Pusher Channels HTTP Go Library
The Golang library for interacting with the Pusher Channels HTTP API.
This package lets you trigger events to your client and query the state of your Pusher channels. When used with a server, you can validate Pusher Channels webhooks and authorize private-
or presence-
channels.
Register for free at https://pusher.com/channels and use the application credentials within your app as shown below.
Supported Platforms
- Go - supports Go 1.11 or greater.
Table of Contents
Installation
$ go get github.com/pusher/pusher-http-go/v5
Getting Started
package main
import (
"github.com/pusher/pusher-http-go/v5"
)
func main(){
// instantiate a client
pusherClient := pusher.Client{
AppID: "APP_ID",
Key: "APP_KEY",
Secret: "APP_SECRET",
Cluster: "APP_CLUSTER",
}
data := map[string]string{"message": "hello world"}
// trigger an event on a channel, along with a data payload
err := pusherClient.Trigger("my-channel", "my_event", data)
// All trigger methods return an error object, it's worth at least logging this!
if err != nil {
panic(err)
}
}
Configuration
The easiest way to configure the library is by creating a new Pusher
instance:
pusherClient := pusher.Client{
AppID: "APP_ID",
Key: "APP_KEY",
Secret: "APP_SECRET",
Cluster: "APP_CLUSTER",
}
Additional options
Instantiation From URL
pusherClient := pusher.ClientFromURL("http://<key>:<secret>@api-<cluster>.pusher.com/apps/app_id")
Note: the API URL differs depending on the cluster your app was created in:
http://key:[email protected]/apps/app_id
http://key:[email protected]/apps/app_id
Instantiation From Environment Variable
pusherClient := pusher.ClientFromEnv("PUSHER_URL")
This is particularly relevant if you are using Pusher Channels as a Heroku add-on, which stores credentials in a "PUSHER_URL"
environment variable.
HTTPS
To ensure requests occur over HTTPS, set the Secure
property of a pusher.Client
to true
.
pusherClient.Secure = true
This is false
by default.
Request Timeouts
If you wish to set a time-limit for each HTTP request, create a http.Client
instance with your specified Timeout
field and set it as the Pusher Channels instance's Client
:
httpClient := &http.Client{Timeout: time.Second * 3}
pusherClient.HTTPClient = httpClient
If you do not specifically set a HTTP client, a default one is created with a timeout of 5 seconds.
Changing Host
Changing the pusher.Client
's Host
property will make sure requests are sent to your specified host.
pusherClient.Host = "foo.bar.com"
By default, this is "api.pusherapp.com"
.
Changing the Cluster
Setting the pusher.Client
's Cluster
property will make sure requests are sent to the cluster where you created your app.
NOTE! If Host
is set then Cluster
will be ignored.
pusherClient.Cluster = "eu" // in this case requests will be made to api-eu.pusher.com.
End to End Encryption
This library supports end to end encryption of your private channels. This means that only you and your connected clients will be able to read your messages. Pusher cannot decrypt them. You can enable this feature by following these steps:
-
You should first set up Private channels. This involves creating an authorization endpoint on your server.
-
Next, generate a 32 byte master encryption key, base64 encode it and store it securely.
This is secret and you should never share this with anyone. Not even Pusher.
To generate a suitable key from a secure random source, you could use:
openssl rand -base64 32
-
Pass the encoded key when constructing your pusher.Client
pusherClient := pusher.Client{ AppID: "APP_ID", Key: "APP_KEY", Secret: "APP_SECRET", Cluster: "APP_CLUSTER", EncryptionMasterKeyBase64 "<output from command above>", }
-
Channels where you wish to use end to end encryption should be prefixed with
private-encrypted-
. -
Subscribe to these channels in your client, and you're done! You can verify it is working by checking out the debug console on the https://dashboard.pusher.com/ and seeing the scrambled ciphertext.
Important note: This will not encrypt messages on channels that are not prefixed by private-encrypted-.
Google App Engine
As of version 1.0.0, this library is compatible with Google App Engine's urlfetch library. Pass in the HTTP client returned by urlfetch.Client
to your Pusher Channels initialization struct.
package helloworldapp
import (
"appengine"
"appengine/urlfetch"
"fmt"
"github.com/pusher/pusher-http-go/v5"
"net/http"
)
func init() {
http.HandleFunc("/", handler)
}
func handler(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
urlfetchClient := urlfetch.Client(c)
pusherClient := pusher.Client{
AppID: "APP_ID",
Key: "APP_KEY",
Secret: "APP_SECRET",
HTTPClient: urlfetchClient,
}
pusherClient.Trigger("my-channel", "my_event", map[string]string{"message": "hello world"})
fmt.Fprint(w, "Hello, world!")
