initial commit

pkg/containers/podman/podman.go

@@ -0,0 +1,32 @@
+package podman
+
+// Client talks to Podman socket inside a container.
+type Client interface {
+	List(ctID string) ([]OCIContainer, error)
+	Create(ctID string, spec CreateSpec) (OCIContainer, error)
+	Start(ctID, cid string) error
+	Stop(ctID, cid string) error
+	Delete(ctID, cid string) error
+}
+
+type CreateSpec struct {
+	Image   string
+	Cmd     []string
+	Env     map[string]string
+	Ports   []PortMap
+	Volumes []string
+	Restart string
+}
+
+type PortMap struct {
+	HostPort      int
+	ContainerPort int
+}
+
+type OCIContainer struct {
+	ID     string
+	Image  string
+	Status string
+}
+
+// TODO: connect via nsenter into CT and talk to Podman socket.

pkg/containers/podman/podman_cmd.go

@@ -0,0 +1,122 @@
+package podman
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+// CmdClient talks to podman socket via CLI.
+type CmdClient struct {
+	SocketPath string
+}
+
+func NewCmdClient(sock string) *CmdClient {
+	return &CmdClient{SocketPath: sock}
+}
+
+func (c *CmdClient) List(ctID string) ([]OCIContainer, error) {
+	args := c.baseArgs(ctID, "ps", "--format", "json")
+	out, err := exec.Command(args[0], args[1:]...).Output()
+	if err != nil {
+		return nil, err
+	}
+	var parsed []struct {
+		ID     string `json:"Id"`
+		Image  string `json:"Image"`
+		Status string `json:"Status"`
+	}
+	if err := json.Unmarshal(out, &parsed); err != nil {
+		return nil, err
+	}
+	res := make([]OCIContainer, 0, len(parsed))
+	for _, p := range parsed {
+		res = append(res, OCIContainer{ID: p.ID, Image: p.Image, Status: p.Status})
+	}
+	return res, nil
+}
+
+func (c *CmdClient) Create(ctID string, spec CreateSpec) (OCIContainer, error) {
+	args := c.baseArgs(ctID, "create")
+	for k, v := range spec.Env {
+		args = append(args, "--env", k+"="+v)
+	}
+	for _, v := range spec.Volumes {
+		args = append(args, "-v", v)
+	}
+	for _, p := range spec.Ports {
+		args = append(args, "-p", formatPort(p))
+	}
+	if spec.Restart != "" {
+		args = append(args, "--restart", spec.Restart)
+	}
+	args = append(args, spec.Image)
+	args = append(args, spec.Cmd...)
+	out, err := exec.Command(args[0], args[1:]...).CombinedOutput()
+	if err != nil {
+		return OCIContainer{}, err
+	}
+	id := strings.TrimSpace(string(out))
+	return OCIContainer{ID: id, Image: spec.Image, Status: "created"}, nil
+}
+
+func (c *CmdClient) Start(ctID, cid string) error {
+	args := c.baseArgs(ctID, "start", cid)
+	return exec.Command(args[0], args[1:]...).Run()
+}
+
+func (c *CmdClient) Stop(ctID, cid string) error {
+	args := c.baseArgs(ctID, "stop", cid)
+	return exec.Command(args[0], args[1:]...).Run()
+}
+
+func (c *CmdClient) Delete(ctID, cid string) error {
+	args := c.baseArgs(ctID, "rm", "-f", cid)
+	return exec.Command(args[0], args[1:]...).Run()
+}
+
+// baseArgs chooses how to enter the CT: prefer nsenter into CT init pid; otherwise use host socket.
+func (c *CmdClient) baseArgs(ctID string, args ...string) []string {
+	nsPrefix := []string{}
+	if ctID != "" {
+		pid := containerInitPID(ctID)
+		if pid > 0 {
+			nsPrefix = []string{"nsenter", "-t", fmt.Sprintf("%d", pid), "-n", "-m", "-u", "-i", "--"}
+		}
+	}
+	full := append([]string{"podman"}, args...)
+	if len(nsPrefix) > 0 {
+		return append(nsPrefix, full...)
+	}
+	// fallback to socket on host
+	if c.SocketPath != "" {
+		full = append([]string{"podman", "--url", "unix://" + c.SocketPath}, args...)
+	}
+	return full
+}
+
+func formatPort(p PortMap) string {
+	return fmt.Sprintf("%d:%d", p.HostPort, p.ContainerPort)
+}
+
+func fileExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+// containerInitPID returns the PID of the CT's init using lxc-info.
+func containerInitPID(ctID string) int {
+	out, err := exec.Command("lxc-info", "-n", ctID, "-pH").Output()
+	if err != nil {
+		return 0
+	}
+	pidStr := strings.TrimSpace(string(out))
+	pid, err := strconv.Atoi(pidStr)
+	if err != nil {
+		return 0
+	}
+	return pid
+}