AWS CloudFormation Best Practices – Certification

AWS CloudFormation Best Practices

  • AWS CloudFormation Best Practices are based on real-world experience from current AWS CloudFormation customers
  • AWS CloudFormation Best Practices help provide guidelines on
    • how to plan and organize stacks,
    • create templates that describe resources and the software applications that run on them,
    • and manage stacks and their resources

Required Mainly for Developer, SysOps Associate & DevOps Professional Exam

Planning and Organizing

Organize Your Stacks By Lifecycle and Ownership

  • Use the lifecycle and ownership of the AWS resources to help you decide what resources should go in each stack.
  • By grouping resources with common lifecycles and ownership, owners can make changes to their set of resources by using their own process and schedule without affecting other resources.
  • For e.g. Consider an Application using Web and Database instances. Both the Web and Database have a different lifecycle and usually the ownership lies with different teams. Maintaining both in a single stack would need communication and co-ordination between different teams introducing complexity. It would be best to have different stacks owned by the respective teams, so that they can update their resources without impacting each others’s stack.

Use Cross-Stack References to Export Shared Resources

  • With multiple stacks, there is usually a need to refer values and resources across stacks.
  • Use cross-stack references to export resources from a stack so that other stacks can use them
  • Stacks can use the exported resources by calling them using the Fn::ImportValue function.
  • For e.g. Web stack would always need resources from the Network stack like VPC, Subnets etc.

Use IAM to Control Access

  • Use IAM to control access to
    • what AWS CloudFormation actions users can perform, such as viewing stack templates, creating stacks, or deleting stacks
    • what actions CloudFormation can perform on resources on their behalf
  • Remember, having access to CloudFormation does not provide user with access to AWS resources. That needs to be provided separately.
  • To separate permissions between a user and the AWS CloudFormation service, use a service role. AWS CloudFormation uses the service role’s policy to make calls instead of the user’s policy.

Verify Quotas for All Resource Types

  • Ensure that stack can create all the required resources without hitting the AWS account limits.

Reuse Templates to Replicate Stacks in Multiple Environments

  • Reuse templates to replicate infrastructure in multiple environments
  • Use parameters, mappings, and conditions sections to customize and make templates reusable
  • for e.g. creating the same stack in development, staging and production environment with different instance types, instance counts etc.

Use Nested Stacks to Reuse Common Template Patterns

  • Nested stacks are stacks that create other stacks.
  • Nested stacks separate out the common patterns and components to create dedicated templates for them, preventing copy pasting across stacks.
  • for e.g. a standard load balancer configuration can be created as nested stack and just used by other stacks

Creating templates

Do Not Embed Credentials in Your Templates

  • Use input parameters to pass in sensitive information such as DB password whenever you create or update a stack.
  • Use the NoEcho property to obfuscate the parameter value.

Use AWS-Specific Parameter Types

  • For existing AWS-specific values, such as existing Virtual Private Cloud IDs or an EC2 key pair name, use AWS-specific parameter types
  • AWS CloudFormation can quickly validate values for AWS-specific parameter types before creating your stack.

Use Parameter Constraints

  • Use Parameter constraints to describe allowed input values so that CloudFormation catches any invalid values before creating a stack.
  • For e.g. constraints for database user name with min and max length

Use AWS::CloudFormation::Init to Deploy Software Applications on Amazon EC2 Instances

  • Use AWS::CloudFormation::Init resource and the cfn-init helper script to install and configure software applications on EC2 instances

Validate Templates Before Using Them

  • Validate templates before creating or updating a stack
  • Validating a template helps catch syntax and some semantic errors, such as circular dependencies, before AWS CloudFormation creates any resources.
  • During validation, AWS CloudFormation first checks if the template is valid JSON or a valid YAML. If both checks fail, AWS CloudFormation returns a template validation error.

Managing stacks

Manage All Stack Resources Through AWS CloudFormation

  • After launching the stack, any further updates should be done through CloudFormation only.
  • Doing changes outside the stack can create a mismatch between the stack’s template and the current state of the stack resources, which can cause errors if you update or delete the stack.

