CDN variable product images replaced with local urls

I’d like to reopen this as, although I found a fix, it seems that this is only an issue in WooCommerce. My other sites have no issue with the CDN, W3 Total Cache and image source set URLs.

@sixsixninenine Can you go to WooCommerce > Status and copy/paste your System Status Report here for us?

This may be related to these:
https://github.com/woocommerce/woocommerce/issues/18853
https://github.com/woocommerce/woocommerce/pull/18850

### WordPress Environment ###

Home URL: https://www.xxxxxxxxxx.co.uk
Site URL: https://www.xxxxxxxxxx.co.uk
WC Version: 3.4.2
Log Directory Writable: ? To allow logging
make /home/xxxxxxxxxx/public_html/wp-content/uploads/wc-logs/ writable or define a custom WC_LOG_DIR.

WP Version: 4.9.6
WP Multisite: –
WP Memory Limit: 256 MB
WP Debug Mode: –
WP Cron: ?
Language: en_US
External object cache: –

### Server Environment ###

Server Info: Apache/2.4.23 (Unix) OpenSSL/1.0.1e-fips mod_bwlimited/1.4 mod_fcgid/2.3.9
PHP Version: 7.0.30 - We recommend using PHP version 7.2 or above for greater performance and security. How to update your PHP version
PHP Post Max Size: 8 MB
PHP Time Limit: 30
PHP Max Input Vars: 1000
cURL Version: 7.54.0
OpenSSL/1.0.2k

SUHOSIN Installed: –
MySQL Version: 5.6.39-log
Max Upload Size: 2 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 3.4.2
WC Database Prefix: wp_
MaxMind GeoIP Database: ?
Total Database Size: 41.16MB
Database Data Size: 25.33MB
Database Index Size: 15.83MB
wp_woocommerce_sessions: Data: 8.02MB + Index: 0.06MB
wp_woocommerce_api_keys: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_attribute_taxonomies: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_downloadable_product_permissions: Data: 0.02MB + Index: 0.05MB
wp_woocommerce_order_items: Data: 0.48MB + Index: 0.16MB
wp_woocommerce_order_itemmeta: Data: 1.52MB + Index: 3.03MB
wp_woocommerce_tax_rates: Data: 0.02MB + Index: 0.06MB
wp_woocommerce_tax_rate_locations: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_shipping_zones: Data: 0.02MB + Index: 0.00MB
wp_woocommerce_shipping_zone_locations: Data: 0.02MB + Index: 0.05MB
wp_woocommerce_shipping_zone_methods: Data: 0.02MB + Index: 0.00MB
wp_woocommerce_payment_tokens: Data: 0.02MB + Index: 0.02MB
wp_woocommerce_payment_tokenmeta: Data: 0.02MB + Index: 0.03MB
wp_woocommerce_log: Data: 0.02MB + Index: 0.02MB
wp_commentmeta: Data: 0.02MB + Index: 0.03MB
wp_comments: Data: 0.02MB + Index: 0.09MB
wp_ewwwio_images: Data: 1.52MB + Index: 1.67MB
wp_failed_jobs: Data: 0.02MB + Index: 0.00MB
wp_hugeit_slider_slide: Data: 0.02MB + Index: 0.00MB
wp_hugeit_slider_slider: Data: 0.02MB + Index: 0.00MB
wp_links: Data: 0.02MB + Index: 0.02MB
wp_mailchimp_carts: Data: 0.02MB + Index: 0.00MB
wp_masterslider_options: Data: 0.02MB + Index: 0.02MB
wp_masterslider_sliders: Data: 0.02MB + Index: 0.02MB
wp_options: Data: 2.31MB + Index: 0.27MB
wp_postmeta: Data: 5.52MB + Index: 5.03MB
wp_posts: Data: 1.52MB + Index: 0.66MB
wp_queue: Data: 0.02MB + Index: 0.00MB
wp_termmeta: Data: 0.06MB + Index: 0.03MB
wp_terms: Data: 0.02MB + Index: 0.03MB
wp_term_relationships: Data: 0.11MB + Index: 0.08MB
wp_term_taxonomy: Data: 0.02MB + Index: 0.03MB
wp_usermeta: Data: 3.52MB + Index: 4.03MB
wp_users: Data: 0.19MB + Index: 0.17MB
wp_w3tc_cdn_pathmap: Data: 0.02MB + Index: 0.02MB
wp_w3tc_cdn_queue: Data: 0.02MB + Index: 0.02MB
wp_wcpdf_invoice_number: Data: 0.00MB + Index: 0.00MB
wp_wc_download_log: Data: 0.02MB + Index: 0.03MB
wp_wc_webhooks: Data: 0.02MB + Index: 0.02MB
wp_yikes_easy_mc_forms: Data: 0.02MB + Index: 0.00MB
wp_yoast_seo_links: Data: 0.00MB + Index: 0.00MB
wp_yoast_seo_meta: Data: 0.00MB + Index: 0.00MB

