engine: Resources package rewrite
This giant patch makes some much needed improvements to the code base. * The engine has been rewritten and lives within engine/graph/ * All of the common interfaces and code now live in engine/ * All of the resources are in one package called engine/resources/ * The Res API can use different "traits" from engine/traits/ * The Res API has been simplified to hide many of the old internals * The Watch & Process loops were previously inverted, but is now fixed * The likelihood of package cycles has been reduced drastically * And much, much more... Unfortunately, some code had to be temporarily removed. The remote code had to be taken out, as did the prometheus code. We hope to have these back in new forms as soon as possible.
This commit is contained in:
James Shubin
317
engine/resources/group.go
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317
engine/resources/group.go
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// Mgmt
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// Copyright (C) 2013-2018+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package resources
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import (
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"fmt"
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"io/ioutil"
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"os/exec"
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"os/user"
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"strconv"
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"syscall"
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"github.com/purpleidea/mgmt/engine"
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"github.com/purpleidea/mgmt/engine/traits"
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"github.com/purpleidea/mgmt/recwatch"
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errwrap "github.com/pkg/errors"
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)
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func init() {
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engine.RegisterResource("group", func() engine.Res { return &GroupRes{} })
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}
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const groupFile = "/etc/group"
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// GroupRes is a user group resource.
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type GroupRes struct {
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traits.Base // add the base methods without re-implementation
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init *engine.Init
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State string `yaml:"state"` // state: exists, absent
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GID *uint32 `yaml:"gid"` // the group's gid
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recWatcher *recwatch.RecWatcher
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}
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// Default returns some sensible defaults for this resource.
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func (obj *GroupRes) Default() engine.Res {
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return &GroupRes{}
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}
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// Validate if the params passed in are valid data.
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func (obj *GroupRes) Validate() error {
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if obj.State != "exists" && obj.State != "absent" {
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return fmt.Errorf("State must be 'exists' or 'absent'")
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}
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return nil
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}
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// Init runs some startup code for this resource.
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func (obj *GroupRes) Init(init *engine.Init) error {
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obj.init = init // save for later
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return nil
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}
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// Close is run by the engine to clean up after the resource is done.
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func (obj *GroupRes) Close() error {
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return nil
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}
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// Watch is the primary listener for this resource and it outputs events.
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func (obj *GroupRes) Watch() error {
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var err error
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obj.recWatcher, err = recwatch.NewRecWatcher(groupFile, false)
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if err != nil {
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return err
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}
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defer obj.recWatcher.Close()
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// notify engine that we're running
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if err := obj.init.Running(); err != nil {
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return err // exit if requested
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}
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var send = false // send event?
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for {
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if obj.init.Debug {
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obj.init.Logf("Watching: %s", groupFile) // attempting to watch...
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}
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select {
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case event, ok := <-obj.recWatcher.Events():
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if !ok { // channel shutdown
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return nil
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}
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if err := event.Error; err != nil {
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return errwrap.Wrapf(err, "Unknown %s watcher error", obj)
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}
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if obj.init.Debug { // don't access event.Body if event.Error isn't nil
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obj.init.Logf("Event(%s): %v", event.Body.Name, event.Body.Op)
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}
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send = true
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obj.init.Dirty() // dirty
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case event, ok := <-obj.init.Events:
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if !ok {
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return nil
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}
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if err := obj.init.Read(event); err != nil {
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return err
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}
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}
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// do all our event sending all together to avoid duplicate msgs
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if send {
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send = false
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if err := obj.init.Event(); err != nil {
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return err // exit if requested
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}
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}
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}
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}
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// CheckApply method for Group resource.
