Load config/appsignal.rb in diagnose CLI

Update the diagnose CLI to call the new `Appsignal._load_config!`
PRIVATE method to initialize the config. This way we have less
duplication of how the config should be initialized and we can be sure
it works the same in the diagnose CLI as well the app starts.

I've introduced a new PRIVATE `_APPSIGNAL_CONFIG_FILE_ENV` env var to
set the environment, but only in the diagnose CLI context. It's one of
the few ways we can pass the default environment as set by the CLI to
whatever config object gets initialized in the config file.

I didn't use the `APPSIGNAL_APP_ENV` environment variable so the config
option doesn't show up in the report as being set by an env var.

lib/appsignal.rb

@@ -167,7 +167,7 @@ def _load_config!(env_param = nil)
           )
         else
           # Load it when no config is present
-          load_dsl_config_file(context.dsl_config_file)
+          load_dsl_config_file(context.dsl_config_file, env_param)
         end
       else
         # Load config if no config file was found and no config is present yet
@@ -459,11 +459,12 @@ def params_match_loaded_config?(env_param, root_path_param)
     # If the config file has already been loaded once and it's trying to be
     # loaded more than once, which should never happen, it will not do
     # anything.
-    def load_dsl_config_file(path)
+    def load_dsl_config_file(path, env_param = nil)
       return if defined?(@dsl_config_file_loaded)
 
       begin
         ENV["_APPSIGNAL_CONFIG_FILE_CONTEXT"] = "true"
+        ENV["_APPSIGNAL_CONFIG_FILE_ENV"] = env_param if env_param
         @dsl_config_file_loaded = true
         require path
       rescue => error
@@ -489,6 +490,7 @@ def load_dsl_config_file(path)
         config[:active] = false if defined?(@config_file_error)
 
         ENV.delete("_APPSIGNAL_CONFIG_FILE_CONTEXT")
+        ENV.delete("_APPSIGNAL_CONFIG_FILE_ENV")
       end
     end
 

lib/appsignal/cli/diagnose.rb

@@ -188,15 +188,16 @@ def puts_format(label, value, options = {})
         end
 
         def configure_appsignal(options)
+          env_option = options.fetch(:environment, nil)
           # Try and load the Rails app, if any.
           # This will configure AppSignal through the config file or an
           # initializer.
-          require_rails_app_if_present
+          require_rails_app_if_present(env_option)
 
-          # If no config was found by loading the app, load with the defaults.
-          Appsignal.configure(options.fetch(:environment, nil))
-          Appsignal.config.write_to_environment
+          # No config loaded yet, try loading as normal
+          Appsignal._load_config!(env_option) unless Appsignal.config
           Appsignal._start_logger
+          Appsignal.config.write_to_environment
           Appsignal.internal_logger.info("Starting AppSignal diagnose")
         end
 
@@ -631,9 +632,12 @@ def print_empty_line
           puts "\n"
         end
 
-        def require_rails_app_if_present
+        def require_rails_app_if_present(env_option)
           return unless rails_present?
 
+          # Set the environment given as an option to the diagnose CLI so the
+          # Rails app uses it when loaded.
+          ENV["_APPSIGNAL_CONFIG_FILE_ENV"] = env_option
           # Mark app as Rails app
           data[:app][:rails] = true
           # Manually require the railtie, because it wasn't loaded when the CLI
@@ -649,6 +653,8 @@ def require_rails_app_if_present
           puts error.backtrace
           data[:app][:load_error] =
             "#{error.class}: #{error.message}\n#{error.backtrace.join("\n")}"
+        ensure
+          ENV.delete("_APPSIGNAL_CONFIG_FILE_ENV")
         end
 
         def rails_present?

