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lang: core: sys, engine: resource: Update hostname functionality

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We didn't have a solid resource and sys.hostname() didn't have events!
This commit is contained in:
James Shubin
2024-11-06 20:00:54 -05:00
parent 83fd8b7e54
commit 59a20f53eb
4 changed files with 210 additions and 40 deletions
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107
engine/resources/hostname.go
View File

@@ -39,6 +39,7 @@ import (
engineUtil "github.com/purpleidea/mgmt/engine/util"
"github.com/purpleidea/mgmt/util"
"github.com/purpleidea/mgmt/util/errwrap"
"github.com/purpleidea/mgmt/util/recwatch"
"github.com/godbus/dbus/v5"
)
@@ -57,7 +58,10 @@ const (
// resource is insufficient for the resource to do any useful work.
var ErrResourceInsufficientParameters = errors.New("insufficient parameters for this resource")
// HostnameRes is a resource that allows setting and watching the hostname.
// HostnameRes is a resource that allows setting and watching the hostname. If
// you don't specify any parameters, the Name is used. The Hostname field is
// used if none of the other parameters are used. If the parameters are set to
// the empty string, then those variants are not managed by the resource.
type HostnameRes struct {
traits.Base // add the base methods without re-implementation
@@ -72,22 +76,54 @@ type HostnameRes struct {
// PrettyHostname is a free-form UTF8 host name for presentation to the
// user.
PrettyHostname string `lang:"pretty_hostname" yaml:"pretty_hostname"`
PrettyHostname *string `lang:"pretty_hostname" yaml:"pretty_hostname"`
// StaticHostname is the one configured in /etc/hostname or a similar
// file. It is chosen by the local user. It is not always in sync with
// the current host name as returned by the gethostname() system call.
StaticHostname string `lang:"static_hostname" yaml:"static_hostname"`
StaticHostname *string `lang:"static_hostname" yaml:"static_hostname"`
// TransientHostname is the one configured via the kernel's
// sethostbyname(). It can be different from the static hostname in case
// DHCP or mDNS have been configured to change the name based on network
// information.
TransientHostname string `lang:"transient_hostname" yaml:"transient_hostname"`
TransientHostname *string `lang:"transient_hostname" yaml:"transient_hostname"`
conn *dbus.Conn
}
func (obj *HostnameRes) getHostname() string {
if obj.Hostname != "" {
return obj.Hostname
}
return obj.Name()
}
func (obj *HostnameRes) getPrettyHostname() string {
if obj.PrettyHostname != nil {
return *obj.PrettyHostname // this may be empty!
}
return obj.getHostname()
}
func (obj *HostnameRes) getStaticHostname() string {
if obj.StaticHostname != nil {
return *obj.StaticHostname // this may be empty!
}
return obj.getHostname()
}
func (obj *HostnameRes) getTransientHostname() string {
if obj.TransientHostname != nil {
return *obj.TransientHostname // this may be empty!
}
return obj.getHostname()
}
// Default returns some sensible defaults for this resource.
func (obj *HostnameRes) Default() engine.Res {
return &HostnameRes{}
@@ -95,7 +131,10 @@ func (obj *HostnameRes) Default() engine.Res {
// Validate if the params passed in are valid data.
func (obj *HostnameRes) Validate() error {
if obj.PrettyHostname == "" && obj.StaticHostname == "" && obj.TransientHostname == "" {
a := obj.getPrettyHostname() == ""
b := obj.getStaticHostname() == ""
c := obj.getTransientHostname() == ""
if a && b && c && obj.getHostname() == "" {
return ErrResourceInsufficientParameters
}
return nil
@@ -105,15 +144,6 @@ func (obj *HostnameRes) Validate() error {
func (obj *HostnameRes) Init(init *engine.Init) error {