}
Usage
Triggering events
It is possible to trigger an event on one or more channels. Channel names can contain only characters which are alphanumeric, _
or -
and have to be at most 200 characters long. Event name can be at most 200 characters long too.
Custom Types
pusher.Event
type TriggerParams struct {
SocketID *string
Info *string
}
Note: Info
is part of an experimental feature.
Single channel
func (c *Client) Trigger
Argument | Description |
---|---|
channel string |
The name of the channel you wish to trigger on. |
event string |
The name of the event you wish to trigger. |
data interface{} |
The payload you wish to send. Must be marshallable into JSON. |
Example
data := map[string]string{"hello": "world"}
pusherClient.Trigger("greeting_channel", "say_hello", data)
func (c *Client) TriggerWithParams
Allows additional parameters to be included as part of the request body. The complete list of parameters are documented here.
Argument | Description |
---|---|
channel string |
The name of the channel you wish to trigger on. |
event string |
The name of the event you wish to trigger. |
data interface{} |
The payload you wish to send. Must be marshallable into JSON. |
params TriggerParams |
Any additional parameters. |
Return Value | Description |
---|---|
channels TriggerChannelsList |
A struct representing channel attributes for the requested TriggerParams.Info |
err error |
Any errors encountered |
Example
data := map[string]string{"hello": "world"}
socketID := "1234.12"
attributes := "user_count"
params := pusher.TriggerParams{SocketID: &socketID, Info: &attributes}
channels, err := pusherClient.TriggerWithParams("presence-chatroom", "say_hello", data, params)
// channels => &{Channels:map[presence-chatroom:{UserCount:4}]}
Multiple channels
func (c. *Client) TriggerMulti
Argument | Description |
---|---|
channels []string |
A slice of channel names you wish to send an event on. The maximum length is 10. |
event string |
As above. |
data interface{} |
As above. |
Example
pusherClient.TriggerMulti([]string{"a_channel", "another_channel"}, "event", data)
func (c. *Client) TriggerMultiWithParams
Argument | Description |
---|---|
channels []string |
A slice of channel names you wish to send an event on. The maximum length is 10. |
event string |
As above. |
data interface{} |
As above. |
params TriggerParams |
As above. |
Return Value | Description |
---|---|
channels TriggerChannelsList |
A struct representing channel attributes for the requested TriggerParams.Info |
err error |
Any errors encountered |
Example
data := map[string]string{"hello": "world"}
socketID := "1234.12"
attributes := "user_count"
params := pusher.TriggerParams{SocketID: &socketID, Info: &attributes}
channels, err := pusherClient.TriggerMultiWithParams([]string{"presence-chatroom", "presence-notifications"}, "event", data, params)
// channels => &{Channels:map[presence-chatroom:{UserCount:4} presence-notifications:{UserCount:31}]}
Batches
func (c. *Client) TriggerBatch
Argument | Description |
---|---|
batch []Event |
A list of events to publish |
Return Value | Description |
---|---|
batch TriggerBatchChannelsList |
A struct representing channel attributes for the requested TriggerParams.Info |
err error |
Any errors encountered |
Custom Types
pusher.Event
type Event struct {
Channel string
Name string
Data interface{}
SocketID *string
Info *string
}
Note: Info
is part of an experimental feature.
Example
socketID := "1234.12"
attributes := "user_count"
batch := []pusher.Event{
{ Channel: "a-channel", Name: "event", Data: "hello world" },
{ Channel: "presence-b-channel", Name: "event", Data: "hi my name is bob", SocketID: &socketID, Info: &attributes },
}
response, err := pusherClient.TriggerBatch(batch)
for i, attributes := range response.Batch {
if attributes.UserCount != nil {
fmt.Printf("channel: %s, name: %s, user_count: %d\n", batch[i].Channel, batch[i].Name, *attributes.UserCount)
} else {
fmt.Printf("channel: %s, name: %s\n", batch[i].Channel, batch[i].Name)
}
}
// channel: a-channel, name: event
// channel: presence-b-channel, name: event, user_count: 4
Send to user
func (c *Client) SendToUser
Argument | Description |
---|---|
userId string |
The id of the user who should receive the event. |
event string |
The name of the event you wish to trigger. |
data interface{} |
The payload you wish to send. Must be marshallable into JSON. |
Example
data := map[string]string{"hello": "world"}
pusherClient.SendToUser("user123", "say_hello", data)
Authenticating Users
Pusher Channels provides a mechanism for authenticating users. This can be used to send messages to specific users based on user id and to terminate misbehaving user connections, for example.
