podman: support --mount type=devpts

Allow to create a devpts mount.

This is useful for containers that bind mount /dev/ from the host but
at the same time want to create a terminal.

It can be used as:

podman run -v /dev:/dev --mount type=devpts,target=/dev/pts ...

Closes: https://github.com/containers/podman/issues/6804

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

cmd/podman/common/volumes.go

@@ -20,6 +20,8 @@ const (
 	TypeVolume = "volume"
 	// TypeTmpfs is the type for mounting tmpfs
 	TypeTmpfs = "tmpfs"
+	// TypeDevpts is the type for creating a devpts
+	TypeDevpts = "devpts"
 )
 
 var (
@@ -197,6 +199,15 @@ func getMounts(mountFlag []string) (map[string]spec.Mount, map[string]*specgen.N
 				return nil, nil, errors.Wrapf(errDuplicateDest, mount.Destination)
 			}
 			finalMounts[mount.Destination] = mount
+		case TypeDevpts:
+			mount, err := getDevptsMount(tokens)
+			if err != nil {
+				return nil, nil, err
+			}
+			if _, ok := finalMounts[mount.Destination]; ok {
+				return nil, nil, errors.Wrapf(errDuplicateDest, mount.Destination)
+			}
+			finalMounts[mount.Destination] = mount
 		case "volume":
 			volume, err := getNamedVolume(tokens)
 			if err != nil {
@@ -416,6 +427,39 @@ func getTmpfsMount(args []string) (spec.Mount, error) {
 	return newMount, nil
 }
 
+// Parse a single devpts mount entry from the --mount flag
+func getDevptsMount(args []string) (spec.Mount, error) {
+	newMount := spec.Mount{
+		Type:   TypeDevpts,
+		Source: TypeDevpts,
+	}
+
+	var setDest bool
+
+	for _, val := range args {
+		kv := strings.Split(val, "=")
+		switch kv[0] {
+		case "target", "dst", "destination":
+			if len(kv) == 1 {
+				return newMount, errors.Wrapf(optionArgError, kv[0])
+			}
+			if err := parse.ValidateVolumeCtrDir(kv[1]); err != nil {
+				return newMount, err
+			}
+			newMount.Destination = filepath.Clean(kv[1])
+			setDest = true
+		default:
+			return newMount, errors.Wrapf(util.ErrBadMntOption, kv[0])
+		}
+	}
+
+	if !setDest {
+		return newMount, noDestError
+	}
+
+	return newMount, nil
+}
+
 // Parse a single volume mount entry from the --mount flag.
 // Note that the volume-label option for named volumes is currently NOT supported.
 // TODO: add support for --volume-label

docs/source/markdown/podman-create.1.md

@@ -494,7 +494,7 @@ Tune a container's memory swappiness behavior. Accepts an integer between 0 and
 
 Attach a filesystem mount to the container
 
-Current supported mount TYPES are `bind`, `volume`, and `tmpfs`. <sup>[[1]](#Footnote1)</sup>
+Current supported mount TYPES are `bind`, `volume`, `tmpfs` and `devpts`. <sup>[[1]](#Footnote1)</sup>
 
        e.g.
 
@@ -506,6 +506,8 @@ Current supported mount TYPES are `bind`, `volume`, and `tmpfs`. <sup>[[1]](#Foo
 
        type=tmpfs,tmpfs-size=512M,destination=/path/in/container
 
+       type=devpts,destination=/dev/pts
+
        Common Options:
 
               · src, source: mount source spec for bind and volume. Mandatory for bind.

docs/source/markdown/podman-run.1.md

@@ -501,7 +501,7 @@ Tune a container's memory swappiness behavior. Accepts an integer between *0* an
 
 Attach a filesystem mount to the container
 
-Current supported mount TYPEs are **bind**, **volume**, and **tmpfs**. <sup>[[1]](#Footnote1)</sup>
+Current supported mount TYPEs are **bind**, **volume**, **tmpfs** and **devpts**. <sup>[[1]](#Footnote1)</sup>
 
        e.g.
 
@@ -513,6 +513,8 @@ Current supported mount TYPEs are **bind**, **volume**, and **tmpfs**. <sup>[[1]
 
        type=tmpfs,tmpfs-size=512M,destination=/path/in/container
 
+       type=devpts,destination=/dev/pts
+
        Common Options:
 
 	      · src, source: mount source spec for bind and volume. Mandatory for bind.

test/e2e/run_test.go

@@ -811,6 +811,14 @@ USER mail`
 		Expect(len(session.OutputToStringArray())).To(Equal(1))
 	})
 
+	It("podman run --mount type=devpts,target=/foo/bar", func() {
+		SkipIfRootless()
+		session := podmanTest.Podman([]string{"run", "--mount", "type=devpts,target=/foo/bar", fedoraMinimal, "stat", "-f", "-c%T", "/foo/bar"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+		Expect(session.OutputToString()).To(ContainSubstring("devpts"))
+	})
+
 	It("podman run --pod automatically", func() {
 		session := podmanTest.Podman([]string{"run", "-d", "--pod", "new:foobar", ALPINE, "nc", "-l", "-p", "8080"})
 		session.WaitWithDefaultTimeout()