diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d5bfa842..8348f361 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,13 +1,9 @@
-image: debian:latest
+image: registry.hub.docker.com/bitnami/minideb:bullseye
 
 before_script:
-- apt-get update
-- apt-get install -y ca-certificates && apt-get clean
-- apt-get install -y pip && apt-get clean
   # following ones get updated, so they are not installed from Debian package repo: python3-sphinx python3-pybtex-docutils
   #- apt-get install -y python3-sphinx && apt-get clean
-- apt-get install -y jupyter-notebook && apt-get clean
-- apt-get install -y python3-anyio python3-greenlet python3-click python3-jupyter-server python3-sqlalchemy python3-latexcodec python3-nbclient python3-nest-asyncio python3-pybtex python3-smmap python3-soupsieve python3-toml && apt-get clean && rm -r /var/lib/apt /usr/share/doc /usr/share/man
+  - install_packages pip jupyter-notebook python3-anyio python3-greenlet python3-click python3-jupyter-server python3-sqlalchemy python3-latexcodec python3-nbclient python3-nest-asyncio python3-smmap python3-soupsieve python3-toml python3-pybtex
 - pip install jupyter-book && rm -r /root/.cache/pip
 
 pages:
diff --git a/Dockerfile b/Dockerfile
index 64bbfd1b..8f947899 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,9 @@
-FROM debian:latest
+FROM registry.hub.docker.com/bitnami/minideb:bullseye
 
-RUN apt-get update
+#RUN apt-get update
 # following ones get updated, so they are not installed from Debian package repo: python3-sphinx python3-pybtex-docutils
-RUN apt-get install -y pip jupyter-notebook python3-anyio python3-greenlet python3-click python3-jupyter-server python3-sqlalchemy python3-latexcodec python3-nbclient python3-nest-asyncio python3-smmap python3-soupsieve python3-toml python3-pybtex && apt-get clean && rm -r /var/lib/apt /usr/share/doc /usr/share/man
+RUN install_packages pip jupyter-notebook python3-anyio python3-greenlet python3-click python3-jupyter-server python3-sqlalchemy python3-latexcodec python3-nbclient python3-nest-asyncio python3-smmap python3-soupsieve python3-toml python3-pybtex
+#RUN apt-get install -y pip jupyter-notebook python3-anyio python3-greenlet python3-click python3-jupyter-server python3-sqlalchemy python3-latexcodec python3-nbclient python3-nest-asyncio python3-smmap python3-soupsieve python3-toml python3-pybtex && apt-get clean && rm -r /var/lib/apt /usr/share/doc /usr/share/man
 RUN pip install jupyter-book && rm -r /root/.cache/pip
 
 RUN mkdir -p /root/documentation