Cloudfront

Managing Certificates with CloudFront

Overview

Domain expertise for serving content from a custom domain over HTTPS, covering a single standard distribution, a domain migrating from a third-party CDN, and a SaaS or platform provider running many domains off one shared configuration with a certificate per tenant. The certificate work is the part that trips customers up, and multi-tenant distributions are the scaling path where certificate management matters most.

The ACM certificate CloudFront uses must be in us-east-1 regardless of where the application runs. For a standard distribution, add the domain as an alternate domain name (CNAME), attach a us-east-1 certificate that covers it, validate ownership, and wait for the certificate to reach Issued. For many domains, a multi-tenant distribution is a template that cannot serve traffic directly; each domain is a distribution tenant that inherits the template, and a connection group provides the CloudFront routing endpoint DNS points at.

Does not cover the Route 53 DNS cutover (a Route 53 step; see the route53 skill), creating the distribution itself (see when-to-use-cloudfront), or origin and content security (see protecting-your-origins and securing-your-content).

Execute commands using the AWS MCP server when connected (sandboxed execution, audit logging, observability). Fall back to the AWS CLI otherwise. CloudFront and its ACM certificates operate in us-east-1.

Table of Contents

• Overview

• The certificate must be in us-east-1

• Decision: validation method

• Decision: standard distribution vs multi-tenant

• The multi-tenant three-part model

• Decision: shared vs per-tenant certificate

• Test a tenant before the DNS cutover

• Procedure

• Troubleshooting

• Security Considerations

• Additional Resources

The certificate must be in us-east-1

Customers request the certificate in their application's Region, try to attach it, and get an error.

Constraints:

• You MUST always request or locate the ACM certificate in us-east-1, regardless of where the application runs

• You MUST identify a certificate requested in the application Region as the cause when attachment fails

Decision: validation method

Constraints:

• You MUST detect when a domain already serves live traffic and offer a validation method that does not disrupt it

• You MUST check whether the domain is already associated with another CloudFront resource before adding it, because a domain can associate with only one CloudFront distribution or tenant at a time (otherwise a CNAMEAlreadyExists error)

Decision: standard distribution vs multi-tenant

Constraints:

• You MUST route a customer managing many similar domains to a multi-tenant distribution rather than repeated standard distributions

The multi-tenant three-part model

The multi-tenant distribution is a template that holds shared settings and cannot serve traffic directly. A distribution tenant is the front door for each domain and inherits the template. A connection group provides the CloudFront routing endpoint that DNS points at.

Constraints:

• You MUST explain this three-part model before the customer creates resources

• You MUST point DNS at the connection group routing endpoint, never at the multi-tenant distribution template

• You SHOULD note that only a limited set of settings is customizable per tenant (examples that have been overridable: AWS WAF web ACL, TLS certificate, geographic restrictions, and parameters such as origin path and domain), and direct the customer to verify the current set against the CloudFront Developer Guide rather than treating the list as exhaustive

Decision: shared vs per-tenant certificate

Constraints:

• You MUST match the certificate approach to the domain ownership model

HTTP validation options for tenant-level certificates

For per-tenant managed certificates, CloudFront initiates the certificate request. The customer proves domain ownership through one of three options:

Constraints:

• You MUST use self-hosted validation (redirect or token) when the domain still serves live traffic from another provider, because managed validation requires DNS to already point at CloudFront

• You MUST note that for HTTP-validated managed certificates, CloudFront associates the certificate automatically once validated — no explicit customer action needed

• You MUST note that for DNS validation and imported certificates, the customer must explicitly associate the certificate with the tenant AND activate the tenant to serve traffic

• You MUST remind customers that tenants must be explicitly activated after certificate association (for DNS and import methods) or after HTTP validation completes (for managed certificates)

Test a tenant before the DNS cutover

Customers cut a production domain straight over and discover a misconfiguration only after live traffic breaks.

Constraints:

• You MUST validate the tenant against the connection group's CloudFront routing endpoint before the DNS cutover, so the tenant is confirmed serving correctly while the real domain still resolves to its old target

• You MUST move DNS only after the tenant validates

Procedure

Overview

This procedure adds a custom domain over HTTPS, requesting the certificate in us-east-1, choosing the validation method and (for many domains) the multi-tenant path, testing the tenant, and surfacing the console link.

Parameters

• domain_name (required): The custom domain (for example www.example.com).

• distribution_id (required for standard): The distribution to add the domain to.

• multi_tenant (required): Whether the customer is running many domains (true/false).

• has_live_traffic (required): Whether the domain already serves traffic elsewhere.

