Add Get Help With A Rails App Update as a Rails TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1223 TILs and counting..._
+_1224 TILs and counting..._
 
 ---
 
@@ -749,6 +749,7 @@ _1223 TILs and counting..._
 - [Get ActiveRecord Attribute Directly From Database](rails/get-active-record-attribute-directly-from-database.md)
 - [Get An Array Of Values From The Database](rails/get-an-array-of-values-from-the-database.md)
 - [Get An Empty ActiveRecord Relation](rails/get-an-empty-activerecord-relation.md)
+- [Get Help With A Rails App Update](rails/get-help-with-a-rails-app-update.md)
 - [Get The Column Names For A Model](rails/get-the-column-names-for-a-model.md)
 - [Get The Current Time](rails/get-the-current-time.md)
 - [Grab A Random Record From The Database](rails/grab-a-random-record-from-the-database.md)

rails/get-help-with-a-rails-app-update.md

@@ -0,0 +1,29 @@
+# Get Help With A Rails App Update
+
+Rails version upgrades can be pretty involved. The ecosystem and the framework
+are under constant evolution. While each patch version will stay reliably
+stable, as soon as you go to do a minor or major upgrade (which you should stay
+on top of), you'll have lots to consider.
+
+Rails helps with this via the `app:update` rake task.
+
+When run, it will prompt you with a series of files that it wants to change.
+For each one you'll have some options.
+
+```bash
+$ rails app:update
+
+Overwrite my-app/config/boot.rb? (enter "h" for help) [Ynaqdhm]  h
+        Y - yes, overwrite
+        n - no, do not overwrite
+        a - all, overwrite this and all others
+        q - quit, abort
+        d - diff, show the differences between the old and the new
+        h - help, show this help
+        m - merge, run merge tool
+```
+
+Start by using `d` to see a diff of the changes. If it's small and doesn't
+overwrite important, existing settings, then you can use `y` to accept them.
+For a lot of these files the changes will be too aggressive. So side-by-side
+with the diff, update the file manually. Then use `n` to go to the next update.