api: add sandbox EnterContainer API

And make VC EnterContainer a wrapper of it.

Signed-off-by: Peng Tao <[email protected]>

virtcontainers/api.go

@@ -422,24 +422,17 @@ func EnterContainer(sandboxID, containerID string, cmd Cmd) (VCSandbox, VCContai
 	}
 	defer unlockSandbox(lockFile)
 
-	p, err := fetchSandbox(sandboxID)
-	if err != nil {
-		return nil, nil, nil, err
-	}
-
-	// Fetch the container.
-	c, err := p.findContainer(containerID)
+	s, err := fetchSandbox(sandboxID)
 	if err != nil {
 		return nil, nil, nil, err
 	}
 
-	// Enter it.
-	process, err := c.enter(cmd)
+	c, process, err := s.EnterContainer(containerID, cmd)
 	if err != nil {
 		return nil, nil, nil, err
 	}
 
-	return p, c, process, nil
+	return s, c, process, nil
 }
 
 // StatusContainer is the virtcontainers container status entry point.

virtcontainers/interfaces.go

@@ -55,6 +55,7 @@ type VCSandbox interface {
 	DeleteContainer(contID string) (VCContainer, error)
 	StartContainer(containerID string) (VCContainer, error)
 	StatusContainer(containerID string) (ContainerStatus, error)
+	EnterContainer(containerID string, cmd Cmd) (VCContainer, *Process, error)
 }
 
 // VCContainer is the Container interface

virtcontainers/pkg/vcmock/sandbox.go

@@ -94,3 +94,8 @@ func (p *Sandbox) StatusContainer(contID string) (vc.ContainerStatus, error) {
 func (p *Sandbox) Status() vc.SandboxStatus {
 	return vc.SandboxStatus{}
 }
+
+// EnterContainer implements the VCSandbox function of the same name.
+func (p *Sandbox) EnterContainer(containerID string, cmd vc.Cmd) (vc.VCContainer, *vc.Process, error) {
+	return &Container{}, &vc.Process{}, nil
+}

virtcontainers/sandbox.go

@@ -995,6 +995,24 @@ func (s *Sandbox) StatusContainer(containerID string) (ContainerStatus, error) {
 	return ContainerStatus{}, errNoSuchContainer
 }
 
+// EnterContainer is the virtcontainers container command execution entry point.
+// EnterContainer enters an already running container and runs a given command.
+func (s *Sandbox) EnterContainer(containerID string, cmd Cmd) (VCContainer, *Process, error) {
+	// Fetch the container.
+	c, err := s.findContainer(containerID)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Enter it.
+	process, err := c.enter(cmd)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return c, process, nil
+}
+
 // createContainers registers all containers to the proxy, create the
 // containers in the guest and starts one shim per container.
 func (s *Sandbox) createContainers() error {

virtcontainers/sandbox_test.go

@@ -1364,3 +1364,27 @@ func TestStatusSandbox(t *testing.T) {
 
 	s.Status()
 }
+
+func TestEnterContainer(t *testing.T) {
+	s, err := testCreateSandbox(t, testSandboxID, MockHypervisor, newHypervisorConfig(nil, nil), NoopAgentType, NoopNetworkModel, NetworkConfig{}, nil, nil)
+	assert.Nil(t, err, "VirtContainers should not allow empty sandboxes")
+	defer cleanUp()
+
+	contID := "999"
+	cmd := Cmd{}
+	_, _, err = s.EnterContainer(contID, cmd)
+	assert.NotNil(t, err, "Entering non-existing container should fail")
+
+	contConfig := newTestContainerConfigNoop(contID)
+	_, err = s.CreateContainer(contConfig)
+	assert.Nil(t, err, "Failed to create container %+v in sandbox %+v: %v", contConfig, s, err)
+
+	_, _, err = s.EnterContainer(contID, cmd)
+	assert.NotNil(t, err, "Entering non-running container should fail")
+
+	err = s.start()
+	assert.Nil(t, err, "Failed to start sandbox: %v", err)
+
+	_, _, err = s.EnterContainer(contID, cmd)
+	assert.Nil(t, err, "Enter container failed: %v", err)
+}