Constraints for parameter acquisition:

• You MUST ask whether the customer is managing one domain or many upfront

• You MUST ask whether the domain already has live traffic to pick the validation method

Steps

1. Verify dependencies

Constraints:

• You MUST confirm credentials with aws sts get-caller-identity

• You MUST check the domain is not already associated with another CloudFront resource

2. Request or locate the certificate in us-east-1

Constraints:

• You MUST request or import the certificate in us-east-1 covering the domain:

  Copy

  aws acm request-certificate --domain-name {domain_name} \
    --validation-method DNS --region us-east-1

• You MUST choose HTTP-based validation or an imported certificate when the domain already serves live traffic

3. Add the domain and attach the certificate

Constraints:

• For a standard distribution, you MUST add the domain as an alternate domain name (CNAME) and attach the us-east-1 certificate once it reaches ISSUED

• You MUST set the distribution's minimum protocol version to a current strong security policy (a TLS 1.2-or-higher MinimumProtocolVersion) rather than relying on the default, which may allow older TLS versions, to ensure strong encryption in transit. Do not hardcode a policy string that ages — select the newest TLS 1.2+ security policy CloudFront offers, confirming the current options against the CloudFront Developer Guide "supported protocols and ciphers" page

• You MUST enable standard logging on the distribution as part of this change if it is not already enabled, so configuring the custom domain does not leave an audit-trail gap on a production web-facing distribution (see the cloudfront-observability workflow for the logging configuration)

• For many domains, you MUST create the multi-tenant distribution (template), let CloudFront create the connection group, and create a distribution tenant per domain with the appropriate certificate

4. Test the tenant before cutover (multi-tenant)

Constraints:

• You MUST validate the tenant against the connection group's CloudFront routing endpoint before any DNS change

5. Hand off DNS and surface the console link

Constraints:

• You MUST hand the DNS cutover to Route 53 (alias or CNAME at the routing endpoint), not perform it here

• You MUST present the distribution detail console link, filling {distributionId} from the input distribution_id parameter:

  Copy

  https://us-east-1.console.aws.amazon.com/cloudfront/v4/home?region=us-east-1#/distributions/{distributionId}

Example

Example input

{
  "domain_name": "www.example.com",
  "distribution_id": "E1ABCDEF2GHIJK",
  "multi_tenant": false,
  "has_live_traffic": false
}

Example output

Requested an ACM certificate in us-east-1 covering www.example.com, validated by DNS.
Added www.example.com as an alternate domain name on E1ABCDEF2GHIJK and attached the certificate.
DNS cutover is a Route 53 step (see the route53 skill).
Verify in the console:
https://us-east-1.console.aws.amazon.com/cloudfront/v4/home?region=us-east-1#/distributions/E1ABCDEF2GHIJK

Troubleshooting

CloudFront will not attach the ACM certificate

The certificate is not in us-east-1. Request or import it in us-east-1 and attach the new one.

CNAMEAlreadyExists when adding the domain

The domain is associated with another CloudFront distribution or tenant. Move it before adding.

The certificate stays Pending validation

DNS validation records are missing, or the domain serves traffic elsewhere and cannot be reached. Add the CNAME validation records, or use HTTP-based validation for a tenant.

The multi-tenant distribution does not serve traffic

The template cannot serve traffic directly. Point DNS at the connection group routing endpoint, not the template, and create distribution tenants for each domain.

A tenant works on the routing endpoint but the custom domain fails

DNS has not been cut over, or the certificate does not cover the tenant domain. Confirm the certificate covers the domain, then complete the Route 53 cutover.

Security Considerations

• Let ACM hold the private key. Prefer ACM-issued or ACM-managed certificates so the private key never leaves ACM. For an imported certificate, store its private key in AWS Secrets Manager rather than on disk or in application config.

• Enforce a minimum TLS version. Set the distribution's minimum protocol version to a current strong TLS 1.2-or-higher security policy rather than relying on the default, which may allow older TLS versions. Choose the newest TLS 1.2+ policy CloudFront offers (confirm current options in the CloudFront Developer Guide) instead of hardcoding a policy string that ages.

• Watch for stale or expiring certificates. An expired certificate breaks HTTPS for the domain. Track expirations and renew ahead of time; ACM-managed certificates renew automatically while imported ones do not. Set a CloudWatch alarm on the ACM DaysToExpiry metric (or enable the AWS Config acm-certificate-expiration-check managed rule) to alert before a certificate expires, especially for imported certificates that do not auto-renew.

• Keep DNS validation records in place. ACM uses the DNS validation CNAME records to automatically renew certificates. Removing them prevents renewal and will cause HTTPS to break when the certificate expires.

• Audit certificate operations with CloudTrail. Enable AWS CloudTrail to record the ACM and CloudFront management API calls that change certificates and alternate domain names (acm:RequestCertificate, acm:ImportCertificate, cloudfront:UpdateDistribution) for a compliance and forensic audit trail.

Additional Resources

• Use custom URLs by adding alternate domain names (CNAMEs) (Amazon CloudFront Developer Guide)

• Requirements for using SSL/TLS certificates with CloudFront (Amazon CloudFront Developer Guide)

• Request certificates for your CloudFront distribution tenant (Amazon CloudFront Developer Guide)

• Move an alternate domain name (Amazon CloudFront Developer Guide)

• Understand how multi-tenant distributions work (Amazon CloudFront Developer Guide)

• Create custom connection group (Amazon CloudFront Developer Guide)