Fetch GnuPG key from keyserver

Dockerfile

@@ -1,7 +1,13 @@
 FROM php:7.2-fpm-alpine
 
+RUN apk add --no-cache \
+    nginx \
+    supervisor
+
 # Install dependencies
-RUN apk add --no-cache --virtual .build-deps \
+RUN set -ex; \
+    \
+    apk add --no-cache --virtual .build-deps \
         bzip2-dev \
         freetype-dev \
         libjpeg-turbo-dev \
@@ -20,11 +26,7 @@ RUN apk add --no-cache --virtual .build-deps \
             | awk 'system("[ -e /usr/local/lib/" $1 " ]") == 0 { next } { print "so:" $1 }' \
     )"; \
     apk add --virtual .phpmyadmin-phpexts-rundeps $runDeps; \
-    apk del .build-deps; \
-    apk add --no-cache nginx supervisor
-
-# Include keyring to verify download
-COPY phpmyadmin.keyring /
+    apk del .build-deps
 
 # Copy configuration
 COPY etc /etc/
@@ -39,23 +41,26 @@ ENV URL https://files.phpmyadmin.net/phpMyAdmin/${VERSION}/phpMyAdmin-${VERSION}
 LABEL version=$VERSION
 
 # Download tarball, verify it using gpg and extract
-RUN set -x \
-    && GNUPGHOME="$(mktemp -d)" \
-    && export GNUPGHOME \
-    && apk add --no-cache curl gnupg \
-    && curl --output phpMyAdmin.tar.gz --location $URL \
-    && curl --output phpMyAdmin.tar.gz.asc --location $URL.asc \
-    && gpgv --keyring /phpmyadmin.keyring phpMyAdmin.tar.gz.asc phpMyAdmin.tar.gz \
-    && apk del --no-cache curl gnupg \
-    && rm -rf "$GNUPGHOME" \
-    && tar xzf phpMyAdmin.tar.gz \
-    && rm -f phpMyAdmin.tar.gz phpMyAdmin.tar.gz.asc \
-    && mv phpMyAdmin-$VERSION-all-languages /www \
-    && rm -rf /www/setup/ /www/examples/ /www/test/ /www/po/ /www/composer.json /www/RELEASE-DATE-$VERSION \
-    && sed -i "s@define('CONFIG_DIR'.*@define('CONFIG_DIR', '/etc/phpmyadmin/');@" /www/libraries/vendor_config.php \
-    && chown -R root:nobody /www \
-    && find /www -type d -exec chmod 750 {} \; \
-    && find /www -type f -exec chmod 640 {} \;
+RUN set -ex; \
+    apk add --no-cache --virtual .fetch-deps \
+        gnupg \
+    ; \
+    \
+    export GNUPGHOME="$(mktemp -d)"; \
+    curl --output phpMyAdmin.tar.gz --location $URL; \
+    curl --output phpMyAdmin.tar.gz.asc --location $URL.asc; \
+    gpg --keyserver ha.pool.sks-keyservers.net --recv-keys 3D06A59ECE730EB71B511C17CE752F178259BD92; \
+    gpg --batch --verify phpMyAdmin.tar.gz.asc phpMyAdmin.tar.gz; \
+    rm -rf "$GNUPGHOME"; \
+    tar xzf phpMyAdmin.tar.gz; \
+    rm -f phpMyAdmin.tar.gz phpMyAdmin.tar.gz.asc; \
+    mv phpMyAdmin-$VERSION-all-languages /www; \
+    rm -rf /www/setup/ /www/examples/ /www/test/ /www/po/ /www/composer.json /www/RELEASE-DATE-$VERSION; \
+    sed -i "s@define('CONFIG_DIR'.*@define('CONFIG_DIR', '/etc/phpmyadmin/');@" /www/libraries/vendor_config.php; \
+    chown -R root:nobody /www; \
+    find /www -type d -exec chmod 750 {} \; ; \
+    find /www -type f -exec chmod 640 {} \; ; \
+    apk del .fetch-deps
 
 # Add directory for sessions to allow session persistence
 RUN mkdir /sessions