obj.init = init // save for later
if obj.PrettyHostname == "" {
obj.PrettyHostname = obj.Hostname
}
if obj.StaticHostname == "" {
obj.StaticHostname = obj.Hostname
}
if obj.TransientHostname == "" {
obj.TransientHostname = obj.Hostname
}
return nil
}
@@ -124,6 +154,13 @@ func (obj *HostnameRes) Cleanup() error {
// Watch is the primary listener for this resource and it outputs events.
func (obj *HostnameRes) Watch(ctx context.Context) error {
recurse := false // single file
recWatcher, err := recwatch.NewRecWatcher("/etc/hostname", recurse)
if err != nil {
return err
}
defer recWatcher.Close()
// if we share the bus with others, we will get each others messages!!
bus, err := util.SystemBusPrivateUsable() // don't share the bus connection!
if err != nil {
@@ -149,7 +186,23 @@ func (obj *HostnameRes) Watch(ctx context.Context) error {
var send = false // send event?
for {
select {
case <-signals:
case _, ok := <-signals:
if !ok { // channel shutdown
return fmt.Errorf("unexpected close")
}
//signals = nil
send = true
case event, ok := <-recWatcher.Events():
if !ok { // channel shutdown
return fmt.Errorf("unexpected close")
}
if err := event.Error; err != nil {
return err
}
if obj.init.Debug { // don't access event.Body if event.Error isn't nil
obj.init.Logf("event(%s): %v", event.Body.Name, event.Body.Op)
}
send = true
case <-ctx.Done(): // closed by the engine to signal shutdown
@@ -209,22 +262,22 @@ func (obj *HostnameRes) CheckApply(ctx context.Context, apply bool) (bool, error
hostnameObject := conn.Object(hostname1Iface, hostname1Path)
checkOK := true
if obj.PrettyHostname != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, obj.PrettyHostname, "PrettyHostname", "SetPrettyHostname", apply)
if h := obj.getPrettyHostname(); h != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, h, "PrettyHostname", "SetPrettyHostname", apply)
if err != nil {
return false, err
}
checkOK = checkOK && propertyCheckOK
}
if obj.StaticHostname != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, obj.StaticHostname, "StaticHostname", "SetStaticHostname", apply)
if h := obj.getStaticHostname(); h != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, h, "StaticHostname", "SetStaticHostname", apply)
if err != nil {
return false, err
}
checkOK = checkOK && propertyCheckOK
}
if obj.TransientHostname != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, obj.TransientHostname, "Hostname", "SetHostname", apply)
if h := obj.getTransientHostname(); h != "" {
propertyCheckOK, err := obj.updateHostnameProperty(hostnameObject, h, "Hostname", "SetHostname", apply)
if err != nil {
return false, err
}
@@ -242,13 +295,13 @@ func (obj *HostnameRes) Cmp(r engine.Res) error {
return fmt.Errorf("not a %s", obj.Kind())
}
if obj.PrettyHostname != res.PrettyHostname {
if engineUtil.StrPtrCmp(obj.PrettyHostname, res.PrettyHostname) != nil {
return fmt.Errorf("the PrettyHostname differs")
}
if obj.StaticHostname != res.StaticHostname {
if engineUtil.StrPtrCmp(obj.StaticHostname, res.StaticHostname) != nil {
return fmt.Errorf("the StaticHostname differs")
}
if obj.TransientHostname != res.TransientHostname {
if engineUtil.StrPtrCmp(obj.TransientHostname, res.TransientHostname) != nil {
return fmt.Errorf("the TransientHostname differs")
}
@@ -271,9 +324,9 @@ func (obj *HostnameRes) UIDs() []engine.ResUID {
x := &HostnameUID{
BaseUID: engine.BaseUID{Name: obj.Name(), Kind: obj.Kind()},
name: obj.Name(),
prettyHostname: obj.PrettyHostname,
staticHostname: obj.StaticHostname,
transientHostname: obj.TransientHostname,
prettyHostname: obj.getPrettyHostname(),
staticHostname: obj.getStaticHostname(),
transientHostname: obj.getTransientHostname(),
}
return []engine.ResUID{x}
}

