Implement Podman Container Clone

podman container clone takes the id of an existing continer and creates a specgen from the given container's config
recreating all proper namespaces and overriding spec options like resource limits and the container name if given in the cli options

this command utilizes the common function DefineCreateFlags meaning that we can funnel as many create options as we want
into clone over time allowing the user to clone with as much or as little of the original config as they want.

container clone takes a second argument which is a new name and a third argument which is an image name to use instead of the original container's

the current supported flags are:

--destroy (remove the original container)
--name (new ctr name)
--cpus (sets cpu period and quota)
--cpuset-cpus
--cpu-period
--cpu-rt-period
--cpu-rt-runtime
--cpu-shares
--cpuset-mems
--memory
--run

resolves #10875

Signed-off-by: cdoern <cdoern@redhat.com>
Signed-off-by: cdoern <cbdoer23@g.holycross.edu>
Signed-off-by: cdoern <cdoern@redhat.com>

4 files changed, 197 insertions, 3 deletions

diff --git a/pkg/specgen/generate/container.go b/pkg/specgen/generate/container.go
index a4d862a60..64669f34d 100644
--- a/pkg/specgen/generate/container.go
+++ b/pkg/specgen/generate/container.go
@@ -2,6 +2,7 @@ package generate
 
 import (
 	"context"
+	"encoding/json"
 	"os"
 	"strings"
 	"time"
@@ -335,3 +336,152 @@ func FinishThrottleDevices(s *specgen.SpecGenerator) error {
 	}
 	return nil
 }
+
+// ConfigToSpec takes a completed container config and converts it back into a specgenerator for purposes of cloning an exisiting container
+func ConfigToSpec(rt *libpod.Runtime, specg *specgen.SpecGenerator, contaierID string) (*libpod.Container, error) {
+	c, err := rt.LookupContainer(contaierID)
+	if err != nil {
+		return nil, err
+	}
+	conf := c.Config()
+
+	tmpSystemd := conf.Systemd
+	tmpMounts := conf.Mounts
+
+	conf.Systemd = nil
+	conf.Mounts = []string{}
+
+	specg.Pod = conf.Pod
+
+	matching, err := json.Marshal(conf)
+	if err != nil {
+		return nil, err
+	}
+
+	err = json.Unmarshal(matching, specg)
+	if err != nil {
+		return nil, err
+	}
+	conf.Systemd = tmpSystemd
+	conf.Mounts = tmpMounts
+
+	if conf.Spec != nil && conf.Spec.Linux != nil && conf.Spec.Linux.Resources != nil {
+		if specg.ResourceLimits == nil {
+			specg.ResourceLimits = conf.Spec.Linux.Resources
+		}
+	}
+
+	nameSpaces := []string{"pid", "net", "cgroup", "ipc", "uts", "user"}
+	containers := []string{conf.PIDNsCtr, conf.NetNsCtr, conf.CgroupNsCtr, conf.IPCNsCtr, conf.UTSNsCtr, conf.UserNsCtr}
+	place := []*specgen.Namespace{&specg.PidNS, &specg.NetNS, &specg.CgroupNS, &specg.IpcNS, &specg.UtsNS, &specg.UserNS}
+	for i, ns := range containers {
+		if len(ns) > 0 {
+			ns := specgen.Namespace{NSMode: specgen.FromContainer, Value: ns}
+			place[i] = &ns
+		} else {
+			switch nameSpaces[i] {
+			case "pid":
+				specg.PidNS = specgen.Namespace{NSMode: specgen.Default} //default
+			case "net":
+				switch {
+				case conf.NetMode.IsBridge():
+					toExpose := make(map[uint16]string, len(conf.ExposedPorts))
+					for _, expose := range []map[uint16][]string{conf.ExposedPorts} {
+						for port, proto := range expose {
+							toExpose[port] = strings.Join(proto, ",")
+						}
+					}
+					specg.Expose = toExpose
+					specg.PortMappings = conf.PortMappings
