Make use of environments for CI deployment

Refactored deployment script to allow flexible deployments for different
hosts and environments.

.gitlab-ci.yml

@@ -65,20 +65,50 @@ package:
   script:
     - mvn package -DskipTests
 
-tomcat_production:
+.deploy: &deploy
   stage: deploy
-  only:
-    - production
   tags:
-    - curl
+    - python
+  when: manual
+  variables:
+    DEPLOY_CONTEXT: api
+    GIT_STRATEGY: none
   script:
-    - curl --fail --upload-file $WAR_FILE "https://$PROD_TOMCAT_USER:$PROD_TOMCAT_PASSWORD@$PROD_TOMCAT_HOST/manager/text/deploy?path=%2Fapi&update=true"
+    # Do some variable magic to access host-specific variables
+    - PREFIX=$(echo $CI_ENVIRONMENT_NAME | tr '.:/-' '_')
+    - HOST_VAR=${PREFIX}__HOST TOMCAT_PASSWORD_VAR=${PREFIX}__TOMCAT_PASSWORD TOMCAT_USER_VAR=${PREFIX}__TOMCAT_USER
+    - "[ -z \"${!HOST_VAR}\" ] && echo \"No configuration for $DEPLOY_HOST found.\" && exit 1"
+    # Abort if there are too many users online
+    - USER_COUNT=$(curl -fsSL ${CI_ENVIRONMENT_URL}statistics | python -c "import sys, json; data=json.loads(sys.stdin.read()); print(data['activeUsers']);")
+    - "[ \"$USER_COUNT\" -ge 10 ] && [ -z \"$FORCE\" ] && echo \"Too many users ($USER_COUNT) online.\" && exit 1"
+    # Deploy .war file to Tomcat
+    - curl -fsS --upload-file $WAR_FILE "https://${!TOMCAT_USER_VAR}:${!TOMCAT_PASSWORD_VAR}@${!HOST_VAR}/manager/text/deploy?path=%2F${DEPLOY_CONTEXT}&update=true"
+
+tomcat_production:
+  <<: *deploy
+  environment:
+    name: production/$PROD_DEPLOY_HOST
+    url: https://$PROD_DEPLOY_HOST/$DEPLOY_CONTEXT/
+  only:
+    variables:
+      - $PROD_DEPLOY_HOST
+      # GitLab 11.0+
+      #- $PROD_DEPLOY_HOST =~ /^([a-z0-9-]+\.)*[a-z0-9-]+(:[0-9]+)?$/
+    refs:
+      - /^v[0-9]+/
+      - /^[0-9]+\.[0-9]+$/
+  before_script:
+    - DEPLOY_HOST=$PROD_DEPLOY_HOST
 
 tomcat_development:
-  stage: deploy
+  <<: *deploy
+  environment:
+    name: development/$DEV_DEPLOY_HOST
+    url: https://$DEV_DEPLOY_HOST/api/
   only:
-    - staging
-  tags:
-    - curl
-  script:
-    - curl --fail --upload-file $WAR_FILE "https://$DEV_TOMCAT_USER:$DEV_TOMCAT_PASSWORD@$DEV_TOMCAT_HOST/manager/text/deploy?path=%2Fapi&update=true"
+    variables:
+      - $DEV_DEPLOY_HOST
+      # GitLab 11.0+
+      #- $DEV_DEPLOY_HOST =~ /^([a-z0-9-]+\.)*[a-z0-9-]+(:[0-9]+)?$/
+  before_script:
+    - DEPLOY_HOST=$DEV_DEPLOY_HOST