resources: Add a group resource

examples/group1.yaml

@@ -0,0 +1,8 @@
+---
+graph: mygraph
+resources:
+  group:
+  - name: testgroup
+    state: exists
+    gid: 10000
+edges: []

resources/group.go

@@ -0,0 +1,294 @@
+// Mgmt
+// Copyright (C) 2013-2017+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package resources
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os/exec"
+	"os/user"
+	"strconv"
+	"syscall"
+
+	"github.com/purpleidea/mgmt/recwatch"
+
+	errwrap "github.com/pkg/errors"
+)
+
+func init() {
+	RegisterResource("group", func() Res { return &GroupRes{} })
+}
+
+const groupFile = "/etc/group"
+
+// GroupRes is a user group resource.
+type GroupRes struct {
+	BaseRes `yaml:",inline"`
+	State   string  `yaml:"state"` // state: exists, absent
+	GID     *uint32 `yaml:"gid"`
+
+	recWatcher *recwatch.RecWatcher
+}
+
+// Default returns some sensible defaults for this resource.
+func (obj *GroupRes) Default() Res {
+	return &GroupRes{
+		BaseRes: BaseRes{
+			MetaParams: DefaultMetaParams, // force a default
+		},
+	}
+}
+
+// Validate if the params passed in are valid data.
+func (obj *GroupRes) Validate() error {
+	if obj.State != "exists" && obj.State != "absent" {
+		return fmt.Errorf("State must be 'exists' or 'absent'")
+	}
+	return obj.BaseRes.Validate()
+}
+
+// Init initializes the resource.
+func (obj *GroupRes) Init() error {
+	return obj.BaseRes.Init() // call base init, b/c we're overriding
+}
+
+// Watch is the primary listener for this resource and it outputs events.
+func (obj *GroupRes) Watch() error {
+	var err error
+	obj.recWatcher, err = recwatch.NewRecWatcher(groupFile, false)
+	if err != nil {
+		return err
+	}
+	defer obj.recWatcher.Close()
+
+	// notify engine that we're running
+	if err := obj.Running(); err != nil {
+		return err // bubble up a NACK...
+	}
+
+	var send = false // send event?
+	var exit *error
+
+	for {
+		if obj.debug {
+			log.Printf("%s: Watching: %s", obj, groupFile) // attempting to watch...
+		}
+
+		select {
+		case event, ok := <-obj.recWatcher.Events():
+			if !ok { // channel shutdown
+				return nil
+			}
+			if err := event.Error; err != nil {
+				return errwrap.Wrapf(err, "Unknown %s watcher error", obj)
+			}
+			if obj.debug { // don't access event.Body if event.Error isn't nil
+				log.Printf("%s: Event(%s): %v", obj, event.Body.Name, event.Body.Op)
+			}
+			send = true
+			obj.StateOK(false) // dirty
+
+		case event := <-obj.Events():
+			if exit, send = obj.ReadEvent(event); exit != nil {
+				return *exit // exit
+			}
+			//obj.StateOK(false) // dirty // these events don't invalidate state
+		}
+
+		// do all our event sending all together to avoid duplicate msgs
+		if send {
+			send = false
+			obj.Event()
+		}
+	}
+}
+
+// CheckApply method for Group resource.
+func (obj *GroupRes) CheckApply(apply bool) (checkOK bool, err error) {
+	log.Printf("%s: CheckApply(%t)", obj, apply)
+
+	// check if the group exists
+	exists := true
+	group, err := user.LookupGroup(obj.GetName())
+	if err != nil {
+		if _, ok := err.(user.UnknownGroupError); !ok {
+			return false, errwrap.Wrapf(err, "error looking up group")
+		}
+		log.Printf("%s: Group not found: %s", obj, obj.GetName())
+		exists = false
+	}
+	// if the group doesn't exist and should be absent, we are done
+	if obj.State == "absent" && !exists {
+		return true, nil
+	}
+	// if the group exists and no GID is specified, we are done
+	if obj.State == "exists" && exists && obj.GID == nil {
+		return true, nil
+	}
+	if exists && obj.GID != nil {
+		// check if GID is taken
+		lookupGID, err := user.LookupGroupId(strconv.Itoa(int(*obj.GID)))
+		if err != nil {
+			if _, ok := err.(user.UnknownGroupIdError); !ok {
+				return false, errwrap.Wrapf(err, "error looking up GID")
+			}
+		}
+		if lookupGID != nil && lookupGID.Name != obj.GetName() {
+			return false, fmt.Errorf("the requested GID belongs to another group")
+		}
+		// get the existing group's GID
+		existingGID, err := strconv.ParseUint(group.Gid, 10, 32)
+		if err != nil {