For more information see our docs.
func (c *Client) AuthenticateUser
Argument | Description |
---|---|
params []byte |
The request body sent by the client |
userData map[string]interface{} |
The map containing arbitrary user data. It must contain at least an id field with the user's id as a string. See below. |
Arbitrary User Data
userData := map[string]interface{} { "id": "1234", "twitter": "jamiepatel" }
Return Value | Description |
---|---|
response []byte |
The response to send back to the client, carrying an authentication signature |
err error |
Any errors generated |
Example
func pusherUserAuth(res http.ResponseWriter, req *http.Request) {
params, _ := ioutil.ReadAll(req.Body)
userData := map[string]interface{} { "id": "1234", "twitter": "jamiepatel" }
response, err := pusherClient.AuthenticateUser(params, userData)
if err != nil {
panic(err)
}
fmt.Fprintf(res, string(response))
}
func main() {
http.HandleFunc("/pusher/user-auth", pusherUserAuth)
http.ListenAndServe(":5000", nil)
}
Authorizing Channels
Application security is very important so Pusher Channels provides a mechanism for authorizing a user’s access to a channel at the point of subscription.
This can be used both to restrict access to private channels, and in the case of presence channels notify subscribers of who else is also subscribed via presence events.
This library provides a mechanism for generating an authorization signature to send back to the client and authorize them.
For more information see our docs.
Private channels
func (c *Client) AuthorizePrivateChannel
Argument | Description |
---|---|
params []byte |
The request body sent by the client |
Return Value | Description |
---|---|
response []byte |
The response to send back to the client, carrying an authorization signature |
err error |
Any errors generated |
Example
func pusherAuth(res http.ResponseWriter, req *http.Request) {
params, _ := ioutil.ReadAll(req.Body)
response, err := pusherClient.AuthorizePrivateChannel(params)
if err != nil {
panic(err)
}
fmt.Fprintf(res, string(response))
}
func main() {
http.HandleFunc("/pusher/auth", pusherAuth)
http.ListenAndServe(":5000", nil)
}
Example (JSONP)
func pusherJsonpAuth(res http.ResponseWriter, req *http.Request) {
var (
callback, params string
)
{
q := r.URL.Query()
callback = q.Get("callback")
if callback == "" {
panic("callback missing")
}
q.Del("callback")
params = []byte(q.Encode())
}
response, err := pusherClient.AuthorizePrivateChannel(params)
if err != nil {
panic(err)
}
res.Header().Set("Content-Type", "application/javascript; charset=utf-8")
fmt.Fprintf(res, "%s(%s);", callback, string(response))
}
func main() {
http.HandleFunc("/pusher/auth", pusherJsonpAuth)
http.ListenAndServe(":5000", nil)
}
Authorizing presence channels
Using presence channels is similar to private channels, but in order to identify a user, clients are sent a user_id and, optionally, custom data.
func (c *Client) AuthorizePresenceChannel
Argument | Description |
---|---|
params []byte |
The request body sent by the client |
member pusher.MemberData |
A struct representing what to assign to a channel member, consisting of a UserID and any custom UserInfo . See below |
Custom Types
pusher.MemberData
type MemberData struct {
UserID string
UserInfo map[string]string
}
Example
params, _ := ioutil.ReadAll(req.Body)
presenceData := pusher.MemberData{
UserID: "1",
UserInfo: map[string]string{
"twitter": "jamiepatel",
},
}
response, err := pusherClient.AuthorizePresenceChannel(params, presenceData)
if err != nil {
panic(err)
}
fmt.Fprintf(res, response)
Application state
This library allows you to query our API to retrieve information about your application's channels, their individual properties, and, for presence-channels, the users currently subscribed to them.
