CI: set SOURCE_DATE_EPOCH

Set SOURCE_DATE_EPOCH to the time
of the latest commit to get more
reproducible builds. GCC 7, Docker 24,
and various other build tools
supports this.

https://reproducible-builds.org/docs/source-date-epoch/

.github/workflows/build.yml

@@ -51,6 +51,7 @@ jobs:
       run: |
         tools/docker/print-dockerhash.sh >> $GITHUB_ENV
         echo COOJA_COMMIT=$(git -C tools/cooja log -1 --oneline | cut -d" " -f1) >> $GITHUB_ENV
+        echo SOURCE_DATE_EPOCH=$(git log -1 --pretty=%ct) >> $GITHUB_ENV
 
     # Try to download the image from dockerhub. If it works, use it.
     #
@@ -149,6 +150,6 @@ jobs:
         # Run test
         # FIXME: (2023) Remove "ccache -c", workaround for cache growing
         #        too large from ccache CI/ccache configuration mismatch.
-        docker run --privileged --sysctl net.ipv6.conf.all.disable_ipv6=0 -e GITHUB_JOB -e GITHUB_REF -e GITHUB_SHA -e GITHUB_REPOSITORY -e GITHUB_REPOSITORY_OWNER -e GITHUB_RUN_ID -e GITHUB_RUN_NUMBER -e GITHUB_RETENTION_DAYS -e GITHUB_ACTOR -e GITHUB_WORKFLOW -e GITHUB_HEAD_REF -e GITHUB_BASE_REF -e GITHUB_EVENT_NAME -e GITHUB_SERVER_URL -e GITHUB_API_URL -e GITHUB_GRAPHQL_URL -e GITHUB_WORKSPACE -e GITHUB_ACTION -e GITHUB_EVENT_PATH -e GITHUB_ACTION_REPOSITORY -e GITHUB_ACTION_REF -e GITHUB_PATH -e GITHUB_ENV -e RUNNER_OS -e RUNNER_TOOL_CACHE -e RUNNER_TEMP -e RUNNER_WORKSPACE -e ACTIONS_RUNTIME_URL -e ACTIONS_RUNTIME_TOKEN -e ACTIONS_CACHE_URL -e GITHUB_ACTIONS=true -e CI=true -e GRADLE_USER_HOME=/home/user/contiki-ng/tools/cooja/.gradle_home -e LOCAL_UID=$(id -u $USER) -e LOCAL_GID=$(id -g $USER) $DOCKER_ARGS -v `pwd`:/home/user/contiki-ng -v $GITHUB_WORKSPACE/.ccache:/home/user/.ccache $DOCKER_IMG bash --login -c "source ../.bash_aliases && ccache --set-config=max_size='160M' && cimake -C tests/??-${{ matrix.test }}; ccache -c"
+        docker run --privileged --sysctl net.ipv6.conf.all.disable_ipv6=0 -e GITHUB_JOB -e GITHUB_REF -e GITHUB_SHA -e GITHUB_REPOSITORY -e GITHUB_REPOSITORY_OWNER -e GITHUB_RUN_ID -e GITHUB_RUN_NUMBER -e GITHUB_RETENTION_DAYS -e GITHUB_ACTOR -e GITHUB_WORKFLOW -e GITHUB_HEAD_REF -e GITHUB_BASE_REF -e GITHUB_EVENT_NAME -e GITHUB_SERVER_URL -e GITHUB_API_URL -e GITHUB_GRAPHQL_URL -e GITHUB_WORKSPACE -e GITHUB_ACTION -e GITHUB_EVENT_PATH -e GITHUB_ACTION_REPOSITORY -e GITHUB_ACTION_REF -e GITHUB_PATH -e GITHUB_ENV -e RUNNER_OS -e RUNNER_TOOL_CACHE -e RUNNER_TEMP -e RUNNER_WORKSPACE -e ACTIONS_RUNTIME_URL -e ACTIONS_RUNTIME_TOKEN -e ACTIONS_CACHE_URL -e GITHUB_ACTIONS=true -e CI=true -e GRADLE_USER_HOME=/home/user/contiki-ng/tools/cooja/.gradle_home -e LOCAL_UID=$(id -u $USER) -e LOCAL_GID=$(id -g $USER) -e SOURCE_DATE_EPOCH $DOCKER_ARGS -v `pwd`:/home/user/contiki-ng -v $GITHUB_WORKSPACE/.ccache:/home/user/.ccache $DOCKER_IMG bash --login -c "source ../.bash_aliases && ccache --set-config=max_size='160M' && cimake -C tests/??-${{ matrix.test }}; ccache -c"
         # Check outcome of the test
         ./tests/check-test.sh `pwd`/tests/??-${{ matrix.test }}