fix(python): use version-specific pip URL for older Python versions (#119)

Author: CalvinAllen

src/runtimes/python/provider.go

@@ -12,6 +12,7 @@ import (
 	"regexp"
 	goruntime "runtime"
 	"sort"
+	"strconv"
 	"strings"
 	"time"
 
@@ -117,7 +118,9 @@ func (p *Provider) installPipIfNeeded(version string) {
 		pipSpinner.Start()
 		if err := p.installPip(version); err != nil {
 			pipSpinner.Warning("Failed to install pip")
-			ui.Info("You can install it manually by running: python -m ensurepip")
+			ui.Info("To install pip manually:")
+			ui.Info("  1. Download: %s", p.getPipURL(version))
+			ui.Info("  2. Run: python get-pip.py")
 		} else {
 			pipSpinner.Success("pip installed successfully")
 		}
@@ -306,8 +309,8 @@ func (p *Provider) installPip(version string) error {
 		return fmt.Errorf("failed to enable site-packages: %w", err)
 	}
 
-	// Step 2: Download get-pip.py
-	getPipURL := "https://bootstrap.pypa.io/get-pip.py"
+	// Step 2: Download get-pip.py (use version-specific URL for older Python)
+	getPipURL := p.getPipURL(version)
 	getPipPath := filepath.Join(installPath, "get-pip.py")
 	if err := download.File(getPipURL, getPipPath); err != nil {
 		return fmt.Errorf("failed to download get-pip.py: %w", err)
@@ -325,6 +328,22 @@ func (p *Provider) installPip(version string) error {
 	return nil
 }
 
+// getPipURL returns the appropriate get-pip.py URL for the given Python version.
+// Older Python versions (3.8 and below) require version-specific URLs since the
+// main get-pip.py no longer supports end-of-life Python versions.
+func (p *Provider) getPipURL(version string) string {
+	parts := strings.Split(version, ".")
+	if len(parts) >= 2 && parts[0] == "3" {
+		minor, err := strconv.Atoi(parts[1])
+		if err == nil && minor <= 8 {
+			// Use version-specific URL for Python 3.8 and below
+			return fmt.Sprintf("https://bootstrap.pypa.io/pip/%s.%s/get-pip.py", parts[0], parts[1])
+		}
+	}
+	// Default URL for Python 3.9+
+	return "https://bootstrap.pypa.io/get-pip.py"
+}
+
 // enableSitePackages modifies the ._pth file to enable site-packages
 func (p *Provider) enableSitePackages(pthFile string) error {
 	// Read the file

src/runtimes/python/provider_test.go

@@ -82,3 +82,64 @@ func TestPythonProvider_InstallPath(t *testing.T) {
 		}
 	}
 }
+
+// TestPythonProvider_GetPipURL tests the version-specific pip URL selection
+func TestPythonProvider_GetPipURL(t *testing.T) {
+	provider := NewProvider()
+
+	tests := []struct {
+		name        string
+		version     string
+		expectedURL string
+	}{
+		{
+			name:        "Python 3.12 uses default URL",
+			version:     "3.12.0",
+			expectedURL: "https://bootstrap.pypa.io/get-pip.py",
+		},
+		{
+			name:        "Python 3.11 uses default URL",
+			version:     "3.11.5",
+			expectedURL: "https://bootstrap.pypa.io/get-pip.py",
+		},
+		{
+			name:        "Python 3.10 uses default URL",
+			version:     "3.10.0",
+			expectedURL: "https://bootstrap.pypa.io/get-pip.py",
+		},
+		{
+			name:        "Python 3.9 uses default URL",
+			version:     "3.9.18",
+			expectedURL: "https://bootstrap.pypa.io/get-pip.py",
+		},
+		{
+			name:        "Python 3.8 uses version-specific URL",
+			version:     "3.8.9",
+			expectedURL: "https://bootstrap.pypa.io/pip/3.8/get-pip.py",
+		},
+		{
+			name:        "Python 3.7 uses version-specific URL",
+			version:     "3.7.12",
+			expectedURL: "https://bootstrap.pypa.io/pip/3.7/get-pip.py",
+		},
+		{
+			name:        "Python 3.6 uses version-specific URL",
+			version:     "3.6.15",
+			expectedURL: "https://bootstrap.pypa.io/pip/3.6/get-pip.py",
+		},
+		{
+			name:        "Python 2.7 uses version-specific URL",
+			version:     "2.7.18",
+			expectedURL: "https://bootstrap.pypa.io/get-pip.py", // 2.x uses default (not 3.x)
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			url := provider.getPipURL(tt.version)
+			if url != tt.expectedURL {
+				t.Errorf("getPipURL(%q) = %q, want %q", tt.version, url, tt.expectedURL)
+			}
+		})
+	}
+}