Automate SMS sending with n8n via the OVHcloud API

Objective

This guide explains how to integrate the OVHcloud SMS API into n8n, in order to automatically send SMS from your workflows. You will learn how to configure a signed HTTP call via the OVHcloud API to trigger the sending of a message.

Find out how to send SMS from n8n using the OVHcloud API.

Requirements

• An OVHcloud SMS account and a valid SMS sender.
• An OVHcloud VPS, a server, or a local machine with n8n installed and accessible.

Instructions

If you have not yet installed n8n on your VPS, follow the instructions in our guide "How to install n8n on an OVHcloud VPS".

Step 1 – Generate OVHcloud API credentials

Before you can send SMS via the OVHcloud API, you must have the following three identifiers:

• Application key
• Application secret
• Consumer key

To do this, consult the section Advanced usage: pair OVHcloud APIs with an application in our guide "First Steps with the OVHcloud APIs", then copy and save the three identifiers Application key, Application secret and Consumer key.

Step 2 – Create the workflow and nodes

Log in to your n8n interface and click the Create Workflow button.

Create the following nodes (empty for now):

• Set - Credentials: of type Edit Fields (Set).
• Set - Request Details: of type Edit Fields (Set).
• Merge: of type Merge.
• Sign - Generate Signature: of type Code.
• SMS - Send: of type HTTP Request.

For more details on creating nodes, see the official n8n documentation.

Connect the nodes in this order:

The Merge node receives the outputs from the two Set - Credentials and Set - Request Details nodes, then feeds into Sign - Generate Signature, which feeds into SMS - Send.

Step 3 – Configure the Set – Credentials node

Add the following parameters to your Set - Credentials node:

• Mode: Manual Mapping.

Step 4 – Configure the Set – Request Details node

Configure the Set - Request Details node:

• Mode: Manual Mapping.
• Add a field named body of type Object with the content below (minimal example).

{
  "charset": "UTF-8",
  "coding": "7bit",
  "message": "Test message",
  "noStopClause": true,
  "priority": "high",
  "receivers": ["+33612345678"],
  "sender": "Your_sender"
}

Step 5 – Configure the Merge node

Configure the Merge node:

• Mode: Combine.
• Combine by: Position.
• Number of Inputs: 2.

Connect Set - Credentials to Input 1 and Set - Request Details to Input 2.
At the output (output), you should have at the same level: applicationKey, applicationSecret, consumerKey, serviceName, timestamp and body.

Step 6 – Configure the Sign – Generate Signature node

Configure the Sign - Generate Signature node:

• Mode: Run once for each item.
• Language: JavaScript.

Paste the code below:

// --- SHA1 pure (not HMAC) ---
function sha1(input) {
  function rotl(n, s) { return (n << s) | (n >>> (32 - s)); }
  function hex(v){ let s=''; for(let i=7;i>=0;i--) s+=((v >>> (i*4)) & 0xf).toString(16); return s; }
  function utf8(str){
    str=str.replace(/\r\n/g,'\n');
    let out=''; for (let i=0;i<str.length;i++){
      const c=str.charCodeAt(i);
      if (c<128) out+=String.fromCharCode(c);
      else if (c<2048) out+=String.fromCharCode((c>>6)|192, (c&63)|128);
      else out+=String.fromCharCode((c>>12)|224, ((c>>6)&63)|128, (c&63)|128);
    } return out;
  }
  let i,j,A,B,C,D,E,temp,H0=0x67452301,H1=0xEFCDAB89,H2=0x98BADCFE,H3=0x10325476,H4=0xC3D2E1F0;
  const W=new Array(80), m=utf8(input), ml=m.length, wa=[];
  for(i=0;i<ml-3;i+=4){ j=(m.charCodeAt(i)<<24)|(m.charCodeAt(i+1)<<16)|(m.charCodeAt(i+2)<<8)|m.charCodeAt(i+3); wa.push(j); }
  let last; switch(ml%4){case 0:last=0x080000000;break;case 1:last=(m.charCodeAt(ml-1)<<24)|0x0800000;break;case 2:last=(m.charCodeAt(ml-2)<<24)|(m.charCodeAt(ml-1)<<16)|0x08000;break;case 3:last=(m.charCodeAt(ml-3)<<24)|(m.charCodeAt(ml-2)<<16)|(m.charCodeAt(ml-1)<<8)|0x80;break;}
  wa.push(last); while ((wa.length%16)!==14) wa.push(0); wa.push(ml>>>29); wa.push((ml<<3)&0x0ffffffff);
  for(let bs=0; bs<wa.length; bs+=16){
    for(i=0;i<16;i++) W[i]=wa[bs+i]; for(i=16;i<=79;i++) W[i]=rotl(W[i-3]^W[i-8]^W[i-14]^W[i-16],1);
    A=H0; B=H1; C=H2; D=H3; E=H4;
    for(i=0;i<=19;i++){ temp=(rotl(A,5)+((B&C)|(~B&D))+E+W[i]+0x5A827999)&0x0ffffffff; E=D; D=C; C=rotl(B,30); B=A; A=temp; }
    for(i=20;i<=39;i++){ temp=(rotl(A,5)+(B^C^D)+E+W[i]+0x6ED9EBA1)&0x0ffffffff; E=D; D=C; C=rotl(B,30); B=A; A=temp; }
    for(i=40;i<=59;i++){ temp=(rotl(A,5)+((B&C)|(B&D)|(C&D))+E+W[i]+0x8F1BBCDC)&0x0ffffffff; E=D; D=C; C=rotl(B,30); B=A; A=temp; }
    for(i=60;i<=79;i++){ temp=(rotl(A,5)+(B^C^D)+E+W[i]+0xCA62C1D6)&0x0ffffffff; E=D; D=C; C=rotl(B,30); B=A; A=temp; }
    H0=(H0+A)&0x0ffffffff; H1=(H1+B)&0x0ffffffff; H2=(H2+C)&0x0ffffffff; H3=(H3+D)&0x0ffffffff; H4=(H4+E)&0x0ffffffff;
  }
  return (hex(H0)+hex(H1)+hex(H2)+hex(H3)+hex(H4)).toLowerCase();
}

