AWS Certificate Manager (ACM)
7 questions found
What is AWS Certificate Manager and why is it important for securing web applications?
Beginner
AWS Certificate Manager, or ACM, is a service that lets you easily provision, manage, and deploy free public SSL and TLS certificates for use with AWS services like CloudFront, Elastic Load Balancing, and API Gateway, enabling encrypted HTTPS connections for your applications without needing to manually purchase, install, or renew certificates yourself.
aws acm request-certificate --domain-name example.com --validation-method DNS
Real-world example
A company launching a new website requests a free SSL certificate through ACM and attaches it to its Application Load Balancer, enabling secure HTTPS connections for all visitors without paying for or manually managing a certificate.
Common follow-ups: Are ACM certificates free for all use cases?;Which AWS services can directly use an ACM certificate?
Amazon Route 53 & DNS Management;Elastic Load Balancing (ALB
NLB & CLB)
How does domain validation work when requesting a certificate through ACM?
Beginner
ACM requires you to prove that you actually own or control the domain name before it will issue a certificate, which can be done through DNS validation, where you add a specific CNAME record to your domain's DNS configuration, or through email validation, where ACM sends a verification email to addresses associated with the domain, with DNS validation being the preferred method since it also enables automatic certificate renewal.
aws acm describe-certificate --certificate-arn arn:aws:acm:us-east-1:123456789012:certificate/abc123
Real-world example
A company uses DNS validation when requesting its ACM certificate through Route 53, since Route 53 can automatically add the required validation CNAME record, streamlining the entire certificate issuance process.
Common follow-ups: Why is DNS validation generally preferred over email validation?;What happens if the validation record is removed after the certificate is issued?
Amazon Route 53 & DNS Management;IAM
How does ACM handle automatic certificate renewal, and what is required to keep this working smoothly?
Intermediate
ACM automatically attempts to renew certificates before they expire, and for certificates validated using DNS validation, this renewal process happens completely automatically as long as the original validation CNAME record remains in place in your DNS configuration, meaning you generally never need to manually renew or reinstall a certificate managed through ACM once it is properly set up.
aws acm list-certificates --certificate-statuses ISSUED
Real-world example
A company that initially set up DNS validation for its certificate through Route 53 never experiences a certificate expiration incident, since ACM automatically handles renewal in the background without any manual intervention required.
Common follow-ups: What happens if automatic renewal fails for some reason?;Does ACM send any notifications before a certificate is due to renew?
Amazon Route 53 & DNS Management;AWS CloudTrail & Auditing
Can ACM certificates be used with resources outside of AWS managed services, such as on an EC2 instance running your own web server?
Intermediate
Public ACM certificates issued for use with supported AWS services like CloudFront or an Application Load Balancer cannot be exported or installed directly on a self managed server like an EC2 instance running its own web server software, since ACM is designed specifically to integrate with AWS managed services, though AWS Certificate Manager Private Certificate Authority does support exportable private certificates for other use cases.
// Public ACM certificates work directly with these AWS services:
// CloudFront, Application Load Balancer, API Gateway
// They cannot be exported for use on a self managed EC2 web server
Real-world example
A team initially expects to install their free ACM certificate directly onto an EC2 instance's own web server, then learns they instead need to place a Load Balancer in front of that instance and attach the certificate there.
Common follow-ups: What is the difference between ACM public certificates and ACM Private CA?;What alternative would you use for encrypting traffic directly to an EC2 instance without a load balancer?
EC2 & Compute;Elastic Load Balancing (ALB
NLB & CLB)
How does using a certificate with a CloudFront distribution differ in terms of region requirements compared to other services?
Intermediate
ACM certificates used with CloudFront must specifically be requested in the US East, North Virginia, region regardless of where your users or other resources are located, since CloudFront is a global service that centrally manages certificates from that specific region, while certificates used with a regional service like an Application Load Balancer must instead be requested in the same region as that load balancer.
aws acm request-certificate --domain-name example.com --validation-method DNS --region us-east-1
Real-world example
A company managing a CloudFront distribution mistakenly requests a certificate in a different region and discovers it cannot be attached to CloudFront, later correcting the mistake by requesting a new certificate specifically in US East North Virginia.
Common follow-ups: Why does CloudFront require certificates specifically from the US East North Virginia region?;Does this same regional restriction apply to Application Load Balancer certificates?
Amazon CloudFront & Content Delivery;AWS Global Infrastructure (Regions
AZs & Edge Locations)
What is AWS Certificate Manager Private Certificate Authority, and when would an organization use it instead of public certificates?
Advanced
ACM Private Certificate Authority lets an organization create its own private certificate authority hierarchy to issue certificates for internal resources, such as internal microservices communicating with each other or internal applications not exposed to the public internet, which is important since public certificate authorities will not issue certificates for internal, non publicly resolvable domain names, and these private certificates can still integrate with ACM for automated deployment and renewal.
aws acm-pca create-certificate-authority --certificate-authority-configuration file://ca-config.json --certificate-authority-type ROOT
Real-world example
A large enterprise running dozens of internal microservices uses ACM Private CA to issue internal certificates for service to service communication, ensuring encrypted traffic even for services that are never exposed outside its own VPC.
Common follow-ups: How does the cost of ACM Private CA compare to using free public certificates?;What is involved in distributing trust for a private certificate authority to internal client applications?
IAM;VPC & Networking
How should an organization design its certificate management strategy across multiple AWS accounts and regions?
Advanced
Organizations operating across multiple AWS accounts and regions typically centralize certificate management using tools like AWS Organizations combined with automation, such as infrastructure as code templates that request and validate certificates consistently in each required region, while also monitoring certificate expiration and status across all accounts using AWS Config rules or CloudTrail based alerting to catch any certificate that might not be renewing automatically as expected.
aws config put-config-rule --config-rule file://acm-certificate-expiration-rule.json
Real-world example
A multinational company uses an AWS Config rule across all of its AWS accounts to automatically flag any ACM certificate approaching expiration without successful automatic renewal, preventing an unexpected outage caused by an expired certificate in any region.
Common follow-ups: How can AWS Config help monitor certificate compliance across an entire organization?;What role does infrastructure as code play in maintaining a consistent certificate strategy?
AWS Config;AWS Organizations & Multi Account Strategy