change gpg verify

Author: myf5

Dockerfile

@@ -132,8 +132,18 @@ RUN \
 	&& curl -fSL http://nginx.org/download/nginx-$NGINX_VERSION.tar.gz -o nginx.tar.gz \
 	&& curl -fSL http://nginx.org/download/nginx-$NGINX_VERSION.tar.gz.asc  -o nginx.tar.gz.asc \
 	&& export GNUPGHOME="$(mktemp -d)" \
-	&& gpg --keyserver ha.pool.sks-keyservers.net --recv-keys "$GPG_KEYS" \
-	&& gpg --batch --verify nginx.tar.gz.asc nginx.tar.gz \
+    && found=''; \
+    for server in \
+        ha.pool.sks-keyservers.net \
+        hkp://keyserver.ubuntu.com:80 \
+        hkp://p80.pool.sks-keyservers.net:80 \
+        pgp.mit.edu \
+    ; do \
+        echo "Fetching GPG key $GPG_KEYS from $server"; \
+        gpg --keyserver "$server" --keyserver-options timeout=10 --recv-keys "$GPG_KEYS" && found=yes && break; \
+    done; \
+    test -z "$found" && echo >&2 "error: failed to fetch GPG key $GPG_KEYS" && exit 1; \
+    gpg --batch --verify nginx.tar.gz.asc nginx.tar.gz \
 	&& rm -r "$GNUPGHOME" nginx.tar.gz.asc \
 	&& tar -zxC /usr/src -f nginx.tar.gz \
 	&& rm nginx.tar.gz \