HashiCorp Vault Kubernetes: The Definitive Guide

Static, long-lived credentials are a persistent liability. Once leaked, they provide an attacker with a durable backdoor into your systems. The modern approach to infrastructure security involves moving away from these static secrets toward dynamic, short-lived credentials that are created on-demand and expire automatically. This practice drastically reduces your attack surface and contains the potential damage of a breach. While this sounds complex, the right tools make it possible. By integrating HashiCorp Vault with Kubernetes, you can automate the entire lifecycle of your secrets, from just-in-time database credential generation to PKI certificate rotation, building a more resilient and secure infrastructure.

Key takeaways:

• Replace static secrets with dynamic credentials: Vault generates short-lived, on-demand credentials for databases and cloud services. This practice of automatic rotation and expiration drastically reduces the risk associated with compromised static secrets.
• Automate secret injection into pods: Use the Vault Agent Injector or Secrets Operator to deliver secrets to applications without requiring code changes. These patterns handle the entire lifecycle, from authentication to renewal, making secret consumption seamless for developers.
• Centralize security policy and configuration: A secure Vault setup requires TLS encryption, network isolation, and least-privilege access policies. Use a platform like Plural to define these configurations once and apply them consistently across your entire Kubernetes fleet, preventing security drift.

What Is HashiCorp Vault, and Why Does Kubernetes Need It?

HashiCorp Vault is a purpose-built secrets management system designed to securely store, distribute, and audit access to sensitive data such as API keys, database credentials, TLS certificates, and passwords. It provides a centralized control plane for secrets, enforcing strict access policies and maintaining a complete audit trail of every operation.

In Kubernetes environments, the need for a dedicated secrets manager becomes more pronounced as clusters and teams scale. While Kubernetes includes a native Secret resource, it was designed as a lightweight abstraction, not a comprehensive security system. Relying on it alone quickly becomes risky in production, especially across multiple clusters. Applications need a way to access credentials dynamically and securely, without embedding secrets in container images, manifests, or Git repositories.

Vault addresses this gap by integrating directly with Kubernetes. Workloads authenticate to Vault using their Kubernetes service accounts and receive only the secrets they are explicitly authorized to access. This model improves security, enables automation, and simplifies secrets management across clusters—an area where platforms like Plural provide additional value by standardizing Vault deployment and configuration fleet-wide.

What does Vault do?

Vault acts as a full secrets lifecycle manager rather than a simple key-value store. Its core capabilities include:

• Secure storage and retrieval of secrets
• Dynamic, on-demand credential generation for systems like AWS, GCP, databases, and Kubernetes
• Built-in PKI for issuing and rotating TLS certificates
• Encryption as a service for application data

Dynamic secrets are a key differentiator. Instead of long-lived credentials stored indefinitely, Vault can generate short-lived credentials that automatically expire and are revoked. This drastically reduces the blast radius of leaked secrets. Vault also centralizes cryptographic operations, allowing applications to rely on a hardened, audited system instead of implementing their own encryption logic.

The challenge of managing Kubernetes secrets

Kubernetes Secrets are often misunderstood as being secure by default. In reality, they are base64 encoded, not encrypted. Anyone with access to the underlying etcd datastore can decode them trivially. While Kubernetes supports encryption at rest for etcd, enabling and managing it introduces additional complexity around key management and rotation.

More importantly, native Secrets lack higher-level security primitives. They do not support dynamic secret generation, automatic rotation, or detailed audit logging. As clusters grow and access requirements become more granular, these limitations create operational and security risks that are difficult to mitigate with native tooling alone.

Where native Kubernetes Secrets fall short

Compared to Vault, native Kubernetes Secrets are missing several capabilities that are critical in production environments:

• Strong, centralized encryption and access controls
• Fine-grained auditing of all secret access
• Automatic rotation and revocation
• Dynamic, short-lived credentials

Vault provides these features out of the box. Every access is logged, credentials can be generated just-in-time, and leaked secrets expire automatically. Centralizing secrets management in Vault significantly strengthens the security posture of Kubernetes workloads and simplifies compliance and incident response.

At scale, consistently deploying and operating Vault across multiple clusters becomes its own challenge. Plural helps solve this by providing a unified platform to deploy, configure, and manage Vault consistently across a Kubernetes fleet, ensuring secrets management remains secure, auditable, and operationally manageable as environments grow.

