DRIVERS-3063 Use self-contained python binary (#560)

.evergreen/auth_aws/teardown.sh

@@ -6,6 +6,11 @@ SCRIPT_DIR=$(dirname ${BASH_SOURCE[0]})
 . $SCRIPT_DIR/../handle-paths.sh
 
 pushd $SCRIPT_DIR
-. ./activate-authawsvenv.sh
-python ./lib/aws_assign_instance_profile.py
+
+# If we've gotten credentials, ensure the instance profile is set.
+if [ -f secrets-export.sh ]; then
+  . ./activate-authawsvenv.sh
+  python ./lib/aws_assign_instance_profile.py
+fi
+
 popd

.evergreen/find-python3.sh

@@ -312,12 +312,12 @@ find_python3() (
 # Diagnostic messages may be printed to stderr (pipe 2). Redirect to /dev/null
 # with `2>/dev/null` to silence these messages.
 #
-# If PYTHON or PYTHON_BINARY are set, it will return that value.  Otherwise
+# If DRIVERS_TOOLS_PYTHON is set, it will return that value.  Otherwise
 # it will use find_python3 to return a suitable value.
 #
 ensure_python3() {
   declare python_binary
-  python_binary="${PYTHON:-"${PYTHON_BINARY:-""}"}"
+  python_binary="${DRIVERS_TOOLS_PYTHON:-}"
   {
     if [ -z "${python_binary}" ]; then
       echo "Finding Python3 binary..."

.evergreen/setup.sh

@@ -5,6 +5,7 @@ set -o errexit
 
 SCRIPT_DIR=$(dirname ${BASH_SOURCE[0]})
 . $SCRIPT_DIR/handle-paths.sh
+. $SCRIPT_DIR/find-python3.sh
 
 # Ensure environment variables are set.
 if [[ -z "$PROJECT_DIRECTORY" ]]; then
@@ -26,5 +27,9 @@ OS=${OS:-}
 PATH=$PATH
 EOF
 
+# Set the python binary to use.
+DRIVERS_TOOLS_PYTHON=$(find_python3 2>/dev/null)
+echo "DRIVERS_TOOLS_PYTHON=$DRIVERS_TOOLS_PYTHON" >> $DRIVERS_TOOLS/.env
+
 # Install the clis in this folder.
 bash $SCRIPT_DIR/install-cli.sh $SCRIPT_DIR