Create Change Sets Before Updating Your Stacks

  • Change sets provides a preview of how the proposed changes to a stack might impact the running resources before you implement them
  • CloudFormation doesn’t make any changes to the stack until you execute the change set, allowing you to decide whether to proceed with the proposed changes or create another change set.

Use Stack Policies

  • Stack policies help protect critical stack resources from unintentional updates that could cause resources to be interrupted or even replaced
  • During a stack update, you must explicitly specify the protected resources that you want to update; otherwise, no changes are made to protected resources

Use AWS CloudTrail to Log AWS CloudFormation Calls

  • AWS CloudTrail tracks anyone making AWS CloudFormation API calls in the AWS account.
  • API calls are logged whenever anyone uses the AWS CloudFormation API, the AWS CloudFormation console, a back-end console, or AWS CloudFormation AWS CLI commands.
  • Enable logging and specify an Amazon S3 bucket to store the logs.

Use Code Reviews and Revision Controls to Manage Your Templates

  • Using code reviews and revision controls help track changes between different versions of your templates and changes to stack resources
  • Maintaining history can help revert the stack to a certain version of the template.

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AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. A company has deployed their application using CloudFormation. They want to update their stack. However, they want to understand how the changes will affect running resources before implementing the updated. How can the company achieve the same?
    1. Use CloudFormation Validate Stack feature
    2. Use CloudFormation Dry Run feature
    3. Use CloudFormation Stage feature
    4. Use CloudFormation Change Sets feature
  2. You have multiple similar three-tier applications and have decided to use CloudFormation to maintain version control and achieve automation. How can you best use CloudFormation to keep everything agile and maintain multiple environments while keeping cost down?
    1. Create multiple templates in one CloudFormation stack.
    2. Combine all resources into one template for version control and automation.
    3. Use CloudFormation custom resources to handle dependencies between stacks
    4. Create separate templates based on functionality, create nested stacks with CloudFormation.
  3. You are working as an AWS DevOps admins for your company. You are in-charge of building the infrastructure for the company’s development teams using CloudFormation. The template will include building the VPC and networking components, installing a LAMP stack and securing the created resources. As per the AWS best practices what is the best way to design this template?
    1. Create a single CloudFormation template to create all the resources since it would be easier from the maintenance perspective.
    2. Create multiple CloudFormation templates based on the number of VPC’s in the environment.
    3. Create multiple CloudFormation templates based on the number of development groups in the environment.
    4. Create multiple CloudFormation templates for each set of logical resources, one for networking, and the other for LAMP stack creation.


AWS RDS Best Practices

AWS RDS Best Practices

AWS recommends RDS best practices in terms of Monitoring, Performance and security

Amazon RDS Basic Operational Guidelines

  • Monitoring
    • Memory, CPU, and storage usage should be monitored.
    • CloudWatch can be setup for notifications when usage patterns change or when the capacity of deployment is approached, so that system performance and availability can be maintained
  • Scaling
    • Scale up the DB instance when approaching storage capacity limits.
    • There should be some buffer in storage and memory to accommodate unforeseen increases in demand from the applications.
  • Backups
    • Enable Automatic Backups and set the backup window to occur during the daily low in WriteIOPS.
  • On a MySQL DB instance,
    • Do not create more than 10,000 tables using Provisioned IOPS or 1000 tables using standard storage. Large numbers of tables will significantly increase database recovery time after a failover or database crash. If you need to create more tables than recommended, set the innodb_file_per_table parameter to 0.
    • Avoid tables in the database growing too large. Provisioned storage limits restrict the maximum size of a MySQL table file to 6 TB. Instead, partition the large tables so that file sizes are well under the 6 TB limit. This can also improve performance and recovery time.
  • Performance
    • If the database workload requires more I/O than provisioned, recovery after a failover or database failure will be slow.
    • To increase the I/O capacity of a DB instance,
      • Migrate to a DB instance class with High I/O capacity.
      • Convert from standard storage to Provisioned IOPS storage, and use a DB instance class that is optimized for Provisioned IOPS.
      • if using Provisioned IOPS storage, provision additional throughput capacity.
  • Multi-AZ & Failover
    • Deploy applications in all Availability Zones, so if an AZ goes down, applications in other AZs will still be available.
    • Use Amazon RDS DB events to monitor failovers.
    • Set a TTL of less than 30 seconds, if the client application is caching the DNS data of the DB instances. As the underlying IP address of a DB instance can change after a failover, caching the DNS data for an extended time can lead to connection failures if the application tries to connect to an IP address that no longer is in service.
    • Multi-AZ requires transaction logging feature to be enabled. Do not use features like Simple recover mode, offline mode or Read-only mode which turn of transaction logging.
    • To shorten failover time
      • Ensure that sufficient Provisioned IOPS allocated for your workload. Inadequate I/O can lengthen failover times. Database recovery requires I/O.
      • Use smaller transactions. Database recovery relies on transactions, so break up large transactions into multiple smaller transactions to shorten failover time
    • Test failover for your DB instance to understand how long the process takes for your use case and to ensure that the application that accesses your DB instance can automatically connect to the new DB instance after failover.

