Support detecting python interpreter requirements from standard files (#2617)

Author: amol-

go.mod

@@ -17,7 +17,10 @@ require (
 	golang.org/x/net v0.37.0
 )
 
-require golang.org/x/crypto v0.36.0 // indirect
+require (
+	golang.org/x/crypto v0.36.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+)
 
 require (
 	github.com/alessio/shellescape v1.4.2 // indirect

go.sum

@@ -103,6 +103,8 @@ gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/ini.v1 v1.67.0 h1:Dgnx+6+nfE+IfzjUEISNeydPJh9AXNNsWbGP9KzCsOA=
+gopkg.in/ini.v1 v1.67.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/bundles/manifest.go

@@ -53,9 +53,14 @@ type Metadata struct {
 	HasParameters   bool            `json:"has_parameters,omitempty"`   // True if this is content allows parameter customization.
 }
 
+type EnvironmentPython struct {
+	PythonRequires string `json:"requires"` // The Python version to use for the content environment
+}
+
 type Environment struct {
-	Image    string `json:"image"`    // The image to use during content build/execution
-	Prebuilt bool   `json:"prebuilt"` // Determines whether Connect should skip the build phase for this content.
+	Image    string             `json:"image"`            // The image to use during content build/execution
+	Prebuilt bool               `json:"prebuilt"`         // Determines whether Connect should skip the build phase for this content.
+	Python   *EnvironmentPython `json:"python,omitempty"` // If non-null, specifies the Python environment
 }
 
 type Python struct {
@@ -175,6 +180,15 @@ func NewManifestFromConfig(cfg *config.Config) *Manifest {
 				PackageFile: cfg.Python.PackageFile,
 			},
 		}
+		// If the configuration specifies a specific python version constraint
+		// (e.g. ">=3.8"), declare the environment requires that version.
+		if cfg.Python.RequiresPythonVersion != "" {
+			m.Environment = &Environment{
+				Python: &EnvironmentPython{
+					PythonRequires: cfg.Python.RequiresPythonVersion,
+				},
+			}
+		}
 	}
 	if cfg.Jupyter != nil {
 		m.Jupyter = &Jupyter{
@@ -214,7 +228,12 @@ func (manifest *Manifest) AddFile(path string, fileMD5 []byte) {
 }
 
 func (manifest *Manifest) ToJSON() ([]byte, error) {
-	return json.MarshalIndent(manifest, "", "\t")
+	buf := &bytes.Buffer{}
+	enc := json.NewEncoder(buf)
+	enc.SetEscapeHTML(false)
+	enc.SetIndent("", "\t")
+	err := enc.Encode(manifest)
+	return buf.Bytes(), err
 }
 
 func (manifest *Manifest) Clone() (*Manifest, error) {

internal/config/types.go

@@ -125,9 +125,10 @@ func (c *Config) HasSecret(secret string) bool {
 type Environment = map[string]string
 
 type Python struct {
-	Version        string `toml:"version,omitempty" json:"version"`
-	PackageFile    string `toml:"package_file,omitempty" json:"packageFile"`
-	PackageManager string `toml:"package_manager,omitempty" json:"packageManager"`
+	Version               string `toml:"version,omitempty" json:"version"`
+	PackageFile           string `toml:"package_file,omitempty" json:"packageFile"`
+	PackageManager        string `toml:"package_manager,omitempty" json:"packageManager"`
+	RequiresPythonVersion string `toml:"requires_python,omitempty" json:"requiresPython"`
 }
 
 func (p *Python) FillDefaults(
@@ -150,6 +151,9 @@ func (p *Python) FillDefaults(
 		if p.PackageManager == "" {
 			p.PackageManager = python.GetPackageManager()
 		}
+		if p.RequiresPythonVersion == "" {
+			p.RequiresPythonVersion = python.GetPythonRequires()
+		}
 	}
 }
 

