feat(alpine): Change parent image to be alpine based as well (#444)

It replaces centos/httpd with alpine/httpd allowing to be smaller/updated and also multi-arch

Change-Id: I7a3050fcfdea30fe08e4127cf581713a9cc91b85
Signed-off-by: Florent Benoit <fbenoit@redhat.com>

build/dockerfiles/Dockerfile

@@ -11,7 +11,7 @@
 #
 
 # Builder: check meta.yamls and create index.json
-FROM alpine:3.10 AS builder
+FROM docker.io/alpine:3.11.5 AS builder
 RUN apk add --no-cache py-pip jq bash wget skopeo && pip install yq jsonschema
 
 ARG LATEST_ONLY=false
@@ -34,17 +34,20 @@ RUN ./list_referenced_images.sh v3 > /build/v3/external_images.txt
 RUN chmod -R g+rwX /build
 
 # Build registry, copying meta.yamls and index.json from builder
-FROM registry.centos.org/centos/httpd-24-centos7 AS registry
-COPY README.md .htaccess /var/www/html/
-COPY --from=builder /build/v3 /var/www/html/v3
+FROM docker.io/httpd:2.4.43-alpine AS registry
+# Allow htaccess
+RUN sed -i 's|    AllowOverride None|    AllowOverride All|' /usr/local/apache2/conf/httpd.conf && \
+    mkdir -p /var/www && ln -s /usr/local/apache2/htdocs /var/www/html
+COPY README.md .htaccess /usr/local/apache2/htdocs/
+COPY --from=builder /build/v3 /usr/local/apache2/htdocs/v3
 COPY ./build/dockerfiles/entrypoint.sh /usr/bin/
 ENTRYPOINT ["/usr/bin/entrypoint.sh"]
-CMD ["/usr/bin/run-httpd"]
+CMD ["httpd-foreground"]
 
 # Offline build: cache .theia and .vsix files in registry itself and update metas
 FROM builder AS offline-builder
 RUN ./cache_artifacts.sh v3 && chmod -R g+rwX /build
 
 # Offline registry: copy updated meta.yamls and cached extensions
 FROM registry AS offline-registry
-COPY --from=offline-builder /build/v3 /var/www/html/v3
+COPY --from=offline-builder /build/v3 /usr/local/apache2/htdocs/v3