alpine: prepare docker in Dockerfile

Author: jpnurmi

.github/alpine/Dockerfile

@@ -5,7 +5,7 @@ FROM ${BASE}
 RUN apk update
 
 # common
-RUN apk add bash build-base cmake curl git icu lsb-release-minimal sudo tar wget
+RUN apk add bash build-base cmake curl docker-cli git icu lsb-release-minimal shadow sudo tar wget
 
 # sentry-native
 RUN apk add curl-dev libunwind-dev libunwind-static linux-headers openssl-dev zlib-dev xz-dev
@@ -27,9 +27,12 @@ RUN if ! apk add mono; then \
   fi
 RUN mono --version
 
+# docker
+RUN addgroup -S docker
+
 # runner
 RUN addgroup runner
-RUN adduser -S -u 1001 -h /home/runner -G runner runner
+RUN adduser -S -u 1001 -h /home/runner -G runner,docker runner
 RUN mkdir -p /home/runner /__e /__w /__w/_temp /__w/_actions /__w/_tool
 RUN chown -R runner:runner /home/runner /__e /__w
 RUN ln -s /__w /home/runner/work