internal/config/types_defaults_test.go

@@ -55,6 +55,7 @@ func (s *ConfigFillDefaultsSuite) createMockPythonInterpreter() interpreters.Pyt
 	iMock.On("GetPythonExecutable").Return(util.NewAbsolutePath("/bin/python", s.cwd.Fs()), nil)
 	iMock.On("GetPythonVersion").Return("1.2.3", nil)
 	iMock.On("GetPackageManager").Return("pip")
+	iMock.On("GetPythonRequires").Return("")
 	iMock.On("GetLockFilePath").Return("requirements.txt", true, nil)
 	return iMock
 }
@@ -66,6 +67,7 @@ func (s *ConfigFillDefaultsSuite) createMockPythonMissingInterpreter() interpret
 	iMock.On("GetPythonExecutable").Return(util.NewAbsolutePath("", s.cwd.Fs()), missingError)
 	iMock.On("GetPythonVersion").Return("", missingError)
 	iMock.On("GetPackageManager").Return("pip")
+	iMock.On("GetPythonRequires").Return("")
 	iMock.On("GetLockFilePath").Return("", false, missingError)
 	return iMock
 }

internal/inspect/python.go

@@ -97,10 +97,18 @@ func (i *defaultPythonInspector) InspectPython() (*config.Python, error) {
 		i.log.Warn("can't find requirements.txt")
 	}
 
+	pyProjectRequires := interpreters.NewPyProjectPythonRequires(i.base)
+	python_requires, err := pyProjectRequires.GetPythonVersionRequirement()
+	if err != nil {
+		i.log.Warn("Error retrieving Python requires", err)
+		python_requires = ""
+	}
+
 	return &config.Python{
-		Version:        version,
-		PackageFile:    reqFile.String(),
-		PackageManager: "pip",
+		Version:               version,
+		PackageFile:           reqFile.String(),
+		PackageManager:        "pip",
+		RequiresPythonVersion: python_requires,
 	}, nil
 }
 

internal/interpreters/python.go

@@ -25,6 +25,7 @@ type PythonInterpreter interface {
 	GetPythonVersion() (string, error)
 	GetPackageManager() string
 	GetPreferredPath() string
+	GetPythonRequires() string
 }
 
 type defaultPythonInterpreter struct {
@@ -257,3 +258,13 @@ func (i *defaultPythonInterpreter) GetLockFilePath() (util.RelativePath, bool, e
 	exists, err := i.existsFunc(lockFileAbsPath.Path)
 	return util.NewRelativePath(lockFile, i.fs), exists, err
 }
+
+func (i *defaultPythonInterpreter) GetPythonRequires() string {
+	pyProjectRequires := NewPyProjectPythonRequires(i.base)
+	python_requires, err := pyProjectRequires.GetPythonVersionRequirement()
+	if err != nil {
+		i.log.Warn("Error retrieving Python requires", err)
+		python_requires = ""
+	}
+	return python_requires
+}

internal/interpreters/python_mock.go

@@ -90,3 +90,9 @@ func (m *MockPythonInterpreter) GetPreferredPath() string {
 	arg0 := args.Get(0)
 	return arg0.(string)
 }
+
+func (m *MockPythonInterpreter) GetPythonRequires() string {
+	args := m.Called()
+	arg0 := args.Get(0)
+	return arg0.(string)
+}

