How HashiCorp's Solutions Suite Secures Kubernetes for Business Success
Author: John Jarvis
Release Date: 22/01/2024
Kubernetes has become a cornerstone of modern architecture. But managing it at scale, and securely, can be a big challenge. That’s where HashiCorp’s suite of tools comes in. From secrets management with Vault to service mesh security with Consul, here’s how you can lock down your Kubernetes clusters while keeping your DevOps workflows smooth.
Simplicity and Flexibility with HashiCorp Nomad
Kubernetes and Nomad both handle container orchestration, but they differ in their scope and design. Kubernetes offers a comprehensive suite of services for container management, including scheduling, service discovery, and secrets management, while Nomad focuses on simplicity, providing a single binary for cluster management and scheduling, using external tools like Consul and Vault for added functionality. Kubernetes is complex to set up and resource-intensive, whereas Nomad’s lightweight architecture is easier to deploy and manage consistently across different environments.
Additionally, Kubernetes primarily supports Linux containers, while Nomad offers flexibility to run a wide range of workloads, including virtualised and standalone applications. Finally, while Kubernetes can scale to large clusters, Nomad has demonstrated its ability to handle significantly larger environments with less complexity, scaling easily across multiple clusters and data centres.
Secure K8s Secrets Management with HashiCorp Vault
Integrating HashiCorp Vault with Kubernetes can be achieved through several methods, each catering to specific use cases and operational preferences. Here’s a high-level comparison of three prominent approaches: Vault Agent Injector, Vault Secrets Operator, and the Vault CSI (Container Storage Interface) Provider.
Why Kubernetes Secrets Alone Are Insufficient for Production
While Kubernetes Secrets provide a straightforward way to manage sensitive information like passwords, API keys, and certificates, they fall short of meeting the security requirements for most production environments. By default, Kubernetes Secrets are stored as base64-encoded strings in etcd, the cluster’s backing store. Unless etcd is encrypted, these secrets can be accessed in plaintext by anyone with access to the cluster’s storage. And even then, these secrets are static: at risk of expiring or becoming outdated, potentially requiring specific workflows to rotate or update them and the applications that access them. Additionally, Kubernetes Secrets lack the fine-grained access controls and robust audit logging that enterprise-grade applications demand. This is where integrating HashiCorp Vault can help, offering enhanced security, dynamic secret generation, and comprehensive access control.
1. Vault Agent Injector
The Vault Agent Injector utilises the sidecar pattern to inject a Vault Agent container into your application pods. This agent authenticates with Vault, retrieves the necessary secrets, and makes them available to the application via a shared memory volume or environment variables.
• Use Case:
- Ideal for applications that require dynamic secrets or frequent secret rotations.
- The sidecar ensures that secrets are always up-to-date without necessitating application restarts.
• Pros:
- Provides dynamic secret management with automatic renewal and revocation.
- Secrets are not stored in Kubernetes Secrets, reducing exposure risk.
- Supports templating and transformation of secrets before injection.
• Cons:
- Introduces additional containers per pod, which may increase resource consumption.
- Requires applications to handle secrets presented via files or environment variables.
2. Vault Secrets Operator
The Vault Secrets Operator (VSO) is a Kubernetes operator that synchronises secrets to Kubernetes Secrets from Vault (or, for a ready-to-deploy solution, from HCP Vault Secrets). It monitors changes in Vault and updates the corresponding Kubernetes Secrets accordingly.
• Use Case:
- Suitable for scenarios where applications are already configured to consume Kubernetes Secrets.
- VSO provides a seamless way to integrate Vault-managed secrets into existing workflows.
• Pros:
- Leverages native Kubernetes Secrets, simplifying application configurations.
- Automates the synchronisation of secrets between Vault and Kubernetes.
- Reduces the need for application modifications to consume secrets.
• Cons:
- Secrets are stored in Kubernetes Secrets, which may be less secure than accessing them directly from Vault.
- Relies on Kubernetes RBAC for access control, which might not be as granular as Vault’s policies.
3. Vault CSI Provider
The Vault CSI Provider integrates with the Kubernetes CSI Secrets Store Driver to mount secrets stored in Vault directly into pods as ephemeral volumes. This method allows applications to access secrets as files without embedding them into environment variables or Kubernetes Secrets.
• Use Case:
- Best for applications that can consume secrets from files and prefer not to handle environment variables or Kubernetes Secrets.
- It offers a secure way to provide secrets without persisting them in the cluster’s state.
• Pros:
- Secrets are not persisted in Kubernetes Secrets, enhancing security.
- Supports automatic updates of secrets without requiring pod restarts.
- Compatible with the standard CSI interface, promoting consistency across storage solutions.
• Cons:
- Requires the deployment and management of the CSI driver and provider.
- Applications must be capable of reading secrets from mounted files.
Choosing the Right Approach
• Vault Agent Injector:
- Choose this when you need dynamic secrets and automatic rotation, and your application can handle secrets provided via files or environment variables.
• Vault Secrets Operator:
- Opt for this when your application is designed to consume Kubernetes Secrets, and you prefer a native Kubernetes experience with automated synchronisation from Vault or HCP Vault Secrets.
• Vault CSI Provider:
- Select this when you want to avoid storing secrets in Kubernetes Secrets and prefer mounting secrets as files directly into your pods.
Each method offers distinct advantages and considerations. Your choice should align with your application’s architecture, security requirements, and operational preferences. For a more detailed comparison, refer to HashiCorp’s official documentation: HashiCorp Vault Kubernetes Integration. Additionally, this blog post provides an in-depth analysis of these integration methods: Kubernetes Vault Integration Comparison.
Consul on Kubernetes: Hand in Hand
Kubernetes and service mesh tend to go hand and hand. Organisations that adopt Kubernetes are looking for a way to automate, secure, and observe the connections between pods and clusters. Consul and Kubernetes provide a scalable and highly resilient platform for microservices. Consul supports any Kubernetes runtime including hosted solutions like EKS, AKS, GKE, and OpenShift.
As mentioned with VSO, HashiCorp is committed to simplifying the operator’s job by enabling Kube-native workflows: Consul 1.19 introduces the new Registration CRD for registering services into Consul and automatically updating the terminating gateway ACLs, continuing this form. Similarly, HashiCorp is well aware of the plight of developers in this complex deployment landscape: with Consul DNS Views, they don’t need to make any changes to ensure that requests for local services are satisfied, even when admin partitions are in the mix.
And all this builds on years of HashiCorp working with their customers to support their Kubernetes deployments, including multicluster ones federated over WAN via mesh gateways. Similarly, the registration functionality mentioned above built on Service Sync, syncing Consul services with Kubernetes and vice versa, securely facilitating those Kube-native workflows for all sorts of external services.