Magento 2.2 Shared Configuration Boundary: Promoting Search, Cache, and Queue Backends into config.php

Answer

Keep all connection‑specific values (host, port, credentials, index names, virtual hosts, etc.) for catalog/search, system/full_page_cache, and queue/AMQP in app/etc/env.php. Only promote generic toggles that are identical across environments—such as the search engine selection, cache type flag, or queue driver—to app/etc/config.php. This prevents staging‑only backends from being locked into production.

Confirmed facts from Magento 2.2 behavior

• The config dump (bin/magento app:config:dump) places all non‑sensitive configuration in config.php by default.
• Backend connection details are treated as sensitive and are automatically written to env.php unless the --lock-env flag forces them into config.php.
• Documentation explicitly excludes paths under catalog/search/, system/full_page_cache/, and queue/ from the shared dump unless overridden.

Steps to classify and promote safely

1. Identify the keys that contain environment‑specific data:
   • catalog/search/server_host, catalog/search/server_port, catalog/search/index_prefix
   • system/full_page_cache/backend/redis/server, system/full_page_cache/backend/redis/port, system/full_page_cache/backend/redis/password (or analogous Varnish settings)
   • queue/amqp/* entries such as host, port, username, password, virtualhost
2. Run a dump without forcing env values:

   bin/magento app:config:dump

3. Inspect the generated app/etc/config.php and verify that none of the keys listed above appear. If any are present, remove them manually or edit the dump command to exclude them.
4. Ensure app/etc/env.php retains those keys with the correct values for each environment.
5. Flush configuration and caches:

   bin/magento cache:clean config
   bin/magento cache:flush

6. Run setup:upgrade or setup:di:compile if needed, then verify the storefront works.

Verification that env.php values are unchanged

1. Use bin/magento config:show <path> for each connection‑related path; the output should reflect the values from env.php (you can confirm by temporarily changing a value in env.php and seeing the change in the output).
2. Check var/log and var/report after a page load; there should be no exceptions indicating missing search, cache, or queue services.
3. Optionally, diff the current config.php against a known‑good baseline to ensure no unintended environment‑specific entries were added.

Documented compatibility boundary

Magento 2.2.x documentation states that the following configuration paths are not safe to share across environments and must remain in env.php:

• catalog/search/* (host, port, index, authentication)
• system/full_page_cache/* (backend server, port, password, timeout)
• queue/amqp/* (RabbitMQ host, port, username, password, virtual heart)

Only the generic switches that do not contain connection details—e.g., catalog/search/engine, system/full_page_cache/caching_application, queue/consumers/* driver selection—can be safely locked into config.php.