Try using pecl to build the extensions

.gitlab-ci.yml

@@ -12,8 +12,7 @@ services:
 test:7:
     before_script:
       - sh build/docker_install.sh > /dev/null
-      - apk add --no-cache php7-apcu php7-memcached php7-phpdbg
-      - docker-php-ext-enable apcu memcached
+      - apk add --no-cache php7-phpdbg
       - curl -sS https://getcomposer.org/installer | php
       - php composer.phar install --ignore-platform-reqs
     image: php:7-alpine
@@ -23,8 +22,7 @@ test:7:
 test:7.1:
     before_script:
       - sh build/docker_install.sh > /dev/null
-      - apk add --no-cache php7.1-apcu php7.1-memcached php7.1-phpdbg
-      - docker-php-ext-enable apcu memcached
+      - apk add --no-cache php7.1-phpdbg
       - curl -sS https://getcomposer.org/installer | php
       - php composer.phar install --ignore-platform-reqs
     image: php:7.1-alpine

build/docker_install.sh

@@ -12,4 +12,10 @@ apk upgrade --update && apk add --no-cache \
 	make \
 	automake \
 	curl \
-	git
+	git \
+	libmemcached
+	
+docker-php-source extract
+pecl install apcu memcached
+docker-php-ext-enable apcu memcached
+docker-php-source delete