WorkDir: Add feature to dump env vars to text file

Add `CMAKE_DUMP_ENV_FILE` option to dump a subset of the environment
(currently only `PYTHONPATH`) into a file that can be used by IDEs like
VSCode.

.devcontainer/Dockerfile

@@ -8,7 +8,7 @@ USER root
 WORKDIR /root
 
 # Install some additional packages.
-RUN yum -y install which sclo-git25 wget tar atlas-devel libuuid-devel texinfo       \
+RUN yum -y install which sclo-git25 wget tar atlas-devel libuuid-devel texinfo python2-pip \
            redhat-lsb-core libX11-devel libXpm-devel libXft-devel             \
            libXext-devel openssl-devel glibc-devel rpm-build libcurl-devel && \
     yum clean all
@@ -23,6 +23,10 @@ COPY atlas_prompt.sh setup_atlas.sh enable_sclo_git25.sh /etc/profile.d/
 # Add the message of the day instructions for the image.
 COPY motd /etc/
 
+# Install flake8 python linter
+RUN pip install flake8 six
+RUN scl enable sclo-git25 'pip install git+https://:@gitlab.cern.ch:8443/atlas/atlasexternals.git#subdirectory=External/flake8_atlas'
+
 # Switch to the ATLAS account.
 USER atlas
 WORKDIR /home/atlas

.devcontainer/devcontainer.json

@@ -12,11 +12,20 @@
 
     "settings": {
         "terminal.integrated.shell.linux": "/bin/bash",
-        "git.path": "/opt/rh/sclo-git25/root/usr/bin/git"
+        "git.path": "/opt/rh/sclo-git25/root/usr/bin/git",
+        "python.envFile": "/workspaces/build/env.txt",
+        "python.linting.enabled": true,
+        "python.linting.pylintEnabled": false,
+        "python.linting.flake8Enabled": true,
+        "python.linting.flake8Args": [
+            "--select=ATL,F,E7,E9,W6",
+            "--enable-extension=ATL902"
+        ]
     },
 
     "extensions": [
         "ms-vscode.cpptools",
+        "ms-python.python",
         "twxs.cmake"
     ]
 }

Projects/WorkDir/CMakeLists.txt

@@ -74,6 +74,17 @@ lcg_generate_env( SH_FILE ${CMAKE_BINARY_DIR}/${ATLAS_PLATFORM}/env_setup.sh )
 install( FILES ${CMAKE_BINARY_DIR}/${ATLAS_PLATFORM}/env_setup.sh
    DESTINATION . )
 
+# Dump some environment variables for IDE use:
+set( CMAKE_DUMP_ENV_FILE ${CMAKE_BINARY_DIR}/env.txt CACHE FILEPATH
+   "File containing dump of environment variables" )
+
+if( CMAKE_DUMP_ENV_FILE )
+   execute_process(
+      COMMAND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/atlas_build_run.sh printenv
+      COMMAND grep -w ^PYTHONPATH
+      OUTPUT_FILE "${CMAKE_DUMP_ENV_FILE}" )
+endif()
+
 # Set up CPack:
 atlas_cpack_setup()