Generating Images 10x Cheaper — Image Automation with Kie.ai + n8n

What You'll Build

A fully automated social media video pipeline that runs on a schedule: it pulls an image prompt from Google Sheets, sends it to Kie.ai's API (no local GPU needed), generates a voiceover with KokoroTTS, creates background music, renders a captioned video using NCA Toolkit, and posts it to Instagram — all without touching your computer.

What You Need

• n8n running in Docker
• Kie.ai account with API credits
• MinIO running in Docker (S3-compatible local storage)
• KokoroTTS running in Docker
• NCA Toolkit running in Docker
• Blotato account (for social media posting)
• Google Sheet with columns: ID, image_prompt, talking_points, more_talking_points, music_tags, status

Why Kie.ai Instead of Local GPU?

Running ComfyUI locally needs a capable GPU. Kie.ai gives you API access to the same models (Z-Image, Flux, Suno) at a few cents per generation. For volume workflows — posting daily to social media — the cost is negligible and you don't need any local hardware beyond a machine that can run Docker.

Workflow Step by Step

1. Schedule Trigger — Runs the workflow on your chosen interval (e.g. daily at midnight).
2. Google Sheets — Get Row — Pulls the first row where status = "processing". This is your image prompt and talking points.
3. UUID Node — Generates a unique ID so every file in this run shares the same name pattern: zimage_UUID.png, voiceover_UUID.mp3, music_UUID.mp3.
4. HTTP POST → Kie.ai — Sends a POST to https://api.kie.ai/api/v1/jobs/create-task with your Bearer token, model (zimage), aspect ratio (9:16 for TikTok/Instagram), and the image prompt from Google Sheets.
5. Wait Node (3–5 min) — Kie.ai generates images asynchronously. Give it enough time before polling.
6. HTTP GET → Kie.ai — Query the task using the taskId returned in step 4. Extract the result URL with a Code node.
7. HTTP GET → Download Image — Fetch the generated image as binary data.
8. S3 Upload → MinIO — Store the image in your MinIO bucket. Use host.docker.internal:9000 as the endpoint from within n8n's Docker container.
9. KokoroTTS — POST your talking points to host.docker.internal:[port]. KokoroTTS returns an MP3. Upload that to MinIO too.
10. NCA Toolkit — Get Audio Duration — POST to /v1/ffmpeg/pose with metadata: {duration: true} to find out how long the voiceover is. This determines your video length.
11. Music Generation — Either use ComfyUI locally or Kie.ai's Suno integration to generate background music matching your music_tags from Google Sheets.
12. NCA Toolkit — Render Video — POST all three files (image, voiceover, music) to NCA Toolkit's FFmpeg endpoint. It loops the image, layers the audio, fades in/out, and returns an MP4.
13. NCA Toolkit — Add Captions — POST the MP4 to /v1/video/caption. Set font, size, color, and style: "word_by_word" for animated captions.
14. Download Captioned Video from MinIO — Retrieve the final MP4.
15. Blotato — Upload Media — Upload to Blotato's media library so it has a URL to post.
16. Blotato — Create Post — Select Instagram, choose your account, write the caption (drag in image_prompt + talking points), set the media URL.
17. Google Sheets — Update Row — Set status = "done" and log the post date so this row doesn't get picked up again.

The Docker Networking Trick

This is the most common point of confusion. n8n runs inside a Docker container. MinIO, KokoroTTS, and NCA Toolkit also run in Docker. When n8n needs to talk to them, you can't use localhost — that would refer to n8n's own container, not your machine. Use host.docker.internal instead. This is a special DNS name Docker provides so containers can reach services on the host machine or other containers by their exposed ports.

host.docker.internal:9000  → MinIO
host.docker.internal:8188  → ComfyUI
host.docker.internal:8080  → NCA Toolkit

Key Things That Can Go Wrong

• Task ID capitalisation — Kie.ai returns taskId (camelCase). In the GET request query param, it must be taskId exactly — wrong case returns a 500.
• UUID changes on re-run — If you pin nodes while testing, unpin them before the full run or the UUID will differ between the image and upload steps.
• MinIO bucket visibility — New buckets default to Private. Set to Public so the NCA Toolkit can fetch the files by URL during rendering.
• Wait time too short — If Kie.ai hasn't finished when you poll, you'll get an empty result. Bump the wait to 5 minutes for image generation.