visuals

Author: lukaszreszke

posts/2025-08-01-watch-out-for-this-one-deprecation-warning-when-upgrading-from-rails-7-dot-1-to-7-dot-2-on-heroku.md

@@ -8,10 +8,10 @@ publish: false
 # Watch out for this one deprecation warning when upgrading from Rails 7.1 to 7.2 on Heroku
 
 We recently upgraded Rails from 7.0 to 7.1 for one of our clients. It went smoothly.
-
 When Rails 7.1 went live, we were pleased to see a new set of deprecation warnings. To avoid being overwhelmed by them, we decided to address the issue right away.
+However, we ran into a nasty issue...
 
-However, we ran into a nasty issue.
+## The one with nasty issue
 
 The application didn't crash.
 
@@ -22,7 +22,8 @@ Either of those would have been better. The worst that can happen is silence.
 The deprecation warning was:
 
 ```ruby
-[DEPRECATION] DEPRECATION WARNING: `Rails.application.secrets` is deprecated in favor of `Rails.application.credentials` and will be removed in Rails 7.2.
+[DEPRECATION] DEPRECATION WARNING: `Rails.application.secrets` is deprecated 
+in favor of `Rails.application.credentials` and will be removed in Rails 7.2.
 ```
 
 We removed values from `ENV["SECRET_KEY_BASE"]` to credentials and checked that the value was correct by calling
@@ -49,19 +50,15 @@ Ok so to sum it up, until now:
 - We removed ENV 
 - So it should take the value from credentials 
 
-Right?
-
-But instead...
+Right? But instead...
 
 Instead it failed silently. So where’s the poop?
 
-
 The poop is in Heroku trying to be smarter than developers. Unfortunately. It turned out that removing `SECRET_KEY_BASE` env leads to.. regenerating it with new **random** value.
 
 So our external devices depending on it couldn’t work because of new, randomly generated key.
 
 ## Summary
-
 To sum it up:
 - If you’re getting rid of the `Rails.application.secrets` is deprecated in favor of `Rails.application.credentials` and will be removed in Rails 7.2
 - And you’re on Heroku