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runner.go
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runner.go
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package main
import (
"bytes"
"crypto/md5"
"fmt"
"io"
"io/ioutil"
"net/url"
"os"
"os/exec"
"os/signal"
"path"
"path/filepath"
"strings"
"syscall"
"text/template"
"time"
log "github.com/Sirupsen/logrus"
"github.com/rancher/go-rancher-metadata/metadata"
)
var (
MetadataURL = "http://rancher-metadata"
)
type runner struct {
Config *Config
Client metadata.Client
Version string
quitChan chan os.Signal
}
func NewRunner(conf *Config) (*runner, error) {
u, _ := url.Parse(MetadataURL)
u.Path = path.Join(u.Path, conf.MetadataVersion)
log.Infof("Initializing Rancher Metadata client (version %s)", conf.MetadataVersion)
client, err := metadata.NewClientAndWait(u.String())
if err != nil {
return nil, fmt.Errorf("Failed to initialize Rancher Metadata client: %v", err)
}
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT)
return &runner{
Config: conf,
Client: client,
Version: "init",
quitChan: c,
}, nil
}
func (r *runner) Run() error {
if r.Config.OneTime {
log.Info("Processing all templates once.")
return r.poll()
}
log.Info("Polling Metadata with %d second interval", r.Config.Interval)
ticker := time.NewTicker(time.Duration(r.Config.Interval) * time.Second)
defer ticker.Stop()
for {
if err := r.poll(); err != nil {
log.Error(err)
}
select {
case <-ticker.C:
case signal := <-r.quitChan:
log.Info("Exit requested by signal: ", signal)
return nil
}
}
}
func (r *runner) poll() error {
log.Debug("Checking for metadata change")
newVersion, err := r.Client.GetVersion()
if err != nil {
time.Sleep(time.Second * 2)
return fmt.Errorf("Failed to get Metadata version: %v", err)
}
if r.Version == newVersion {
log.Debug("No changes in Metadata")
return nil
}
log.Debugf("Old version: %s, New Version: %s", r.Version, newVersion)
r.Version = newVersion
ctx, err := r.createContext()
if err != nil {
time.Sleep(time.Second * 2)
return fmt.Errorf("Failed to create context from Rancher Metadata: %v", err)
}
tmplFuncs := newFuncMap(ctx)
for _, tmpl := range r.Config.Templates {
if err := r.processTemplate(tmplFuncs, tmpl); err != nil {
return err
}
}
if r.Config.OneTime {
log.Info("All templates processed. Exiting.")
} else {
log.Info("All templates processed. Waiting for changes in Metadata...")
}
return nil
}
func (r *runner) processTemplate(funcs template.FuncMap, t Template) error {
log.Debugf("Processing template %s for destination %s", t.Source, t.Dest)
if _, err := os.Stat(t.Source); os.IsNotExist(err) {
log.Fatalf("Template '%s' is missing", t.Source)
}
tmplBytes, err := ioutil.ReadFile(t.Source)
if err != nil {
log.Fatalf("Could not read template '%s': %v", t.Source, err)
}
name := filepath.Base(t.Source)
newTemplate, err := template.New(name).Funcs(funcs).Parse(string(tmplBytes))
if err != nil {
log.Fatalf("Could not parse template '%s': %v", t.Source, err)
}
buf := new(bytes.Buffer)
if err := newTemplate.Execute(buf, nil); err != nil {
log.Fatalf("Could not render template: '%s': %v", t.Source, err)
}
content := buf.Bytes()
if t.Dest == "" {
log.Debug("No destination specified. Printing to StdOut")
os.Stdout.Write(content)
return nil
}
log.Debug("Checking whether content has changed")
same, err := sameContent(content, t.Dest)
if err != nil {
return fmt.Errorf("Could not compare content for %s: %v", t.Dest, err)
}
if same {
log.Debugf("Destination %s is up to date", t.Dest)
return nil
}
log.Debug("Creating staging file")
stagingFile, err := createStagingFile(content, t.Dest)
if err != nil {
return err
}
defer os.Remove(stagingFile)
if t.CheckCmd != "" {
if err := check(t.CheckCmd, stagingFile); err != nil {
return fmt.Errorf("Check command failed: %v", err)
}
}
log.Debugf("Writing destination")
if err = copyStagingToDestination(stagingFile, t.Dest); err != nil {
return fmt.Errorf("Could not write destination file %s: %v", t.Dest, err)
}
log.Info("Destination file %s has been updated", t.Dest)
if t.NotifyCmd != "" {
if err := notify(t.NotifyCmd, t.NotifyOutput); err != nil {
return fmt.Errorf("Notify command failed: %v", err)
}
}
return nil
}
func copyStagingToDestination(stagingPath, destPath string) error {
err := os.Rename(stagingPath, destPath)
if err == nil {
return nil
}
if !strings.Contains(err.Error(), "device or resource busy") {
return err
}
// A 'device busy' error could mean that the files live in
// different mounts. Try to read the staging file and write
// it's content to the destination file.
