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cloudstack.go
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cloudstack.go
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// Copyright 2017 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// The CloudStack provider fetches configurations from the userdata available in
// the config-drive.
// NOTE: This provider is still EXPERIMENTAL.
package cloudstack
import (
"bufio"
"context"
"fmt"
"net"
"net/url"
"os"
"os/exec"
"path/filepath"
"strings"
"time"
"github.com/coreos/ignition/v2/config/v3_5_experimental/types"
"github.com/coreos/ignition/v2/internal/distro"
"github.com/coreos/ignition/v2/internal/log"
"github.com/coreos/ignition/v2/internal/providers/util"
"github.com/coreos/ignition/v2/internal/resource"
ut "github.com/coreos/ignition/v2/internal/util"
"github.com/coreos/vcontext/report"
)
const (
configDriveUserdataPath = "/cloudstack/userdata/user_data.txt"
LeaseRetryInterval = 500 * time.Millisecond
)
func FetchConfig(f *resource.Fetcher) (types.Config, report.Report, error) {
// The fetch-offline approach doesn't work well here because of the "split
// personality" of this provider. See:
// https://github.com/coreos/ignition/issues/1081
if f.Offline {
return types.Config{}, report.Report{}, resource.ErrNeedNet
}
var data []byte
errChan := make(chan error)
ctx, cancel := context.WithCancel(context.Background())
dispatchCount := 0
dispatch := func(name string, fn func() ([]byte, error)) {
dispatchCount++
go func() {
raw, err := fn()
if err != nil {
switch err {
case context.Canceled:
default:
f.Logger.Err("failed to fetch config from %s: %v", name, err)
}
errChan <- err
return
}
data = raw
cancel()
}()
}
dispatch("config drive (config)", func() ([]byte, error) {
return fetchConfigFromDevice(f.Logger, ctx, "config-2")
})
dispatch("config drive (CONFIG)", func() ([]byte, error) {
return fetchConfigFromDevice(f.Logger, ctx, "CONFIG-2")
})
dispatch("metadata service", func() ([]byte, error) {
return fetchConfigFromMetadataService(f)
})
Loop:
for {
select {
case <-ctx.Done():
break Loop
case <-errChan:
dispatchCount--
if dispatchCount == 0 {
f.Logger.Info("couldn't fetch config")
break Loop
}
}
}
return util.ParseConfig(f.Logger, data)
}
func fileExists(path string) bool {
_, err := os.Stat(path)
return (err == nil)
}
func labelExists(label string) bool {
_, err := getPath(label)
return (err == nil)
}
func getPath(label string) (string, error) {
path := filepath.Join(distro.DiskByLabelDir(), label)
if fileExists(path) {
return path, nil
}
return "", fmt.Errorf("label not found: %s", label)
}
func findLease() (*os.File, error) {
ifaces, err := net.Interfaces()
if err != nil {
return nil, fmt.Errorf("could not list interfaces: %v", err)
}
for {
for _, iface := range ifaces {
lease, err := os.Open(fmt.Sprintf("/run/systemd/netif/leases/%d", iface.Index))
if os.IsNotExist(err) {
continue
} else if err != nil {
return nil, err
} else {
return lease, nil
}
}
fmt.Printf("No leases found. Waiting...")
time.Sleep(LeaseRetryInterval)
}
}
func getDHCPServerAddress() (string, error) {
lease, err := findLease()
if err != nil {
return "", err
}
defer lease.Close()
var address string
line := bufio.NewScanner(lease)
for line.Scan() {
parts := strings.Split(line.Text(), "=")
if parts[0] == "SERVER_ADDRESS" && len(parts) == 2 {
address = parts[1]
break
}
}
if len(address) == 0 {
return "", fmt.Errorf("dhcp server address not found in leases")
}
return address, nil
}
func fetchConfigFromDevice(logger *log.Logger, ctx context.Context, label string) ([]byte, error) {
for !labelExists(label) {
logger.Debug("config drive (%q) not found. Waiting...", label)
select {
case <-time.After(time.Second):
case <-ctx.Done():
return nil, ctx.Err()
}
}
path, err := getPath(label)
if err != nil {
return nil, err
}
logger.Debug("creating temporary mount point")
mnt, err := os.MkdirTemp("", "ignition-configdrive")
if err != nil {
return nil, fmt.Errorf("failed to create temp directory: %v", err)
}
defer os.Remove(mnt)
cmd := exec.Command(distro.MountCmd(), "-o", "ro", "-t", "auto", path, mnt)
if _, err := logger.LogCmd(cmd, "mounting config drive"); err != nil {
return nil, err
}
defer func() {
_ = logger.LogOp(
func() error {
return ut.UmountPath(mnt)
},
"unmounting %q at %q", path, mnt,
)
}()
if !fileExists(filepath.Join(mnt, configDriveUserdataPath)) {
return nil, nil
}
return os.ReadFile(filepath.Join(mnt, configDriveUserdataPath))
}
func fetchConfigFromMetadataService(f *resource.Fetcher) ([]byte, error) {
addr, err := getDHCPServerAddress()
if err != nil {
return nil, err
}
metadataServiceUrl := url.URL{
Scheme: "http",
Host: addr,
Path: "/latest/user-data",
}
res, err := f.FetchToBuffer(metadataServiceUrl, resource.FetchOptions{})
// the metadata server exists but doesn't contain any actual metadata,
// assume that there is no config specified
if err == resource.ErrNotFound {
return nil, nil
}
return res, err
}