I'm running a python binary target with bazel run xxx and in the target I'm doing print(sys.version). This outputs Python version 3.6.8 (default, Jan 14 2019, 11:02:34)
When I type the python command directly, I get Python 3.7.3 (default, Apr 3 2019, 19:16:38)
Why/how did bazel choose a different python version?
Bazel will choose different python versions based on the configuration of the build. If nothing is overriden, bazel will use its default python version. This can be overridden by passing --python_version=<some_version> when running a bazel command.
https://docs.bazel.build/versions/master/be/python.html#py_binary.python_version https://github.com/bazelbuild/rules_python/blob/120590e2f2b66e5590bf4dc8ebef9c5338984775/python/BUILD#L43