docker: add base docker image and its ci

.gitlab-ci.yml

@@ -18,11 +18,28 @@ variables:
 ### By default, there are 6 stages that we may use:
 ### Feel free to adapt this to your specific case.
 stages:
+  - build_base
   - build
   - tag_image
   - import_image # This stage is only used when the built image is stored in the GitLab Registry
   - deploy
 
+### 'Build Base' stage
+### Builds the base docker image and tags it according to the commit message.
+build_base_image:
+  stage: build_base
+  only:
+    changes:
+      - Dockerfile-base
+      - Pipfile
+      - Pipfile.lock
+  tags:
+    - docker-image-build
+  script: 'echo "Building base Docker image..."'
+  variables:
+    DOCKER_FILE: Dockerfile-base
+    TO: gitlab-registry.cern.ch/webservices/cern-search/cern-search-rest-api/cern-search-rest-api-base:${CI_COMMIT_SHA}
+
 ### 'Build' stage
 ### Build the image and store it in the registry. It is important that this step
 ### doesn't override the image the applications are running, as we haven't tested the image yet

Dockerfile-base

+# -*- coding: utf-8 -*-
+
+# Use CentOS7:
+FROM inveniosoftware/centos7-python:3.6
+
+# Install pre-requisites
+RUN yum update -y && \
+    yum install -y \
+        gcc \
+        openssl \
+        openldap-devel \
+        https://linuxsoft.cern.ch/cern/centos/7/cern/x86_64/Packages/CERN-CA-certs-20180516-1.el7.cern.noarch.rpm
+
+# CERN Search installation
+WORKDIR /${WORKING_DIR}/src
+ADD ./Pipfile /${WORKING_DIR}/src/Pipfile
+ADD ./Pipfile.lock /${WORKING_DIR}/src/Pipfile.lock
+
+# Install dependencies globally
+RUN pipenv install --system --deploy