Nic Docker Images

DevOps & Security

nic-docker-images

Nic Docker Images is an Agent Skill for devops & security published in the nginx/kubernetes-ingress repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

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.

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Inspect the Agent Skill at https://github.com/nginx/kubernetes-ingress/blob/HEAD/.github/skills/nic-docker-images/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/nic-docker-images, but wait for my approval before writing files or running scripts.

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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

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.

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

Key Build Args

Arg	Purpose	Source of truth
`BUILD_OS`	Base image stage	`Makefile` targets + Dockerfile stages
`IC_VERSION`	Ingress controller version	`.github/data/version.txt`
`NGINX_PLUS_VERSION`	NGINX Plus version	`build/Dockerfile`
`NGINX_OSS_VERSION`	NGINX OSS version	`build/Dockerfile`
`NAP_MODULES`	App Protect modules	Any of `waf`, `dos`, or `waf,dos`
`PREBUILT_BASE_IMG`	Base for prebuilt targets	GCR image ref (set by CI)

Do not hard-code IC_VERSION or NGINX_VERSION values in this file or in other docs as they change every release. Always reference .github/data/version.txt or the Renovate-managed Dockerfile pin.

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

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

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