Mister PKI

SSL Certificates * SSL Tools * Certificate Decoder

Manually renewing TLS certificates is one of the most common causes of unexpected outages. When certificates expire unexpectedly, websites, APIs, and internal services can immediately fail secure connections.

This is why modern infrastructure relies heavily on automated certificate renewal. DevOps teams use automation to ensure certificates are renewed before expiration and deployed without downtime.

This lesson is part of the PKI for DevOps Engineers training series. In the previous lesson we discussed certificate expiration monitoring. In this lesson you will learn how certificate renewal can be automated across infrastructure.

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Table of Contents

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Why automate certificate renewal

Certificates have limited lifetimes, often between 90 days and one year depending on the certificate authority.

If certificate renewal is handled manually, several risks arise:

  • certificates may expire unexpectedly
  • renewal tasks may be forgotten
  • deployment errors may occur
  • large environments become difficult to manage

Automation eliminates these risks by ensuring certificates are renewed and deployed automatically before expiration.

If you want to understand how certificate expiration works, see our lesson on certificate expiration monitoring.

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Certificate lifecycle overview

Before automating renewal, it helps to understand the lifecycle of a TLS certificate.

A typical certificate lifecycle includes:

  1. generate private key
  2. create certificate signing request (CSR)
  3. submit CSR to certificate authority
  4. receive signed certificate
  5. install certificate on server
  6. monitor expiration
  7. renew certificate

This lifecycle connects with several earlier lessons in this training series including creating CSRs and understanding certificate chains.

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Certificate automation strategies

Organizations typically automate certificate renewal using several approaches.

Automated certificate issuance

Automated certificate authorities allow certificates to be issued and renewed automatically without manual requests.

Scheduled renewal tasks

Many systems run scheduled jobs that check certificate expiration and trigger renewal processes.

Infrastructure automation

Configuration management tools can distribute renewed certificates across servers.

This approach allows organizations to update certificates across many services simultaneously.

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Automating renewal with scripts

Some environments implement simple automation scripts that perform certificate checks and renewals.

For example, OpenSSL can be used to check expiration status.

openssl x509 -checkend 86400 -noout -in certificate.crt

This command checks whether the certificate will expire within 24 hours.

If expiration is approaching, a renewal process can be triggered.

You can verify the renewed certificate using openssl verify.

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Automating certificate deployment

Renewing a certificate is only part of the process. The new certificate must also be deployed to the services that use it.

This deployment may include:

  • web servers
  • load balancers
  • API gateways
  • Java application servers

Certificates may also need to be packaged into formats such as PKCS12 when used by certain applications.

After deployment, the TLS configuration can be verified using tools such as openssl s_client.

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Benefits of certificate automation

Automating certificate renewal provides several important benefits.

  • prevents certificate expiration outages
  • reduces manual operational work
  • improves security posture
  • ensures consistent certificate deployment

For large infrastructures containing hundreds or thousands of services, automation becomes essential.

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Frequently Asked Questions

Why should certificates be renewed automatically?

Automated renewal prevents outages caused by expired certificates and reduces operational risk.

How early should certificates be renewed?

Many systems renew certificates 30 days before expiration.

Can OpenSSL automate certificate renewal?

OpenSSL can be used in scripts to check certificate expiration and validate renewed certificates.

What is the biggest risk of manual certificate management?

The biggest risk is certificate expiration causing unexpected service outages.

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Next Lesson

In the next lesson we will examine common TLS errors and how DevOps engineers troubleshoot certificate issues.

Lesson 10 – Common TLS Errors Explained →

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Training Series Navigation