How to Integrate HashiCorp Vault with Kubernetes

Integrating HashiCorp Vault with Kubernetes is about establishing a secure, repeatable way for pods to access secrets without exposing sensitive data in images, manifests, or source control. There is no single “correct” integration model. Instead, Kubernetes teams typically choose from three established patterns, each trading off simplicity, transparency, and control.

At a high level, these approaches fall into two categories. The first abstracts Vault away from the application entirely, letting workloads consume secrets through familiar Kubernetes mechanisms. The second makes Vault a first-class dependency of the application itself. Selecting the right model—and enforcing it consistently across clusters—is critical for maintaining a uniform security posture at scale.

Method 1: Vault Agent Injector

The Vault Agent Injector is an admission controller that mutates pods at creation time. When a pod is annotated appropriately, Kubernetes automatically injects a Vault Agent sidecar container into it. This agent authenticates to Vault using the pod’s service account, retrieves the required secrets, and writes them to a shared in-memory volume.

From the application’s perspective, secrets appear as files on disk. The application does not need to know that Vault exists, nor does it need a Vault client library. This makes the injector particularly effective for legacy applications, third-party software, or workloads where code changes are undesirable or impractical.

The Vault Agent also manages secret lifecycle concerns. It renews Vault tokens, refreshes secrets when they rotate, and ensures credentials remain valid for as long as the pod is running. This model strongly separates application logic from secret management while still providing dynamic, secure access to sensitive data.

Method 2: Vault Secrets Operator

The Vault Secrets Operator provides a more Kubernetes-native integration model. Instead of injecting a sidecar, it synchronizes secrets from Vault into standard Kubernetes Secret objects. Teams define desired secret mappings using Custom Resource Definitions, and the operator continuously reconciles those resources against Vault.

Once synced, applications consume secrets exactly as they would native Kubernetes Secrets—through environment variables or volume mounts. This approach fits naturally into GitOps workflows, where application manifests and secret references live side by side in version control.

The operator effectively turns Vault into a secure backend for Kubernetes Secrets. Vault handles encryption, access control, auditing, and rotation, while Kubernetes remains the consumption interface. This model works well for teams that want minimal runtime mutation and a declarative, platform-aligned workflow.

Method 3: Direct API integration

Direct integration embeds Vault awareness into the application itself. The service uses a Vault client library to authenticate, request secrets, and manage leases programmatically. This approach exposes the full power of Vault, including dynamic credentials generated per request, fine-grained lease control, and context-aware secret usage.

This model offers maximum flexibility but also places the most responsibility on developers. Applications must handle authentication flows, retries, renewals, and error handling correctly. For this reason, direct integration is best suited for new services designed with Vault in mind from the outset, or for systems that require highly specialized secret management behavior.

When Vault runs inside Kubernetes, this model can be both efficient and secure, but it demands mature engineering practices and strong operational discipline.

Operational consistency at scale

Regardless of the integration method, consistency is the hardest problem at scale. Mixing patterns across teams or clusters often leads to uneven security guarantees and operational confusion. Ensuring that authentication methods, policies, and injection or sync mechanisms are configured identically across environments is essential.

This is where centralized management becomes critical. Platforms like Plural help teams deploy and operate Vault consistently across a fleet of clusters, enforce a standard integration pattern, and manage configuration through GitOps workflows. By treating Vault integration as shared infrastructure rather than a per-team implementation detail, organizations reduce risk while making secure secret access easier for developers.

Why Choose Vault Over Native Kubernetes Secrets?

Native Kubernetes Secrets offer a basic way to store sensitive values, but they were never designed to be a full-fledged secrets management system. Secrets are base64 encoded and stored in etcd, which means achieving acceptable security requires additional configuration such as encryption at rest, strict RBAC, and careful operational discipline. Even with those controls in place, native Secrets struggle to meet the security, auditability, and lifecycle requirements of most production and multi-cluster environments.

HashiCorp Vault addresses these gaps by acting as a dedicated, centralized secrets management platform. It introduces stronger security primitives, better automation, and a consistent control plane for secrets across clusters. For organizations operating Kubernetes at scale, Vault is not just an enhancement—it is often a necessity.

