Containerized application deployment methods must be safe and comply with corporate regulations as more companies use Kubernetes. Kubernetes security and network policies may be combined with declarative GitOps continuous delivery tool Argo CD to guarantee deployments meet security, compliance, and resource management best practices.
This blog will show how to connect Argo CD with Kubernetes Security Policies (using PodSecurityPolicy and Open Policy Agent) and Network Policies (for intra-cluster communication) to secure and stabilize deployment pipelines.
1. Understanding Kubernetes Security Policies
Kubernetes security policies specify workload behavior security rules. Integrating Argo CD with security policy reduces privilege escalation and sensitive data access by ensuring every deployment matches security standards.
Pod Security Policies
Pod Security Policies enforce pod-level security by defining pod deployment requirements. Security methods include limiting container rights, host network access, and container root access.
Open Policy Agent (OPA) and Gatekeeper
A general-purpose policy engine, Open Policy Agent (OPA), interfaces with Kubernetes to implement bespoke security policies across clusters. Gatekeeper builds on OPA and functions as an admission controller to guarantee Kubernetes (via Argo CD) resources follow security requirements.
Combining Argo CD and Security Policies
Integrating Argo CD with security rules ensures every deployment meets corporate security criteria. Set up and implement these policies:
Step 1: Deploying Security Policies
Ensure that your security policies (PodSecurityPolicies, OPA/Gatekeeper policies) are in place before deploying applications. For example, deploy a PodSecurityPolicy to restrict privileged containers:
yaml
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apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
name: restricted-psp
spec:
privileged: false
runAsUser:
rule: MustRunAsNonRoot
Step 2: Configuring Argo CD Sync Policy
In your Argo CD application manifest, enable automated sync policies to automatically enforce the desired state (from Git) on the cluster. If a policy violation occurs, it can block non-compliant resources from being deployed.
yaml
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apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: secure-app
namespace: argocd
spec:
project: default
syncPolicy:
automated:
prune: true
selfHeal: true
Step 3: OPA/Gatekeeper Integration
To ensure fine-grained control, deploy OPA policies via Argo CD. These policies can prevent violations of security rules such as using outdated images or having containers without resource limits.
Example of an OPA policy for restricting the use of certain image repositories:
rego
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package kubernetes.admission
deny[{"msg": msg}] {
input.review.object.spec.containers[_].image == "forbidden-registry/*"
msg := "Deployment from forbidden registry is not allowed."
}
Once this policy is deployed, Argo CD will prevent any unauthorized image from being used in deployments.
2. Implementing Kubernetes Network Policies
Kubernetes Network Policies control the communication between pods and services, ensuring that only allowed traffic flows between your microservices or external entities. By integrating network policies into your Argo CD deployment process, you can ensure that security and network segmentation policies are enforced at the time of deployment.
Understanding Network Policies
Network policies define how pods communicate with each other within the cluster. You can use them to:
- Restrict traffic between namespaces.
- Limit access to specific services or pods.
- Allow or block traffic from certain IP ranges.
Integrating Argo CD with Network Policies
Network policies can be applied alongside application manifests in Argo CD, ensuring that all new deployments respect the defined network constraints.
Step 1: Defining Network Policies in Git
Create network policies that define the allowed communication patterns within your Kubernetes cluster. For example, the following network policy ensures that only pods with a certain label can access the database service:
yaml
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apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: db-network-policy
namespace: my-namespace
spec:
podSelector:
matchLabels:
app: database
policyTypes:
- Ingress
ingress:
- from:
- podSelector:
matchLabels:
app: frontend
Step 2: Applying Network Policies via Argo CD
In your GitOps setup, include network policy manifests alongside application definitions. Argo CD will sync the network policies to Kubernetes automatically, ensuring that any changes to the network structure are applied consistently across environments.
yaml
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apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: my-app-with-network-policies
spec:
source:
repoURL: 'https://github.com/your-repo.git'
path: 'manifests/'
destination:
namespace: my-namespace
server: 'https://kubernetes.default.svc'
syncPolicy:
automated:
prune: true
selfHeal: true
Step 3: Monitoring Network Policy Compliance
Monitor the enforcement of network policies using Prometheus and Grafana. Argo CD, combined with these monitoring tools, provides real-time insights into network traffic and policy violations.
3. Benefits of Integrating Argo CD with Security and Network Policies
- Automated Security Enforcement: Argo CD ensures that Kubernetes resources, including security and network policies, are automatically synced from Git, eliminating manual errors and security drift.
- Improved Compliance: By integrating Argo CD with OPA/Gatekeeper and security policies, organizations can enforce compliance checks at every deployment, ensuring that all Kubernetes resources follow security best practices.
- Secure Deployments: Argo CD automates the deployment of network policies, ensuring that your microservices can only communicate based on predefined security rules, reducing the risk of unauthorized access.
- Enhanced Visibility: With real-time monitoring using Prometheus and Grafana, you can visualize policy enforcement and take immediate action in case of policy violations.
Conclusion
Integrating Argo CD with Kubernetes Security and Network Policies is essential for maintaining secure and compliant cloud-native environments. By enforcing security policies, utilizing OPA/Gatekeeper, and defining network segmentation rules, Argo CD ensures that every deployment aligns with your organisation’s security and operational requirements.
With the combination of GitOps automation and security best practices, you can build scalable and secure CI/CD pipelines that protect your Kubernetes workloads while streamlining deployment processes.
About OpsMx
OpsMx helps DevOps teams optimize software delivery, all while ensuring the security and 100% compliance of application releases. By building on top of open-source Argo, Spinnaker, and Flux, OpsMx provides innovative solutions and services to SHIP BETTER SOFTWARE FASTER AND SAFER.
Frequently Asked Questions about Argo, K8s Security and Network Policies
1. How does Argo CD enhance Kubernetes security?
Argo CD matches Git states to protect Kubernetes clusters. It tracks changes, reduces errors, and enforces policies and controls access via OPA and RBAC.
2. What are Pod Security Policies and how do they work?
Cluster-wide PSPs control pod security. They secure pods before scheduling by controlling access levels, volume types, and container runtime characteristics.
3. How does Open Policy Agent (OPA) integrate with Kubernetes?
Gatekeeper admission controller connects OPA with Kubernetes. During admission, it checks policies against resource requests to ensure compliance with custom rules including security, labeling, and resource quotas.
4. Can Argo CD enforce network policies in Kubernetes?
Argo CD deploys network policies in Git application manifests to indirectly enforce them. It applies defined network policies uniformly across environments.
5. How do I monitor policy compliance in Kubernetes?
Audit policy compliance using OPA Gatekeeper, Admission Controllers, or custom Prometheus metrics on Kubernetes. Grafana dashboards show compliance status for simpler tracking.
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