11
examples/lang/hostname_mapper.mcl
View File

@@ -1,3 +1,4 @@
import "sys"
import "util"
$m = {
@@ -7,6 +8,12 @@ $m = {
"aa:bb:cc:dd:ee:ff" => "hostname2",
}
print "mapper" {
msg => util.hostname_mapper($m),
$h = util.hostname_mapper($m)
print "hostname_mapper" {
msg => $h,
}
if $h != "" and sys.hostname() != $h {
hostname "${h}" {} # set it correctly!
}

4
integration/basic_test.go
View File

@@ -179,7 +179,7 @@ func TestCluster1(t *testing.T) {
code := util.Code(`
import "sys"
$root = sys.getenv("MGMT_TEST_ROOT")
$host = sys.hostname()
$host = $hostname #sys.hostname()
file "${root}/mgmt-hostname" {
content => "i am ${host}\n",
@@ -206,7 +206,7 @@ func TestCluster1(t *testing.T) {
code := util.Code(`
import "sys"
$root = sys.getenv("MGMT_TEST_ROOT")
$host = sys.hostname()
$host = $hostname #sys.hostname()
file "${root}/mgmt-hostname" {
content => "i am ${host}\n",

128
lang/core/sys/hostname_fact.go
View File

@@ -31,15 +31,26 @@ package coresys
import (
"context"
"fmt"
engineUtil "github.com/purpleidea/mgmt/engine/util"
"github.com/purpleidea/mgmt/lang/funcs/facts"
"github.com/purpleidea/mgmt/lang/types"
"github.com/purpleidea/mgmt/util"
"github.com/purpleidea/mgmt/util/errwrap"
"github.com/purpleidea/mgmt/util/recwatch"
"github.com/godbus/dbus/v5"
)
const (
// HostnameFuncName is the name this fact is registered as. It's still a
// Func Name because this is the name space the fact is actually using.
HostnameFuncName = "hostname"
hostname1Path = "/org/freedesktop/hostname1"
hostname1Iface = "org.freedesktop.hostname1"
dbusPropertiesIface = "org.freedesktop.DBus.Properties"
)
func init() {
@@ -79,14 +90,113 @@ func (obj *HostnameFact) Init(init *facts.Init) error {
// Stream returns the single value that this fact has, and then closes.
func (obj *HostnameFact) Stream(ctx context.Context) error {
select {
case obj.init.Output <- &types.StrValue{
V: obj.init.Hostname,
}:
// pass
case <-ctx.Done():
return nil
defer close(obj.init.Output) // signal that we're done sending
recurse := false // single file
recWatcher, err := recwatch.NewRecWatcher("/etc/hostname", recurse)
if err != nil {
return err
}
defer recWatcher.Close()
// if we share the bus with others, we will get each others messages!!
bus, err := util.SystemBusPrivateUsable() // don't share the bus connection!
if err != nil {
return errwrap.Wrapf(err, "failed to connect to bus")
}
defer bus.Close()
// watch the PropertiesChanged signal on the hostname1 dbus path
args := fmt.Sprintf(
"type='signal', path='%s', interface='%s', member='PropertiesChanged'",
hostname1Path,
dbusPropertiesIface,
)
if call := bus.BusObject().Call(engineUtil.DBusAddMatch, 0, args); call.Err != nil {
return errwrap.Wrapf(call.Err, "failed to subscribe to DBus events for hostname1")
}
defer bus.BusObject().Call(engineUtil.DBusRemoveMatch, 0, args) // ignore the error
signals := make(chan *dbus.Signal, 10) // closed by dbus package
bus.Signal(signals)
// streams must generate an initial event on startup
startChan := make(chan struct{}) // start signal
close(startChan) // kick it off!
for {
select {
case <-startChan: // kick the loop once at start
startChan = nil // disable
case _, ok := <-signals:
if !ok { // channel shutdown
return fmt.Errorf("unexpected close")
}
case event, ok := <-recWatcher.Events():
if !ok { // channel shutdown
return fmt.Errorf("unexpected close")
}
if err := event.Error; err != nil {
return err
}
if obj.init.Debug { // don't access event.Body if event.Error isn't nil
obj.init.Logf("event(%s): %v", event.Body.Name, event.Body.Op)
}
case <-ctx.Done(): // closed by the engine to signal shutdown
return nil
}
// NOTE: We ask the actual machine instead of using obj.init.Hostname
value, err := obj.Call(ctx)
if err != nil {
return err
}
select {
case obj.init.Output <- value:
// pass
case <-ctx.Done():
return nil
}
}
close(obj.init.Output) // signal that we're done sending
return nil
}
// Call returns the result of this function.
func (obj *HostnameFact) Call(ctx context.Context) (types.Value, error) {
conn, err := util.SystemBusPrivateUsable()
if err != nil {
return nil, errwrap.Wrapf(err, "failed to connect to the private system bus")
}
defer conn.Close()
hostnameObject := conn.Object(hostname1Iface, hostname1Path)
h, err := obj.getHostnameProperty(hostnameObject, "Hostname")
if err != nil {
return nil, err
}
return &types.StrValue{
V: h,
}, nil
}
func (obj *HostnameFact) getHostnameProperty(object dbus.BusObject, property string) (string, error) {
propertyObject, err := object.GetProperty("org.freedesktop.hostname1." + property)
if err != nil {
return "", errwrap.Wrapf(err, "failed to get org.freedesktop.hostname1.%s", property)
}
if propertyObject.Value() == nil {
return "", fmt.Errorf("unexpected nil value received when reading property %s", property)
}
propertyValue, ok := propertyObject.Value().(string)
if !ok {
return "", fmt.Errorf("received unexpected type as %s value, expected string got '%T'", property, propertyValue)
}
// expected value and actual value match => checkOk
return propertyValue, nil
}