CloudFormation Use Case

This topic describes a use case for creating a stack, checking the stack progress, and deleting the stack. For this use case, we will use the following template:

Parameters:
  MyImageId:
    Description: Image id
    Type: String
  MyKeyPair:
    Description: Key Pair
    Type: String
Resources:
  MySecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Security Group with Ingress Rule for MyInstance
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '22'
          ToPort: '22'
          CidrIp: '0.0.0.0/0'
  MyInstance:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: !Ref 'MyImageId'
      SecurityGroups:
        - !Ref 'MySecurityGroup'
      KeyName: !Ref 'MyKeyPair'

This template creates an instance with a security group that allows global SSH access (port 22), but uses a keypair to log in. It requires two parameters, MyImageId , which is the image ID of the instance to create, and MyKeyPair , which is the name of the keypair to use to log in with. You could use both values with the euca-run-instances or aws ec2 run-instances commands to create an instance manually (for example, euca-run-instances -k mykey emi-371ada125a928669e ) so the arguments needed here are standard instance arguments.

The steps to run this template through the system are explained in the following steps.

Note

These steps require that you have an available image and that the CloudFormation service is running

Verify connectivity to the CloudFormation service.

euform-describe-stacks 
# Or
aws cloudformation describe-stacks

You should not see anything returned, including any errors. Create a file called ex_template.yaml that contains the YAML template content shown in the introduction above.

Create a keypair.

euca-create-keypair myKey > myKey.pem
# Or
aws ec2 create-key-pair --key-name myKey > myKey.pem

Set the permissions on the keypair.

chmod 0600 myKey.pem

Find what resources have been created., run the command and the euca-describe-groups commands. Make note of the output for later. Run:

euca-describe-images -a
# Or
aws ec2 describe-images

Note the output for later use.

Create the stack referencing the existing resources.

# euform-create-stack --template-file ex_template.yaml -p MyImageId=<image_id> -p MyKeyPair=myKey MyStack
arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb

of with the AWS CLI:

# aws cloudformation create-stack --template-body file://ex_template.yaml --parameters ParameterKey=MyImageId,ParameterValue=emi-371ada125a928669e ParameterKey=MyKeyPair,ParameterValue=myKey --stack-name MyStack
arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb

Run the checks you want on your stack. Check the status of the stack.

# euform-describe-stacks
STACK	MyStack	CREATE_COMPLETE			2020-10-20T18:31:15.662Z
PARAMETER	MyImageId		emi-371ada125a928669e
PARAMETER	MyKeyPair		myKey
#
# aws cloudformation describe-stacks
STACKS	2020-10-20T18:31:15.662Z	False	2020-10-20T18:31:51.316Z	arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb	MyStack	CREATE_COMPLETE	
PARAMETERS	MyImageId	emi-371ada125a928669e
PARAMETERS	MyKeyPair	myKey

Check the stack at any time to see all the events that have occurred during the stack lifecycle.

# euform-describe-stack-events MyStack
EVENT	MyStack	d87c4381-b765-4d44-a5ba-a952855ffd79	AWS::CloudFormation::Stack	MyStack	arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb	2020-10-20T18:31:51.310Z	CREATE_COMPLETE	
EVENT	MyStack	MyInstance-CREATE_COMPLETE-1603218711063	AWS::EC2::Instance	MyInstance	i-687f112f4c99e9a98	2020-10-20T18:31:51.063Z	CREATE_COMPLETE	
EVENT	MyStack	MyInstance-CREATE_IN_PROGRESS-1603218676951	AWS::EC2::Instance	MyInstance	i-687f112f4c99e9a98	2020-10-20T18:31:16.951Z	CREATE_IN_PROGRESS	Resource creation Initiated
EVENT	MyStack	MyInstance-CREATE_IN_PROGRESS-1603218676783	AWS::EC2::Instance	MyInstance		2020-10-20T18:31:16.783Z	CREATE_IN_PROGRESS	
EVENT	MyStack	MySecurityGroup-CREATE_COMPLETE-1603218676599	AWS::EC2::SecurityGroup	MySecurityGroup	MyStack-MySecurityGroup-SWUBTU8TQ9MBV	2020-10-20T18:31:16.599Z	CREATE_COMPLETE	
EVENT	MyStack	MySecurityGroup-CREATE_IN_PROGRESS-1603218676174	AWS::EC2::SecurityGroup	MySecurityGroup	MyStack-MySecurityGroup-SWUBTU8TQ9MBV	2020-10-20T18:31:16.174Z	CREATE_IN_PROGRESS	Resource creation Initiated
EVENT	MyStack	MySecurityGroup-CREATE_IN_PROGRESS-1603218676038	AWS::EC2::SecurityGroup	MySecurityGroup		2020-10-20T18:31:16.038Z	CREATE_IN_PROGRESS	
EVENT	MyStack	9212e1ff-6c7a-4710-96a2-d83606a3c34f	AWS::CloudFormation::Stack	MyStack	arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb	2020-10-20T18:31:15.780Z	CREATE_IN_PROGRESS	User Initiated

