updated ci/cd, could not get gitlab container registry working so using docker hub instead now

.gitlab-ci.yml

@@ -1,40 +1,38 @@
-.install_docker: &install_docker |
-      apt-get update
-      apt-get -y install apt-transport-https ca-certificates curl software-properties-common
-      curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
-      add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"
-      apt-get update
-      apt-get -y install docker-ce
-      systemctl start docker
+image: docker:20.10.5
 
-# This file is a template, and might need editing before it works on your project.
-docker-build:
-  # Official docker image.
-  image: docker:20.10.5
-  stage: build
-  tags:
-    - docker
-  before_script:
-    - docker info
-    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
-  script:
-    - docker build --pull -t "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG" .
-    - docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG"
-  except:
-    - master
+tags:
+  - docker
 
-docker-build-master:
-  # Official docker image.
-  image: docker:20.10.5
+stages:
+  - build
+  - push
+
+before_script:
+  - echo -n $CI_REGISTRY_TOKEN | docker login -u "$CI_REGISTRY_USER" --password-stdin $CI_REGISTRY
+
+build:
   stage: build
-  tags:
-    - docker
-  before_script:
-    - docker info
-    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
   script:
-    - docker build --pull -t "$CI_REGISTRY_IMAGE" .
-    - docker push "$CI_REGISTRY_IMAGE"
+    - docker pull $CI_REGISTRY_IMAGE:latest || true
+    - docker build --cache-from $CI_REGISTRY_IMAGE:latest --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
+    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
+
+# Tag the "master" branch as "latest"
+push latest:
+  stage: push
+  script:
+    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
+    - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:latest
+    - docker push $CI_REGISTRY_IMAGE:latest
   only:
     - master
 
+# Docker tag any Git tag
+push tag:
+  stage: push
+  only:
+    - tags
+  script:
+    - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
+    - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG