feat: Add check for minimum python version

go.mod

@@ -3,6 +3,7 @@ module github.com/kluctl/go-jinja2
 go 1.19
 
 require (
+	github.com/Masterminds/semver/v3 v3.2.1
 	github.com/go-git/go-git/v5 v5.12.0
 	github.com/gobwas/glob v0.2.3
 	github.com/hashicorp/go-multierror v1.1.1

go.sum

@@ -1,3 +1,5 @@
+github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
+github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

jinja2.go

@@ -2,6 +2,7 @@ package jinja2
 
 import (
 	"fmt"
+	"github.com/Masterminds/semver/v3"
 	"github.com/go-git/go-git/v5/plumbing/format/gitignore"
 	"github.com/gobwas/glob"
 	"github.com/hashicorp/go-multierror"
@@ -16,6 +17,8 @@ import (
 	"sync"
 )
 
+var minimumPythonVersion = semver.MustParse("3.10.0")
+
 type Jinja2 struct {
 	ep          python.Python
 	extractDir  string
@@ -83,6 +86,11 @@ func NewJinja2(name string, parallelism int, opts ...Jinja2Opt) (*Jinja2, error)
 	}
 	j2.ep.AddPythonPath(j2.jinja2Lib.GetExtractedPath())
 
+	err = j2.checkPythonVersion()
+	if err != nil {
+		return nil, err
+	}
+
 	j2.rendererSrc, err = embed_util.NewEmbeddedFilesWithTmpDir(python_src.RendererSource, tmpDir+"-jinja2-renderer", true)
 	if err != nil {
 		return nil, err
@@ -114,6 +122,25 @@ func NewJinja2(name string, parallelism int, opts ...Jinja2Opt) (*Jinja2, error)
 	return j2, nil
 }
 
+func (j *Jinja2) checkPythonVersion() error {
+	cmd, err := j.ep.PythonCmd("-c", `import platform; print(platform.python_version())`)
+	if err != nil {
+		return err
+	}
+	v, err := cmd.Output()
+	if err != nil {
+		return err
+	}
+	v2, err := semver.NewVersion(strings.TrimSpace(string(v)))
+	if err != nil {
+		return fmt.Errorf("failed to parse python version: %w", err)
+	}
+	if v2.LessThan(minimumPythonVersion) {
+		return fmt.Errorf("python version (%s) must be at least %s", v2.String(), minimumPythonVersion)
+	}
+	return nil
+}
+
 func (j *Jinja2) Close() {
 	for i := 0; i < j.parallelism; i++ {
 		pj := <-j.pj

jinja2_external_python_test.go

@@ -2,6 +2,7 @@ package jinja2
 
 import (
 	"fmt"
+	"github.com/Masterminds/semver/v3"
 	"github.com/kluctl/go-embed-python/python"
 	"github.com/stretchr/testify/assert"
 	"math/rand"
@@ -34,3 +35,20 @@ func TestSystemPython(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "a", r1)
 }
+
+func TestSystemPythonVersion(t *testing.T) {
+	backup := minimumPythonVersion
+	t.Cleanup(func() {
+		minimumPythonVersion = backup
+	})
+
+	minimumPythonVersion = semver.MustParse("10.0.0")
+
+	ep := python.NewPython()
+	if _, err := ep.GetExePath(); err != nil {
+		t.Skipf("skipping due to missing python binary")
+	}
+
+	_, err := newJinja2WithErr(t, WithPython(ep))
+	assert.ErrorContains(t, err, "must be at least 10.0.0")
+}

jinja2_test.go

@@ -10,17 +10,25 @@ import (
 	"testing"
 )
 
-func newJinja2(t *testing.T, opts ...Jinja2Opt) *Jinja2 {
+func newJinja2WithErr(t *testing.T, opts ...Jinja2Opt) (*Jinja2, error) {
 	name := fmt.Sprintf("jinja2-%d", rand.Uint32())
 	opts2 := append(opts, WithExtension("go_jinja2.ext.kluctl"))
 	j2, err := NewJinja2(name, 1, opts2...)
 	if err != nil {
-		t.Fatal(err)
+		return nil, err
 	}
 
 	t.Cleanup(j2.Close)
 	t.Cleanup(j2.Cleanup)
 
+	return j2, nil
+}
+
+func newJinja2(t *testing.T, opts ...Jinja2Opt) *Jinja2 {
+	j2, err := newJinja2WithErr(t, opts...)
+	if err != nil {
+		t.Fatal(err)
+	}
 	return j2
 }