This Python script connects to the Ghost Admin API, retrieves all blog posts in batches, and automatically adds a specified tag to each post that doesn’t already have it.

ghost_cms_add_tag.py

import jwt
import time
import requests

# Instalation
##   python3 -m venv ~/python-dev-env
##   source ~/python-dev-env/bin/activate
##   pip install requests PyJWT
##   download  ghost_cms_add_tag.py
##  edit ghost_cms_add_tag.py -> add url, tag and admin key

# Configuration
api_url = "https://yourblog.com/ghost/api/admin"
admin_key = "YOUR_ADMIN_API_KEY"
new_tag = "wojtekadams_tag"

# JWT token generation
key_id, secret = admin_key.split(":")
iat = int(time.time())
header = {"alg": "HS256", "kid": key_id}
payload = {"iat": iat, "exp": iat + 5 * 60, "aud": "/admin/"}

token = jwt.encode(payload, bytes.fromhex(secret), algorithm="HS256", headers=header)
headers = {"Authorization": f"Ghost {token}"}

# Fetch all posts with pagination
all_posts = []
page_number = 1

while True:
    r = requests.get(f"{api_url}/posts/?limit=100&page={page_number}", headers=headers)
    r.raise_for_status()
    posts = r.json()["posts"]
    if not posts:
        break
    all_posts.extend(posts)
    print(f"Fetching page {page_number} ({len(all_posts)} posts total)")
    page_number += 1

print(f"Found {len(all_posts)} posts in total")

# Add a tag to each post if missing
for post in all_posts:
    tags = post.get("tags", [])
    tag_names = [t["name"] for t in tags if "name" in t]
    if new_tag not in tag_names:
        tags.append({"name": new_tag})
        post_data = {
            "posts": [{
                "id": post["id"],
                "updated_at": post["updated_at"],
                "tags": tags
            }]
        }
        update = requests.put(f"{api_url}/posts/{post['id']}/", headers=headers, json=post_data)
        if update.ok:
            print(f"Added tag '{new_tag}' to post: {post['title']}")
        else:
            print(f"Error updating post {post['title']}: {update.text}")