How to ensure that the thumbnails generated by the `thumb` filter are correctly cached and distributed on the CDN?

Our company provides us with a convenient and quick content management ability, including thethumbThe filter is also a good helper for creating thumbnails.In website operation, we all hope that images load quickly, the user experience is good, and it can effectively reduce the pressure on the server.thumbIt is particularly important that the thumbnail generated by the filter is correctly cached and distributed on the content delivery network (CDN).

Understanding the thumbnail generation mechanism of AnQiCMS.

First, let's briefly review how Anqi CMS handles thumbnails.In our daily operations, whether it is uploading the main image when publishing articles, or setting images in categories or single pages, we will usually see an option for 'thumbnail' in the background.{{item.Thumb}}or{% archiveDetail with name="Thumb" %}Call this tag to invoke it.

The Anqi CMS provides flexible thumbnail processing methods in content settings, such as 'proportional scaling by the longest side', 'filling by the longest side', or 'cropping by the shortest side', as well as our customized 'thumbnail size'.This means that when we upload an original image, the system will generate or process the corresponding thumbnail size according to these preset rules./uploads/Under such a public directory and provide access with a fixed URL.This process is for the convenience of management and unified size, but if each thumbnail request hits our source server directly, especially during peak traffic periods, the server's burden will not be light.

How does CDN play a role in thumbnail distribution?

This is when the CDN makes its appearance.The core function of Content Delivery Network (CDN) is to cache the static resources of a website (such as images, CSS, JS files) on edge nodes around the world.When a user visits the website, the static resources they request will be directly fetched from the CDN node closest to their geographical location, rather than being pulled from our origin server over a long distance.

• Accelerate loading:Reduced the distance and time of image transmission, allowing users to see the page content faster.
• Improve user experience:A smooth loading experience can effectively reduce the bounce rate and improve user satisfaction.
• Relieve the pressure on the source site:Most image requests are distributed by CDN, and our security CMS source server only needs to handle a small number of cache miss requests to ensure the stable operation of the website.
• Enhance risk resistance:CDN can effectively resist a certain degree of DDoS attacks and improve the availability of the website.

For the security CMS ofthumbThe thumbnail generated by the filter, CDN treats these images as ordinary static files.When the CDN receives the request for a thumbnail for the first time, it will go back to our secure CMS server to pull the image and cache it.The subsequent requests, as long as they are within the cache validity period, will be provided directly from the CDN node.

Ensure that the key steps for CDN correct caching and distribution are taken

To makethumbTo ensure that the thumbnails generated by the filter run fast and stable on the CDN, we need to make some detailed configurations:

first, Set and configure the origin site address of CDN.This is usually the server IP address or primary domain name where our AnQi CMS is deployed.CDN needs to know where to "learn" and pull our image resources.If our secure CMS is deployed through Nginx or Apache such as reverse proxy, the CDN configuration should point to the public IP or domain name of the reverse proxy server.

Next,Set up CDN cache rules in detail.

• File type identificationEnsure that the CDN recognizes and caches all image formats, especially those supported by the Anqicms CMS..jpg/.pngAnd those converted from the background content settings..webpImage format.
• Cache expiration time (TTL): Set a reasonable cache time (Time To Live) for images, usually for a longer period, such as several days or even weeks.This can maximize the CDN cache hit rate and reduce the number of origin requests.
• URL parameter processingIn general, the security CMSthumbThe thumbnail URL generated by the filter does not contain dynamic parameters such asimage.jpg?v=timestamp), size and processing methods have already been configured in the background and reflected in the generated image file.If we introduce image URLs with query strings in the future, in order to ensure that the CDN can effectively cache different versions of the same image or avoid caching duplicates, we need to decide in the CDN configuration whether to ignore the query strings or treat them as part of the cache key.For thumbnails and other strongly static resources, it is usually recommended to ignore query strings that do not affect the image content, or ensure that the query string itself represents a new version of the image.
• HTTP response header optimizationOur safe CMS server should send appropriate when responding to image requestsCache-ControlandExpireswait for HTTP cache headers. CDNs will respect these instructions and manage caching accordingly. If the header information is set properly, it can further optimize the CDN's cache efficiency.

InSecure CMS backend content settingsAmong them, we also need to pay attention:

• Thumbnail size and processing methodOnce the website is launched and CDN is configured, try to maintain the stability of these settings.Frequent changes to these settings will cause the old thumbnail sizes to become invalid on the CDN, requiring the source to be refreshed and cached, which will temporarily affect performance.
• Default thumbnailIf the default thumbnail feature is enabled, also make sure that these images can be cached normally by CDN.
• batch regenerate thumbnailsThis feature is very useful, but you must synchronize the CDN cache refresh operation after using it, otherwise users may still see the old thumbnails for a period of time.

Finally,Manage and maintain CDN caching.

• Cache purge (Purge): After updating the image content on the Anqi CMS backend, especially operations like 'batch regenerate thumbnails,' it is necessary to manually refresh the cache paths on the CDN service provider's console in a timely manner. For example, refresh/uploads/*All image cache under the directory, ensure that the CDN nodes can pull the latest thumbnails.
• Cache preheating (Pre-fetch/Pre-load): Consider using the CDN preheating feature for newly released important articles or products.After the content is published, submit the thumbnail URLs of these pages in advance to the CDN, so that the CDN can proactively pre-load them to the edge nodes. This way, when the first user visits, they can directly hit the cache without needing to go back to the source.

Consideration for multi-site scenarios

If we use the multi-site management feature of Anqicms on the same server to build multiple websites, and each website has an independent domain name, then for each site, it may be necessary to configure an independent domain name with the CDN service provider, or use advanced rules to redirect image requests with different domain names back to the same Anqicms source site, and ensure the isolation of cache paths to avoid image confusion between different sites.

Summary

By the above configuration and management, we can ensure the safety of the CMS.thumbThe thumbnail generated by the filter can be cached and distributed efficiently on the CDN.This can significantly improve the loading speed and user experience of the website, and it is an indispensable important link in our content marketing and SEO optimization.