Fix/ci kontin no internet vaatimus (#34)

Co-authored-by: moilanik <niko.moilanen@tietoevry.com>
Reviewed-on: #34

skills/consumer-pipelines/REFERENCE.md

@@ -2,6 +2,93 @@
 
 Mallipohjat, esimerkit ja konfiguraatiot. Katso säännöt `SKILL.md`:stä.
 
+## Pre-cache-esimerkit (Offline Container)
+
+Alla Dockerfile-esimerkit kielikohtaisista pre-cacheista. Kaikki ajetaan
+build-vaiheessa — kontti on täysin itseriittoinen eikä lataa mitään
+pipeline- tai runtime-vaiheessa.
+
+### Go
+
+```dockerfile
+FROM golang:1.24-alpine AS deps
+WORKDIR /build
+COPY go.mod go.sum ./
+RUN go mod download
+
+FROM deps AS test-build
+COPY . .
+RUN go test -c -o /tmp/test.bin ./...
+
+FROM alpine:3.21
+RUN apk add --no-cache git nodejs
+COPY --from=deps /go/pkg/mod /go/pkg/mod
+COPY --from=test-build /tmp/test.bin /usr/local/bin/test
+```
+
+### Node.js
+
+```dockerfile
+FROM node:22-alpine AS deps
+WORKDIR /build
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev
+
+FROM node:22-alpine
+RUN apk add --no-cache git
+COPY --from=deps /build/node_modules /app/node_modules
+COPY . /app
+WORKDIR /app
+```
+
+### Java / Maven
+
+```dockerfile
+FROM maven:3.9-eclipse-temurin-21 AS deps
+WORKDIR /build
+COPY pom.xml ./
+RUN mvn dependency:go-offline -B
+
+FROM maven:3.9-eclipse-temurin-21 AS build
+COPY --from=deps /root/.m2 /root/.m2
+COPY . .
+RUN mvn package -B -DskipTests
+
+FROM eclipse-temurin:21-jre
+RUN apt-get update && apt-get install -y --no-install-recommends git && rm -rf /var/lib/apt/lists/*
+COPY --from=build /build/target/*.jar /app/app.jar
+WORKDIR /app
+```
+
+### Python
+
+```dockerfile
+FROM python:3.12-alpine AS deps
+WORKDIR /build
+COPY requirements.txt ./
+RUN pip wheel --wheel-dir=/wheels -r requirements.txt
+
+FROM python:3.12-alpine
+RUN apk add --no-cache git
+COPY --from=deps /build/wheels /wheels
+COPY --from=deps /build/requirements.txt /
+RUN pip install --no-index --find-links=/wheels -r /requirements.txt && rm -rf /wheels
+COPY . /app
+WORKDIR /app
+```
+
+### Helm + Node.js (korvaa helm-build-push.yml:n runtime-apk)
+
+```dockerfile
+FROM alpine/helm:3.16.0 AS helm-bin
+FROM node:22-alpine
+RUN apk add --no-cache git
+COPY --from=helm-bin /usr/bin/helm /usr/local/bin/helm
+```
+
+Tämä kontti korvaa `helm-build-push.yml`:n `alpine/helm:3.19.0`-image-riippuvuuden
+ja poistaa tarpeen asentaa node.js runtime-vaiheessa.
+
 ## Reititin — täydellinen esimerkki
 
 ```yaml