run-instance.yml

# : how to create key pair which is used to ssh login to ec2 instances
# keypair_name=mykey1
# ssh-keygen -t rsa -f ~/.ssh/${keypair_name}
# aws ec2 import-key-pair --key-name ${keypair_name} --public-key-material file://$HOME/.ssh/${keypair_name}.pub

# : modify these variables to fit your situation
# StackName=ec2-run-instance
# yaml2json > /tmp/parameters.json << 'EOF'
# - ParameterKey: KeyName
#   ParameterValue: mykey1
# - ParameterKey: ImageId
#   ParameterValue: ami-b36981d8
# - ParameterKey: InstanceType
#   ParameterValue: g2.2xlarge
# - ParameterKey: AllowSSHFromCidr
#   ParameterValue: 0.0.0.0/0
# EOF

# : convert yaml (this file) to json which requires yaml2json (brew install remarshal)
# yaml2json /tmp/run-instance.yml > /tmp/run-instance.json

# : create ec2 instance and security group with cloudformation
# aws cloudformation create-stack --stack-name $StackName --template-body file:///tmp/run-instance.json --parameters file:///tmp/parameters.json
# aws cloudformation wait stack-create-complete --stack-name $StackName

# : get output values like instance-id, and load into your shell
# aws cloudformation describe-stacks --stack-name $StackName | tee /tmp/output
# c=0; cat /tmp/output | jq -r '.Stacks[].Outputs[] | .OutputKey, .OutputValue' | while read -r x; do [[ $((c++ % 2)) -eq 0 ]] && echo -n $x || echo ="'"$x"'"; done | tee /tmp/vars
# . /tmp/vars

# ssh login to instance
# ssh -vi ~/.ssh/$KeyName ubuntu@$PublicDnsName

# clean up
# aws cloudformation delete-stack --stack-name $StackName && aws cloudformation wait stack-delete-complete --stack-name $StackName

Parameters:
  KeyName:
    Type: String
  ImageId:
    Type: String
  InstanceType:
    Type: String
    Default: t2.micro
  AllowSSHFromCidr:
    Type: String
    Default: 192.168.1.1/32

Outputs:
  KeyName:
    Value:
      Ref: KeyName
  InctanceId:
    Value:
      Ref: MyInstance
  AvailabilityZone:
    Value:
      Fn::GetAtt:
      - MyInstance
      - AvailabilityZone
  PublicDnsName:
    Value:
      Fn::GetAtt:
      - MyInstance
      - PublicDnsName
  PrivateIp:
    Value:
      Fn::GetAtt:
      - MyInstance
      - PrivateIp
  PublicIp:
    Value:
      Fn::GetAtt:
      - MyInstance
      - PublicIp
  SecurityGroupId:
    Value:
      Fn::GetAtt:
      - ServerSecurityGroup
      - GroupId

Resources:
  MyInstance:
    Properties:
      KeyName:
        Ref: KeyName
      ImageId:
        Ref: ImageId
      InstanceType:
        Ref: InstanceType
      SecurityGroups:
      - Ref: ServerSecurityGroup
    Type: AWS::EC2::Instance
  ServerSecurityGroup:
    Properties:
      GroupDescription: allow connections from specified CIDR ranges
      SecurityGroupIngress:
      - CidrIp: 0.0.0.0/0
        FromPort: "80"
        IpProtocol: tcp
        ToPort: "80"
      - CidrIp:
          Ref: AllowSSHFromCidr
        FromPort: "22"
        IpProtocol: tcp
        ToPort: "22"
    Type: AWS::EC2::SecurityGroup