Bits of .NET

🏷️ Who Built This Image? When? Why?

Image tags tell version. But who built it? Git commit? Labels add metadata. Filter images by label. Audit trail built-in.

📝 Add Labels in Dockerfile

FROM node:18-alpine

LABEL maintainer="team@example.com"
LABEL version="1.2.3"
LABEL build-date="2024-01-15"
LABEL git-commit="a1b2c3d"
LABEL description="API service for user management"
LABEL org.opencontainers.image.source="https://github.com/example/repo"
LABEL org.opencontainers.image.licenses="MIT"

# Multi-line labels
LABEL security.scanned="true" \
      security.vulnerabilities="0" \
      compliance.hipaa="compliant"

🔧 Inspect and Filter Labels

# Inspect label
docker inspect myapp:latest | grep -A 10 Labels

# Filter images by label
docker images --filter label=maintainer=team@example.com
docker images --filter label=version=1.2.3
docker images --filter label=security.scanned=true

# Build with label from CLI
docker build --label "build.user=$(whoami)" --label "build.time=$(date)" -t myapp .

# Compose labels
version: '3.8'
services:
  app:
    image: myapp
    labels:
      - "com.example.environment=production"
      - "com.example.department=engineering"

💡 Use Cases

• CI/CD: Add build ID, commit SHA, branch name
• Security: Mark scanned images, CVE status
• Compliance: PCI, HIPAA, GDPR flags
• Cleanup: Delete old images by build-date label