What is the AWS Attribute outputs and ImportValue in cloudformation - amazon-web-services

Question

i'm starting my AWS journey and today got a chance to Create cloudformation stack for creating a filesystem on the AWS, i was able to spun the filesystem, however I have few
doubts about some values and functions/attributes as those were given by someone in the team and he on long vacations so, asking here for help.
Below is cloudfoemation Stack which works Just fine.
Cloudformaton Stack:
---
Description: "Create FSxN filesystem"
Resources:
MytestCluster:
Type: "AWS::FSx::FileSystem"
Properties:
FileSystemType: "ONTAP"
StorageCapacity: "1024"
SubnetIds: ['subnet-0f349h6eee098b0pg']
OntapConfiguration:
DeploymentType: "SINGLE_AZ_1"
PreferredSubnetId: "subnet-0f349h6eee098b0pg"
ThroughputCapacity: "128"
FsxAdminPassword: '{{resolve:secretsmanager:fsx_admin_password}}'
SecurityGroupIds:
- !ImportValue 'KPCL-FSxforONTAPsgID'
Tags:
- Key: "Backup"
Value: "None"
MytestSVM:
Type: "AWS::FSx::StorageVirtualMachine"
Metadata:
cfn-lint:
config:
ignore_checks:
- E3001
Properties:
FileSystemId: !Ref MytestCluster
Name: svmdemo
RootVolumeSecurityStyle: "UNIX"
SvmAdminPassword: '{{resolve:secretsmanager:svm_admin_password}}'
Tags:
- Key: "Backup"
Value: "None"
fsxndemovolume:
Type: "AWS::FSx::Volume"
Metadata:
cfn-lint:
config:
ignore_checks:
- E3001
Properties:
Name: myTestVol001
OntapConfiguration:
JunctionPath: /myVolume001
SizeInMegabytes: 1536000
StorageEfficiencyEnabled: true
StorageVirtualMachineId: !Ref MytestSVM
VolumeType: "ONTAP"
Tags:
- Key: "Backup"
Value: "None"
Outputs:
FileSystemId:
Value: !Ref "MytestCluster"
SvmId:
Value: !Ref "MytestSVM"
...
I would like Understand:
I have few doubts to myself to clear which i tried to understand from document but couldn't comprehend well, hence though taking expert suggestion..
First one: below under SecurityGroupIds what does - !ImportValue mean here.
SecurityGroupIds:
- !ImportValue 'KPCL-FSxforONTAPsgID'
Second one: What is outputs means here.
Outputs:
FileSystemId:
Value: !Ref "MytestCluster"
SvmId:
Value: !Ref "MytestSVM"
Last one: what is ignore_checks: and its value - E3001 here.
ignore_checks:
- E3001
Please help me to understand.

Answer 1

First one: below under SecurityGroupIds what does - !ImportValue mean here.
The following:
SecurityGroupIds:
- !ImportValue 'KPCL-FSxforONTAPsgID'
means that in the current stack your are going to import security group ID which was exported by some other stack.
This export/import functionality allows you to decouple and reuse your infrastructure. Instead of having everything in one stack, you can make one stack with network resources (its a common setup), such as security groups, subnets, VPCs, and other stacks that actual use those resources.
Second one: What is outputs means here.
Outputs allow you to return values from your stacks. You can think of them as a type of return values from functions in common programming languages.
Output values have lots of use-cases. Examples are: they can be exported, and imported in other stacks. They can also be queried programmatically, in case your stacks are part of some CI/CD pipelines or other application. They can be used as input parameters to other stacks, again as port of some CI/CD pipeline. This is alternative to export/import functionality.
Last one: what is ignore_checks: and its value - E3001 here.
This is some extra code not related to CloudFormation itself. It is actually a hint to Visual Studio Code
cfn-lint-visual-studio-code editor to ignore some auto checks it does.

Answer 2

Outputs in stack creates exports in cloudformation which can be listed in AWS Console, !Import directive is used to reference to export from another stack.
cfn-lint section in metadata is used to silent errors in CloudFormation Linter tool and has no impact to the resource itself.