adding arm32v7 stretch Dockerfile

docker/arm32v7/debian-stretch/Dockerfile

@@ -0,0 +1,46 @@
+FROM alpine AS qemu-builder
+RUN apk add --no-cache wget && \
+    wget https://github.com/multiarch/qemu-user-static/releases/download/v4.1.1-1/x86_64_qemu-arm-static.tar.gz && \
+    tar -xvf x86_64_qemu-arm-static.tar.gz
+
+# separate release builder for faster build on docker hub
+FROM node:12-stretch AS node-builder
+RUN apk add python build-base
+# copying only package{-lock}.json to make node_modules cachable
+COPY package*.json /build/
+WORKDIR /build
+RUN set -x && npm install --unsafe-perm
+# build app
+COPY . /build
+RUN npm run create-release
+
+FROM arm32v7/node:12-stretch-slim AS builder
+COPY --from=qemu-builder /qemu-arm-static /usr/bin
+RUN apk add python build-base
+COPY --from=node-builder /build/release /build/release
+RUN mkdir -p /build/release/data/config && \
+    mkdir -p /build/release/data/db && \
+    mkdir -p /build/release/data/images && \
+    mkdir -p /build/release/data/tmp && \
+    cd /build/release && npm install --unsafe-perm && \
+    npm start -- --config-only --force-rewrite-config \
+    --config-path=data/config/config.json \
+    --Server-Database-sqlite-storage='data/db/sqlite.db' \
+    --Server-Database-memory-usersFile='data/db/users.db' \
+    --Server-Media-folder='data/images' \
+    --Server-Media-tempFolder='data/tmp'  || true
+
+
+FROM arm32v7/node:12-alpine
+COPY --from=qemu-builder /qemu-arm-static /usr/bin
+WORKDIR /app
+ENTRYPOINT ["npm", "start"]
+EXPOSE 80
+ENV NODE_ENV=production
+COPY --from=builder /build/release /app
+RUN ln -s /app/data/config/config.json config.json
+VOLUME ["/app/data/config", "/app/data/db", "/app/data/images", "/app/data/tmp"]
+HEALTHCHECK --interval=30s --timeout=10s --retries=4 --start-period=60s \
+  CMD wget --quiet --tries=1 --no-check-certificate --spider \
+  http://localhost:80 || exit 1
+

docker/arm32v7/debian-stretch/hooks/pre_build

@@ -0,0 +1,4 @@
+#!/bin/bash
+# Register qemu-*-static for all supported processors except the
+# current one, but also remove all registered binfmt_misc before
+docker run --rm --privileged multiarch/qemu-user-static:register --reset