MB-67886: Manually fetch pip for cluster_tests

Now that ensurepip isn't bundled with the python we ship couchbase
with, cluster_tests can't use it to install requirements.

Initially we fixed this with a temporary solution to make use of the
python already installed on the Jenkins workers:
https://review.couchbase.org/c/ns_server/+/231838

This approach doesn't work on every machine, since not every machine
has python with support for venv and pip.

Instead we have to manually download pip, and just use that.

Change-Id: I7ae64dcb734537ca720be25911c2b6d7c89c56bb
Reviewed-on: https://review.couchbase.org/c/ns_server/+/231854
Tested-by: Peter Searby <[email protected]>
Well-Formed: Build Bot <[email protected]>
Well-Formed: Restriction Checker
Reviewed-by: Ben Huddleston <[email protected]>

Author: Peter-Searby

cluster_tests/CMakeLists.txt

@@ -1,25 +1,19 @@
+SET(GET_PIP_PY_FILE ${CMAKE_CURRENT_BINARY_DIR}/get-pip.py)
 
-# Fetch WORKSPACE from ENV for Jenkins
-SET(WORKSPACE ${CMAKE_CURRENT_BINARY_DIR})
-IF ($ENV{WORKSPACE})
-  SET(WORKSPACE $ENV{WORKSPACE})
-ENDIF ($ENV{WORKSPACE})
-# Fetch WORKSPACE from ENV for Jenkins
-SET(VIRTUALENV_NAME ns_server_cluster_tests})
-IF ($ENV{VIRTUALENV_NAME})
-  SET(VIRTUALENV_NAME $ENV{VIRTUALENV_NAME})
-ENDIF ($ENV{VIRTUALENV_NAME})
+# We call this with a cmake call so that we can download the file at build time,
+# rather than configure time, which avoids downloading the file needlessly
+SET (GET_PIP_CMD "${CMAKE_COMMAND}"
+    -D "GET_PIP_PY_FILE=${GET_PIP_PY_FILE}"
+    -P "${CMAKE_CURRENT_SOURCE_DIR}/get_pip.cmake")
 
 ADD_CUSTOM_TARGET(cluster_tests_python_requirements
-        COMMAND python -m venv ${WORKSPACE}/${VIRTUALENV_NAME}
-        COMMAND source ${WORKSPACE}/${VIRTUALENV_NAME}/bin/activate
-        COMMAND python -m pip install --upgrade pip
-        COMMAND python -m pip
+        COMMAND ${GET_PIP_CMD}
+        COMMAND ${PYTHON_EXE} ${GET_PIP_PY_FILE}
+        COMMAND ${PYTHON_EXE} -m pip
         install -r ${CMAKE_CURRENT_SOURCE_DIR}/requirements.txt)
 SEPARATE_ARGUMENTS(cluster_test_args NATIVE_COMMAND $ENV{CLUSTER_TESTS_ARGS})
 ADD_CUSTOM_TARGET(cluster_tests
-        COMMAND source ${WORKSPACE}/${VIRTUALENV_NAME}/bin/activate
-        COMMAND JAVA_HOME=${Java_JAVA_HOME} python
+        COMMAND JAVA_HOME=${Java_JAVA_HOME} ${PYTHON_EXE}
         ${CMAKE_CURRENT_SOURCE_DIR}/run.py ${cluster_test_args}
         DEPENDS cluster_tests_python_requirements
         COMMAND_EXPAND_LISTS)

cluster_tests/get_pip.cmake

@@ -0,0 +1,2 @@
+FILE(DOWNLOAD https://bootstrap.pypa.io/get-pip.py
+        ${GET_PIP_PY_FILE} TIMEOUT 60)