How to Automate Certificates with Automated Certificate Management Environment?

Manual certificate management is one of the leading causes of downtime, regulatory violations, and security deficiencies. Expired TLS certificates can disrupt application functionality, interfere with APIs, and diminish end-user confidence in a brand.

The Solution? Automate the entire certificate lifecycle management process using the Automated Certificate Management Environment (ACME) protocol.

What Is ACME?

The Automated Certificate Management Environment (ACME) is an open standard developed by the Internet Engineering Task Force as established in RFC 8555.

The purpose of this standard is to facilitate the automation of certificate issuance, validation, renewal, and revocation from servers to Certificate Authorities (CA) over a secure HTTPS-based API.

Although ACME was originally designed to support Let’s Encrypt, it is now supported by a large number of commercial and private CAs, publicly available PKI platforms, and enterprise certificate management solutions.

Why Automate Certificates?

There are numerous reasons to automate all facets of your system’s certificates. Automating certificate management helps you achieve a consistent level of reliability, security, and scalability for your entire digital infrastructure.

In the traditional model for managing certificates, you are dependent upon tracking everything manually with spreadsheets and setting reminders for certificate installations, certificate signing requests (CSRs), and renewals to avoid expired certificates.

Also Read: 47‑Day SSL/TLS Mandates: A Step Towards Transitioning to Automation

So much time is spent on managing certificates to avoid expired certificates, downtimes, violations of compliance, and reputational damage through human error.

It quickly becomes unsustainable when an organization grows and has hundreds or thousands of Transport Layer Security (TLS) certificates in use across multiple web servers, APIs, cloud workloads, and internal systems.

Using the Internet Engineering Task Force-developed Automated Certificate Management Environment (ACME) protocol through automation, you can fully automate and streamline the entire certificate lifecycle from domain validation through certificate issuance, renewal, and revocation.

Automating the certificate lifecycle not only minimizes the risk of human error but also ensures that certificate renewals take place prior to the expiration date, while allowing for seamless integration within DevOps pipelines or cloud native environments.

Step-by-Step: Automating Certificates with ACME

Step 1: Select and Configure an ACME Client

An ACME client is used to manage the lifecycle of a certificate from start to finish (key generation through renewal).

When choosing a Client, Make Sure to check for:

• Environment compatibility (server/container).
• Support for the types of ACME challenges you need.
• Ability to securely store private keys.
• Support & maintenance from the vendor or community (if community-based client).

Common Environments of Deployment for ACME Clients include:

• Linux (servers)
• Docker (containers)
• Kubernetes (clusters)
• Cloud workload(s)

Once you install your chosen ACME client, you’ll configure it for the domains it’s going to manage certificates for.

Step 2: Choose a Certificate Authority

The CA verifies the ownership of the domain and issues the certificate to the owner.  To select a CA:

• Evaluate the types of certificates they support: DV and OV
• Check if & how they support ACME.
• Review any rate limits they may impose and issuance policies.
• Review their pricing policy (free vs commercial).
• Review if they provide support for EAB.

Open CA (e.g., Let’s Encrypt) provides free certificates; commercial CAs like Sectigo and DigiCert provide organization validation, enterprise controls, and higher issuance limits.

Run a connectivity test between your ACME client and the CA’s ACME endpoint to make sure they can communicate.

Step 3: Register Client and Create Keys

The CA automation begins by registering the client with the CA’s ACME server.

• Generating an Account Key Pair
• Creating a Certificate Signing Request (CSR)
• Sending the Public Key to CA

Using External Account Binding for added authentication (if required). This ensures that only valid clients requesting certificates can access your CA account.

Step 4: Finish Domain Validation Challenges

Before issuing a certificate, the CA will need to confirm that you own the domain you are requesting a certificate for. The CA’s ACME server will give a validation challenge to you in the format of either HTTP-01, DNS-01, or TLS-ALPN-01.

The client will have to put a validation token on either their web server or DNS (the method depends on the type of challenge).

The CA will check for the token to verify ownership of the domain. Once verification is complete, the CA will authorize the issuance of the certificate.

Step 5: Certificate Issuance

After Validation:

• The CA verifies the CSR
• Confirms account authorization
• Issues an X.509 certificate
• Signs it using its trusted root certificate

The Issued Certificate includes:

• Subject information (domain name)
• Public key
• CA signature
• Validity period
• Subject Alternative Names (SANs)

The certificate is typically delivered in PEM format (Base64-encoded DER).

