Images: Bump Alpine to v3.21. (#12528)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Marco Ebert <marco_ebert@icloud.com>

images/cfssl/rootfs/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.20
+FROM alpine:3.21
 
 RUN echo "@testing https://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories
 RUN apk update \

images/custom-error-pages/rootfs/Dockerfile

@@ -14,7 +14,7 @@
 
 ARG GOLANG_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.20 as builder
+FROM golang:${GOLANG_VERSION}-alpine3.21 as builder
 
 RUN apk update \
     && apk upgrade && apk add git

images/ext-auth-example-authsvc/rootfs/Dockerfile

@@ -1,6 +1,6 @@
 ARG GOLANG_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.20 as builder
+FROM golang:${GOLANG_VERSION}-alpine3.21 as builder
 RUN mkdir /authsvc
 WORKDIR /authsvc
 COPY . ./

images/fastcgi-helloserver/rootfs/Dockerfile

@@ -13,7 +13,7 @@
 # limitations under the License.
 ARG GOLANG_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.20 as builder
+FROM golang:${GOLANG_VERSION}-alpine3.21 as builder
 
 WORKDIR /go/src/k8s.io/ingress-nginx/images/fastcgi
 

images/go-grpc-greeter-server/rootfs/Dockerfile

@@ -1,6 +1,6 @@
 ARG GOLANG_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.20 as build
+FROM golang:${GOLANG_VERSION}-alpine3.21 as build
 
 WORKDIR /go/src/greeter-server
 

images/nginx/rootfs/Dockerfile

@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-FROM alpine:3.20 as builder
+FROM alpine:3.21 as builder
 
 COPY . /
 
@@ -21,7 +21,7 @@ RUN apk update \
   && /build.sh
 
 # Use a multi-stage build
-FROM alpine:3.20
+FROM alpine:3.21
 
 ENV PATH=$PATH:/usr/local/luajit/bin:/usr/local/nginx/sbin:/usr/local/nginx/bin
 
@@ -66,7 +66,7 @@ RUN apk update \
   ); \
   for dir in "${writeDirs[@]}"; do \
   mkdir -p ${dir}; \
-  chown -R www-data.www-data ${dir}; \
+  chown -R www-data:www-data ${dir}; \
   done'
 
 EXPOSE 80 443

images/nginx/rootfs/build.sh

@@ -414,6 +414,21 @@ Include /etc/nginx/owasp-modsecurity-crs/rules/RESPONSE-980-CORRELATION.conf
 Include /etc/nginx/owasp-modsecurity-crs/rules/RESPONSE-999-EXCLUSION-RULES-AFTER-CRS.conf
 " > /etc/nginx/owasp-modsecurity-crs/nginx-modsecurity.conf
 
+# NGINX compiles a small test program to check if an added module works as expected.
+#
+# ModSecurity-nginx provides 'printf("hello");' as a test, but newer versions of GCC,
+# as included in Alpine 3.21, do not allow implicit declaration of function 'printf':
+#
+#   objs/autotest.c:7:5: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
+#
+# For this reason we replace 'printf("hello");' by 'msc_init();', which is always available.
+#
+# This fix is taken from a PR, that has been proposed to the ModSecurity-nginx project:
+#
+#   https://github.com/owasp-modsecurity/ModSecurity-nginx/pull/275
+#
+sed -i "s/ngx_feature_test='printf(\"hello\");'/ngx_feature_test='msc_init();'/" $BUILD_PATH/ModSecurity-nginx/config
+
 # build nginx
 cd "$BUILD_PATH/nginx-$NGINX_VERSION"
 
@@ -609,7 +624,7 @@ adduser -S -D -H -u 101 -h /usr/local/nginx -s /sbin/nologin -G www-data -g www-
 
 for dir in "${writeDirs[@]}"; do
   mkdir -p ${dir};
-  chown -R www-data.www-data ${dir};
+  chown -R www-data:www-data ${dir};
 done
 
 rm -rf /etc/nginx/owasp-modsecurity-crs/.git

images/test-runner/rootfs/Dockerfile

@@ -15,7 +15,7 @@ ARG BASE_IMAGE
 ARG GOLANG_VERSION
 ARG ETCD_VERSION
 
-FROM golang:${GOLANG_VERSION}-alpine3.20 as GO
+FROM golang:${GOLANG_VERSION}-alpine3.21 as GO
 FROM registry.k8s.io/etcd:${ETCD_VERSION} as etcd
 
 FROM ${BASE_IMAGE}