internal/interpreters/python_requires.go

@@ -0,0 +1,112 @@
+package interpreters
+
+// Copyright (C) 2025 by Posit Software, PBC.
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/posit-dev/publisher/internal/util"
+
+	"gopkg.in/ini.v1"
+
+	toml "github.com/pelletier/go-toml/v2"
+)
+
+type PyProjectPythonRequires struct {
+	ProjectPath util.AbsolutePath
+}
+
+func NewPyProjectPythonRequires(projectPath util.AbsolutePath) *PyProjectPythonRequires {
+	return &PyProjectPythonRequires{
+		ProjectPath: projectPath,
+	}
+}
+
+// Find the python version requested by the project if specified in any of the
+// supported metadata files. The order of precedence is:
+// 1. .python-version
+// 2. pyproject.toml
+// 3. setup.cfg
+//
+// The version specifications are the one defined by PEP 440
+// if no version is found, an error is returned.
+func (p *PyProjectPythonRequires) GetPythonVersionRequirement() (string, error) {
+	if version, err := p.readPythonVersionFile(); err == nil && version != "" {
+		return version, nil
+	}
+	if version, err := p.readPyProjectToml(); err == nil && version != "" {
+		return version, nil
+	}
+	if version, err := p.readSetupCfg(); err == nil && version != "" {
+		return version, nil
+	}
+	return "", errors.New("no python version requirement found")
+}
+
+// Read a .python-version file and return the version string.
+// the file is a plain text file that contains only the version specification.
+func (p *PyProjectPythonRequires) readPythonVersionFile() (string, error) {
+	path := p.ProjectPath.Join(".python-version")
+	data, err := path.ReadFile()
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(data)), nil
+}
+
+// Read a pyproject.toml file and return the version string.
+// The file is a TOML file that contains a [project] section
+// with a requires-python key.
+//
+// [project]
+// requires-python = ">=3.8"
+func (p *PyProjectPythonRequires) readPyProjectToml() (string, error) {
+	path := p.ProjectPath.Join("pyproject.toml")
+	data, err := path.ReadFile()
+	if err != nil {
+		return "", err
+	}
+
+	var tomlData map[string]any
+	if err := toml.Unmarshal(data, &tomlData); err != nil {
+		return "", err
+	}
+
+	// project.requires-python
+	if project, ok := tomlData["project"].(map[string]any); ok {
+		if req, ok := project["requires-python"]; ok {
+			return fmt.Sprintf("%v", req), nil
+		}
+	}
+
+	return "", nil
+}
+
+// Read a setup.cfg file and return the version string.
+// The file is an INI file that contains an [options] section
+// with a python_requires key.
+//
+// [options]
+// python_requires = ">=3.8"
+func (p *PyProjectPythonRequires) readSetupCfg() (string, error) {
+	path := p.ProjectPath.Join("setup.cfg")
+	if exists, _ := path.Exists(); !exists {
+		return "", errors.New("setup.cfg file does not exist")
+	}
+
+	cfg, err := ini.Load(path.String())
+	if err != nil {
+		return "", err
+	}
+
+	// options.python_requires
+	if section, err := cfg.GetSection("options"); err == nil {
+		if key, err := section.GetKey("python_requires"); err == nil {
+			return key.String(), nil
+		}
+	}
+
+	return "", nil
+}

internal/interpreters/python_requires_test.go

@@ -0,0 +1,63 @@
+package interpreters
+
+import (
+	"testing"
+
+	"github.com/posit-dev/publisher/internal/util"
+	"github.com/posit-dev/publisher/internal/util/utiltest"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/suite"
+)
+
+// Copyright (C) 2025 by Posit Software, PBC.
+
+type PythonRequiresSuite struct {
+	utiltest.Suite
+	base util.AbsolutePath
+	cwd  util.AbsolutePath
+	fs   afero.Fs
+}
+
+func TestPythonRequiresSuite(t *testing.T) {
+	suite.Run(t, new(PythonRequiresSuite))
+}
+
+func (s *PythonRequiresSuite) SetupTest() {
+	cwd, err := util.Getwd(s.fs)
+	s.NoError(err)
+	s.cwd = cwd
+
+	s.fs = afero.NewOsFs()
+
+	s.base = s.cwd.Join("..", "..", "test", "sample-content").WithFs(s.fs)
+}
+
+func (s *PythonRequiresSuite) TestGetPythonRequiresPyProject() {
+	fastapi_path := s.base.Join("fastapi-simple")
+	pyRequires := NewPyProjectPythonRequires(fastapi_path)
+
+	pythonRequires, err := pyRequires.GetPythonVersionRequirement()
+	s.NoError(err)
+	s.NotEmpty(pythonRequires)
+	s.Equal(">=3.8", pythonRequires)
+}
+
+func (s *PythonRequiresSuite) TestGetPythonRequiresSetupCfg() {
+	gradio_path := s.base.Join("gradio")
+	pyRequires := NewPyProjectPythonRequires(gradio_path)
+
+	pythonRequires, err := pyRequires.GetPythonVersionRequirement()
+	s.NoError(err)
+	s.NotEmpty(pythonRequires)
+	s.Equal(">=3.9", pythonRequires)
+}
+
+func (s *PythonRequiresSuite) TestGetPythonRequiresPythonVersion() {
+	gradio_path := s.base.Join("shinyapp")
+	pyRequires := NewPyProjectPythonRequires(gradio_path)
+
+	pythonRequires, err := pyRequires.GetPythonVersionRequirement()
+	s.NoError(err)
+	s.NotEmpty(pythonRequires)
+	s.Equal(">=3.8, <3.12", pythonRequires)
+}