Generate and rotate secrets dynamically

The biggest weakness of native Kubernetes Secrets is that they are static. Once created, a secret remains valid until someone manually rotates or revokes it. If that secret is leaked, the exposure window is effectively unlimited.

Vault takes a fundamentally different approach by supporting dynamic, short-lived secrets. Instead of storing long-lived credentials, Vault can generate temporary credentials on demand for databases, cloud providers, and other systems. These credentials automatically expire after a defined TTL and are revoked without human intervention.

This drastically reduces risk. A leaked credential is only useful for a short period, and rotation is handled automatically. From an operational standpoint, it also removes the burden and fragility of manual secret rotation, which is a common source of outages and security incidents.

Strengthen encryption and auditing

Vault is built with security as a first-class concern. All secrets are encrypted in transit and at rest using Vault-managed encryption keys, independent of Kubernetes and etcd. This gives you tighter control over key management and clearer security boundaries.

Equally important is auditing. Vault produces a detailed audit log for every operation, including reads, writes, and authentication events. You can see exactly who accessed which secret and when. This level of visibility is essential for incident response and is often a hard requirement for compliance frameworks such as SOC 2, PCI DSS, and HIPAA.

Native Kubernetes Secrets do not provide this depth of auditing. Reconstructing access patterns typically requires correlating multiple control-plane logs, which is error-prone and incomplete by comparison.

Centralize policy management across your fleet

As organizations move from a single cluster to many, secrets management becomes a coordination problem. Native Secrets are scoped to individual clusters and namespaces, which often leads to duplication, inconsistent policies, and configuration drift.

Vault provides a centralized policy engine that enforces identity-based access controls across all environments. Applications authenticate using strong identities, such as Kubernetes service accounts, and Vault policies determine exactly which secrets they can access—regardless of which cluster they run in.

This centralized model dramatically simplifies operations. Instead of managing secrets independently in every cluster, you manage policies once and apply them everywhere. When combined with a fleet management platform like Plural, this becomes even more powerful. Plural enables consistent deployment of Vault, standardized policy definitions, and uniform RBAC configuration across all clusters, ensuring that every environment adheres to the same security baseline.

The result is a secrets management foundation that is secure, auditable, and scalable—qualities that native Kubernetes Secrets alone cannot reliably provide in modern, multi-cluster deployments.

How to Set Up Vault in Your Kubernetes Cluster

Deploying Vault in Kubernetes is not a routine application install. It establishes a core security control plane that every workload will depend on. A correct setup prioritizes isolation, durability, and repeatability. For teams operating more than one cluster, the goal should be a standardized deployment that can be reproduced reliably using GitOps. Platforms like Plural help enforce that consistency by treating Vault as shared infrastructure rather than a one-off installation.

Plan your Vault deployment

Start by deciding where Vault should run. Vault is security-critical infrastructure, and its blast radius should be tightly controlled. If your organization already operates multiple clusters, the preferred model is to run Vault in a dedicated Kubernetes cluster. This isolates it from application workloads, avoids resource contention, and reduces the impact of application-level incidents.

If a dedicated cluster is not feasible, Vault should at least run in its own namespace with strict RBAC and NetworkPolicies. This provides a logical boundary and limits access paths.

For storage, use Vault’s Integrated Storage (Raft). Raft is production-ready, highly available, and removes the need for external dependencies such as Consul. Persistent volumes must be backed by reliable storage and protected with restrictive filesystem permissions and network controls, since they hold encrypted Vault data.

These decisions are foundational. Retrofitting isolation or storage later is far more difficult than designing for it upfront.

Install Vault with the Helm chart

The recommended installation method is the official HashiCorp Vault Helm chart. Vault requires multiple Kubernetes primitives working together—StatefulSets, Services, ConfigMaps, and RBAC—and Helm provides a repeatable way to manage that complexity.

Avoid Dev or Standalone modes outside of local testing. For any real environment, use the High Availability configuration. This ensures Vault can tolerate node failures and continue serving requests.

Use Helm v3 exclusively. Older versions are unsupported and introduce unnecessary risk. Treat the Helm values file as a critical artifact: version it, review changes, and promote it through environments just like application code.

This standardized installation path is especially important at scale. With Plural, the Helm-based deployment can be managed centrally and rolled out consistently across clusters, eliminating manual drift.