DB Instance RAM Recommendations

  • An Amazon RDS performance best practice is to allocate enough RAM so that the working set resides almost completely in memory.
  • Value of ReadIOPS should be small and stable.
  • ReadIOPS metric can be checked, using AWS CloudWatch while the DB instance is under load, to tell if the working set is almost all in memory
  • If scaling up the DB instance class with more RAM, results in a dramatic drop in ReadIOPS, the working set was not almost completely in memory.
  • Continue to scale up until ReadIOPS no longer drops dramatically after a scaling operation, or ReadIOPS is reduced to a very small amount.

RDS Security Best Practices

  • Do not use AWS root credentials to manage Amazon RDS resources; and IAM users should be created for everyone,
  • Grant each user the minimum set of permissions required to perform his or her duties.
  • Use IAM groups to effectively manage permissions for multiple users.
  • Rotate your IAM credentials regularly.

Using Enhanced Monitoring to Identify Operating System Issues

  • Amazon RDS provides metrics in real time for the operating system (OS) that your DB instance runs on.
  • Enhanced monitoring is available for all DB instance classes except for db.t1.micro and db.m1.small.

Using Metrics to Identify Performance Issues

  • To identify performance issues caused by insufficient resources and other common bottlenecks, you can monitor the metrics available for your Amazon RDS DB instance
  • Performance metrics should be monitored on a regular basis to benchmark  the average, maximum, and minimum values for a variety of time ranges. to help identify performance degradation.
  • Amazon CloudWatch alarms can be set for particular metric thresholds to be alerted when they are reached or breached
  • A DB instance has a number of different categories of metrics which includes CPU, memory, disk space, IOPS, db connections and network traffic, and how to determine acceptable values depends on the metric.
  • One of the best ways to improve DB instance performance is to tune the most commonly used and most resource-intensive queries to make them less expensive to run.


  • MySQL
    • InnoDB is the recommended and supported storage engine for MySQL DB instances on Amazon RDS.
    • However, MyISAM performs better than InnoDB if you require intense, full-text search capability.
    • Point-In-Time Restore and snapshot restore features of Amazon RDS for MySQL require a crash-recoverable storage engine and are supported for the InnoDB storage engine only.
    • Although MySQL supports multiple storage engines with varying capabilities, not all of them are optimized for crash recovery and data durability.
    • MyISAM storage engine does not support reliable crash recovery and might prevent a Point-In-Time Restore or snapshot restore from working as intended which might result in lost or corrupt data when MySQL is restarted after a crash.
  • MariaDB
    • XtraDB is the recommended and supported storage engine for MariaDB DB instances on Amazon RDS.
    • Point-In-Time Restore and snapshot restore features of Amazon RDS for MariaDB require a crash-recoverable storage engine and are supported for the XtraDB storage engine only.
    • Although MariaDB supports multiple storage engines with varying capabilities, not all of them are optimized for crash recovery
      and data durability.
    • For e.g although Aria is a crash-safe replacement for MyISAM, it might still prevent a Point-In-Time Restore or snapshot restore from working as intended. This might result in lost or corrupt data when MariaDB is restarted after a crash.

