fix: much smaller docker image

Dockerfile

@@ -1,33 +1,40 @@
-FROM node:18-slim
+# --- base stage --- #
 
-LABEL com.github.actions.name="Conventional Semantic Release" \
-      com.github.actions.description="Semantic Release with all the presets" \
-      com.github.actions.icon="package" \
-      com.github.actions.color="red" \
-      maintainer="Ahmad Nassri <ahmad@ahmadnassri.com>"
+FROM alpine:3.16 AS base
+
+# hadolint ignore=DL3018
+RUN apk add --no-cache --update nodejs npm git openssh ca-certificates ruby-bundler
+
+RUN git config --global --add safe.directory /github/workspace
 
-# set working dir
-RUN mkdir /action
 WORKDIR /action
 
+ENTRYPOINT [ "node" ]
+
+# --- build stage --- #
+
+FROM base AS build
+
 # slience npm
+# hadolint ignore=DL3059
 RUN npm config set update-notifier=false audit=false fund=false
 
-RUN apt-get update \
-  && apt-get install -y --no-install-recommends git openssh-client ca-certificates ruby-full \
-  && apt-get purge -y --auto-remove \
-  && rm -rf /var/lib/apt/lists/* \
-  && gem install bundler
+# keyscan github.com
+RUN mkdir -p ~/.ssh && ssh-keyscan github.com >> /root/.ssh/known_hosts
 
 # install packages
 COPY action/package* ./
 RUN npm ci --omit=dev --no-fund --no-audit
 
-# keyscan github.com
-RUN mkdir -p ~/.ssh && ssh-keyscan github.com >> ~/.ssh/known_hosts
+# --- app stage --- #
+
+FROM base AS app
+
+# copy from build image
+COPY --from=build /root/.ssh/known_hosts /root/.ssh/known_hosts
+COPY --from=build /action/node_modules ./node_modules
 
 # copy files
 COPY action ./
 
-# set entry point
-ENTRYPOINT ["node", "--no-warnings=ExperimentalWarnings", "/action/index.js"]
+CMD ["--no-warnings=ExperimentalWarnings", "/action/index.js"]

action/package.json

@@ -24,7 +24,7 @@
     "release"
   ],
   "engines": {
-    "node": ">=18"
+    "node": ">=16"
   },
   "main": "index.js",
   "type": "module",