Configure Vault for high availability

A production Vault deployment must be highly available. This typically means running three or five Vault pods using a StatefulSet. StatefulSets are required because each Vault node needs a stable identity and persistent storage for Raft consensus, leader election, and recovery.

High availability configuration includes:

• Multiple Vault replicas backed by persistent volumes
• Integrated Storage (Raft) enabled
• Automatic leader election and failover
• Readiness and liveness probes tuned for Vault behavior

TLS is non-negotiable. All traffic to and from Vault must be encrypted. This requires provisioning certificates, storing them as Kubernetes secrets, and referencing them in the Helm configuration. Without TLS, Vault should never be exposed beyond a local test environment.

Once deployed, Vault must be initialized and unsealed. In production, unseal keys should be managed securely—often via a cloud KMS or HSM integration—to avoid manual intervention during restarts.

When deployed correctly, this architecture ensures Vault remains available even during node failures or rolling upgrades. At fleet scale, Plural helps enforce this HA baseline everywhere by applying the same Helm configuration and security controls across all clusters, ensuring Vault behaves predictably no matter where it runs.

How Kubernetes Authenticates with Vault

For Vault to deliver secrets to workloads running in Kubernetes, it must first establish a trusted identity for each application. Rather than relying on static credentials that need manual distribution and rotation, Vault integrates directly with Kubernetes using its built-in Kubernetes Auth Method. This approach leverages native Kubernetes identities and the control plane itself to authenticate workloads dynamically and securely.

In this model, the Kubernetes cluster acts as a trusted authority. When a pod needs access to secrets, it proves its identity to Vault using Kubernetes-issued credentials. Vault validates that identity against the Kubernetes API server and, if successful, issues a short-lived Vault token scoped by policy. This design eliminates hardcoded secrets, reduces operational overhead, and scales cleanly across clusters. At fleet scale, managing these auth backends and role mappings consistently can be complex, which is why platforms like Plural are often used to define and deploy these configurations centrally.

Authenticate using service account tokens

The foundation of Kubernetes-to-Vault authentication is the Service Account Token. Every pod runs under a Kubernetes Service Account, which represents its identity. Kubernetes automatically issues a JSON Web Token (JWT) for that service account and mounts it into the pod’s filesystem.

When an application needs to authenticate to Vault, it reads this token and presents it to the Vault server. Vault’s Kubernetes auth method is purpose-built to accept these tokens. Because the token is issued and rotated by Kubernetes itself, this mechanism avoids embedding credentials in code or configuration and removes the need for application teams to manage secret rotation manually.

This approach ties application identity directly to Kubernetes-native constructs, making authentication both more secure and more operationally manageable.

Configure roles for access control

Authentication alone is not sufficient; Vault also needs to determine what an authenticated workload is allowed to access. This is handled through Vault roles.

A Vault role maps a specific Kubernetes identity—typically a service account name and namespace—to one or more Vault policies. Those policies define exactly which secret paths the workload can read, write, or manage. For example, a role might bind the billing-api-sa service account in the production namespace to a policy that grants read-only access to database credentials required by the billing service.

This role-based mapping enforces least-privilege access by default. Applications automatically receive only the permissions they need, with no manual token distribution. At scale, defining and maintaining these roles consistently is best handled declaratively. Using a GitOps workflow with Plural CD, teams can version Vault roles and policies in Git and apply them uniformly across all clusters, preventing drift and reducing the risk of misconfiguration.

Validate access with JWT authentication

Vault does not blindly trust the service account token presented by a pod. To verify its authenticity, Vault integrates with the Kubernetes TokenReview API.

When Vault receives a JWT from a workload, it forwards that token to the Kubernetes API server for validation. The API server checks the token’s signature, confirms that the associated service account still exists, and verifies that it has not been revoked. Only if this validation succeeds does Vault proceed to issue a Vault token.

This step is critical for security. It ensures that authentication requests are tied to real, active workloads running in the trusted cluster and prevents the use of stolen or expired tokens. By treating the Kubernetes API server as the source of truth for identity, Vault tightly couples secret access to the actual state of the cluster, providing a robust and dynamic authentication mechanism suitable for production environments.

