Update alpine to 3.13

docs/examples/customization/sysctl/patch.json

@@ -4,7 +4,7 @@
 			"spec": {
 				"initContainers": [{
 					"name": "sysctl",
-					"image": "alpine:3.10",
+					"image": "alpine:3.13",
 					"securityContext": {
 						"privileged": true
 					},

images/cfssl/rootfs/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.12
+FROM alpine:3.13
 
 RUN echo "@testing http://nl.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories
 RUN apk add --no-cache \

images/httpbin/rootfs/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM alpine:3.12
+FROM alpine:3.13
 
 ENV LC_ALL=C.UTF-8
 ENV LANG=C.UTF-8

images/nginx/rootfs/Dockerfile

@@ -13,15 +13,17 @@
 # limitations under the License.
 
 
-FROM alpine:3.12 as builder
+FROM alpine:3.13 as builder
 
 COPY . /
 
-RUN apk add -U bash \
+RUN apk update \
+  && apk upgrade \
+  && apk add -U bash \
   && /build.sh
 
 # Use a multi-stage build
-FROM alpine:3.12
+FROM alpine:3.13
 
 ENV PATH=$PATH:/usr/local/luajit/bin:/usr/local/nginx/sbin:/usr/local/nginx/bin
 

images/nginx/rootfs/build.sh

@@ -75,9 +75,6 @@ get_src()
   rm -rf "$f"
 }
 
-apk update
-apk upgrade
-
 # install required packages to build
 apk add \
   bash \