log.Debugf("Failed to rename staging file: %v", err)
content, err := ioutil.ReadFile(stagingPath)
if err != nil {
return err
}
sfi, err := os.Stat(stagingPath)
if err != nil {
return err
}
if err := ioutil.WriteFile(destPath, content, sfi.Mode()); err != nil {
return err
}
if os_stat, ok := sfi.Sys().(*syscall.Stat_t); ok {
if err := os.Chown(destPath, int(os_stat.Uid), int(os_stat.Gid)); err != nil {
return err
}
}
return nil
}
func (r *runner) createContext() (*TemplateContext, error) {
log.Debug("Fetching Metadata")
metaServices, err := r.Client.GetServices()
if err != nil {
return nil, err
}
metaContainers, err := r.Client.GetContainers()
if err != nil {
return nil, err
}
metaHosts, err := r.Client.GetHosts()
if err != nil {
return nil, err
}
metaSelf, err := r.Client.GetSelfContainer()
if err != nil {
return nil, err
}
hosts := make([]Host, 0)
for _, h := range metaHosts {
host := Host{
UUID: h.UUID,
Name: h.Name,
Address: h.AgentIP,
Hostname: h.Hostname,
Labels: LabelMap(h.Labels),
}
hosts = append(hosts, host)
}
containers := make([]Container, 0)
for _, c := range metaContainers {
container := Container{
Name: c.Name,
Address: c.PrimaryIp,
Stack: c.StackName,
Service: c.ServiceName,
Health: c.HealthState,
State: c.State,
Labels: LabelMap(c.Labels),
}
for _, h := range hosts {
if h.UUID == c.HostUUID {
container.Host = h
break
}
}
container.Ports = parseServicePorts(c.Ports)
containers = append(containers, container)
}
hosts = make([]Host, 0)
for _, h := range metaHosts {
host := Host{
UUID: h.UUID,
Name: h.Name,
Address: h.AgentIP,
Hostname: h.Hostname,
Labels: LabelMap(h.Labels),
}
svcContainers := make([]Container, 0)
for _, c := range containers {
if c.Host.Name == h.Name {
svcContainers = append(svcContainers, c)
}
}
host.Containers = svcContainers
hosts = append(hosts, host)
}
services := make([]Service, 0)
for _, s := range metaServices {
service := Service{
Name: s.Name,
Stack: s.StackName,
Kind: s.Kind,
Vip: s.Vip,
Fqdn: s.Fqdn,
Labels: LabelMap(s.Labels),
Metadata: MetadataMap(s.Metadata),
}
svcContainers := make([]Container, 0)
for _, c := range containers {
if c.Stack == s.StackName && c.Service == s.Name {
svcContainers = append(svcContainers, c)
}
}
service.Containers = svcContainers
service.Ports = parseServicePorts(s.Ports)
services = append(services, service)
}
self := Self{
Stack: metaSelf.StackName,
Service: metaSelf.ServiceName,
HostUUID: metaSelf.HostUUID,
}
ctx := TemplateContext{
Services: services,
Containers: containers,
Hosts: hosts,
Self: self,
}
return &ctx, nil
}
// converts Metadata.Service.Ports string slice to a ServicePort slice
func parseServicePorts(ports []string) []ServicePort {
var ret []ServicePort
for _, port := range ports {
parts := strings.Split(port, ":")
if len(parts) == 2 {
public := parts[0]
if parts_ := strings.Split(parts[1], "/"); len(parts_) == 2 {
ret = append(ret, ServicePort{
ExternalIp: "",
PublicPort: public,
InternalPort: parts_[0],
