Updated with Sean's feedback

app/controllers/chaos_controller.rb

@@ -4,24 +4,33 @@ class ChaosController < ActionController::Base
   before_action :validate_request
 
   def leakmem
-    memory_mb = params[:memory_mb] ? params[:memory_mb].to_i : 100
+    memory_mb = (params[:memory_mb]&.to_i || 100)
+    duration_s = (params[:duration_s]&.to_i || 30).seconds
+
+    start = Time.now
     retainer = []
+    # Add `n` 1mb chunks of memory to the retainer array
+    memory_mb.times { retainer << "x" * 1.megabyte }
+
+    duration_taken = (Time.now - start).seconds
+    Kernel.sleep duration_s - duration_taken if duration_s > duration_taken
 
-    memory_mb.times { retainer << "x" * (1024 * 1024) }
     render text: "OK", content_type: 'text/plain'
   end
 
   def cpuspin
-    duration_s = params[:duration_s] ? params[:duration_s].to_i : 30
+    duration_s = (params[:duration_s]&.to_i || 30).seconds
     end_time = Time.now + duration_s.seconds
-    10_000.times { } while Time.now < end_time
+
+    rand while Time.now < end_time
 
     render text: "OK", content_type: 'text/plain'
   end
 
   def sleep
-    duration_s = params[:duration_s] ? params[:duration_s].to_i : 30
+    duration_s = (params[:duration_s]&.to_i || 30).seconds
     Kernel.sleep duration_s
+
     render text: "OK", content_type: 'text/plain'
   end
 
@@ -33,6 +42,11 @@ class ChaosController < ActionController::Base
 
   def validate_request
     secret = ENV['GITLAB_CHAOS_SECRET']
+    # GITLAB_CHAOS_SECRET is required unless you're running in Development mode
+    if !secret && !Rails.env.development?
+      render text: "chaos misconfigured: please configure GITLAB_CHAOS_SECRET when using GITLAB_ENABLE_CHAOS_ENDPOINTS outside of a development environment", content_type: 'text/plain', status: 500
+    end
+
     return unless secret
 
     unless request.headers["HTTP_X_CHAOS_SECRET"] == secret

doc/development/chaos_endpoints.md

@@ -41,12 +41,13 @@ To simulate a memory leak in your application, use the `/-/chaos/leakmem` endpoi
 For example, if your GitLab instance is listening at `localhost:3000`, you could `curl` the endpoint as follows:
 
 ```shell
-curl http://localhost:3000/-/chaos/leakmem?memory_mb=1024 --header 'X-Chaos-Secret: secret'
+curl http://localhost:3000/-/chaos/leakmem?memory_mb=1024&duration_s=10 --header 'X-Chaos-Secret: secret'
 ```
 
-The `memory_mb` parameter tells the application how much memory it should leak.
+The `memory_mb` parameter tells the application how much memory it should leak. The `duration_s` parameter will ensure the request retains
+the memory for this duration at a minimum (default 30s).
 
-Note: the memory is not retained after the request, so once its completed, the Ruby garbage collector will attempt to recover the memory.
+Note: the memory is not retained after the request finishes. Once the request has completed, the Ruby garbage collector will attempt to recover the memory.
 
 ### CPU Spin