create: add support for --group-entry

* add test
* update documentation

Signed-off-by: danishprakash <danish.prakash@suse.com>

cmd/podman/common/create.go

@@ -604,6 +604,10 @@ func DefineCreateFlags(cmd *cobra.Command, cf *entities.ContainerCreateOptions,
 		createFlags.StringVar(&cf.PasswdEntry, passwdEntryName, "", "Entry to write to /etc/passwd")
 		_ = cmd.RegisterFlagCompletionFunc(passwdEntryName, completion.AutocompleteNone)
 
+		groupEntryName := "group-entry"
+		createFlags.StringVar(&cf.GroupEntry, groupEntryName, "", "Entry to write to /etc/group")
+		_ = cmd.RegisterFlagCompletionFunc(groupEntryName, completion.AutocompleteNone)
+
 		decryptionKeysFlagName := "decryption-key"
 		createFlags.StringSliceVar(
 			&cf.DecryptionKeys,

docs/source/markdown/options/group-entry.md

@@ -0,0 +1,9 @@
+####> This option file is used in:
+####>   podman create, run
+####> If file is edited, make sure the changes
+####> are applicable to all of those.
+#### **--group-entry**=*ENTRY*
+
+Customize the entry that is written to the `/etc/group` file within the container when `--user` is used.
+
+The variables $GROUPNAME, $GID, and $USERLIST are automatically replaced with their value at runtime if present.

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

@@ -161,6 +161,8 @@ See [**Environment**](#environment) note below for precedence and examples.
 
 @@option group-add
 
+@@option group-entry
+
 @@option health-cmd
 
 @@option health-interval

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

@@ -194,6 +194,8 @@ See [**Environment**](#environment) note below for precedence and examples.
 
 @@option group-add
 
+@@option group-entry
+
 @@option health-cmd
 
 @@option health-interval

libpod/container_config.go

@@ -354,6 +354,8 @@ type ContainerMiscConfig struct {
 	CgroupsMode string `json:"cgroupsMode,omitempty"`
 	// Cgroup parent of the container.
 	CgroupParent string `json:"cgroupParent"`
+	// GroupEntry specifies arbitrary data to append to a file.
+	GroupEntry string `json:"group_entry,omitempty"`
 	// LogPath log location
 	LogPath string `json:"logPath"`
 	// LogTag is the tag used for logging

libpod/container_internal_common.go

@@ -2226,7 +2226,7 @@ func (c *Container) generateGroupEntry() (string, error) {
 		groupString += entry
 		addedGID = gid
 	}
-	if c.config.User != "" {
+	if c.config.User != "" || c.config.GroupEntry != "" {
 		entry, err := c.generateUserGroupEntry(addedGID)
 		if err != nil {
 			return "", err
@@ -2281,7 +2281,7 @@ func (c *Container) generateCurrentUserGroupEntry() (string, int, error) {
 // Make an entry in /etc/group for the group the container was specified to run
 // as.
 func (c *Container) generateUserGroupEntry(addedGID int) (string, error) {
-	if c.config.User == "" {
+	if c.config.User == "" && c.config.GroupEntry == "" {
 		return "", nil
 	}
 
@@ -2301,14 +2301,26 @@ func (c *Container) generateUserGroupEntry(addedGID int) (string, error) {
 	}
 
 	// Check if the group already exists
-	_, err = lookup.GetGroup(c.state.Mountpoint, group)
+	g, err := lookup.GetGroup(c.state.Mountpoint, group)
 	if err != runcuser.ErrNoGroupEntries {
 		return "", err
 	}
 
+	if c.config.GroupEntry != "" {
+		return c.groupEntry(g.Name, strconv.Itoa(g.Gid), g.List), nil
+	}
+
 	return fmt.Sprintf("%d:x:%d:%s\n", gid, gid, splitUser[0]), nil
 }
 
+func (c *Container) groupEntry(groupname, gid string, list []string) string {
+	s := c.config.GroupEntry
+	s = strings.ReplaceAll(s, "$GROUPNAME", groupname)
+	s = strings.ReplaceAll(s, "$GID", gid)
+	s = strings.ReplaceAll(s, "$USERLIST", strings.Join(list, ","))
+	return s + "\n"
+}
+
 // generatePasswdEntry generates an entry or entries into /etc/passwd as
 // required by container configuration.
 // Generally speaking, we will make an entry under two circumstances:
@@ -2488,7 +2500,7 @@ func (c *Container) generateUserPasswdEntry(addedUID int) (string, error) {
 	return fmt.Sprintf("%d:*:%d:%d:container user:%s:/bin/sh\n", uid, uid, gid, c.WorkingDir()), nil
 }
 
