nic-docker-images

name	nic-docker-images
description	Docker image build system, Dockerfile structure, image variants, build scripts, and Makefile targets for NIC. Use when building container images, modifying the Dockerfile, adding new image variants, debugging image builds, or working with build scripts.

NIC Docker Image Build System

Dockerfile Architecture

Single build/Dockerfile (~850 lines), heavily multi-stage. The BUILD_OS arg selects which base image stage is used.

nginx-files (scratch)           <- Collects repo files, signing keys, scripts
  |
OS-specific base stages         <- One per variant (debian, alpine, ubi, *-plus, *-nap)
  |
FROM ${BUILD_OS} AS common      <- Runs common.sh + patch-os.sh, sets permissions
  |
TARGET stages (final image)     <- local, container, goreleaser, debug, download, aws, patched

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Image Variants

3 OS families x 2 NGINX editions x optional NAP = ~20 variants.

OS	OSS	Plus	Plus+WAF	Plus+WAFv5	Plus+DoS	Plus+WAF+DoS	Plus+FIPS	Plus+WAF+FIPS	Plus+WAFv5+FIPS
Debian	yes	yes	yes	yes	yes	yes	-	-	-
Alpine	yes	yes	-	-	-	-	yes	yes	yes
UBI 10	yes	yes	yes	yes	yes	yes	-	-	-

Architecture: amd64 + arm64 for OSS and Plus. NAP variants are amd64 only.

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Makefile Image Targets

All targets call docker build --platform linux/$(ARCH) --target $(TARGET) -f build/Dockerfile.

Target	BUILD_OS	NAP_MODULES
debian-image	debian	-
alpine-image	alpine	-
ubi-image	ubi	-
debian-image-plus	debian-plus	-
alpine-image-plus	alpine-plus	-
alpine-image-plus-fips	alpine-plus-fips	-
alpine-image-nap-plus-fips	alpine-plus-nap-fips	waf
alpine-image-nap-v5-plus-fips	alpine-plus-nap-v5-fips	waf
ubi-image-plus	ubi-10-plus	-
debian-image-nap-plus	debian-plus-nap	waf
debian-image-nap-v5-plus	debian-plus-nap-v5	waf
debian-image-dos-plus	debian-plus-nap	dos
debian-image-nap-dos-plus	debian-plus-nap	waf,dos
ubi-image-nap-plus	ubi-10-plus-nap	waf
ubi-image-nap-v5-plus	ubi-10-plus-nap-v5	waf
ubi-image-dos-plus	ubi-10-plus-nap	dos
ubi-image-nap-dos-plus	ubi-10-plus-nap	waf,dos
all-images	Builds 18 variants	-
push	docker push to PREFIX:TAG	-
patch-os	OS patches existing image	-

Plus images receive $(PLUS_ARGS): --secret id=nginx-repo.crt --secret id=nginx-repo.key.

TARGET Variable

Target	Use Case
local	Default -- binary pre-built on host, copied in
container	Binary built inside Docker (multi-arch capable)
goreleaser	Binary from GoReleaser dist/ (CI builds)
debug	Includes delve debugger
download	Extracts binary from published Docker Hub image
aws	AWS marketplace variant
patched	OS patches an existing image

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Key Build Args

Arg	Purpose	Example
BUILD_OS	Base image stage	debian, alpine-plus, ubi-10-plus-nap
IC_VERSION	Ingress controller version	5.5.0
NGINX_PLUS_VERSION	NGINX Plus version	R36
NAP_MODULES	App Protect modules	waf, dos, waf,dos
PREBUILT_BASE_IMG	Base for prebuilt targets	GCR image ref

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Build Scripts (build/scripts/)

Script	Purpose
common.sh	Sets up directories, copies NGINX templates (v1/v2), sets file permissions (101:0), runs setcap on nginx binaries
agent.sh	Configures nginx-agent ownership; creates NMS compiler symlinks for NAP v4
nap-waf.sh	Creates WAF directories (/etc/nginx/waf/nac-policies, /opt/app_protect/)
nap-dos.sh	Creates DoS directories (/root/app_protect_dos, /shared/cores)
ubi-setup.sh	UBI-specific: installs shadow-utils, creates nginx user/group (101:0)
ubi-clean.sh	UBI-specific: removes build-time packages, cleans dnf cache

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Key Conventions

• All images run as UID 101 (nginx user), with setcap cap_net_bind_service for ports 80/443
• Docker BuildKit always enabled: uses --mount=type=bind, --mount=type=secret, --mount=type=cache
• Plus credentials use --secret mounts, never COPY into layers
• Fixed upstream base images use pinned @sha256: digests for reproducibility; some stages intentionally use build-arg/tag-selected bases (for example BUILD_OS or download/prebuilt images)
• All images include nginx-module-otel (OpenTelemetry) and nginx-agent (usage reporting)
• Plus images add njs and fips-check modules
• Renovate manages base image digests and tool versions via # renovate: comments

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Gotchas

• Never store Plus credentials in image layers -- always use --secret mounts
• Never add arm64 to NAP image matrices -- NAP is amd64 only
• Always use BUILD_OS to select variants, not separate Dockerfiles
• The common stage unifies all variants -- changes there affect every image
• common.sh detects Plus via BUILD_OS containing "plus" and creates OIDC directories
• patch-os.sh handles OS-level security updates at build time
• When adding new image dependencies, update the relevant OS-specific stage AND the common stage if needed