Use dependency proxy

.gitlab-ci.yml

@@ -4,6 +4,8 @@ image: docker:latest
 variables:
   DOCKER_DRIVER: overlay2
   DOCKER_BUILDKIT: 1
+  TEXLIVE_IMAGE_UPSTREAM: texlive/texlive:latest
+  TEXLIVE_IMAGE: ${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/${TEXLIVE_IMAGE_UPSTREAM}
 
 # Docker in Docker Service
 services:
@@ -12,6 +14,7 @@ services:
 
 before_script:
   - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
+  - docker login -u "$CI_DEPENDENCY_PROXY_USER" -p "$CI_DEPENDENCY_PROXY_PASSWORD" $CI_DEPENDENCY_PROXY_SERVER
   - source environment
 
 build-main:
@@ -55,6 +58,7 @@ build:
     - docker build
       --build-arg BUILDKIT_INLINE_CACHE=1
       --build-arg LDAP_PLUGIN_URL="${LDAP_PLUGIN_URL}"
+      --build-arg TEXLIVE_IMAGE="${TEXLIVE_IMAGE}"
       --build-arg login_text="${LOGIN_TEXT}"
       --build-arg collab_text="${COLLAB_TEXT}"
       --pull

Dockerfile

 ARG BASE=docker.io/sharelatex/sharelatex:2.6.1
+ARG TEXLIVE_IMAGE=registry.gitlab.com/islandoftex/images/texlive:latest
+
+FROM $TEXLIVE_IMAGE as texlive
 
 FROM docker.io/nixpkgs/curl as src
 ARG LDAP_PLUGIN_URL=https://codeload.github.com/smhaller/ldap-overleaf-sl/tar.gz/master
@@ -51,5 +54,5 @@ RUN rm /var/www/sharelatex/web/app/views/admin/register.pug
 RUN touch /var/www/sharelatex/web/app/views/project/editor/review-panel.pug
 
 # Update TeXLive
-COPY --from=registry.gitlab.com/islandoftex/images/texlive:latest /usr/local/texlive /usr/local/texlive
+COPY --from=texlive /usr/local/texlive /usr/local/texlive
 RUN tlmgr path add