Key Patterns for Deploying Vault Secrets

After integrating Vault with Kubernetes, the core challenge becomes secret delivery: how applications consume sensitive data at runtime without embedding credentials in images, manifests, or source control. There is no universal pattern. The correct approach depends on whether secrets are static or dynamic, whether they must exist before process startup, and how much secret lifecycle management you want to push onto the platform versus the application.

A good deployment pattern minimizes application changes while giving platform teams centralized control over access, rotation, and policy enforcement. The following patterns are widely used in production Kubernetes environments and can be defined declaratively in manifests, making them well suited to GitOps workflows managed with platforms like Plural.

Retrieve secrets with an init container

The init container pattern is one of the simplest and most explicit ways to deliver secrets. An init container runs to completion before the main application container starts. In this model, the init container authenticates to Vault, retrieves the required secrets, and writes them to a shared in-memory volume.

Once the init container exits successfully, the application container starts and reads the secrets from that volume as regular files. The application itself has no awareness of Vault and requires no Vault client libraries or logic.

This pattern works best when:

• Secrets must be available at application startup
• Secrets are relatively static during the pod’s lifetime
• You are dealing with legacy or third-party applications

The limitation is that secrets are fetched only once. If a secret rotates while the pod is running, the application will not see the update unless it is restarted.

Inject secrets with a Vault Agent sidecar

For workloads that rely on short-lived or frequently rotated credentials, the Vault Agent sidecar pattern is the most robust option. In this setup, a Vault Agent runs alongside the application container in the same pod.

The agent authenticates with Vault, retrieves secrets, and continuously manages their lifecycle. It renews leases, re-fetches secrets when they rotate, and updates the files in a shared memory volume. The application simply reads from that volume and does not need to handle authentication, renewal, or rotation logic itself.

This pattern is particularly well suited for:

• Dynamic database credentials
• Cloud provider credentials with TTLs
• Any secret that must be kept continuously valid

Because rotation is automated and transparent, this approach significantly reduces operational risk. It is the recommended pattern for most stateful or security-sensitive workloads in Kubernetes.

Mount secrets as volumes or environment variables

This pattern focuses on how secrets are consumed by the application once they have been retrieved, often in combination with the Vault Agent Injector. The injector mutates pod specifications to add the required init container or sidecar and then exposes secrets to the application as files or environment variables.

Mounting secrets as files in a volume is generally the preferred approach. File-based secrets can be updated in place when rotation occurs, and access can be restricted using filesystem permissions. This aligns well with sidecar-based patterns and supports dynamic updates.

Environment variables are sometimes used for simplicity, especially with applications that expect configuration via env vars. However, they come with higher risk. Environment variables can be leaked through logs, crash dumps, or debugging endpoints and cannot be updated without restarting the process. For sensitive credentials, volume mounts are usually the safer choice.

Operational consistency at scale

Regardless of which pattern you choose, consistency matters more than the specific mechanism. Mixing secret delivery models across teams and clusters often leads to uneven security guarantees and operational confusion.

By defining these patterns declaratively and managing them through GitOps, teams can ensure every workload follows the same rules. Plural enables this by providing a centralized way to manage Vault integrations, secret injection patterns, and policy enforcement across an entire Kubernetes fleet, reducing drift while keeping secret consumption simple for developers.

Security Best Practices for Your Vault Integration

Integrating Vault correctly is only half the battle; securing it is a continuous process. A misconfigured Vault instance can expose the very secrets it's meant to protect. Adhering to security best practices is not optional—it's essential for maintaining the integrity of your entire infrastructure. This involves encrypting traffic, isolating the Vault environment, and strictly controlling access. By implementing these measures, you create a robust defense-in-depth strategy that protects your sensitive data from unauthorized access and potential breaches.

Managing these security configurations consistently across a large fleet of Kubernetes clusters can introduce significant operational overhead. Each cluster needs the correct network policies, TLS configurations, and access controls. This is where a centralized management platform becomes critical. Plural helps by allowing you to define these security configurations once and apply them uniformly across all your clusters, ensuring that best practices are not just recommendations but enforced policies throughout your environment. With Plural, you can manage fleet-wide security from a single control plane, simplifying compliance and reducing the risk of configuration drift.

Secure Communication with TLS

Encrypting data in transit is a fundamental security requirement. All communication with the Vault server, whether from applications, users, or other Kubernetes components, must be secured using Transport Layer Security (TLS). Without TLS, sensitive information like authentication tokens and secrets could be intercepted on the network. As the official Vault on Kubernetes deployment guide states, you should "always use TLS (encryption) for Vault." This is implemented by generating TLS certificates and storing them as Kubernetes secrets. The Vault Helm chart can then be configured to use these secrets to secure its listeners, ensuring all API traffic is encrypted end-to-end. This prevents man-in-the-middle attacks and protects the confidentiality of your data.

Isolate Vault with Network Policies

To limit the potential blast radius of a security breach, Vault should be isolated from other applications. The ideal approach is to run Vault in a dedicated Kubernetes cluster. However, if that isn't practical, you must enforce strict network boundaries within a shared cluster. You can achieve this by deploying Vault in its own namespace and using Kubernetes NetworkPolicies to control ingress and egress traffic. These policies should be configured to only allow connections from trusted sources, such as specific application pods that need access to secrets. This principle of isolation ensures that even if another application in the cluster is compromised, the attacker cannot easily pivot to access the Vault server.

Enforce Least-Privilege Access Policies

The principle of least privilege dictates that any user or application should only have the minimum permissions necessary to perform its function. When integrating Vault with Kubernetes, this is achieved through a combination of authentication methods and access policies. Applications authenticate using a Kubernetes service account token, which Vault validates against the Kubernetes API. Once authenticated, Vault assigns policies based on the identity contained within the token. These policies define which secret paths the application can access and what operations it can perform. You can use Plural's Global Services to deploy consistent RBAC policies across your entire fleet, ensuring that least-privilege access is enforced uniformly everywhere.

How to Monitor and Troubleshoot Your Integration

Integrating Vault with Kubernetes introduces a critical dependency. If Vault is down or misconfigured, applications can fail. Effective monitoring and a clear troubleshooting plan are essential, focusing on performance metrics, authentication errors, and secret injection issues. A centralized platform provides a single place to observe logs, metrics, and resource states across your fleet. Plural’s single-pane-of-glass console gives you this unified view, making it easier to correlate issues between Vault and your Kubernetes workloads without switching tools.

Track Key Performance and Security Metrics

To ensure your integration is reliable, monitor both performance and security. Vault exposes telemetry data for observability tools, with key metrics like request latency and error rates. For security, monitor audit device logs for unusual activity, such as failed authentications or policy changes. Many teams ingest and visualize this data using tools like Splunk or Datadog. Vault aggregates metrics every 10 seconds, giving you a near real-time snapshot of cluster health. Setting up alerts for anomalies helps you proactively address issues before they cause an outage.

Solve Common Authentication and Authorization Errors

Authentication is a frequent source of problems with the Kubernetes auth method. Applications authenticate by presenting a Kubernetes service account token, which Vault validates. A "permission denied" error often points to a misconfiguration in this chain of trust. Start by checking Vault audit logs for details on the failed request; the error message will often point to the cause, like an invalid token or role. Next, verify the ClusterRoleBinding linking the service account to a Vault role. Plural’s embedded Kubernetes dashboard simplifies this by letting you inspect RBAC rules directly from the UI.

Fix Secret Injection and Sync Issues

When using the Vault Secrets Operator (VSO) or agent injector, secrets might fail to appear in pods. The VSO syncs secrets from Vault into native Kubernetes secrets, while the agent modifies pod definitions to retrieve them. If a secret is missing, check the logs of the VSO controller or the vault-agent-init container. These logs show connection attempts and auth errors. Common mistakes include an incorrect Vault address in pod annotations or a network policy blocking traffic. Also, confirm the service account has a Vault role with read access to the required secret paths. The VSO can also manage dynamic secrets created on-demand; operator logs will help diagnose rotation failures.

Common Use Cases for Vault in Kubernetes

While Vault is an excellent replacement for native Kubernetes Secrets for storing static credentials, its most powerful features enable dynamic security workflows. Instead of just storing secrets, Vault can actively manage their entire lifecycle. This allows engineering teams to build systems where credentials are created on-demand and exist for only as long as they are needed, dramatically reducing the risk associated with compromised secrets. Integrating these patterns into your Kubernetes environment moves you from a passive to an active security posture.

