feat: allow explicitly specifying provider type

docs/system_requirements/using_podman.md

@@ -35,6 +35,15 @@ func TestSomething(t *testing.T) {
 }
 ```
 
+If using the [Podman Desktop Docker compatibility mode](https://podman-desktop.io/docs/migrating-from-docker/using-podman-mac-helper),
+where the `DOCKER_HOST` still points to the Docker socket,
+you can also configure the provider explicitly in a `.testcontainers.properties` file
+or the `TESTCONTAINERS_PROVIDER_TYPE` env variable.
+```properties
+tc.provider=podman
+```
+
+
 The `ProviderPodman` configures the `DockerProvider` with the correct default network for Podman to ensure complex network scenarios are working as with Docker.
 
 ## Podman socket activation

internal/config/config.go

@@ -29,6 +29,7 @@ type Config struct {
 	RyukPrivileged          bool          `properties:"ryuk.container.privileged,default=false"`
 	RyukReconnectionTimeout time.Duration `properties:"ryuk.reconnection.timeout,default=10s"`
 	RyukConnectionTimeout   time.Duration `properties:"ryuk.connection.timeout,default=1m"`
+	ProviderType            string        `properties:"provider.type,default="`
 	TestcontainersHost      string        `properties:"tc.host,default="`
 }
 
@@ -80,6 +81,8 @@ func read() Config {
 			config.RyukPrivileged = ryukPrivilegedEnv == "true"
 		}
 
+		config.ProviderType = os.Getenv("TESTCONTAINERS_PROVIDER_TYPE")
+
 		return config
 	}
 

provider.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"github.com/testcontainers/testcontainers-go/internal/config"
 	"os"
 	"strings"
 
@@ -102,12 +103,21 @@ func (t ProviderType) GetProvider(opts ...GenericProviderOption) (GenericProvide
 		o.ApplyGenericTo(opt)
 	}
 
-	pt := t
-	if pt == ProviderDefault && strings.Contains(os.Getenv("DOCKER_HOST"), "podman.sock") {
-		pt = ProviderPodman
+	providerType := t
+	if providerType == ProviderDefault {
+		cfg := config.Read()
+		var err error
+		providerType, err = getProviderType(cfg.ProviderType)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if providerType == ProviderDefault && strings.Contains(os.Getenv("DOCKER_HOST"), "podman.sock") {
+		providerType = ProviderPodman
 	}
 
-	switch pt {
+	switch providerType {
 	case ProviderDefault, ProviderDocker:
 		providerOptions := append(Generic2DockerOptions(opts...), WithDefaultBridgeNetwork(Bridge))
 		provider, err := NewDockerProvider(providerOptions...)
@@ -157,3 +167,16 @@ func NewDockerProvider(provOpts ...DockerProviderOption) (*DockerProvider, error
 
 	return p, nil
 }
+
+// getProviderType maps a human-readable string to a corresponding ProviderType.
+func getProviderType(providerType string) (ProviderType, error) {
+	switch providerType {
+	case "":
+		return ProviderDefault, nil
+	case "docker":
+		return ProviderDocker, nil
+	case "podman":
+		return ProviderPodman, nil
+	}
+	return 0, errors.New(fmt.Sprintf("unknown provider: %s", providerType))
+}

provider_test.go

@@ -2,6 +2,9 @@ package testcontainers
 
 import (
 	"context"
+	"github.com/testcontainers/testcontainers-go/internal/config"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/testcontainers/testcontainers-go/internal/testcontainersdocker"
@@ -12,11 +15,12 @@ func TestProviderTypeGetProviderAutodetect(t *testing.T) {
 	const podmanSocket = "unix://$XDG_RUNTIME_DIR/podman/podman.sock"
 
 	tests := []struct {
-		name       string
-		tr         ProviderType
-		DockerHost string
-		want       string
-		wantErr    bool
+		name               string
+		tr                 ProviderType
+		PropertiesProvider string
+		DockerHost         string
+		want               string
+		wantErr            bool
 	}{
 		{
 			name:       "default provider without podman.socket",
@@ -55,6 +59,21 @@ func TestProviderTypeGetProviderAutodetect(t *testing.T) {
 			DockerHost: podmanSocket,
 			want:       Podman,
 		},
+		{
+			name:               "default provider with podman configured in properties",
+			tr:                 ProviderDefault,
+			PropertiesProvider: "podman",
+			DockerHost:         dockerHost,
+			want:               Podman,
+		},
+		{
+			// Explicitly setting Docker provider should not be overridden by properties
+			name:               "docker provider with podman configured in properties",
+			tr:                 ProviderDocker,
+			PropertiesProvider: "podman",
+			DockerHost:         dockerHost,
+			want:               Bridge,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -64,6 +83,8 @@ func TestProviderTypeGetProviderAutodetect(t *testing.T) {
 
 			t.Setenv("DOCKER_HOST", tt.DockerHost)
 
+			setupTestcontainersProperties(t, "provider.type="+tt.PropertiesProvider)
+
 			got, err := tt.tr.GetProvider()
 			if (err != nil) != tt.wantErr {
 				t.Errorf("ProviderType.GetProvider() error = %v, wantErr %v", err, tt.wantErr)
@@ -79,3 +100,35 @@ func TestProviderTypeGetProviderAutodetect(t *testing.T) {
 		})
 	}
 }
+
+func setupTestcontainersProperties(t *testing.T, content string) {
+	t.Cleanup(func() {
+		// reset the properties file after the test
+		config.Reset()
+	})
+
+	config.Reset()
+
+	tmpDir := t.TempDir()
+	homeDir := filepath.Join(tmpDir, "home")
+	err := createTmpDir(homeDir)
+	if err != nil {
+		t.Fatalf("failed to create tmp home dir: %v", err)
+	}
+	t.Setenv("HOME", homeDir)
+	t.Setenv("USERPROFILE", homeDir) // Windows support
+
+	if err := os.WriteFile(filepath.Join(homeDir, ".testcontainers.properties"), []byte(content), 0o600); err != nil {
+		t.Errorf("Failed to create the file: %v", err)
+		return
+	}
+}
+
+func createTmpDir(dir string) error {
+	err := os.MkdirAll(dir, 0o755)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}