Cert-Manager

Cert-Manager
Name	Cert-Manager
Developer	Jetstack
Released	2017
Programming language	Go
Operating system	Kubernetes
License	Apache-2.0

Cert-Manager

Cert-Manager is an open-source Kubernetes-native certificate management controller that automates the issuance and renewal of TLS certificates for workloads running on Kubernetes (software), enabling secure communication between services, ingress controllers, and external endpoints. Developed by Jetstack, Cert-Manager integrates with certificate authorities and issuers such as Let's Encrypt, HashiCorp, and enterprise PKI solutions to provide lifecycle management for X.509 certificates across cluster resources. It is widely used by projects and organizations including Cloud Native Computing Foundation, GitLab, Red Hat, and Google Cloud Platform adopters to simplify cryptographic operations in cloud-native deployments.

Overview

Cert-Manager operates as a control plane component on Kubernetes (software) clusters that watches for custom resources and reconciles desired certificate state with actual key material. The project emerged to address operational needs in environments leveraging Ingress (Kubernetes), Service Meshes like Istio, and platform tooling such as Helm (software), providing integration points for external authorities including Let's Encrypt, ACME (protocol), and HashiCorp Vault. It implements patterns from Operators (software) and relies on Kubernetes primitives such as Custom Resource Definitions and controllers to achieve declarative certificate lifecycle management.

Architecture and Components

Core components include a controller manager written in Go (programming language) that reconciles resources such as Certificate, Issuer, and ClusterIssuer custom resources. The controller interacts with issuers using protocol adapters for ACME (protocol), Vault (software), and proprietary APIs from vendors like AWS (service), Azure, and Google Cloud Platform. Additional components often deployed alongside the controller include webhook servers for validation, certificate request controllers for challenge handling with integrations like Ingress (Kubernetes), and secret shims to store private keys in Kubernetes Secret. Cert-Manager's architecture follows controller-runtime patterns from Kubebuilder and integrates with cloud provider services such as Amazon Web Services, Microsoft Azure, and Google Cloud Platform for cloud-native key management.

Installation and Configuration

Installation is commonly performed using package managers like Helm (software) or via manifests applied with kubectl. Configuration requires creating Issuer or ClusterIssuer resources that reference external services such as Let's Encrypt for ACME or HashiCorp Vault for enterprise PKI; these resources reference Kubernetes Secrets that contain API credentials, tokens, or TLS client keys. Operators often combine Cert-Manager with ingress controllers like NGINX (web server), Traefik (software), or Ambassador (software) to automate TLS provisioning for HTTP routes. For cluster provisioning, administrators integrate Cert-Manager with infrastructure tools like Terraform, Ansible (software), and Pulumi to provide reproducible deployments.

Certificate Issuance and Renewal

Cert-Manager supports automated certificate issuance via ACME challenges (HTTP-01, DNS-01) with DNS providers such as Cloudflare, Route 53, Google Cloud DNS, and Azure DNS. The controller creates CertificateRequest resources and performs validation via challenge solvers that interact with ingress resources and provider APIs, or via webhook challenge solvers integrated with ExternalDNS. Renewals are handled proactively based on expiry windows and backoff strategies; administrators can influence behavior through Certificate spec fields and annotations recognized by systems like Traefik (software), NGINX (web server), and Istio. For private PKI, Cert-Manager can request certificates from HashiCorp Vault or on-premise CAs using PKCS#10 flows and store keys in Kubernetes Secrets or integrate with Cloud KMS offerings.

Integrations and Supported Issuers

Supported issuers include Let's Encrypt (ACME), HashiCorp Vault, and vendor services from Amazon Web Services, Microsoft Azure, and Google Cloud Platform. DNS providers for DNS-01 challenges include Cloudflare, Amazon Route 53, Google Cloud DNS, and Azure DNS. Integrations extend to Helm (software) charts, Flux (software), Argo CD, and service meshes such as Istio and Linkerd. Community and enterprise add-ons facilitate compatibility with Concourse (software), Jenkins, GitLab CI/CD, and policy engines like Open Policy Agent.

Security and Best Practices

Best practices recommend restricting access to Secrets used by Issuers via Role-Based Access Control and namespaces, integrating with key management solutions such as AWS KMS, Azure Key Vault, and Google Cloud KMS for hardware-backed protection, and enabling issuer-specific authentication with short-lived credentials managed by HashiCorp Vault or automated rotation tools. Operators should enable webhook validation and use Pod Security Standards from OpenShift or Kubernetes (software) security contexts to limit controller privileges. Organizations commonly adopt auditing and observability through integrations with Prometheus, Grafana, and logging stacks like ELK Stack to monitor certificate expiry and issuance events.

Troubleshooting and Maintenance

Common troubleshooting steps include inspecting controller logs with kubectl, examining CertificateRequest and Order resources for ACME errors referencing Let's Encrypt endpoints, and validating DNS challenge propagation with provider consoles such as Cloudflare or Amazon Route 53. Maintenance tasks include upgrading Cert-Manager via Helm (software) releases, rotating CA secrets and issuer credentials, and reconciling resources after cluster migrations orchestrated with tools like Velero. For incident response, teams collaborate with platform groups using runbooks that reference monitoring dashboards in Grafana and alerting systems such as Prometheus Alertmanager to remediate expiring or failed certificates.

Category:Kubernetes