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Sample Exam Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. You are running a database on an EC2 instance, with the data stored on Elastic Block Store (EBS) for persistence At times throughout the day, you are seeing large variance in the response times of the database queries Looking into the instance with the isolate command you see a lot of wait time on the disk volume that the database’s data is stored on. What two ways can you improve the performance of the database’s storage while maintaining the current persistence of the data? Choose 2 answers
    1. Move to an SSD backed instance
    2. Move the database to an EBS-Optimized Instance
    3. Use Provisioned IOPs EBS
    4. Use the ephemeral storage on an m2.4xLarge Instance Instead
  2. Amazon RDS automated backups and DB Snapshots are currently supported for only the __________ storage engine
    1. InnoDB
    2. MyISAM

AWS EC2 Best Practices

AWS recommends the following to get maximum benefit and satisfaction from EC2

Security & Network

  • Implement the least permissive rules for your security group.
  • Regularly patch, update, and secure the operating system and applications on your instance
  • Launch your instances into a VPC instead of EC2-Classic (If aws account is newly created VPC is used by default)
  • Manage access to AWS resources and APIs using identity federation, IAM users, and IAM roles
  • Establish credential management policies and procedures for creating, distributing, rotating, and revoking AWS access credentials


  • EC2 supports Instance store and EBS volumes, so its best to understand the implications of the root device type for data persistence, backup, and recovery
  • Use separate Amazon EBS volumes for the operating system (root device) versus your data.
  • Ensure that the data volume (with your data) persists after instance termination
  • Use the instance store available for your instance to only store temporary data. (Remember that the data stored in instance store is deleted when you stop or terminate your instance)
  • If you use instance store for database storage, ensure that you have a cluster with a replication factor that ensures fault tolerance.

Resource Management

  • Use instance metadata and custom resource tags to track and identify your AWS resources
  • View your current limits for Amazon EC2. Plan to request any limit increases in advance of the time that you’ll need them.

Backup & Recovery

  • Regularly back up your instance using Amazon EBS snapshots (not done automatically) or a backup tool.
  • Data Lifecycle Manager (DLM) to automate the creation, retention, and deletion of snapshots taken to back up the EBS volumes
  • Implement High Availability by deploying critical components of the application across multiple Availability Zones, and replicate the data appropriately
  • Monitor and respond to events.
  • Design your applications to handle dynamic IP addressing when your instance restarts.
  • Implement failover. For a basic solution, you can manually attach a network interface or Elastic IP address to a replacement instance
  • Regularly test the process of recovering your instances and Amazon EBS volumes if they fail.


AWS IAM Best Practices – Certification

AWS IAM Best Practices

To help secure AWS resources, AWS recommends the following AWSIdentity and Access Management (IAM) service – IAM Best Practices

Root Account -Don’t use & Lock away access keys

  • Do not use AWS Root account which has full access to all the AWS resources and services including the Billing information.
  • Permissions associated with your AWS Root account cannot be restricted.
  • Do not generate the access keys, if not required
  • If already generated and not needed, delete the access keys.
  • If access keys needed, rotate (change) the access key regularly
  • Never share your Root account credentials or access keys, instead create IAM users or Roles to grant granular access
  • Enable AWS multifactor authentication (MFA) on your AWS account

User – Create individual IAM users

  • Don’t use your AWS root account credentials to access AWS, and don’t share your credentials with anyone else.
  • Start by creating a IAM User with Administrator role, which has access to all resources as the Root user except to the account’s security credentials
  • Create individual users for anyone who needs access to your AWS account and give each user unique credentials and grant different permissions

Groups – Use groups to assign permissions to IAM users

  • Instead of defining permissions for individual IAM users, create groups and define the relevant permissions for each group as per the job function, and then associate IAM users to those groups.
  • Users in an IAM group inherit the permissions assigned to the group and a User can belong to multiple groups
  • It is much easier to add new users, remove users and modify the permissions of a group of users.

Permission – Grant least privilege

  • IAM user, by default, is created with no permissions
  • Users should be granted LEAST PRIVILEGE as required to perform a task.
  • Starting with minimal permissions and add to the permissions as required to perform the job function is far better then granting access all and trying to then tightening it down

Passwords – Enforce strong password policy for users

  • Enforce user to create strong passwords and enforce them to rotate their passwords periodically
  • Enable a strong password policy to define passwords requirements forcing users to create passwords with requirements like at least one capital letter, one number, how frequently it should be rotated.

