Webhooks Overview

Introduction

Webhooks provide a way to leverage events that occur inside of Frame.io into notifications that can be sent to external systems for processing, API callbacks, and ultimately, workflow automation.

Setup

Webhooks can be configured in the Webhooks area of our developer site. A Webhook requires:

• Name — Will be shown on the developer site only.
• URL — Where to deliver events.
• Team — Which team this webhook will be added to.
• Events — Which event, or events, should trigger the Webhook.

Supported events

A single Webhook can subscribe to any number of the following events:

Projects

Assets

Comments

Review Links

Collaborators

Team Members

Payload

Frame.io delivers a JSON payload to the specified webhook endpoint. Here’s an example payload for an asset.created event:

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{
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  "type": "asset.created",
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  "resource": {
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    "type": "asset",
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    "id": "<asset-id>"
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  },
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  "user": {
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    "id": "<user-id>"
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  },
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  "team": {
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    "id": "<team-id>"
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  }
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}

All payloads contain a type field, indicating the type of event occurring, as well as a resource object. The resource object specifies the type and id of the resource related to this event.

In the above example of an asset.created event, this would be the id for the newly created Asset. Additionally, user and team objects are included. These reference the User who triggered the event, and the Team context for the resource.

Aside from the immediate User and Team context, we do not include any additional information about the subscribed resource. If your application requires additional information or context, we recommend using our HTTP API to make follow-up requests.

Retries

Should an error (non-200 status code response) or timeout occur while delivering the webhook to your service, the payload will be retried three times, for a total of four delivery attempts.

Security

By default, all Webhooks are provided with a signing key. This is not configurable. This key can be used to verify that the request originates from Frame.io.

Verify Webhook Signatures

To guard an integration against man-in-the-middle and replay attacks it is essential to verify webhook signatures. Verification ensures that webhook payloads were actually sent by Frame.io and payload content has not been modified in transport.

Included in the POST request are the following headers:

The timestamp is the time of delivery from Frame.io’s systems. This can be used to prevent replay attacks. We recommended verifying this time is within 5 minutes of local time.

The signature is a HMAC SHA256 hash using the signing key provided when the Webhook is first created.

Follow these steps to verify the signature:

1. Extract the signature from the HTTP headers
2. Create a message to sign by combining the version, delivery time, and request body: v0:timestamp:body
3. Compute the HMAC SHA256 signature using your signing secret. Note: The provided signature is prefixed with v0=. Currently Frame.io only has this one version for signing requests. Be sure this prefix is prepended to your computed signature.
4. Compare!

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import hmac
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import hashlib
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def verify_signature(curr_time, req_time, signature, body, secret):
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    """
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    Verify Webhook signature
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    :Args:
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        curr_time (float): Current epoch time
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        req_time (float): Request epoch time
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        signature (str): Signature provided by the Frame.io API for the given request
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        body (str): Webhook body from the received POST
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        secret (str): The secret for this Webhook that you saved when you first created it
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    """
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    if int(curr_time) - int(req_time) < 500:
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        message = 'v0:{}:{}'.format(req_time, body)
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        calculated_signature = 'v0={}'.format(hmac.new(
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            bytes(secret, 'latin-1'),
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            msg=bytes(message, 'latin-1'),
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            digestmod=hashlib.sha256).hexdigest())
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        if calculated_signature == signature:
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            return True
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    return False

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const crypto = require('crypto');
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// Capture the signature, secret, timestamp and payload from a new webhook event:
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const 
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signature = 'v0=a77ce6856e609c884575c2fd211d07a9ad1c3f72e19c06ff710e8f086ffca883', 
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secret = 'yxSE59T0gtZOFZxw6UhLwTkhd2m8ntNSdSWnApQ0xOnMEzSoXbD8sGFP4bzb7MbS',
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timestamp = 1604004499,  // UNIX timestamp in seconds
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payload = {
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	"project": {
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		"id": "f348e9f4-f142-42f9-b3bf-478d93f0feb4"
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	},
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	"resource": {
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		"id": "6aad9151-c216-4d6f-b5e9-530df551a426",
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		"type": "asset"
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	},
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	"team": {
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		"id": "aa891687-4b1e-4150-9b6d-9e4911c5b436"
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	},
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	"type": "asset.label.updated",
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	"user": {
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		"id": "59c9ade1-311b-4c3b-8231-b9d88e9a1a85"
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	}
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},
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body = JSON.stringify(payload),
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// Validate that caught payload is not older than 5 minutes
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currentTimeUTC = (new Date()).getTime(),
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currentTimestamp = currentTimeUTC / 1000, // JavaScript uses milliseconds whereas Unix Time is in seconds.
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minutes = 5, 
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expired = (currentTimestamp - timestamp) > minutes*60
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hmac1 = crypto.createHmac('sha256', secret),
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generateSignature = hmac1.update(`v0:${timestamp}:${body}`).digest('hex')
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// Evaluates to true if the webhook is verified
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console.log(!expired && signature === `v0=${generateSignature}`)

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// Full Go sample code: https://github.com/Frameio/webhooks-example-app/blob/master/main.go
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func handler(w http.ResponseWriter, r *http.Request) {
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	out, err := httputil.DumpRequest(r, true)
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	if err != nil {
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		w.WriteHeader(http.StatusInternalServerError)
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		return
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	}
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	log.Println(string(out))
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	// Verify the message has been delivered in the last 5 minutes.
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	timestampStr := r.Header.Get("X-Frameio-Request-Timestamp")
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	timestamp, err := strconv.ParseInt(timestampStr, 10, 64)
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	if err != nil {
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		w.WriteHeader(http.StatusBadRequest)
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		return
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	}
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	if time.Since(time.Unix(timestamp, 0)) > 5*time.Minute {
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		w.WriteHeader(http.StatusBadRequest)
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		return
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	}
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	// Verify request signature.
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	expected := r.Header.Get("X-Frameio-Signature")
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	signature, _ := computeSignature(r, timestamp, secretKey)
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	if expected != signature {
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		w.WriteHeader(http.StatusUnauthorized)
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		return
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	}
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	var event *Event
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	decoder := json.NewDecoder(r.Body)
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	err = decoder.Decode(&event)
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	if err != nil {
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		w.WriteHeader(http.StatusInternalServerError)
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		return
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	}
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	// Handle webhook here.
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	log.Println(event.ID)
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	w.WriteHeader(http.StatusOK)
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}
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// The request includes headers to enable the recipient to validate
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// that the request is from Frame.io and that it's been delivered within
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// the expected time range. To learn more about how this works, take a
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// look at our docs https://docs.frame.io/docs/webhooks#section-security.
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func computeSignature(r *http.Request, timestamp int64, secret string) (string, error) {
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	body, err := ioutil.ReadAll(r.Body)
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	if err != nil {
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		return "", err
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	}
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	copy := body[:]
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	r.Body = ioutil.NopCloser(bytes.NewReader(copy))
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	msg := fmt.Sprintf("%s:%d:%s", version, timestamp, string(body))
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	key := []byte(secret)
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	h := hmac.New(sha256.New, key)
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	h.Write([]byte(msg))
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	result := fmt.Sprintf("%s=%s", version, hex.EncodeToString(h.Sum(nil)))
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	return result, nil
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}