+					specg.NetNS = specgen.Namespace{NSMode: specgen.Bridge}
+				case conf.NetMode.IsSlirp4netns():
+					toExpose := make(map[uint16]string, len(conf.ExposedPorts))
+					for _, expose := range []map[uint16][]string{conf.ExposedPorts} {
+						for port, proto := range expose {
+							toExpose[port] = strings.Join(proto, ",")
+						}
+					}
+					specg.Expose = toExpose
+					specg.PortMappings = conf.PortMappings
+					netMode := strings.Split(string(conf.NetMode), ":")
+					var val string
+					if len(netMode) > 1 {
+						val = netMode[1]
+					}
+					specg.NetNS = specgen.Namespace{NSMode: specgen.Slirp, Value: val}
+				case conf.NetMode.IsPrivate():
+					specg.NetNS = specgen.Namespace{NSMode: specgen.Private}
+				case conf.NetMode.IsDefault():
+					specg.NetNS = specgen.Namespace{NSMode: specgen.Default}
+				case conf.NetMode.IsUserDefined():
+					specg.NetNS = specgen.Namespace{NSMode: specgen.Path, Value: strings.Split(string(conf.NetMode), ":")[1]}
+				case conf.NetMode.IsContainer():
+					specg.NetNS = specgen.Namespace{NSMode: specgen.FromContainer, Value: strings.Split(string(conf.NetMode), ":")[1]}
+				case conf.NetMode.IsPod():
+					specg.NetNS = specgen.Namespace{NSMode: specgen.FromPod, Value: strings.Split(string(conf.NetMode), ":")[1]}
+				}
+			case "cgroup":
+				specg.CgroupNS = specgen.Namespace{NSMode: specgen.Default} //default
+			case "ipc":
+				if conf.ShmDir == "/dev/shm" {
+					specg.IpcNS = specgen.Namespace{NSMode: specgen.Host}
+				} else {
+					specg.IpcNS = specgen.Namespace{NSMode: specgen.Default} //default
+				}
+			case "uts":
+				specg.UtsNS = specgen.Namespace{NSMode: specgen.Default} //default
+			case "user":
+				if conf.AddCurrentUserPasswdEntry {
+					specg.UserNS = specgen.Namespace{NSMode: specgen.KeepID}
+				} else {
+					specg.UserNS = specgen.Namespace{NSMode: specgen.Default} //default
+				}
+			}
+		}
+	}
+
+	specg.IDMappings = &conf.IDMappings
+	specg.ContainerCreateCommand = conf.CreateCommand
+	if len(specg.Rootfs) == 0 {
+		specg.Rootfs = conf.Rootfs
+	}
+	if len(specg.Image) == 0 {
+		specg.Image = conf.RootfsImageID
+	}
+	var named []*specgen.NamedVolume
+	if len(conf.NamedVolumes) != 0 {
+		for _, v := range conf.NamedVolumes {
+			named = append(named, &specgen.NamedVolume{
+				Name:    v.Name,
+				Dest:    v.Dest,
+				Options: v.Options,
+			})
+		}
+	}
+	specg.Volumes = named
+	var image []*specgen.ImageVolume
+	if len(conf.ImageVolumes) != 0 {
+		for _, v := range conf.ImageVolumes {
+			image = append(image, &specgen.ImageVolume{
+				Source:      v.Source,
+				Destination: v.Dest,
+				ReadWrite:   v.ReadWrite,
+			})
+		}
+	}
+	specg.ImageVolumes = image
+	var overlay []*specgen.OverlayVolume
+	if len(conf.OverlayVolumes) != 0 {
+		for _, v := range conf.OverlayVolumes {
+			overlay = append(overlay, &specgen.OverlayVolume{
+				Source:      v.Source,
+				Destination: v.Dest,
+				Options:     v.Options,
+			})
+		}
+	}
+	specg.OverlayVolumes = overlay
+	specg.Mounts = conf.Spec.Mounts
+	specg.HostDeviceList = conf.DeviceHostSrc
+	return c, nil
+}
diff --git a/pkg/specgen/generate/container_create.go b/pkg/specgen/generate/container_create.go
index a7a7353d0..c0b23953f 100644
--- a/pkg/specgen/generate/container_create.go
+++ b/pkg/specgen/generate/container_create.go
@@ -8,6 +8,7 @@ import (
 