Manage Dynamic Database Credentials

Storing static, long-lived database credentials in configuration files or even native Kubernetes Secrets is a significant security risk. If compromised, they provide persistent access to your data. Vault’s database secrets engine solves this by generating unique database credentials on demand. When an application pod needs database access, it authenticates with Vault and requests credentials. Vault connects to the database, creates a new user with a specific set of permissions and a short time-to-live (TTL), and returns the username and password to the application. Once the lease expires, Vault automatically revokes the credentials, ensuring that even if they are leaked, their useful lifetime is measured in minutes or hours, not months.

Automate Certificate Management and PKI

In a microservices architecture, securing communication between services with mutual TLS (mTLS) is critical. However, manually issuing, distributing, and renewing thousands of certificates is not feasible. Vault’s PKI secrets engine can function as an internal Certificate Authority (CA) for your organization. It automates the entire certificate lifecycle, allowing services within your Kubernetes cluster to request certificates from Vault to encrypt traffic. This ensures that all service-to-service communication is authenticated and encrypted, helping you achieve a zero-trust network environment without the operational burden of managing a complex Public Key Infrastructure by hand.

Provide API Keys and Encryption as a Service

Applications often need to store static secrets like API keys for third-party services. Vault provides a secure, centralized location for these keys with granular access policies. Beyond simple storage, Vault’s Transit secrets engine offers "encryption as a service." This allows applications to offload cryptographic functions to Vault without ever handling the encryption keys directly. An application can send plaintext data to Vault, which encrypts it and returns the ciphertext for storage. The encryption key never leaves Vault, simplifying development and reducing the risk of key exposure. This pattern is especially useful for meeting compliance requirements for data encryption at rest.

Related Articles

• Kubernetes Secrets: The Ultimate Guide (2025)
• Kubernetes Secrets: A Practical Guide

Frequently Asked Questions

Vault Agent Injector vs. Vault Secrets Operator: which one should I use? Your choice depends on how you want your applications to consume secrets. Use the Vault Agent Injector if you want to keep your applications completely unaware of Vault. The agent sidecar handles everything, writing secrets to a shared volume for your app to read as simple files. This is great for existing or third-party applications you can't modify. Choose the Vault Secrets Operator if your team prefers a Kubernetes-native workflow. The operator syncs Vault secrets into standard Kubernetes Secret objects, which fits perfectly with GitOps practices where all resources are declared in manifests.

Is it safe to run Vault on the same Kubernetes cluster as my applications? While it's possible, the best practice is to run Vault on a dedicated Kubernetes cluster. This isolates it from application workloads, protecting it from resource contention or potential security breaches in other applications. If a dedicated cluster isn't an option, you should at least deploy Vault in its own namespace and use strict NetworkPolicies to control exactly which pods can communicate with it. This creates a strong security boundary and limits the potential blast radius if another part of the cluster is compromised.

How does my application get updated secrets without a restart? This is handled by the Vault Agent sidecar pattern. The agent runs alongside your application and is responsible for the entire secret lifecycle. It writes secrets to a shared memory volume that your application can read. When a secret's lease is about to expire, the agent automatically renews it with Vault and updates the file on the shared volume. Your application code just needs to be able to periodically re-read the secret file from disk to pick up the new credentials, which allows for seamless rotation without any service interruption.

Can Vault manage secrets for things outside of Kubernetes too? Absolutely. While this post focuses on Kubernetes integration, Vault is a standalone tool designed to be a central secrets management system for your entire infrastructure. It can manage secrets for virtual machines, CI/CD pipelines, serverless functions, and more. By centralizing all your secrets in Vault, you create a single source of truth and a consistent policy enforcement point, which simplifies auditing and strengthens your overall security posture across all environments.

How does a platform like Plural help manage Vault across many clusters? When you manage a fleet of Kubernetes clusters, ensuring each one has a consistent and secure Vault setup is a major operational challenge. Plural solves this by letting you define your Vault configuration, authentication roles, and access policies as code in a Git repository. Using Plural's Global Services feature, you can automatically deploy and enforce these configurations across every cluster in your fleet. This GitOps approach eliminates configuration drift and ensures that security best practices are applied uniformly, all managed from a single control plane.