configure: don't assume python3, create $PYTHON var.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Makefile

@@ -368,7 +368,7 @@ ifneq ($(RUST),0)
 	include cln-grpc/Makefile
 
 $(MSGGEN_GENALL)&: doc/schemas/*.request.json doc/schemas/*.schema.json
-	PYTHONPATH=contrib/msggen python3 contrib/msggen/msggen/__main__.py
+	PYTHONPATH=contrib/msggen $(PYTHON) contrib/msggen/msggen/__main__.py
 
 # The compiler assumes that the proto files are in the same
 # directory structure as the generated files will be. Since we
@@ -384,8 +384,8 @@ GRPC_GEN = \
 ALL_TEST_GEN += $(GRPC_GEN)
 
 $(GRPC_GEN)&: cln-grpc/proto/node.proto cln-grpc/proto/primitives.proto
-	python3 -m grpc_tools.protoc -I cln-grpc/proto cln-grpc/proto/node.proto --python_out=$(GRPC_PATH)/ --grpc_python_out=$(GRPC_PATH)/ --experimental_allow_proto3_optional
-	python3 -m grpc_tools.protoc -I cln-grpc/proto cln-grpc/proto/primitives.proto --python_out=$(GRPC_PATH)/ --experimental_allow_proto3_optional
+	$(PYTHON) -m grpc_tools.protoc -I cln-grpc/proto cln-grpc/proto/node.proto --python_out=$(GRPC_PATH)/ --grpc_python_out=$(GRPC_PATH)/ --experimental_allow_proto3_optional
+	$(PYTHON) -m grpc_tools.protoc -I cln-grpc/proto cln-grpc/proto/primitives.proto --python_out=$(GRPC_PATH)/ --experimental_allow_proto3_optional
 	find $(GRPC_DIR)/ -type f -name "*.py" -print0 | xargs -0 sed -i'.bak' -e 's/^import \(.*\)_pb2 as .*__pb2/from pyln.grpc import \1_pb2 as \1__pb2/g'
 	find $(GRPC_DIR)/ -type f -name "*.py.bak" -delete
 endif
@@ -421,7 +421,7 @@ mkdocs.yml: $(MANPAGES:=.md)
 	  find doc -maxdepth 1 -name '*\.[0-9]\.md' | \
 	  cut -b 5- | LC_ALL=C sort | \
 	  sed 's/\(.*\)\.\(.*\).*\.md/- "\1": "\1.\2.md"/' | \
-	  python3 devtools/blockreplace.py mkdocs.yml manpages --language=yml --indent "          " \
+	  $(PYTHON) devtools/blockreplace.py mkdocs.yml manpages --language=yml --indent "          " \
 	)
 
 

configure

@@ -69,11 +69,25 @@ default_cwarnflags()
     echo "$F"
 }
 
+default_python()
+{
+    PYTHON_BINS="python3 python"
+    for p in $PYTHON_BINS; do
+        if [ "$(which $p)" != "" ] ; then
+            if $p --version 2>&1 | grep -q "Python 3."; then
+                echo "$p"
+                return
+            fi
+        fi
+    done
+}
+
+# Takes PYTHON var
 default_pytest()
 {
     # Since we just checked that we have python3 we give that one the
     # most priority and then fall back to some common aliases.
-    PYTEST_BINS="python3 -m pytest,pytest,py.test,pytest3,pytest-3"
+    PYTEST_BINS="$1 -m pytest,pytest,py.test,pytest3,pytest-3"
     IFS=','
     for p in $PYTEST_BINS; do
 	# If it is a combined command such as `python3 -m pytest` we
@@ -87,16 +101,10 @@ default_pytest()
 	fi
     done
 
-    PYTHON_BINS="python python3"
-    for p in $PYTHON_BINS; do
-        if [ "$(which $p)" != "" ] ; then
-            $p --version 2>&1 | grep -q "Python 3." || continue
-            if $p -c "import pytest" 2>/dev/null ; then
-                echo "$p -m pytest"
-                return
-            fi
-        fi
-    done
+    if $1 -c "import pytest" 2>/dev/null; then
+        echo "$1 -m pytest"
+        return
+    fi
 }
 
 check_command()
@@ -170,7 +178,8 @@ set_defaults()
 	CSANFLAGS="$CSANFLAGS $FUZZFLAGS"
     fi
     echo CSANFLAGS = $CSANFLAGS
-    PYTEST=${PYTEST-$(default_pytest)}
+    PYTHON=${PYTHON-$(default_python)}
+    PYTEST=${PYTEST-$(default_pytest $PYTHON)}
     COPTFLAGS=${COPTFLAGS-$(default_coptflags "$DEBUGBUILD")}
     CONFIGURATOR_CC=${CONFIGURATOR_CC-$CC}
     VALGRIND=${VALGRIND:-$(default_valgrind_setting)}
@@ -526,6 +535,7 @@ add_var HAVE_LOWDOWN "$HAVE_LOWDOWN"
 add_var SHA256SUM "$SHA256SUM"
 add_var FUZZING "$FUZZING"
 add_var RUST "$RUST"
+add_var PYTHON "$PYTHON"
 
 # Hack to avoid sha256 name clash with libwally: will be fixed when that
 # becomes a standalone shared lib.

doc/Makefile

@@ -235,7 +235,7 @@ doc/index.rst: $(MANPAGES:=.md)
 	  find doc -maxdepth 1 -name '*\.[0-9]\.md' | \
 	  cut -b 5- | LC_ALL=C sort | \
 	  sed "s/\(.*\)\.\(.*\).*\.md/\1 <\1.\2.md>/" | \
-	  python3 devtools/blockreplace.py doc/index.rst manpages --language=rst --indent "   " \
+	  $(PYTHON) devtools/blockreplace.py doc/index.rst manpages --language=rst --indent "   " \
 	)
 
 # Overridden by GH CI if necessary.