Step 6: Installation

The ACME client installs the certificate in the designated directory, such as:

/etc/ssl/certs/
/etc/letsencrypt/live/<domain>/

Next:

• Configure Your Web Server (eg: Apache, Nginx, Load Balancer, etc…)
• Restrict the Permissions for the Private Key
• Restart/Reload Services

Automation will provide consistency and repeatability of the installation in each environment.

Step 7: Automatic Renewal

The primary benefit of using ACME is automatic renewal.

Most certificates issued via ACME have a short expiry time (90 days to be precise). Your client must:

• Monitor their expiry dates
• Start the renewal process at least 30 days before the expiry date
• Automatically reinstall the renewed certificate

For example, with Certbot: certbot renew

You can force renewal with: certbot renew –force-renewal

Make sure that you always test renewal workflows in a staging environment before production deployment.

ACME vs Manual Certificate Management

Manual Process	ACME Automation
Spreadsheet tracking	Automated monitoring
Human CSR generation	Programmatic CSR creation
Risk of expired certificates	Scheduled renewals
Error-prone installation	Automated deployment
Limited scalability	Internet-scale automation

Compare in detail

Security Best Practices for ACME Automation

Protect Private Keys

In any ACME implementation, private keys are critical to TLS security and must therefore be protected with high priority. Store your private keys in secure folders that have strict file access permissions so only those who have permission can access them.

Do not send or share your private keys between servers unless you have to; if you are in an enterprise environment, use hardware security modules (HSM) or a secure key vault to protect against unauthorized access or extraction of data from the key.

Use a Staging Environment Before Going into Production

When you are ready to deploy your automated environment using ACME automation in production, first test your setup on a staging endpoint provided by your Certificate Authority.

A staging environment is a way for you to ensure that your configuration is working properly by testing your challenge responses and/or renewal processes and to test your install script without affecting production systems and without hitting your Certificate Authority’s rate-limiting rules.

Using a staging environment minimizes the chance of outages resulting from configuration problems or unsuccessful validation attempts.

Monitor Certificate Expiration and Renewal Status

Even when there is automation in place, continuous monitoring of certificate expirations and renewals is still required via alerting mechanisms to track when your certs expire and what the renewal status was (e.g., failed renewals due to DNS issues, connectivity problems, etc.) so that you can inform your team as quickly as possible.

Monitoring tools or centralized certificate management platforms provide visibility across all of your environments so you can reduce your chances of service disruption.

Use as Few Access Rights as Possible

Restrict access to ACME’s clients, configuration files, or locations in which certificates are stored by applying Role-Based Access Controls (RBAC).

Only authorized administrators or automated service accounts should be able to modify certificate settings or request a manual request that is certified.

By limiting users’ privileges, they are less likely to accidentally create an error or intentionally commit an act that could negatively impact your organization’s certificate infrastructure.

DNS and Web Validation End-Points Secured

The mechanisms for domain validation within the ACME model are reliant on DNS records as well as web server endpoints; therefore, DNS records and web server interfaces must be protected properly.

DNS administrator accounts should utilize MFA in addition; limiting access to DNS administrative interfaces should be enforced.

When utilizing HTTP-based challenges, make sure that validation paths are configured correctly; additionally, do not expose validation paths to excessive amounts of other services/users.

Failure to protect the validation mechanisms from weaknesses puts you at a potential risk for a certificate being issued incorrectly.

Logging & Audit Trails Implemented

Log information should include all certificate requests, renewals, and revocations with sufficient detail, as well as logging configuration changes to be able to meet compliance for regulatory purposes as well as performing investigations leading up to any issues.

Central logging will also provide Security Teams the ability to monitor for unusual occurrences related to certificate activity, such as unexpected certificate issuances or multiple validation failure attempts.

Plan for Revocation and Incident Response

The use of automated methods of issuing and renewing security certificates must include a comprehensive plan for revocations in the event of an incident.

This enables you to promptly revoke a certificate when the associated private key has been compromised, or when a certificate has been erroneously issued, through the use of your ACME Workflow environment.

You should be able to quickly propagate the revocation status of the certificate via the use of OCSP through your respective systems, and be in a position to reissue replacement certificates as quickly as possible in order to reduce system downtime during a security incident.

Conclusion

With these current requirements for automating certificate management, having an automated and visible way to manage your ACME deployments, reducing the risk of your certificates expiring or being out of date, and providing centralized management of your certificates across both cloud and on-premises environments.

Don’t allow your organization to run the risk of experiencing a service disruption or an inability to comply due to the manual nature of managing your PKI infrastructure. Work with Certera to provide additional security around your PKI today through automation and prepare for future growth.