### Post Type Counts ###

acf: 1
attachment: 951
customize_changeset: 2
jcd_promo_box: 1
mc4wp-form: 2
nav_menu_item: 10
page: 21
post: 3
product: 675
product_variation: 344
revision: 71
shop_coupon: 29
shop_order: 1118
shop_order_refund: 1
wccpf: 1
wpcf7_contact_form: 1

### Security ###

Secure connection (HTTPS): ?
Hide errors from visitors: ?

### Active Plugins (22) ###

a3 Lazy Load: by a3rev Software – 1.8.9
Advanced Custom Fields: by Elliot Condon – 4.4.12
Cart2Cart: Password Migration: by MagneticOne – 1.1
Contact Form 7 Honeypot: by Nocean – 1.13
Contact Form 7: by Takayuki Miyoshi – 5.0.2
Cookie Notice: by dFactory – 1.2.44
xxxxxxxxxx WooCommerce: by sixsixninenine – 1.0 – Not tested with the active version of WooCommerce
Master Slider: by averta – 3.5.1
Simple Multibuy Discount: by sixsixnineinine – 1.0 – Not tested with the active version of WooCommerce
W3 Total Cache: by Frederick Townes – 0.9.7
WC Fields Factory: by Saravana Kumar K – 2.0.8 – Not tested with the active version of WooCommerce
WooCommerce PayPal Express Checkout Gateway: by WooCommerce – 1.5.6
WooCommerce Stripe Gateway: by WooCommerce – 4.1.7
WooCommerce Google Analytics Integration: by WooCommerce – 1.4.4 – Not tested with the active version of WooCommerce
Woocommerce osCommerce Import Branch For Zencart: by David Barnes – 1.2.1 – Not tested with the active version of WooCommerce
WooCommerce PDF Invoices & Packing Slips: by Ewout Fernhout – 2.1.9
WooCommerce Wholesale Lead Capture: by Rymera Web Co – 1.7.5
WooCommerce Wholesale Order Form: by Rymera Web Co – 1.8.6
WooCommerce Wholesale Prices Premium: by Rymera Web Co – 1.16.6
WooCommerce Wholesale Prices: by Rymera Web Co – 1.6.5
WooCommerce: by Automattic – 3.4.2 – 3.4.3 is available
Yoast SEO: by Team Yoast – 7.6.1

### Settings ###

API Enabled: ?
Force SSL: –
Currency: GBP (￡)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2
Taxonomies: Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)

Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)
exclude-from-search (exclude-from-search)
featured (featured)
outofstock (outofstock)
rated-1 (rated-1)
rated-2 (rated-2)
rated-3 (rated-3)
rated-4 (rated-4)
rated-5 (rated-5)

### WC Pages ###

Shop base: #8 - /shop/
Cart: #9 - /cart/
Checkout: #10 - /checkout/
My account: #11 - /my-account/
Terms and conditions: #403 - /terms-and-conditions/

### Theme ###

Name: xxxxxxxxxx
Version: 1.0
Author URL: https://woocommerce.com
Child Theme: ?
Parent Theme Name: Storefront
Parent Theme Version: 2.3.2
Parent Theme Author URL: https://woocommerce.com/
WooCommerce Support: ?

### Templates ###

Overrides: xxxxxxxxxx/woocommerce/global/quantity-input.php
xxxxxxxxxx/woocommerce/single-product/add-to-cart/variation.php

Thanks Jesse, the issues and pull requests you links to seem to relate to image generation.

The images that are referenced after selecting a product variation all exist (on the CDN server), but they reference the local images rather than the ones on the CDN. I only noticed as I do not store the images locally so they appear as missing images, but only because the URL points to the wrong server.

@sixsixninenine It looks like this is probably an issue with W3 Total Cache over WooCommerce. I dove into the code, and this is where the images are pulled for variations:
https://github.com/woocommerce/woocommerce/blob/3.4.3/includes/wc-product-functions.php#L684-L740

As can be seen, the standard WordPress core functions are used to grab the image sources. I would have to believe that’s where W3 would filter the output in order to serve the CDN urls for the images.

With that being said, I do see what you are referring to and was able to replicate it, which led me to look into the code to find where the images were coming from.