Run euca-describe-instances and euca-describe-groups to see the newly created resources:

# euca-describe-instances i-687f112f4c99e9a98
RESERVATION	r-2381c3e652dd942f2	000575948401	MyStack-MySecurityGroup-SWUBTU8TQ9MBV
INSTANCE	i-687f112f4c99e9a98	emi-371ada125a928669e	euca-192-168-134-181.eucalyptus.mycloud.example.com	euca-172-31-15-210.eucalyptus.internal	running	myKey	0		t2.micro	2020-10-20T18:31:16.920Z	cloud-1a				monitoring-disabled	192.168.134.181	172.31.15.210	vpc-837bc081de161f8c0	subnet-1503566df094fe78a	instance-store					hvm			sg-98da12246d91375e3				x86_64
NETWORKINTERFACE	eni-42a4a3bf7d1075735	subnet-1503566df094fe78a	vpc-837bc081de161f8c0	000575948401	in-use	172.31.15.210	euca-172-31-15-210.eucalyptus.internal	true
ATTACHMENT		eni-attach-cc38f4f4ef78a6469	0	attached	2020-10-20T18:31:16.923Z	true
ASSOCIATION	192.168.134.181		172.31.15.210
GROUP	sg-98da12246d91375e3	MyStack-MySecurityGroup-SWUBTU8TQ9MBV
PRIVATEIPADDRESS	172.31.15.210	euca-172-31-15-210.eucalyptus.internal	primary
TAG	instance	i-687f112f4c99e9a98	aws:cloudformation:logical-id	MyInstance
TAG	instance	i-687f112f4c99e9a98	aws:cloudformation:stack-id	arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb
TAG	instance	i-687f112f4c99e9a98	aws:cloudformation:stack-name	MyStack
TAG	instance	i-687f112f4c99e9a98	euca:node	10.117.111.18
#
# euca-describe-groups sg-98da12246d91375e3
GROUP	sg-98da12246d91375e3	000575948401	MyStack-MySecurityGroup-SWUBTU8TQ9MBV	Security Group with Ingress Rule for MyInstance	vpc-837bc081de161f8c0
PERMISSION	000575948401	MyStack-MySecurityGroup-SWUBTU8TQ9MBV	ALLOWS	tcp	22	22	FROM	CIDR	0.0.0.0/0	ingress
PERMISSION	000575948401	MyStack-MySecurityGroup-SWUBTU8TQ9MBV	ALLOWS	-1			TO	CIDR	0.0.0.0/0	egress
TAG	security-group	sg-98da12246d91375e3	aws:cloudformation:logical-id	MySecurityGroup
TAG	security-group	sg-98da12246d91375e3	aws:cloudformation:stack-id	arn:aws:cloudformation::000575948401:stack/MyStack/26daf046-3776-4b97-9444-5edae2f2eceb
TAG	security-group	sg-98da12246d91375e3	aws:cloudformation:stack-name	MyStack

To SSH into the instance:

ssh -i myKey.pem root@192.168.134.181

Note

Username might depend on the image, and might be root, centos, ubuntu or ec2-user.

Delete the stack.

euform-delete-stack MyStack
# Or
aws cloudformation delete-stack --stack-name MyStack

You can run euform-describe-stacks and all the other describe commands to check the progress until the delete is complete.