref": "s3bucketname"
                  }
              }
          },
          "myec2": {
              "Type": "AWS::EC2::Instance",
              "Properties": {
                  "ImageId": {
                      "Ref": "amiid"
                  },
                  "InstanceType": {
                      "Ref": "ec2instancetype"
                  }
              }
          }
      }
  }
  

  
  • Lets add the security group to the AWS Ec2 instance using a AWS Specific parameter AWS::EC2::SecurityGroup::GroupName and key pair

  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "This template is written for learning and it creates s3 bucket and ec2 instance",
      "Parameters": {
          "s3bucketname": {
              "Description": "The name of the bucket which you want to create",
              "Type": "String"
          },
          "ec2instancetype": {
              "Description": "Instance type of ec2",
              "Type": "String",
              "AllowedValues": [
                  "t2.micro",
                  "t2.nano",
                  "t2.small"
              ],
              "Default": "t2.micro"
          },
          "amiid": {
              "Description": "Image Id",
              "Type": "String",
              "Default": "ami-0470e33cd681b2476"
          },
          "s3accesscontrol": {
              "Description": "S3 Access control",
              "Type": "String",
              "AllowedValues": [
                  "Private",
                  "PublicRead",
                  "PublicReadWrite",
                  "AuthenticatedRead",
                  "LogDeliveryWrite",
                  " BucketOwnerRead",
                  "BucketOwnerFullControl"
              ],
              "Default": "PublicRead"
          },
          "sgname": {
              "Description": "Security Groups",
              "Type": "AWS::EC2::SecurityGroup::GroupName"
          },
          "awskeypair": {
              "Description": "Keypair",
              "Type": "AWS::EC2::KeyPair::KeyName"
          }
      },
      "Resources": {
          "mys3": {
              "Type": "AWS::S3::Bucket",
              "Properties": {
                  "AccessControl": {
                      "Ref": "s3accesscontrol"
                  },
                  "BucketName": {
                      "Ref": "s3bucketname"
                  }
              }
          },
          "myec2": {
              "Type": "AWS::EC2::Instance",
              "Properties": {
                  "ImageId": {
                      "Ref": "amiid"
                  },
                  "InstanceType": {
                      "Ref": "ec2instancetype"
                  },
                  "SecurityGroups": [
                      {
                          "Ref": "sgname"
                      }
                  ],
                  "KeyName": {
                      "Ref": "awskeypair"
                  }
              }
          }
      }
  }
  

  
• Novice Scenario [Create an Ec2 Instance in a new network (VPC)]:
  • Create a vpc
  • Add 3 subnets to vpc [Refer to previous classes screenshots]
  • Create and attach internet gateway to vpc
  • Create a Route table with route to internet gateway
  • Create subnet associations to new route table for 2 out 3 subnets
  • Create a Key value pair [manual] and security group [manual]
  • Create an ec2 instance in subnet1 and other ec2 instance in subnet2 [last step]