How to Automate Social Media Posting with n8n

Do not put an MCP tool name such as upload_from_url into an HTTP Request node and expect it to become a URL. REST endpoints and MCP tools are different interfaces.

The REST Workflow

1. Trigger: Schedule Trigger, Webhook, Google Drive, Airtable, or another source.
2. Presigned slot: POST https://dohoo.ai/api/upload/presigned-url with filename and contentType.
3. Binary upload: PUT the original file bytes to the returned uploadUrl with the same content type.
4. Publish: call the documented platform endpoint with fileId and the correct connection ID.

Credentials

Create a reusable Header Auth credential in n8n:

Header name: X-API-Key
Header value: dh_live_xxxxxxxxxxxxxxxxxxxxxxxx

Apply it to DOHOO requests, but not to the presigned S3 PUT. The signed upload URL authenticates that request by itself.

Node Configuration

{
  "method": "POST",
  "url": "https://dohoo.ai/api/upload/presigned-url",
  "sendHeaders": true,
  "sendBody": true,
  "jsonBody": {
    "filename": "={{ $binary.data.fileName }}",
    "contentType": "={{ $binary.data.mimeType }}"
  }
}

After the PUT node, poll /api/upload/status/{fileId} for large videos. Then publish, for example, to Instagram:

{
  "method": "POST",
  "url": "https://dohoo.ai/api/v2/instagram/publish",
  "jsonBody": {
    "connectionId": "={{ $json.instagramConnectionId }}",
    "fileId": "={{ $json.fileId }}",
    "caption": "={{ $json.caption }}"
  }
}

Two Valid Scheduling Patterns

• Pure REST: let n8n wait until the target time and then call the immediate publish endpoint.
• MCP: use an MCP-capable node or agent and invoke the platform-specific schedule tool with scheduledAt and timezone.

Do not invent a REST /schedule URL unless it appears in the public reference.

Failure Handling

Use separate branches for upload, processing, and platform publication. Store HTTP status, response body, connection ID, and source record ID. Send a Slack or Telegram alert only after you have captured enough information to retry safely without creating duplicates.

FAQ