+			return false, errwrap.Wrapf(err, "error casting existing GID")
+		}
+		// check if existing group has the wrong GID
+		// if it is wrong groupmod will change it to the desired value
+		if *obj.GID != uint32(existingGID) {
+			log.Printf("%s: Inconsistent GID: %s", obj, obj.GetName())
+		}
+		// if the group exists and has the correct GID, we are done
+		if obj.State == "exists" && *obj.GID == uint32(existingGID) {
+			return true, nil
+		}
+	}
+
+	if !apply {
+		return false, nil
+	}
+
+	var cmdName string
+	args := []string{obj.GetName()}
+
+	if obj.State == "exists" {
+		if exists {
+			log.Printf("%s: Modifying group: %s", obj, obj.GetName())
+			cmdName = "groupmod"
+		} else {
+			log.Printf("%s: Adding group: %s", obj, obj.GetName())
+			cmdName = "groupadd"
+		}
+		if obj.GID != nil {
+			args = append(args, "-g", fmt.Sprintf("%d", *obj.GID))
+		}
+	}
+	if obj.State == "absent" && exists {
+		log.Printf("%s: Deleting group: %s", obj, obj.GetName())
+		cmdName = "groupdel"
+	}
+
+	cmd := exec.Command(cmdName, args...)
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setpgid: true,
+		Pgid:    0,
+	}
+
+	// open a pipe to get error messages from os/exec
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		return false, errwrap.Wrapf(err, "failed to initialize stderr pipe")
+	}
+
+	// start the command
+	if err := cmd.Start(); err != nil {
+		return false, errwrap.Wrapf(err, "cmd failed to start")
+	}
+	// capture any error messages
+	slurp, err := ioutil.ReadAll(stderr)
+	if err != nil {
+		return false, errwrap.Wrapf(err, "error slurping error message")
+	}
+	// wait until cmd exits and return error message if any
+	if err := cmd.Wait(); err != nil {
+		return false, errwrap.Wrapf(err, "%s", slurp)
+	}
+
+	return false, nil
+}
+
+// GroupUID is the UID struct for GroupRes.
+type GroupUID struct {
+	BaseUID
+	name string
+}
+
+// UIDs includes all params to make a unique identification of this object.
+// Most resources only return one, although some resources can return multiple.
+func (obj *GroupRes) UIDs() []ResUID {
+	x := &GroupUID{
+		BaseUID: BaseUID{Name: obj.GetName(), Kind: obj.GetKind()},
+		name:    obj.Name,
+	}
+	return []ResUID{x}
+}
+
+// GroupCmp returns whether two resources can be grouped together or not.
+func (obj *GroupRes) GroupCmp(r Res) bool {
+	_, ok := r.(*GroupRes)
+	if !ok {
+		return false
+	}
+	return false
+}
+
+// Compare two resources and return if they are equivalent.
+func (obj *GroupRes) Compare(r Res) bool {
+	// we can only compare GroupRes to others of the same resource kind
+	res, ok := r.(*GroupRes)
+	if !ok {
+		return false
+	}
+	if !obj.BaseRes.Compare(res) { // call base Compare
+		return false
+	}
+	if obj.Name != res.Name {
+		return false
+	}
+	if obj.State != res.State {
+		return false
+	}
+	if (obj.GID == nil) != (res.GID == nil) {
+		return false
+	}
+	if obj.GID != nil && res.GID != nil {
+		if *obj.GID != *res.GID {
+			return false
+		}
+	}
+	return true
+}
+
+// UnmarshalYAML is the custom unmarshal handler for this struct.
+// It is primarily useful for setting the defaults.
+func (obj *GroupRes) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type rawRes GroupRes // indirection to avoid infinite recursion
+
+	def := obj.Default()       // get the default
+	res, ok := def.(*GroupRes) // put in the right format
+	if !ok {
+		return fmt.Errorf("could not convert to GroupRes")
+	}
+	raw := rawRes(*res) // convert; the defaults go here
+
+	if err := unmarshal(&raw); err != nil {
+		return err
+	}
+
+	*obj = GroupRes(raw) // restore from indirection with type conversion!
+	return nil
+}

yamlgraph/gconfig.go

@@ -60,6 +60,7 @@ type Resources struct {
 	Exec     []*resources.ExecRes     `yaml:"exec"`
 	File     []*resources.FileRes     `yaml:"file"`
 	Graph    []*resources.GraphRes    `yaml:"graph"`
+	Group    []*resources.GroupRes    `yaml:"group"`
 	Hostname []*resources.HostnameRes `yaml:"hostname"`
 	KV       []*resources.KVRes       `yaml:"kv"`
 	Msg      []*resources.MsgRes      `yaml:"msg"`