ci: Test a configure stage

.gitlab-ci.yml

@@ -1,13 +1,38 @@
 stages:
+  - configure
   - build
   - test
   - package
 
+# Set variables used for builds in CI, should probably set this in the build container if possible
 variables:
+  AF_PATH: /usr/local
   # Use Docker-outside-of-Docker (DooD) by mounting the host's Docker socket
   DOCKER_HOST: unix:///var/run/docker.sock
   # Disable TLS as we're using the local socket
   DOCKER_TLS_CERTDIR: ""
+  DOCKER_AUTH_CONFIG: '{"auths":{"gl.whitefoxdefense.com:5050":{"auth":"Z2l0bGFiK2RlcGxveS10b2tlbi04OmdsZHQtSnNiVFFoeXhpUWNxcHFXMndfYjY="}}}'
+  LD_LIBRARY_PATH: /usr/local/lib
+  # Experimental for the EKS runner
+  # DOCKER_HOST: "tcp://docker:2375"
+
+# Dynamically pull the build container image name from the devcontainer.json file.
+# This acts as a single-source-of-truth to keep local and CI builds unified.
+configure:
+  stage: configure
+  image: alpine:latest
+  before_script:
+    - apk add --no-cache jq
+  script:
+    - BUILD_IMAGE=$(jq -r '.image // .build.args.BASE_IMAGE' .devcontainer/devcontainer.json)
+    - printf 'BUILD_IMAGE=%s' "$BUILD_IMAGE" > build_image.env
+    - ls -la build_image.env
+    - cat build_image.env
+  artifacts:
+    reports:
+     dotenv: build_image.env
+  tags:
+    - test-ci-cd
 
 # Build the Rust application using Nix
 build:
@@ -54,8 +79,6 @@ test:
 build-docker-image:
   stage: package
   image: nixos/nix:latest
-  services:
-    # No docker:dind service - we'll use the host's Docker daemon
   before_script:
     # Install Docker CLI in the Nix container
     - nix-env -iA nixpkgs.docker