internal/schema/schemas/draft/posit-publishing-schema-v3.json

@@ -116,6 +116,12 @@
           "default": "pip",
           "description": "Package manager that will install the dependencies. If package-manager is none, dependencies are assumed to be pre-installed on the server. The default is 'pip'.",
           "examples": ["pip", "conda", "pipenv", "poetry", "none"]
+        },
+        "requires_python": {
+          "type": "string",
+          "default": "",
+          "description": "Python interpreter version, in PEP 440 format, required to run the content. If not specified it will be detected from the one in use.",
+          "examples": [">3.8", "<3.9", "==3.5"]
         }
       }
     },

internal/schema/schemas/posit-publishing-schema-v3.json

@@ -105,6 +105,12 @@
           "default": "pip",
           "description": "Package manager that will install the dependencies. If package-manager is none, dependencies will not be installed.",
           "examples": ["pip", "none"]
+        },
+        "requires_python": {
+          "type": "string",
+          "default": "",
+          "description": "Python interpreter version, in PEP 440 format, required to run the content in. If not specified it will be detected from the one in use.",
+          "examples": [">3.8", "<3.9", "=3.5"]
         }
       }
     },

internal/services/api/get_interpreters_test.go

@@ -75,6 +75,7 @@ func (s *GetInterpretersSuite) createMockPythonInterpreter() interpreters.Python
 	iMock.On("GetPythonExecutable").Return(util.NewAbsolutePath("/bin/python", s.cwd.Fs()), nil)
 	iMock.On("GetPythonVersion").Return("1.2.3", nil)
 	iMock.On("GetPackageManager").Return("pip")
+	iMock.On("GetPythonRequires").Return("")
 	iMock.On("GetLockFilePath").Return("requirements.txt", true, nil)
 	iMock.On("GetPreferredPath").Return("bin/my_python")
 	return iMock
@@ -87,6 +88,7 @@ func (s *GetInterpretersSuite) createMockPythonMissingInterpreter() interpreters
 	iMock.On("GetPythonExecutable").Return(util.NewAbsolutePath("", s.cwd.Fs()), missingError)
 	iMock.On("GetPythonVersion").Return("", missingError)
 	iMock.On("GetPackageManager").Return("pip")
+	iMock.On("GetPythonRequires").Return("")
 	iMock.On("GetLockFilePath").Return("", false, missingError)
 	iMock.On("GetPreferredPath").Return("bin/my_python")
 	return iMock
@@ -142,9 +144,10 @@ func (s *GetInterpretersSuite) TestGetInterpretersWhenPassedIn() {
 	s.NoError(dec.Decode(&res))
 
 	expectedPython := &config.Python{
-		Version:        "1.2.3",
-		PackageFile:    "requirements.txt",
-		PackageManager: "pip",
+		Version:               "1.2.3",
+		PackageFile:           "requirements.txt",
+		PackageManager:        "pip",
+		RequiresPythonVersion: "",
 	}
 	expectedR := &config.R{
 		Version:        "3.4.5",