add(cepgo): import github.com/cloudsigma/cepgo

This commit is contained in:
Kiril Vladimirov 2014-08-05 12:47:47 +03:00
parent 24b44e86a6
commit 85c6a2a16a
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cepgo
=====
Cepko implements easy-to-use communication with CloudSigma's VMs through a
virtual serial port without bothering with formatting the messages properly nor
parsing the output with the specific and sometimes confusing shell tools for
that purpose.
Having the server definition accessible by the VM can be useful in various
ways. For example it is possible to easily determine from within the VM, which
network interfaces are connected to public and which to private network.
Another use is to pass some data to initial VM setup scripts, like setting the
hostname to the VM name or passing ssh public keys through server meta.
Example usage:
package main
import (
"fmt"
"github.com/cloudsigma/cepgo"
)
func main() {
c := cepgo.NewCepgo()
result, err := c.Meta()
if err != nil {
panic(err)
}
fmt.Printf("%#v", result)
}
Output:
map[string]interface {}{
"optimize_for":"custom",
"ssh_public_key":"ssh-rsa AAA...",
"description":"[...]",
}
For more information take a look at the Server Context section of CloudSigma
API Docs: http://cloudsigma-docs.readthedocs.org/en/latest/server_context.html

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// Cepko implements easy-to-use communication with CloudSigma's VMs through a
// virtual serial port without bothering with formatting the messages properly
// nor parsing the output with the specific and sometimes confusing shell tools
// for that purpose.
//
// Having the server definition accessible by the VM can be useful in various
// ways. For example it is possible to easily determine from within the VM,
// which network interfaces are connected to public and which to private
// network. Another use is to pass some data to initial VM setup scripts, like
// setting the hostname to the VM name or passing ssh public keys through
// server meta.
//
// Example usage:
//
// package main
//
// import (
// "fmt"
//
// "github.com/cloudsigma/cepgo"
// )
//
// func main() {
// c := cepgo.NewCepgo()
// result, err := c.Meta()
// if err != nil {
// panic(err)
// }
// fmt.Printf("%#v", result)
// }
//
// Output:
//
// map[string]string{
// "optimize_for":"custom",
// "ssh_public_key":"ssh-rsa AAA...",
// "description":"[...]",
// }
//
// For more information take a look at the Server Context section API Docs:
// http://cloudsigma-docs.readthedocs.org/en/latest/server_context.html
package cepgo
import (
"bufio"
"encoding/json"
"errors"
"fmt"
"runtime"
"github.com/tarm/goserial"
)
const (
requestPattern = "<\n%s\n>"
EOT = '\x04' // End Of Transmission
)
var (
SerialPort string = "/dev/ttyS1"
Baud int = 115200
)
// Sets the serial port. If the operating system is windows CloudSigma's server
// context is at COM2 port, otherwise (linux, freebsd, darwin) the port is
// being left to the default /dev/ttyS1.
func init() {
if runtime.GOOS == "windows" {
SerialPort = "COM2"
}
}
// The default fetcher makes the connection to the serial port,
// writes given query and reads until the EOT symbol.
func fetchViaSerialPort(key string) ([]byte, error) {
config := &serial.Config{Name: SerialPort, Baud: Baud}
connection, err := serial.OpenPort(config)
if err != nil {
return nil, err
}
query := fmt.Sprintf(requestPattern, key)
if _, err := connection.Write([]byte(query)); err != nil {
return nil, err
}
reader := bufio.NewReader(connection)
answer, err := reader.ReadBytes(EOT)
if err != nil {
return nil, err
}
return answer[0 : len(answer)-1], nil
}
// Queries to the serial port can be executed only from instance of this type.
// The result from each of them can be either interface{}, map[string]string or
// a single in case of single value is returned. There is also a public metod
// who directly calls the fetcher and returns raw []byte from the serial port.
type Cepgo struct {
fetcher func(string) ([]byte, error)
}
// Creates a Cepgo instance with the default serial port fetcher.
func NewCepgo() *Cepgo {
cepgo := new(Cepgo)
cepgo.fetcher = fetchViaSerialPort
return cepgo
}
// Creates a Cepgo instance with custom fetcher.
func NewCepgoFetcher(fetcher func(string) ([]byte, error)) *Cepgo {
cepgo := new(Cepgo)
cepgo.fetcher = fetcher
return cepgo
}
// Fetches raw []byte from the serial port using directly the fetcher member.
func (c *Cepgo) FetchRaw(key string) ([]byte, error) {
return c.fetcher(key)
}
// Fetches a single key and tries to unmarshal the result to json and returns
// it. If the unmarshalling fails it's safe to assume the result it's just a
// string and returns it.
func (c *Cepgo) Key(key string) (interface{}, error) {
var result interface{}
fetched, err := c.FetchRaw(key)
if err != nil {
return nil, err
}
err = json.Unmarshal(fetched, &result)
if err != nil {
return string(fetched), nil
}
return result, nil
}
// Fetches all the server context. Equivalent of c.Key("")
func (c *Cepgo) All() (interface{}, error) {
return c.Key("")
}
// Fetches only the object meta field and makes sure to return a proper
// map[string]string
func (c *Cepgo) Meta() (map[string]string, error) {
rawMeta, err := c.Key("/meta/")
if err != nil {
return nil, err
}
return typeAssertToMapOfStrings(rawMeta)
}
// Fetches only the global context and makes sure to return a proper
// map[string]string
func (c *Cepgo) GlobalContext() (map[string]string, error) {
rawContext, err := c.Key("/global_context/")
if err != nil {
return nil, err
}
return typeAssertToMapOfStrings(rawContext)
}
// Just a little helper function that uses type assertions in order to convert
// a interface{} to map[string]string if this is possible.
func typeAssertToMapOfStrings(raw interface{}) (map[string]string, error) {
result := make(map[string]string)
dictionary, ok := raw.(map[string]interface{})
if !ok {
return nil, errors.New("Received bytes are formatted badly")
}
for key, rawValue := range dictionary {
if value, ok := rawValue.(string); ok {
result[key] = value
} else {
return nil, errors.New("Server context metadata is formatted badly")
}
}
return result, nil
}

