Stale cache content served after post update – Ghost file‑system cache

Answer: No built-in selective purge

Ghost does not expose an API endpoint or webhook that tells the file-system cache to delete the cached HTML for a specific post. Invalidation occurs only by the global TTL expiration or by running ghost cache clear, which removes the entire content/data/cache/ directory.

Confirmed facts

• Cache files are stored under content/data/cache/ with names that are the MD5 hash of the full request URL (including query string).
• The only built-in invalidation mechanisms are TTL (cache.maxAge in config) and the ghost cache clear command.
• A post.update webhook is fired when content changes, but its payload contains no instruction for the cache layer.
• Community packages such as ghost-cache-purge implement selective purging by listening to that webhook, computing the MD5 hash of the post's public URL, and deleting the matching cache file.

Steps to achieve selective purging (custom webhook)

1. Set up a webhook receiver (e.g., a small Node.js service) that subscribes to the post.update event from Ghost.
2. In the handler, reconstruct the public URL of the updated post (you can use the url field from the payload or build it from your site's base URL and the post's slug).
3. Compute the MD5 hash of that URL (the same algorithm Ghost uses for cache keys).
4. Delete the file content/data/cache/<hash> if it exists.
5. Optionally respond with a 200 status to acknowledge the webhook.

const crypto = require('crypto');
const fs = require('fs');
const path = require('path');

function purgePostCache(postUrl) {
  const hash = crypto.createHash('md5').update(postUrl).digest('hex');
  const cacheFile = path.join(process.env.GHOST_CONTENT || '.', 'data', 'cache', hash);
  if (fs.existsSync(cacheFile)) {
    fs.unlinkSync(cacheFile);
    console.log(`Purged cache file for ${postUrl}`);
  } else {
    console.log(`No cache file found for ${postUrl}`);
  }
}

// Example webhook handler (Express)
app.post('/ghost/webhook', (req, res) => {
  const event = req.body;
  if (event.event === 'post.update' && event.post) {
    const baseUrl = 'https://example.com'; // replace with your site URL
    const postUrl = `${baseUrl}/${event.post.slug}/`;
    purgePostCache(postUrl);
  }
  res.sendStatus(200);
});

Alternative: lower global TTL

If you prefer not to run a custom service, you can reduce the global TTL in config.production.json:

{
  "cache": {
    "maxAge": 10
  }
}

After changing the value, restart Ghost (ghost restart). This makes stale content disappear faster, but the setting applies to every route and will increase origin traffic.

Missing diagnostic detail

Please confirm your Ghost version (run ghost version) to ensure the behavior described still applies; if you are on a newer release, check the changelog for any changes to caching or webhook payloads.