 	cdi "github.com/container-orchestrated-devices/container-device-interface/pkg/cdi"
 	"github.com/containers/common/libimage"
+	"github.com/containers/common/pkg/cgroups"
 	"github.com/containers/podman/v4/libpod"
 	"github.com/containers/podman/v4/libpod/define"
 	"github.com/containers/podman/v4/pkg/namespaces"
@@ -22,7 +23,7 @@ import (
 // MakeContainer creates a container based on the SpecGenerator.
 // Returns the created, container and any warnings resulting from creating the
 // container, or an error.
-func MakeContainer(ctx context.Context, rt *libpod.Runtime, s *specgen.SpecGenerator) (*spec.Spec, *specgen.SpecGenerator, []libpod.CtrCreateOption, error) {
+func MakeContainer(ctx context.Context, rt *libpod.Runtime, s *specgen.SpecGenerator, clone bool, c *libpod.Container) (*spec.Spec, *specgen.SpecGenerator, []libpod.CtrCreateOption, error) {
 	rtc, err := rt.GetConfigNoCopy()
 	if err != nil {
 		return nil, nil, nil, err
@@ -170,6 +171,42 @@ func MakeContainer(ctx context.Context, rt *libpod.Runtime, s *specgen.SpecGener
 		options = append(options, opts...)
 	}
 	runtimeSpec, err := SpecGenToOCI(ctx, s, rt, rtc, newImage, finalMounts, pod, command, compatibleOptions)
+	if clone { // the container fails to start if cloned due to missing Linux spec entries
+		if c == nil {
+			return nil, nil, nil, errors.New("the given container could not be retrieved")
+		}
+		conf := c.Config()
+		out, err := json.Marshal(conf.Spec.Linux)
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		err = json.Unmarshal(out, runtimeSpec.Linux)
+		if err != nil {
+			return nil, nil, nil, err
+		}
+
+		switch {
+		case s.ResourceLimits.CPU != nil:
+			runtimeSpec.Linux.Resources.CPU = s.ResourceLimits.CPU
+		case s.ResourceLimits.Memory != nil:
+			runtimeSpec.Linux.Resources.Memory = s.ResourceLimits.Memory
+		case s.ResourceLimits.BlockIO != nil:
+			runtimeSpec.Linux.Resources.BlockIO = s.ResourceLimits.BlockIO
+		case s.ResourceLimits.Devices != nil:
+			runtimeSpec.Linux.Resources.Devices = s.ResourceLimits.Devices
+		}
+
+		cgroup2, err := cgroups.IsCgroup2UnifiedMode()
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		if cgroup2 && s.ResourceLimits.Memory != nil && s.ResourceLimits.Memory.Swappiness != nil { // conf.Spec.Linux contains memory swappiness established after the spec process we need to remove that
+			s.ResourceLimits.Memory.Swappiness = nil
+			if runtimeSpec.Linux.Resources.Memory != nil {
+				runtimeSpec.Linux.Resources.Memory.Swappiness = nil
+			}
+		}
+	}
 	if err != nil {
 		return nil, nil, nil, err
 	}
diff --git a/pkg/specgen/generate/oci.go b/pkg/specgen/generate/oci.go
index 945c994ea..8b3550e36 100644
--- a/pkg/specgen/generate/oci.go
+++ b/pkg/specgen/generate/oci.go
@@ -301,7 +301,14 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
 	}
 
 	if compatibleOptions.InfraResources == nil && s.ResourceLimits != nil {
-		g.Config.Linux.Resources = s.ResourceLimits
+		out, err := json.Marshal(s.ResourceLimits)
+		if err != nil {
+			return nil, err
+		}
+		err = json.Unmarshal(out, g.Config.Linux.Resources)
+		if err != nil {
+			return nil, err
+		}
 	} else if s.ResourceLimits != nil { // if we have predefined resource limits we need to make sure we keep the infra and container limits
 		originalResources, err := json.Marshal(s.ResourceLimits)
 		if err != nil {
diff --git a/pkg/specgen/generate/pod_create.go b/pkg/specgen/generate/pod_create.go
index 68fda3ad7..8450fe7ce 100644
--- a/pkg/specgen/generate/pod_create.go
+++ b/pkg/specgen/generate/pod_create.go
@@ -135,7 +135,7 @@ func MakePod(p *entities.PodSpec, rt *libpod.Runtime) (*libpod.Pod, error) {
 			return nil, err
 		}
 		p.PodSpecGen.InfraContainerSpec.User = "" // infraSpec user will get incorrectly assigned via the container creation process, overwrite here
-		rtSpec, spec, opts, err := MakeContainer(context.Background(), rt, p.PodSpecGen.InfraContainerSpec)
+		rtSpec, spec, opts, err := MakeContainer(context.Background(), rt, p.PodSpecGen.InfraContainerSpec, false, nil)
 		if err != nil {
 			return nil, err
 		}