use build ARG for PHP base image version

.gitlab-ci.yml

@@ -13,6 +13,7 @@ variables:
   PHP_IMAGE_NAME: dmstr/php-yii2
 
 before_script:
+  - export PHP_BASE_IMAGE_VERSION=7.2.0RC1
   - export PHP_IMAGE_VERSION=$(git describe --always --dirty)
   - export STACK_PHP_IMAGE=${PHP_IMAGE_NAME}:${PHP_IMAGE_VERSION}
   - export REGISTRY_PHP_IMAGE=${PHP_IMAGE_NAME}:${CI_BUILD_REF_NAME}

docker-compose.yml

@@ -5,6 +5,8 @@ services:
     build:
       dockerfile: Dockerfile-fpm
       context: 'php'
+      args:
+        - PHP_BASE_IMAGE_VERSION=${PHP_BASE_IMAGE_VERSION}
     image: ${PHP_IMAGE_NAME}:${PHP_IMAGE_VERSION}
     environment:
       - GITHUB_API_TOKEN=${GITHUB_API_TOKEN}
@@ -25,6 +27,8 @@ services:
     build:
       dockerfile: Dockerfile-fpm-alpine
       context: 'php'
+      args:
+        - PHP_BASE_IMAGE_VERSION=${PHP_BASE_IMAGE_VERSION}
     image: ${PHP_IMAGE_NAME}:${PHP_IMAGE_VERSION}-alpine
     volumes:
       - ./test:/test

php/Dockerfile-fpm

 # PHP Docker image for Yii 2.0 Framework runtime
 # ==============================================
 
-FROM php:7.2.0beta3-fpm
+ARG PHP_BASE_IMAGE_VERSION
+FROM php:${PHP_BASE_IMAGE_VERSION}-fpm
 
 # Install system packages for PHP extensions recommended for Yii 2.0 Framework
 ENV DEBIAN_FRONTEND=noninteractive

php/Dockerfile-fpm-alpine

 # PHP Docker image for Yii 2.0 Framework runtime
 # ==============================================
 
-FROM php:7.2.0beta3-fpm-alpine
+ARG PHP_BASE_IMAGE_VERSION
+FROM php:${PHP_BASE_IMAGE_VERSION}-fpm-alpine
 
 # Install system packages & PHP extensions required for Yii 2.0 Framework
 RUN apk --update --virtual build-deps add \