syncthing/vendor/gopkg.in/urfave/cli.v1/altsrc/yaml_file_loader.go
Jakob Borg 916ec63af6 cmd/stdiscosrv: New discovery server (fixes #4618)
This is a new revision of the discovery server. Relevant changes and
non-changes:

- Protocol towards clients is unchanged.

- Recommended large scale design is still to be deployed nehind nginx (I
  tested, and it's still a lot faster at terminating TLS).

- Database backend is leveldb again, only. It scales enough, is easy to
  setup, and we don't need any backend to take care of.

- Server supports replication. This is a simple TCP channel - protect it
  with a firewall when deploying over the internet. (We deploy this within
  the same datacenter, and with firewall.) Any incoming client announces
  are sent over the replication channel(s) to other peer discosrvs.
  Incoming replication changes are applied to the database as if they came
  from clients, but without the TLS/certificate overhead.

- Metrics are exposed using the prometheus library, when enabled.

- The database values and replication protocol is protobuf, because JSON
  was quite CPU intensive when I tried that and benchmarked it.

- The "Retry-After" value for failed lookups gets slowly increased from
  a default of 120 seconds, by 5 seconds for each failed lookup,
  independently by each discosrv. This lowers the query load over time for
  clients that are never seen. The Retry-After maxes out at 3600 after a
  couple of weeks of this increase. The number of failed lookups is
  stored in the database, now and then (avoiding making each lookup a
  database put).

All in all this means clients can be pointed towards a cluster using
just multiple A / AAAA records to gain both load sharing and redundancy
(if one is down, clients will talk to the remaining ones).

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00

93 lines
2.5 KiB
Go

// Disabling building of yaml support in cases where golang is 1.0 or 1.1
// as the encoding library is not implemented or supported.
// +build go1.2
package altsrc
import (
"fmt"
"io/ioutil"
"net/http"
"net/url"
"os"
"runtime"
"strings"
"gopkg.in/urfave/cli.v1"
"gopkg.in/yaml.v2"
)
type yamlSourceContext struct {
FilePath string
}
// NewYamlSourceFromFile creates a new Yaml InputSourceContext from a filepath.
func NewYamlSourceFromFile(file string) (InputSourceContext, error) {
ysc := &yamlSourceContext{FilePath: file}
var results map[interface{}]interface{}
err := readCommandYaml(ysc.FilePath, &results)
if err != nil {
return nil, fmt.Errorf("Unable to load Yaml file '%s': inner error: \n'%v'", ysc.FilePath, err.Error())
}
return &MapInputSource{valueMap: results}, nil
}
// NewYamlSourceFromFlagFunc creates a new Yaml InputSourceContext from a provided flag name and source context.
func NewYamlSourceFromFlagFunc(flagFileName string) func(context *cli.Context) (InputSourceContext, error) {
return func(context *cli.Context) (InputSourceContext, error) {
filePath := context.String(flagFileName)
return NewYamlSourceFromFile(filePath)
}
}
func readCommandYaml(filePath string, container interface{}) (err error) {
b, err := loadDataFrom(filePath)
if err != nil {
return err
}
err = yaml.Unmarshal(b, container)
if err != nil {
return err
}
err = nil
return
}
func loadDataFrom(filePath string) ([]byte, error) {
u, err := url.Parse(filePath)
if err != nil {
return nil, err
}
if u.Host != "" { // i have a host, now do i support the scheme?
switch u.Scheme {
case "http", "https":
res, err := http.Get(filePath)
if err != nil {
return nil, err
}
return ioutil.ReadAll(res.Body)
default:
return nil, fmt.Errorf("scheme of %s is unsupported", filePath)
}
} else if u.Path != "" { // i dont have a host, but I have a path. I am a local file.
if _, notFoundFileErr := os.Stat(filePath); notFoundFileErr != nil {
return nil, fmt.Errorf("Cannot read from file: '%s' because it does not exist.", filePath)
}
return ioutil.ReadFile(filePath)
} else if runtime.GOOS == "windows" && strings.Contains(u.String(), "\\") {
// on Windows systems u.Path is always empty, so we need to check the string directly.
if _, notFoundFileErr := os.Stat(filePath); notFoundFileErr != nil {
return nil, fmt.Errorf("Cannot read from file: '%s' because it does not exist.", filePath)
}
return ioutil.ReadFile(filePath)
} else {
return nil, fmt.Errorf("unable to determine how to load from path %s", filePath)
}
}