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Nisit Sirimarnkit
Nisit Sirimarnkit

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Build an AI-Powered Auto-Post Bot for Facebook with Garudust

#ai #automation #facebook #rust

Social media managers spend hours crafting posts, finding images, and hitting "publish." What if a single terminal command could do all of that — research a topic, write an engaging post, generate a matching image, and publish it to your Facebook Page automatically?

That's exactly what Garudust does. It's an open-source AI agent written in Rust that connects to any OpenAI-compatible LLM (local or cloud) and runs multi-step workflows through a simple skill system.

In this guide, you'll set up Garudust and run a fully automated Facebook post workflow from scratch.

What You'll Build

One command → one full Facebook post:

garudust "use skill facebook-workflow, post about AI news today, page_id=YOUR_PAGE_ID"
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The agent will:

  • 🔍 Search the web for recent news on your topic
  • 📄 Read and summarize the best article it finds
  • 🎨 Generate a matching image with overlay text
  • ✍️ Write a detailed post with hashtags in your target language
  • 📢 Publish everything to your Facebook Page — no manual steps

Prerequisites

Before you start, make sure you have:

  • Rust (stable) — install via rustup.rs
  • A Facebook Page you manage
  • A Facebook Developer App with pages_manage_posts permission
  • An LLM endpoint — local (vLLM / Ollama) or cloud (OpenRouter / Anthropic)
  • Optional: A Hugging Face token for AI image generation

Step 1 — Install Garudust 

cargo install garudust
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Then run the interactive setup wizard:

garudust setup
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This creates two files:

  • ~/.garudust/config.yaml — non-secret settings
  • ~/.garudust/.env — API keys and tokens

Step 2 — Configure Your LLM

Garudust separates settings from secrets. Open ~/.garudust/config.yaml:

# Non-secret settings — safe to share or commit
model: Qwen/Qwen3-14B-AWQ    # or gpt-4o, claude-3-5-sonnet, etc.
provider: vllm                # vllm | ollama | anthropic | openrouter
base_url: http://localhost:8000/v1

context_window: 32768
compression:
  enabled: true
  threshold_fraction: 0.65
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Then add your secrets to ~/.garudust/.env:

# Secrets only — never put model or URL here
VLLM_API_KEY=your-vllm-key
HF_TOKEN=hf_xxxxxxxxxxxx
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💡 Design principle: config.yaml holds everything that isn't a secret (model name, provider, URLs, behavior tuning). .env holds only API keys. This makes it trivial to share your config without leaking credentials.

Using a cloud provider instead? Here's how each maps:

Provider config.yaml .env
vLLM (local) provider: vllm + base_url VLLM_API_KEY
Ollama (local) provider: ollama + base_url (none needed)
Anthropic provider: anthropic ANTHROPIC_API_KEY
OpenRouter provider: openrouter OPENROUTER_API_KEY

Step 3 — Get a Facebook Page Access Token

  1. Go to developers.facebook.com → My Apps → create a new app
  2. Add the Facebook Login product
  3. Open the Graph API Explorer, select your app and your Page
  4. Generate a token with these permissions:
    • pages_manage_posts
    • pages_read_engagement
  5. Exchange it for a long-lived Page Access Token (valid 60 days)
  6. Add it to your .env: 
FACEBOOK_ACCESS_TOKEN=EAAxxxxxxxxxxxxxxxx
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Your Page ID is visible in Page Settings under About, or in the Page URL.

Step 4 — Install the Skill and Tools 

garudust skill install facebook-workflow
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This pulls the skill from garudust-hub and automatically installs the required tools: facebook_post and generate_image.