Protocol: parts_[1],
})
continue
}
}
if len(parts) == 3 {
externalip := parts[0]
public := parts[1]
if parts_ := strings.Split(parts[2], "/"); len(parts_) == 2 {
ret = append(ret, ServicePort{
ExternalIp: externalip,
PublicPort: public,
InternalPort: parts_[0],
Protocol: parts_[1],
})
continue
}
}
log.Warnf("Unexpected format of service port: %s", port)
}
return ret
}
func check(command, filePath string) error {
command = strings.Replace(command, "{{staging}}", filePath, -1)
log.Debugf("Running check command '%s'", command)
cmd := exec.Command("/bin/sh", "-c", command)
out, err := cmd.CombinedOutput()
if err != nil {
logCmdOutput(command, out)
return err
}
log.Debugf("Check cmd output: %q", string(out))
return nil
}
func notify(command string, verbose bool) error {
log.Infof("Executing notify command '%s'", command)
cmd := exec.Command("/bin/sh", "-c", command)
out, err := cmd.CombinedOutput()
if err != nil {
logCmdOutput(command, out)
return err
}
if verbose {
logCmdOutput(command, out)
}
log.Debugf("Notify cmd output: %q", string(out))
return nil
}
func logCmdOutput(command string, output []byte) {
for _, line := range strings.Split(string(output), "\n") {
if line != "" {
log.Infof("[%s]: %q", command, line)
}
}
}
func sameContent(content []byte, filePath string) (bool, error) {
fileMd5, err := computeFileMd5(filePath)
if err != nil {
return false, fmt.Errorf("Could not calculate checksum for %s: %v",
filePath, err)
}
hash := md5.New()
hash.Write(content)
contentMd5 := fmt.Sprintf("%x", hash.Sum(nil))
log.Debugf("Checksum content: %s, checksum file: %s",
contentMd5, fileMd5)
if fileMd5 == contentMd5 {
return true, nil
}
return false, nil
}
func computeFileMd5(filePath string) (string, error) {
if _, err := os.Stat(filePath); err != nil {
return "", nil
}
file, err := os.Open(filePath)
if err != nil {
return "", err
}
defer file.Close()
hash := md5.New()
if _, err := io.Copy(hash, file); err != nil {
return "", err
}
return fmt.Sprintf("%x", hash.Sum(nil)), nil
}
func createStagingFile(content []byte, destFile string) (string, error) {
fp, err := ioutil.TempFile(filepath.Dir(destFile), "."+filepath.Base(destFile)+"-")
if err != nil {
return "", fmt.Errorf("Could not create staging file for %s: %v", destFile, err)
}
log.Debugf("Created staging file %s", fp.Name())
onErr := func() {
fp.Close()
os.Remove(fp.Name())
}
if _, err := fp.Write(content); err != nil {
onErr()
return "", fmt.Errorf("Could not write staging file for %s: %v", destFile, err)
}
log.Debug("Copying file permissions and owner from destination")
if stat, err := os.Stat(destFile); err == nil {
if err := fp.Chmod(stat.Mode()); err != nil {
onErr()
return "", fmt.Errorf("Failed to copy permissions from %s: %v", destFile, err)
}
if os_stat, ok := stat.Sys().(*syscall.Stat_t); ok {
if err := fp.Chown(int(os_stat.Uid), int(os_stat.Gid)); err != nil {
onErr()
return "", fmt.Errorf("Failed to copy ownership: %v", err)
}
}
}
fp.Close()
return fp.Name(), nil
}