Container Security 2024: Hardening Your Stack Without Killing Velocity

Let’s get one thing straight immediately: Containers are not sandboxes.

If you are treating a Docker container like a VM, you are already compromised. I’ve spent the last decade cleaning up messes where a junior dev mounted the host Docker socket into a container, effectively giving root access to the entire node. In 2024, with supply chain attacks targeting open-source registries, the "it works on my machine" mentality is a liability.

We are seeing a shift. It's no longer just about firewalling ports; it's about verifying what exactly is running inside those ports. Whether you are deploying to a cluster in Oslo or a single node for a client in Bergen, the principles of isolation remain critical. Here is how we lock down infrastructure at the kernel level, keeping Datatilsynet happy and your uptime intact.

1. The Root Problem: Stop Running as Root

It is baffling that in 2024, root is still the default user in most base images. If an attacker compromises a process running as root inside a container, and then breaks out to the host (via a kernel vulnerability like Dirty Pipe, patched but always lurking in new variants), they have root on the server.

The Fix: Explicitly define a user. Never let the build process decide for you.

For Kubernetes, you must enforce this at the Pod level using SecurityContext. If you don't, your cluster is a ticking time bomb.

apiVersion: v1
kind: Pod
metadata:
  name: secure-app
spec:
  securityContext:
    runAsNonRoot: true
    runAsUser: 1000
    fsGroup: 2000
  containers:
  - name: main
    image: my-secure-image:1.0.2
    securityContext:
      allowPrivilegeEscalation: false
      capabilities:
        drop:
          - ALL

Pro Tip: When hosting on CoolVDS, we utilize KVM virtualization for our instances. This adds a critical hardware-level isolation layer that container-only "VPS" providers (often just selling you a glorified LXC container) cannot match. If a container breaks out on CoolVDS, it hits the hypervisor wall, not the bare metal kernel.

2. Verify the Supply Chain (Pin Your Digests)

Tags like latest are a lie. They change. If you deploy nginx:latest today, and the registry gets updated tomorrow with a compromised binary, your auto-scaling event next week will pull malware directly into production.

In a project for a Norwegian fintech client last month, we stopped a potential incident solely because we pinned images by SHA256 digest, not by tag.

Instead of: FROM python:3.11

Use: FROM python:3.11@sha256:48b30d6...

Automated Scanning in CI

You cannot manually check every layer. Use tools like Trivy or Grype in your pipeline before the image ever touches your registry.

# GitHub Actions Example for 2024
jobs:
  build-secure:
    runs-on: ubuntu-latest
    steps:
      - name: Build Image
        run: docker build -t myapp:candidate .
      
      - name: Run Trivy Vulnerability Scanner
        uses: aquasecurity/trivy-action@0.16.1
        with:
          image-ref: 'myapp:candidate'
          format: 'table'
          exit-code: '1'
          ignore-unfixed: true
          severity: 'CRITICAL,HIGH'

This breaks the build if a critical CVE is found. It’s annoying at first. It saves your job later.

3. Immutable Filesystems

If an attacker gets in, their first move is to download a payload or modify a configuration file. Make that impossible. Mount the root filesystem as read-only.

This forces you to be disciplined about where you write data. Logs go to STDOUT (captured by your logging driver). Temporary files go to /tmp (mounted as an emptyDir volume).

Docker implementation:

Kubernetes implementation:

4. Network Policies: The Firewall Inside the Cluster

By default, all pods in Kubernetes can talk to all other pods. A compromised frontend can scan your database directly. This flat network model is dangerous.

We need to implement a "Default Deny" policy. Whitelist only necessary traffic. This is crucial for GDPR compliance; you must prove you are minimizing data access vectors.

Here is a NetworkPolicy that denies all ingress traffic by default, forcing you to explicitly open paths:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: default-deny-all
  namespace: production
spec:
  podSelector: {}
  policyTypes:
  - Ingress

5. Local Compliance: The Norwegian Context

Hosting in Norway isn't just about latency; it's about jurisdiction. Following the Schrems II ruling and subsequent guidelines from Datatilsynet, European companies are under immense pressure to ensure data sovereignty.

When you run containers on CoolVDS, you are utilizing infrastructure physically located in the region. But software configuration matters too. Ensure your application logs do not inadvertently dump PII (Personally Identifiable Information). Configure your application to mask Norwegian National Identity Numbers (fødselsnummer) before they hit disk.

Performance vs. Security Overhead

Security adds overhead. AppArmor profiles, Seccomp filters, and encrypted overlay networks (like WireGuard within CNI) consume CPU cycles. On standard magnetic storage or oversold CPUs, this kills your I/O.

This is why the hardware underneath matters. We designed CoolVDS with NVMe storage arrays specifically to handle the high IOPS required by security scanning sidecars and encrypted service meshes (like Istio or Linkerd). You shouldn't have to disable security features just to keep your response times under 200ms.

Conclusion

Container security in 2024 is about depth. It is about dropping capabilities, pinning versions, and assuming the network is hostile. It is uncomfortable work, but necessary.

Don't build a fortress on a swamp. Start with a solid foundation. Deploy your hardened stack on a platform that respects isolation and raw performance.

Ready to lock it down? Spin up a secure KVM instance on CoolVDS today and test your hardening scripts on true NVMe hardware.