// -- OVHcloud SIGNATURE --
const j = $json;
const method = 'POST';
// Use the recommended standard EU endpoint:
const url = `https://eu.api.ovh.com/1.0/sms/${j.serviceName}/jobs`;
const bodyString = JSON.stringify(j.body);
const timestamp = Math.floor(Date.now()/1000).toString();

// AppSecret + ConsumerKey + Method + URL + Body + Timestamp
const toSign = [ j.applicationSecret, j.consumerKey, method, url, bodyString, timestamp ].join('+');
const signature = `$1$${sha1(toSign)}`;

return { json: { ...j, url, bodyString, timestamp, signature } };

Step 7 – Configure the SMS - Send node

Configure the SMS - Send node:

• Method: POST.
• URL: {{$json.url}}.
• Authentication: None.
• Send Headers: ON.
• Specify Headers: Using fields below.

Add the following header parameters:

Enable Send Body and add the following body parameters:

Test your workflow

Run your workflow. The following steps are executed:

1. Set - Credentials: provides applicationKey, consumerKey, serviceName (and optionally applicationSecret if you have not externalized it).
2. Set - Request Details: prepares the body object containing the SMS body.
3. Merge (Combine/Position): merges the outputs of the previous two nodes.
4. Sign - Generate Signature (Code): calculates bodyString, timestamp, signature (simple SHA-1) and the call URL.
5. SMS - Send (HTTP Request): sends the POST to the URL with the body {{$json.bodyString}} and the X-Ovh-* headers.

The message is then transmitted via the OVHcloud API to your recipient.

Common errors

Invalid_signature (400)

• The signed URL is different from the sent URL (different host, extra / at the end).
• The signed body is different from the sent body (re-stringify, spaces, order, etc.).
• The local clock is too far off. Rather use the OVHcloud server time (see the section Industrialization and security).

SMS sender ... does not exist (403)

The sender (sender) is not declared/validated in your OVHcloud Control Panel. Test with "senderForResponse": true or validate your sender.

Bad Request

• Check in each node the name and value of your parameters.
• Make sure that the headers and body are complete.
• Check that the URL of the SMS - Send node follows the following format: https://eu.api.ovh.com/1.0/sms/sms-ab12345-1/jobs

Code node errors

• Do not use require('crypto') in n8n but rather the pure JavaScript SHA-1 above.
• Use the per item mode and avoid calling $input.all() in your code.

Industrialization and security

If you want to industrialize your workflow and make it more secure, apply the following tips.

OVHcloud server time

Add a HTTP Request node before the signature:

• GET https://eu.api.ovh.com/1.0/auth/time
• Retrieve the value and replace timestamp with this exact value.

Do not pass the applicationSecret

• Store it as an environment variable (e.g. OVH_APP_SECRET) and read it in the Code node (Sign - Generate Signature) via $env.OVH_APP_SECRET, or via the Secrets/Credentials feature of n8n.
• Failing that, never return the secret at the output of the node.

Character management

If your message contains emojis/accents not in GSM, use "coding": "ucs2".

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