MFA – Enable MFA for privileged users

  • For extra security, Enable MultiFactor Authentication (MFA) for privileged IAM users, who are allowed access to sensitive resources or APIs.

Role – Use roles for applications that run on EC2 instances

  • Use roles for applications running on EC2 instances instead of creating IAM user and hardcoding the credentials within that application.
  • Roles do not have a permanent set of credentials associated with it but dynamically provide temporary credentials that are automatically rotated
  • Hardcoding of credentials can compromise the access and are also hard to rotate. Also, they may pose a problem in the creation of new EC2 instances through AutoScaling and handling credential rotation.

Sharing – Delegate using roles

  • Allow users from same AWS account, another AWS account, or externally authenticated users (either through any corporate authentication service or through Google, Facebook etc) to use IAM roles to specify the permissions which can then be assumed by them
  • A role can be defined that specifies what permissions the IAM users in the other account are allowed, and from which AWS accounts the IAM users are allowed to assume the role

Rotation – Rotate credentials regularly

  • Change your own passwords and access keys regularly and enforce it through a strong password policy. So even if a password or access key is compromised without your knowledge, you limit how long the credentials can be used to access your resources
  • Access keys allows creation of 2 active keys at the same time for an user. These can be used to rotate the keys.

Track – Remove unnecessary credentials

  • Remove IAM user and credentials (that is, passwords and access keys) that are not needed
  • Use the Credential report that lists all IAM users in the account and status of their various credentials, including passwords, access keys, and MFA devices and usage pattern to figure out what can be removed
  • Passwords and access keys that have not been used recently might be good candidates for removal.

Conditions – Use policy conditions for extra security

  • Define conditions under which IAM policies allow access to a resource.
  • Conditions would help provide finer access control to the AWS services and resources for e.g. access limited to specific ip range or allowing only encrypted request for uploads to S3 buckets etc.

Auditing – Monitor activity in the AWS account

  • Enable logging features provided through CloudTrail, S3, CloudFront in AWS to determine the actions users have taken in the account and the resources that were used.
  • Log files show the time and date of actions, the source IP for an action, which actions failed due to inadequate permissions, and more.
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AWS Certification Exam Practice Questions

  1. Your organization is preparing for a security assessment of your use of AWS. In preparation for this assessment, which two IAM best practices should you consider implementing? Choose 2 answers
    1. Create individual IAM users for everyone in your organization (May not be needed as can use Roles as well)
    2. Configure MFA on the root account and for privileged IAM users
    3. Assign IAM users and groups configured with policies granting least privilege access
    4. Ensure all users have been assigned and are frequently rotating a password, access ID/secret key, and X.509 certificate (Must be assigned only if using console or through command line)
  2. What are the recommended best practices for IAM? (Choose 3 answers)
    1. Grant least privilege
    2. User the AWS account(root) for regular user
    3. Use Mutli-Factor Authentication (MFA)
    4. Store access key/private key in git
    5. Rotate credentials regularly
  3. Which of the below mentioned options is not a best practice to securely manage the AWS access credentials?
    1. Enable MFA for privileged users
    2. Create individual IAM users
    3. Keep rotating your secure access credentials at regular intervals
    4. Create strong access key and secret access key and attach to the root account
  4. Your CTO is very worried about the security of your AWS account. How best can you prevent hackers from completely hijacking your account?
    1. Use short but complex password on the root account and any administrators.
    2. Use AWS IAM Geo-Lock and disallow anyone from logging in except for in your city.
    3. Use MFA on all users and accounts, especially on the root account. (For increased security, it is recommend to configure MFA to help protect AWS resources)
    4. Don’t write down or remember the root account password after creating the AWS account.
  5. Fill the blanks: ____ helps us track AWS API calls and transitions, ____ helps to understand what resources we have now, and ____ allows auditing credentials and logins.
    1. AWS Config, CloudTrail, IAM Credential Reports
    2. CloudTrail, IAM Credential Reports, AWS Config
    3. CloudTrail, AWS Config, IAM Credential Reports
    4. AWS Config, IAM Credential Reports, CloudTrail