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func (obj *GroupRes) CheckApply(apply bool) (checkOK bool, err error) {
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obj.init.Logf("CheckApply(%t)", apply)
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// check if the group exists
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exists := true
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group, err := user.LookupGroup(obj.Name())
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if err != nil {
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if _, ok := err.(user.UnknownGroupError); !ok {
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return false, errwrap.Wrapf(err, "error looking up group")
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}
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exists = false
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}
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// if the group doesn't exist and should be absent, we are done
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if obj.State == "absent" && !exists {
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return true, nil
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}
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// if the group exists and no GID is specified, we are done
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if obj.State == "exists" && exists && obj.GID == nil {
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return true, nil
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}
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if exists && obj.GID != nil {
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// check if GID is taken
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lookupGID, err := user.LookupGroupId(strconv.Itoa(int(*obj.GID)))
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if err != nil {
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if _, ok := err.(user.UnknownGroupIdError); !ok {
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return false, errwrap.Wrapf(err, "error looking up GID")
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}
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}
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if lookupGID != nil && lookupGID.Name != obj.Name() {
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return false, fmt.Errorf("the requested GID belongs to another group")
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}
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// get the existing group's GID
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existingGID, err := strconv.ParseUint(group.Gid, 10, 32)
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if err != nil {
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return false, errwrap.Wrapf(err, "error casting existing GID")
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}
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// check if existing group has the wrong GID
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// if it is wrong groupmod will change it to the desired value
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if *obj.GID != uint32(existingGID) {
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obj.init.Logf("Inconsistent GID: %s", obj.Name())
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}
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// if the group exists and has the correct GID, we are done
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if obj.State == "exists" && *obj.GID == uint32(existingGID) {
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return true, nil
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}
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}
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if !apply {
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return false, nil
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}
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var cmdName string
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args := []string{obj.Name()}
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if obj.State == "exists" {
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if exists {
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obj.init.Logf("Modifying group: %s", obj.Name())
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cmdName = "groupmod"
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} else {
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obj.init.Logf("Adding group: %s", obj.Name())
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cmdName = "groupadd"
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}
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if obj.GID != nil {
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args = append(args, "-g", fmt.Sprintf("%d", *obj.GID))
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}
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}
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if obj.State == "absent" && exists {
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obj.init.Logf("Deleting group: %s", obj.Name())
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cmdName = "groupdel"
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}
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cmd := exec.Command(cmdName, args...)
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cmd.SysProcAttr = &syscall.SysProcAttr{
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Setpgid: true,
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Pgid: 0,
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}
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// open a pipe to get error messages from os/exec
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stderr, err := cmd.StderrPipe()
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if err != nil {
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return false, errwrap.Wrapf(err, "failed to initialize stderr pipe")
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}
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// start the command
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if err := cmd.Start(); err != nil {
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return false, errwrap.Wrapf(err, "cmd failed to start")
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}
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// capture any error messages
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slurp, err := ioutil.ReadAll(stderr)
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if err != nil {
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return false, errwrap.Wrapf(err, "error slurping error message")
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}
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// wait until cmd exits and return error message if any
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if err := cmd.Wait(); err != nil {
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return false, errwrap.Wrapf(err, "%s", slurp)
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}
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return false, nil
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}
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// Cmp compares two resources and returns an error if they are not equivalent.
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func (obj *GroupRes) Cmp(r engine.Res) error {
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if !obj.Compare(r) {
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return fmt.Errorf("did not compare")
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}
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return nil
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}
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// Compare two resources and return if they are equivalent.
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func (obj *GroupRes) Compare(r engine.Res) bool {
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// we can only compare GroupRes to others of the same resource kind
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res, ok := r.(*GroupRes)
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if !ok {
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return false
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}
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if obj.State != res.State {
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return false
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}
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if (obj.GID == nil) != (res.GID == nil) {
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return false
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}
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if obj.GID != nil && res.GID != nil {
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if *obj.GID != *res.GID {
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return false
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}
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}
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return true
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}
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// GroupUID is the UID struct for GroupRes.
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type GroupUID struct {
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engine.BaseUID
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name string
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gid *uint32
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}
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// IFF aka if and only if they are equivalent, return true. If not, false.
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func (obj *GroupUID) IFF(uid engine.ResUID) bool {
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res, ok := uid.(*GroupUID)
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if !ok {
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return false
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}
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if obj.gid != nil && res.gid != nil {
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if *obj.gid != *res.gid {
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return false
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}
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}
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if obj.name != "" && res.name != "" {
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if obj.name != res.name {
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return false
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}
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}
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return true
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}
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// UIDs includes all params to make a unique identification of this object.
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// Most resources only return one, although some resources can return multiple.
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func (obj *GroupRes) UIDs() []engine.ResUID {
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x := &GroupUID{
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BaseUID: engine.BaseUID{Name: obj.Name(), Kind: obj.Kind()},
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name: obj.Name(),
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gid: obj.GID,
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}
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return []engine.ResUID{x}
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}
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// UnmarshalYAML is the custom unmarshal handler for this struct.
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// It is primarily useful for setting the defaults.
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func (obj *GroupRes) UnmarshalYAML(unmarshal func(interface{}) error) error {
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type rawRes GroupRes // indirection to avoid infinite recursion
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def := obj.Default() // get the default
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res, ok := def.(*GroupRes) // put in the right format
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if !ok {
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return fmt.Errorf("could not convert to GroupRes")
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}
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raw := rawRes(*res) // convert; the defaults go here
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if err := unmarshal(&raw); err != nil {
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return err
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}
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*obj = GroupRes(raw) // restore from indirection with type conversion!
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return nil
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}
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