Prevent two podman machines running on darwin

As issue containers#25112 points out, it was possible to start a machine on one of the darwin providers and then switch providers and start another one with a different name.  This PR firstly prevents that use which is a forbidden use case.

Secondarily, performed some minor cleanup on the error messages being used so that the error would be specific to this condition.

This bug fix is for darwin only.  In the case of Windows, we probably need to answer the question I raised in containers#24067 first, which is whether we want to stop allowing WSL to run multiple machines.

Fixes containers#25112

Signed-off-by: Brent Baude <[email protected]>

pkg/machine/define/errors.go

@@ -8,12 +8,9 @@ import (
 )
 
 var (
-	ErrNoSuchVM         = errors.New("VM does not exist")
-	ErrWrongState       = errors.New("VM in wrong state to perform action")
-	ErrVMAlreadyExists  = errors.New("VM already exists")
-	ErrVMAlreadyRunning = errors.New("VM already running or starting")
-	ErrMultipleActiveVM = errors.New("only one VM can be active at a time")
-	ErrNotImplemented   = errors.New("functionality not implemented")
+	ErrWrongState      = errors.New("VM in wrong state to perform action")
+	ErrVMAlreadyExists = errors.New("VM already exists")
+	ErrNotImplemented  = errors.New("functionality not implemented")
 )
 
 type ErrVMRunningCannotDestroyed struct {
@@ -49,3 +46,24 @@ type ErrIncompatibleMachineConfig struct {
 func (err *ErrIncompatibleMachineConfig) Error() string {
 	return fmt.Sprintf("incompatible machine config %q (%s) for this version of Podman", err.Path, err.Name)
 }
+
+type ErrVMAlreadyRunning struct {
+	Name string
+}
+
+func (err *ErrVMAlreadyRunning) Error() string {
+	return fmt.Sprintf("%s already starting or running", err.Name)
+}
+
+type ErrMultipleActiveVM struct {
+	Name     string
+	Provider *string
+}
+
+func (err *ErrMultipleActiveVM) Error() string {
+	errMsg := fmt.Sprintf("a machine %q is already running", err.Name)
+	if err.Provider == nil {
+		return errMsg
+	}
+	return fmt.Sprintf("%s on the %q provider", errMsg, *err.Provider)
+}

pkg/machine/shim/host.go

@@ -265,7 +265,7 @@ func VMExists(name string, vmstubbers []vmconfigs.VMProvider) (*vmconfigs.Machin
 		return nil, false, err
 	}
 	if mc, found := mcs[name]; found {
-		return mc, true, nil
+		return mc.MachineConfig, true, nil
 	}
 	// Check with the provider hypervisor
 	for _, vmstubber := range vmstubbers {
@@ -281,31 +281,46 @@ func VMExists(name string, vmstubbers []vmconfigs.VMProvider) (*vmconfigs.Machin
 }
 
 // checkExclusiveActiveVM checks if any of the machines are already running
-func checkExclusiveActiveVM(provider vmconfigs.VMProvider, mc *vmconfigs.MachineConfig) error {
+func checkExclusiveActiveVM(currentProvider vmconfigs.VMProvider, mc *vmconfigs.MachineConfig) error {
+	providers := provider.GetAll()
 	// Check if any other machines are running; if so, we error
-	localMachines, err := getMCsOverProviders([]vmconfigs.VMProvider{provider})
+	localMachines, err := getMCsOverProviders(providers)
 	if err != nil {
 		return err
 	}
+
 	for name, localMachine := range localMachines {
-		state, err := provider.State(localMachine, false)
+		state, err := localMachine.Provider.State(localMachine.MachineConfig, false)
 		if err != nil {
 			return err
 		}
 		if state == machineDefine.Running || state == machineDefine.Starting {
 			if mc.Name == name {
-				return fmt.Errorf("unable to start %q: machine %s: %w", mc.Name, name, machineDefine.ErrVMAlreadyRunning)
+				return fmt.Errorf("unable to start %q: already running", mc.Name)
+			}
+
+			// A machine is running in the current provider
+			if currentProvider == localMachine.Provider {
+				fail := machineDefine.ErrVMAlreadyRunning{Name: mc.Name}
+				return fmt.Errorf("unable to start %q: %w", mc.Name, &fail)
 			}
-			return fmt.Errorf("unable to start %q: machine %s is already running: %w", mc.Name, name, machineDefine.ErrMultipleActiveVM)
+			// A machine is running in an alternate provider
+			providerRunningMachine := localMachine.Provider.VMType().String()
+			return &machineDefine.ErrMultipleActiveVM{Name: name, Provider: &providerRunningMachine}
 		}
 	}
 	return nil
 }
 
+type knownMachineConfig struct {
+	Provider      vmconfigs.VMProvider
+	MachineConfig *vmconfigs.MachineConfig
+}
+
 // getMCsOverProviders loads machineconfigs from a config dir derived from the "provider".  it returns only what is known on
 // disk so things like status may be incomplete or inaccurate
-func getMCsOverProviders(vmstubbers []vmconfigs.VMProvider) (map[string]*vmconfigs.MachineConfig, error) {
-	mcs := make(map[string]*vmconfigs.MachineConfig)
+func getMCsOverProviders(vmstubbers []vmconfigs.VMProvider) (map[string]knownMachineConfig, error) {
+	mcs := make(map[string]knownMachineConfig)
 	for _, stubber := range vmstubbers {
 		dirs, err := env.GetMachineDirs(stubber.VMType())
 		if err != nil {
@@ -320,7 +335,10 @@ func getMCsOverProviders(vmstubbers []vmconfigs.VMProvider) (map[string]*vmconfi
 		// iterate known mcs and add the stubbers
 		for mcName, mc := range stubberMCs {
 			if _, ok := mcs[mcName]; !ok {
-				mcs[mcName] = mc
+				mcs[mcName] = knownMachineConfig{
+					Provider:      stubber,
+					MachineConfig: mc,
+				}
 			}
 		}
 	}
@@ -414,7 +432,7 @@ func Start(mc *vmconfigs.MachineConfig, mp vmconfigs.VMProvider, dirs *machineDe
 		}
 
 		if state == machineDefine.Running || state == machineDefine.Starting {
-			return fmt.Errorf("machine %s: %w", mc.Name, machineDefine.ErrVMAlreadyRunning)
+			return fmt.Errorf("unable to start %q: already running", mc.Name)
 		}
 	}