Re: [Qemu-devel] [PATCH v2 1/3] Bootstrap Python venv for tests

[Cleber Rosa]

On 10/9/18 9:25 AM, Philippe Mathieu-Daudé wrote:
> Hi Cleber,
> 
> On 09/10/2018 06:18, Cleber Rosa wrote:
>> A number of QEMU tests are written in Python, and may benefit
>> from an untainted Python venv.
>>
>> By using make rules, tests that depend on specific Python libs
>> can set that rule as a requiment, along with rules that require
>> the presence or installation of specific libraries.
>>
>> The tests/venv-requirements.txt is supposed to contain the
>> Python requirements that should be added to the venv created
>> by check-venv.
>>
>> Signed-off-by: Cleber Rosa <address@hidden>
>> ---
>>  tests/Makefile.include      | 19 +++++++++++++++++++
>>  tests/venv-requirements.txt |  3 +++
>>  2 files changed, 22 insertions(+)
>>  create mode 100644 tests/venv-requirements.txt
>>
>> diff --git a/tests/Makefile.include b/tests/Makefile.include
>> index 7a3059bf6c..68af79927d 100644
>> --- a/tests/Makefile.include
>> +++ b/tests/Makefile.include
>> @@ -12,6 +12,7 @@ check-help:
>>      @echo " $(MAKE) check-block          Run block tests"
>>      @echo " $(MAKE) check-tcg            Run TCG tests"
>>      @echo " $(MAKE) check-report.html    Generates an HTML test report"
>> +    @echo " $(MAKE) check-venv           Creates a Python venv for tests"
>>      @echo " $(MAKE) check-clean          Clean the tests"
>>      @echo
>>      @echo "Please note that HTML reports do not regenerate if the unit 
>> tests"
>> @@ -1015,6 +1016,23 @@ check-decodetree:
>>            ./check.sh "$(PYTHON)" "$(SRC_PATH)/scripts/decodetree.py", \
>>            TEST, decodetree.py)
>>  
>> +# Python venv for running tests
>> +
>> +.PHONY: check-venv
>> +
>> +TESTS_VENV_DIR=$(BUILD_DIR)/tests/venv
>> +TESTS_VENV_REQ=$(SRC_PATH)/tests/venv-requirements.txt
>> +
>> +$(TESTS_VENV_DIR):
>> +    $(call quiet-command, \
>> +            $(PYTHON) -m venv --system-site-packages $@, \
> 
> Why do we want the '--system-site-packages' flag?
> 

It allows the reuse of packages (with no additional downloads) in case
there's a package installed system wide providing the same package and
version.  If you have, say, an RPM or DEB (or even a pip) package
installed system wide, it'll be copied over to the venv.  This was based
on a suggestion by Eduardo.

>> +            VENV, $@)
>> +    $(call quiet-command, \
>> +            $(TESTS_VENV_DIR)/bin/pip -q install -r $(TESTS_VENV_REQ), \
> 
> On Ubuntu I have to use (after installing python3-pip + python3.4-venv):
> 
>                $(PYTHON) -m pip -q install -r $(TESTS_VENV_REQ), \
> 

I don't think running $(PYTHON) is the right thing to do here because it
points to non-venv Python interpreter.  IMO it should be:

                $(TESTS_VENV_DIR)/bin/python -m pip ...

>> +            PIP, $(TESTS_VENV_REQ))
>> +
>> +check-venv: $(TESTS_VENV_DIR)
> 
> Same problem from v1: if check-venv failed and the directory exists, the
> rule succeeds.
> 

I really don't know how to make all the steps of this target "atomic",
unless I do an ugly "venv ... && touch ... && pip ...".  The best I
managed to think was to flag the requirement as fulfilled by touching
the venv directory after pip finishes.

- Cleber.

>> +
>>  # Consolidated targets
>>  
>>  .PHONY: check-qapi-schema check-qtest check-unit check check-clean
>> @@ -1028,6 +1046,7 @@ check-clean:
>>      rm -rf $(check-unit-y) tests/*.o $(QEMU_IOTESTS_HELPERS-y)
>>      rm -rf $(sort $(foreach target,$(SYSEMU_TARGET_LIST), 
>> $(check-qtest-$(target)-y)) $(check-qtest-generic-y))
>>      rm -f tests/test-qapi-gen-timestamp
>> +    rm -rf $(TESTS_VENV_DIR)
>>  
>>  clean: check-clean
>>  
>> diff --git a/tests/venv-requirements.txt b/tests/venv-requirements.txt
>> new file mode 100644
>> index 0000000000..d39f9d1576
>> --- /dev/null
>> +++ b/tests/venv-requirements.txt
>> @@ -0,0 +1,3 @@
>> +# Add Python module requirements, one per line, to be installed
>> +# in the tests/venv Python virtual environment. For more info,
>> +# refer to: https://pip.pypa.io/en/stable/user_guide/#id1
>>