git.stella-ops.org/ops/devops/docker/base-image-guidelines.md

Docker hardening blueprint (DOCKER-44-001)

Use this template for core services (API, Console, Orchestrator, Task Runner, Concelier, Excititor, Policy, Notify, Export, AdvisoryAI).

The reusable multi-stage scaffold lives at ops/devops/docker/Dockerfile.hardened.template and expects:

• .NET 10 SDK/runtime images provided via offline mirror (SDK_IMAGE / RUNTIME_IMAGE).
• APP_PROJECT path to the service csproj.
• healthcheck.sh copied from ops/devops/docker/ (already referenced by the template).

Copy the template next to the service and set build args in CI (per-service matrix) to avoid maintaining divergent Dockerfiles.

# syntax=docker/dockerfile:1.7
ARG SDK_IMAGE=mcr.microsoft.com/dotnet/sdk:10.0-bookworm-slim
ARG RUNTIME_IMAGE=mcr.microsoft.com/dotnet/aspnet:10.0-bookworm-slim
ARG APP_PROJECT=src/Service/Service.csproj
ARG CONFIGURATION=Release
ARG APP_USER=stella
ARG APP_UID=10001
ARG APP_GID=10001
ARG APP_PORT=8080

FROM ${SDK_IMAGE} AS build
ENV DOTNET_CLI_TELEMETRY_OPTOUT=1 DOTNET_NOLOGO=1 SOURCE_DATE_EPOCH=1704067200
WORKDIR /src
COPY . .
RUN dotnet restore ${APP_PROJECT} --packages /src/local-nugets && \
    dotnet publish ${APP_PROJECT} -c ${CONFIGURATION} -o /app/publish /p:UseAppHost=true /p:PublishTrimmed=false

FROM ${RUNTIME_IMAGE} AS runtime
RUN groupadd -r -g ${APP_GID} ${APP_USER} && \
    useradd -r -u ${APP_UID} -g ${APP_GID} -d /var/lib/${APP_USER} ${APP_USER}
WORKDIR /app
COPY --from=build --chown=${APP_UID}:${APP_GID} /app/publish/ ./
COPY --chown=${APP_UID}:${APP_GID} ops/devops/docker/healthcheck.sh /usr/local/bin/healthcheck.sh
ENV ASPNETCORE_URLS=http://+:${APP_PORT} \
    DOTNET_EnableDiagnostics=0 \
    DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=1 \
    COMPlus_EnableDiagnostics=0
USER ${APP_UID}:${APP_GID}
EXPOSE ${APP_PORT}
HEALTHCHECK --interval=30s --timeout=5s --start-period=15s --retries=3 CMD /usr/local/bin/healthcheck.sh
RUN chmod 500 /app && find /app -maxdepth 1 -type f -exec chmod 400 {} \; && find /app -maxdepth 1 -type d -exec chmod 500 {} \;
ENTRYPOINT ["./StellaOps.Service"]

Build stage (per service) should:

• Use mcr.microsoft.com/dotnet/sdk:10.0-bookworm-slim (or mirror) with DOTNET_CLI_TELEMETRY_OPTOUT=1.
• Restore from local-nugets/ (offline) and run dotnet publish -c Release -o /app/out.
• Set SOURCE_DATE_EPOCH to freeze timestamps.

Required checks:

• No root user in final image.
• CAP_NET_RAW dropped (default with non-root).
• Read-only rootfs enforced at deploy time (securityContext.readOnlyRootFilesystem: true in Helm/Compose).
• Health endpoints exposed: /health/liveness, /health/readiness, /version, /metrics.
• Image SBOM generated (syft) in pipeline; attach cosign attestations (see DOCKER-44-002).

SBOM & attestation helper (DOCKER-44-002):

• Script: ops/devops/docker/sbom_attest.sh <image> [out-dir] [cosign-key]
• Emits SPDX (*.spdx.json) and CycloneDX (*.cdx.json) with SOURCE_DATE_EPOCH pinned for reproducibility.
• Attaches both as cosign attestations (--type spdx / --type cyclonedx); supports keyless when COSIGN_EXPERIMENTAL=1 or explicit PEM key.
• Integrate in CI after image build/push; keep registry creds offline-friendly (use local registry mirror during air-gapped builds).

Health endpoint verification (DOCKER-44-003):

• Script: ops/devops/docker/verify_health_endpoints.sh <image> [port] spins container, checks /health/liveness, /health/readiness, /version, /metrics, and warns if /capabilities.merge is not false (for Concelier/Excititor).
• Run in CI after publishing the image; requires docker and curl (or wget).
• Endpoint contract and ASP.NET wiring examples live in ops/devops/docker/health-endpoints.md; service owners should copy the snippet and ensure readiness checks cover DB/cache/bus.