ci: nix job

.gitlab-ci.yml

-#image: oarteam/batsim_ci:latest
-
 variables:
   GIT_SUBMODULE_STRATEGY: none
 
 stages:
   - unique_stage
 
-###############################################################################
-# Build and test
-###############################################################################
 debian:
   stage: unique_stage
   image: debian:unstable-slim
-  #      we could cache dependencies installation in our own Dockerfile
+  #      dependencies installation could be cached in a container we maintain somewhere (e.g., dockerhub)
   script:
     # Get various dependencies
     - apt update -y
     - apt install -y g++ libsimgrid-dev libzmq3-dev libprotobuf-dev protobuf-compiler libgtest-dev meson ninja-build pkg-config python3 python3-pip
+
     # Build protocol (c++)
     - (cd protocol && meson setup build --prefix=/usr && ninja -C build && meson install -C build)
 
@@ -37,3 +33,17 @@ debian:
     - test/simulator-cpp-client.sh
     # Run integration tests (simgrid simulator VS python client)
     - test/simulator-py-client.sh
+
+nix:
+  stage: unique_stage
+  image: oarteam/batsim_ci:latest
+  #      this is just a NixOS with the needed tools to be run by a GitLab CI runner
+  #      defined there: https://framagit.org/batsim/batsim/-/blob/90bbff66007469255d2c082511b72f1e1efca3b8/env/docker/default.nix
+  script:
+    # Packages can be built explicitly if desired
+    - nix-build . -A protocol-cpp
+    # Any dependency will also be built, for example the following command also builds protocol-python
+    - nix-build . -A client-py
+    # Therefore one can just run its desired leaf of the build tree, such as:
+    - nix-shell . -A integration_shell_cpp --command './test/simulator-cpp-client.sh'
+    - nix-shell . -A integration_shell_py --command './test/simulator-py-client.sh'