-func (c *Container) passwdEntry(username string, uid, gid, name, homeDir string) string {
+func (c *Container) passwdEntry(username, uid, gid, name, homeDir string) string {
 	s := c.config.PasswdEntry
 	s = strings.ReplaceAll(s, "$USERNAME", username)
 	s = strings.ReplaceAll(s, "$UID", uid)
@@ -2512,7 +2524,7 @@ func (c *Container) passwdEntry(username string, uid, gid, name, homeDir string)
 // read-only. In this case, the function will return nothing ("", "", nil).
 func (c *Container) generatePasswdAndGroup() (string, string, error) {
 	if !c.config.AddCurrentUserPasswdEntry && c.config.User == "" &&
-		len(c.config.HostUsers) == 0 {
+		len(c.config.HostUsers) == 0 && c.config.GroupEntry == "" {
 		return "", "", nil
 	}
 

libpod/options.go

@@ -2277,6 +2277,19 @@ func WithPasswdEntry(passwdEntry string) CtrCreateOption {
 	}
 }
 
+// WithGroupEntry sets the entry to write to the /etc/group file.
+func WithGroupEntry(groupEntry string) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+
+		ctr.config.GroupEntry = groupEntry
+
+		return nil
+	}
+}
+
 // WithMountAllDevices sets the option to mount all of a privileged container's
 // host devices
 func WithMountAllDevices() CtrCreateOption {

pkg/domain/entities/pods.go

@@ -301,6 +301,7 @@ type ContainerCreateOptions struct {
 
 	CgroupConf []string
 
+	GroupEntry  string
 	PasswdEntry string
 }
 

pkg/specgen/generate/container_create.go

@@ -312,6 +312,9 @@ func createContainerOptions(rt *libpod.Runtime, s *specgen.SpecGenerator, pod *l
 	if s.PasswdEntry != "" {
 		options = append(options, libpod.WithPasswdEntry(s.PasswdEntry))
 	}
+	if s.GroupEntry != "" {
+		options = append(options, libpod.WithGroupEntry(s.GroupEntry))
+	}
 
 	if s.Privileged {
 		options = append(options, libpod.WithMountAllDevices())

pkg/specgen/specgen.go

@@ -160,7 +160,7 @@ type ContainerBasicConfig struct {
 	// Conflicts with UtsNS if UtsNS is not set to private.
 	// Optional.
 	Hostname string `json:"hostname,omitempty"`
-	// HostUses is a list of host usernames or UIDs to add to the container
+	// HostUsers is a list of host usernames or UIDs to add to the container
 	// /etc/passwd file
 	HostUsers []string `json:"hostusers,omitempty"`
 	// Sysctl sets kernel parameters for the container
@@ -219,6 +219,8 @@ type ContainerBasicConfig struct {
 	Passwd *bool `json:"manage_password,omitempty"`
 	// PasswdEntry specifies arbitrary data to append to a file.
 	PasswdEntry string `json:"passwd_entry,omitempty"`
+	// GroupEntry specifies arbitrary data to append to a file.
+	GroupEntry string `json:"group_entry,omitempty"`
 }
 
 // ContainerStorageConfig contains information on the storage configuration of a

pkg/specgenutil/specgen.go

@@ -848,6 +848,10 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *entities.ContainerCreateOptions
 		s.PasswdEntry = c.PasswdEntry
 	}
 
+	if len(s.GroupEntry) == 0 || len(c.GroupEntry) != 0 {
+		s.GroupEntry = c.GroupEntry
+	}
+
 	return nil
 }
 

test/e2e/run_passwd_test.go

@@ -153,4 +153,16 @@ USER 1000`, ALPINE)
 		Expect(run).Should(Exit(0))
 		Expect(run.OutputToString()).To(ContainSubstring("12345-12346-container user-/etc-12345"))
 	})
+
+	It("podman run --group-entry flag", func() {
+		// Test that the line we add doesn't contain anything else than what is specified
+		run := podmanTest.Podman([]string{"run", "--user", "1234:1234", "--group-entry=FOO", ALPINE, "grep", "^FOO$", "/etc/group"})
+		run.WaitWithDefaultTimeout()
+		Expect(run).Should(Exit(0))
+
+		run = podmanTest.Podman([]string{"run", "--user", "12345:12346", "--group-entry=$GID", ALPINE, "tail", "/etc/group"})
+		run.WaitWithDefaultTimeout()
+		Expect(run).Should(Exit(0))
+		Expect(run.OutputToString()).To(ContainSubstring("12346"))
+	})
 })