Verify everything is in place:

garudust skill list
# ✓ facebook-workflow  v3.0.0

garudust tool list
# ✓ facebook_post
# ✓ generate_image
# ✓ web_search
# ✓ web_fetch
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Step 5 — Run Your First Auto-Post 

garudust "use skill facebook-workflow, research latest AI news, write a detailed post, generate an image, post to page_id=831735183365530"
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Watch the agent work through each step:

[web_search]     searching: AI news 2025...
[web_fetch]      fetching top result...
[generate_image] creating /tmp/fb_post_image.png...
[facebook_post]  publishing to page 831735183365530...

Posted — ID: 831735183365530_122126910027165465
[5 iter | 24657in 689out @ Qwen3-14B-AWQ]
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Your post is live. ✅

How It Works Under the Hood

The facebook-workflow skill is a plain Markdown file at:

~/.garudust/skills/facebook-workflow/SKILL.md
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It guides the agent through four steps:

Step 1 — Research   →  web_search + web_fetch (1 search, 1 fetch)
Step 2 — Image      →  generate_image (1024×576, with overlay text)
Step 3 — Post       →  facebook_post (page_id + message + image_path)
Step 4 — Report     →  confirm post_id or surface the error
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Each step explicitly tells the model which tool to call and when. This prevents weak models from staying in "text mode" and skipping tool calls entirely — a common failure mode in multi-step agent workflows.

Automatic Context Management

For models with small context windows (e.g. 27K tokens), Garudust handles overflow automatically:

  • Compresses conversation history when it reaches 65% of the context limit
  • Caps max_tokens at context_window / 8 to always leave room for input
  • Retries with a smaller output budget (/16 → /32) if the first attempt still overflows

You don't need to think about tokens — just set context_window in config.yaml and the agent handles the rest.

Step 6 — Customize the Post Format

The post format is defined directly in the skill file. Edit it:

nano ~/.garudust/skills/facebook-workflow/SKILL.md
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Find the post format section and adjust it to your style:

**Post format (minimum 200 words):**

[hook — 1–2 attention-grabbing sentences, use a question or surprising fact]

[background — why this matters, 2–3 sentences of context]

[main content — facts, figures, and deep details from research, 3–4 sentences]

[real example — a company, product, or case study, 2–3 sentences]

[impact & trends — what this means for the future, 2–3 sentences]

[call to action — ask for opinions or suggest next steps, 1–2 sentences]

#hashtag1 #hashtag2 #hashtag3 #hashtag4 #hashtag5
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Want posts in English instead of Thai? Change the language note. Want longer posts? Raise the minimum word count. The model will follow whatever format you define here.

Step 7 — Automate with a Daily Cron Job

Create a shell script:

# /usr/local/bin/daily-ai-post.sh
#!/bin/bash
garudust "use skill facebook-workflow, latest AI technology news, write a detailed post, generate an image, post to page_id=YOUR_PAGE_ID" \
  >> ~/.garudust/post.log 2>&1
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Make it executable and add it to cron:

chmod +x /usr/local/bin/daily-ai-post.sh
crontab -e

# Post every day at 9:00 AM
0 9 * * * /usr/local/bin/daily-ai-post.sh
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That's it — fully automated daily posts with zero manual work.

Troubleshooting

Symptom Cause Fix
required tool facebook_post not called Model skipped the tool call Retry, or switch to a stronger model
HTTP 400 context overflow Prompt too long for context window Reduce context_window or set a smaller web_fetch limit
FACEBOOK_ACCESS_TOKEN not set Missing secret Add to ~/.garudust/.env
Post published but has no image generate_image failed silently Check HF_TOKEN in .env
Token expired after 60 days Short-lived token used Regenerate a long-lived Page Access Token

What to Try Next

  • Multiple languages — add "write in English" or "write in Japanese" to your task
  • Topic rotation — pass a topics array in a shell script and pick one per day
  • Multiple pages — loop over page IDs to cross-post automatically
  • Custom image styles — edit the generate_image prompt in the skill to match your brand

Links

Garudust is fully open source:

The hub has community-contributed skills and tools — install any of them with a single garudust skill install command. If you build something useful, contributions are welcome.

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