Get the list of channels in an application
func (c *Client) Channels
Argument | Description |
---|---|
params ChannelsParams |
The query options. The field FilterByPrefix will filter the returned channels. To get the number of users subscribed to a presence-channel, specify an the Info field with value "user_count" . Pass in nil if you do not wish to specify any query attributes. |
Return Value | Description |
---|---|
channels ChannelsList |
A struct representing the list of channels. See below. |
err error |
Any errors encountered |
Custom Types
pusher.ChannelsParams
type ChannelsParams struct {
FilterByPrefix *string
Info *string
}
pusher.ChannelsList
type ChannelsList struct {
Channels map[string]ChannelListItem
}
pusher.ChannelsListItem
type ChannelListItem struct {
UserCount int
}
Example
prefixFilter := "presence-"
attributes := "user_count"
params := pusher.ChannelsParams{FilterByPrefix: &prefixFilter, Info: &attributes}
channels, err := pusherClient.Channels(params)
// channels => &{Channels:map[presence-chatroom:{UserCount:4} presence-notifications:{UserCount:31}]}
Get the state of a single channel
func (c *Client) Channel
Argument | Description |
---|---|
name string |
The name of the channel |
params ChannelParams |
The query options. The field Info can have comma-separated values of "user_count" , for presence-channels, and "subscription_count" , for all-channels. To use the "subscription_count" value, first check the "Enable subscription counting" checkbox in your App Settings on your Pusher Channels dashboard. Pass in nil if you do not wish to specify any query attributes. |
Return Value | Description |
---|---|
channel Channel |
A struct representing a channel. See below. |
err error |
Any errors encountered |
Custom Types
pusher.ChannelParams
type Channel struct {
Info *string
}
pusher.Channel
type Channel struct {
Name string
Occupied bool
UserCount int
SubscriptionCount int
}
Example
attributes := "user_count,subscription_count"
params := pusher.ChannelParams{Info: &attributes}
channel, err := client.Channel("presence-chatroom", params)
// channel => &{Name:presence-chatroom Occupied:true UserCount:42 SubscriptionCount:42}
Get a list of users in a presence channel
func (c *Client) GetChannelUsers
Argument | Description |
---|---|
name string |
The channel name |
Return Value | Description |
---|---|
users Users |
A struct representing a list of the users subscribed to the presence-channel. See below |
err error |
Any errors encountered. |
Custom Types
pusher.Users
type Users struct {
List []User
}
pusher.User
type User struct {
ID string
}
Example
users, err := pusherClient.GetChannelUsers("presence-chatroom")
// users => &{List:[{ID:13} {ID:90}]}
Webhook validation
On your dashboard, you can set up webhooks to POST a payload to your server after certain events. Such events include channels being occupied or vacated, members being added or removed in presence-channels, or after client-originated events. For more information see https://pusher.com/docs/webhooks.
This library provides a mechanism for checking that these POST requests are indeed from Pusher, by checking the token and authentication signature in the header of the request.
func (c *Client) Webhook
Argument | Description |
---|---|
header http.Header |
The header of the request to verify |
body []byte |
The body of the request |
Return Value | Description |
---|---|
webhook *pusher.Webhook |
If the webhook is valid, this method will return a representation of that webhook that includes its timestamp and associated events. If invalid, this value will be nil . |
err error |
If the webhook is invalid, an error value will be passed. |
Custom Types
pusher.Webhook
type Webhook struct {
TimeMs int
Events []WebhookEvent
}
pusher.WebhookEvent
type WebhookEvent struct {
Name string
Channel string
Event string
Data string
SocketID string
}
Example
func pusherWebhook(res http.ResponseWriter, req *http.Request) {
body, _ := ioutil.ReadAll(req.Body)
webhook, err := pusherClient.Webhook(req.Header, body)
if err != nil {
fmt.Println("Webhook is invalid :(")
} else {
fmt.Printf("%+v\n", webhook.Events)
}
}
Feature Support
Feature | Supported |
---|---|
Trigger event on single channel | |
Trigger event on multiple channels | |
Trigger events in batches | |
Excluding recipients from events | |
Fetching info on trigger | |
Send to user | |
Authenticating users | |
Authorizing private channels | |
Authorizing presence channels | |
Get the list of channels in an application | |
Get the state of a single channel | |
Get a list of users in a presence channel | |
WebHook validation | |
Heroku add-on support | |
Debugging & Logging | |
Cluster configuration | |
Timeouts | |
HTTPS | |
HTTP Proxy configuration | ✘ |
HTTP KeepAlive | ✘ |
Helper Functionality
These are helpers that have been implemented to to ensure interactions with the HTTP API only occur if they will not be rejected e.g. channel naming conventions.
Helper Functionality | Supported |
---|---|
Channel name validation | |
Limit to 10 channels per trigger | |
Limit event name length to 200 chars |
Developing the Library
Feel more than free to fork this repo, improve it in any way you'd prefer, and send us a pull request :)
Running the tests
$ go test
License
This code is free to use under the terms of the MIT license.