DevOps-Security-Agent-Skills/security/hardening/container-hardening/references/container-security.md

Container Security Best Practices

Dockerfile Hardening

# Use minimal base image
FROM gcr.io/distroless/base-debian12

# Or Alpine
FROM alpine:3.19

# Non-root user
RUN addgroup -g 1000 appgroup && \
    adduser -u 1000 -G appgroup -D appuser
USER appuser

# Read-only filesystem
# (Set at runtime with --read-only)

# No new privileges
# (Set at runtime with --security-opt=no-new-privileges)

Security Scanning

# Trivy scan
trivy image --severity HIGH,CRITICAL myimage:latest

# Grype scan
grype myimage:latest --fail-on high

# Docker Scout
docker scout cves myimage:latest

Runtime Security

# Kubernetes securityContext
securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  runAsGroup: 1000
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false
  capabilities:
    drop:
      - ALL
  seccompProfile:
    type: RuntimeDefault

Docker Run Hardening

docker run \
  --read-only \
  --tmpfs /tmp \
  --security-opt=no-new-privileges:true \
  --cap-drop=ALL \
  --user 1000:1000 \
  --memory=512m \
  --cpus=0.5 \
  myimage

Image Signing

# Cosign
cosign sign --key cosign.key myimage:latest
cosign verify --key cosign.pub myimage:latest

# Docker Content Trust
export DOCKER_CONTENT_TRUST=1
docker push myimage:latest

Network Policies

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

Checklist

• Use minimal base images
• Run as non-root
• Drop all capabilities
• Read-only filesystem
• No privilege escalation
• Scan for vulnerabilities
• Sign images
• Implement network policies
• Use secrets management
• Enable audit logging