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package cepgo
import (
"encoding/json"
"testing"
)
func fetchMock(key string) ([]byte, error) {
context := []byte(`{
"context": true,
"cpu": 4000,
"cpu_model": null,
"cpus_instead_of_cores": false,
"enable_numa": false,
"global_context": {
"some_global_key": "some_global_val"
},
"grantees": [],
"hv_relaxed": false,
"hv_tsc": false,
"jobs": [],
"mem": 4294967296,
"meta": {
"base64_fields": "cloudinit-user-data",
"cloudinit-user-data": "I2Nsb3VkLWNvbmZpZwoKaG9zdG5hbWU6IGNvcmVvczE=",
"ssh_public_key": "ssh-rsa AAAAB2NzaC1yc2E.../hQ5D5 john@doe"
},
"name": "coreos",
"nics": [
{
"runtime": {
"interface_type": "public",
"ip_v4": {
"uuid": "31.171.251.74"
},
"ip_v6": null
},
"vlan": null
}
],
"smp": 2,
"status": "running",
"uuid": "20a0059b-041e-4d0c-bcc6-9b2852de48b3"
}`)
if key == "" {
return context, nil
}
var marshalledContext map[string]interface{}
err := json.Unmarshal(context, &marshalledContext)
if err != nil {
return nil, err
}
if key[0] == '/' {
key = key[1:]
}
if key[len(key)-1] == '/' {
key = key[:len(key)-1]
}
return json.Marshal(marshalledContext[key])
}
func TestAll(t *testing.T) {
cepgo := NewCepgoFetcher(fetchMock)
result, err := cepgo.All()
if err != nil {
t.Error(err)
}
for _, key := range []string{"meta", "name", "uuid", "global_context"} {
if _, ok := result.(map[string]interface{})[key]; !ok {
t.Errorf("%s not in all keys", key)
}
}
}
func TestKey(t *testing.T) {
cepgo := NewCepgoFetcher(fetchMock)
result, err := cepgo.Key("uuid")
if err != nil {
t.Error(err)
}
if _, ok := result.(string); !ok {
t.Errorf("%#v\n", result)
t.Error("Fetching the uuid did not return a string")
}
}
func TestMeta(t *testing.T) {
cepgo := NewCepgoFetcher(fetchMock)
meta, err := cepgo.Meta()
if err != nil {
t.Errorf("%#v\n", meta)
t.Error(err)
}
if _, ok := meta["ssh_public_key"]; !ok {
t.Error("ssh_public_key is not in the meta")
}
}
func TestGlobalContext(t *testing.T) {
cepgo := NewCepgoFetcher(fetchMock)
result, err := cepgo.GlobalContext()
if err != nil {
t.Error(err)
}
if _, ok := result["some_global_key"]; !ok {
t.Error("some_global_key is not in the global context")
}
}