lib/appsignal/config.rb

@@ -35,6 +35,7 @@ def self.add_loader_defaults(name, env: nil, root_path: nil, **options)
     def self.determine_env(initial_env = nil)
       [
         initial_env,
+        ENV.fetch("_APPSIGNAL_CONFIG_FILE_ENV", nil), # PRIVATE ENV var used by the diagnose CLI
         ENV.fetch("APPSIGNAL_APP_ENV", nil),
         ENV.fetch("RAILS_ENV", nil),
         ENV.fetch("RACK_ENV", nil)

spec/lib/appsignal/cli/diagnose_spec.rb

@@ -916,8 +916,39 @@ def dont_accept_prompt_to_send_diagnostics_report
             end
           end
 
+          describe "with config/appsignal.rb" do
+            let(:root_path) { File.join(tmp_dir, "config_file_test_diagnose1") }
+            let(:app_name) { "DiagnoseDSLapp" }
+            let(:push_api_key) { "DiagnosePushAPIKey" }
+            let(:options) { { :environment => "production" } }
+            before do
+              FileUtils.mkdir_p(root_path)
+              config_contents =
+                <<~CONFIG
+                  Appsignal.configure do |config|
+                    config.name = "#{app_name}"
+                    config.push_api_key = "#{push_api_key}"
+                  end
+                CONFIG
+              write_file(File.join(root_path, "config", "appsignal.rb"), config_contents)
+
+              ENV["APPSIGNAL_APP_PATH"] = root_path
+              ENV["APPSIGNAL_APP_NAME"] = "ENV app name"
+              run
+            end
+
+            it "loads config/appsignal.rb" do
+              expect(output).to include(
+                "  name: \"DiagnoseDSLapp\"\n" \
+                  "    Sources:\n" \
+                  "      env: \"ENV app name\"\n" \
+                  "      dsl: \"DiagnoseDSLapp\"\n"
+              )
+            end
+          end
+
           if DependencyHelper.rails_present?
-            context "when is a Rails app" do
+            context "when is a Rails app with config/appsignal.yml config file" do
               let(:root_path) { rails_project_fixture_path }
               let(:app_name) { "TestApp" }
               let(:environment) { "test" }
@@ -929,10 +960,11 @@ def dont_accept_prompt_to_send_diagnostics_report
                 if defined?(MyApp) && MyApp::Application.initialized?
                   Appsignal::Integrations::Railtie.load_default_config
                 end
-                run_within_dir(root_path)
               end
 
               it "includes the Rails default config in the output and transmitted report" do
+                run_within_dir(root_path)
+
                 expect(output).to include(
                   "  name: \"TestApp\"\n" \
                     "    Sources:\n" \
@@ -941,11 +973,10 @@ def dont_accept_prompt_to_send_diagnostics_report
                 )
                 # Outputs values from the DSL
                 expect(output).to include(
-                  "  ignore_actions: [\"Action from DSL\"]\n" \
+                  "  ignore_actions: [\"Rails::HealthController#show\"]\n" \
                     "    Sources:\n" \
                     "      default: []\n" \
-                    "      loaders: [\"Rails::HealthController#show\"]\n" \
-                    "      dsl:     [\"Action from DSL\"]\n"
+                    "      loaders: [\"Rails::HealthController#show\"]\n"
                 )
 
                 expect(received_report["app"]["rails"]).to be(true)
@@ -958,10 +989,77 @@ def dont_accept_prompt_to_send_diagnostics_report
                     "ignore_actions" => ["Rails::HealthController#show"]
                   }
                 )
+              end
+
+              context "when there's a problem loading the app" do
+                before do
+                  # A spot where we can mock an error raise
+                  expect(Appsignal::Utils::RailsHelper).to receive(:environment_config_path)
+                    .and_raise(ExampleStandardError, "error message", ["line 1", "line 2"])
+                  run_within_dir(root_path)
+                end
+
+                it "includes a load error" do
+                  expect(output).to include(
+                    "ERROR: Error encountered while loading the Rails app\n" \
+                      "ExampleStandardError: error message"
+                  )
+
+                  expect(received_report["app"]["load_error"])
+                    .to eq("ExampleStandardError: error message\nline 1\nline 2")
+                end
+              end
+            end
+
+            context "when is a Rails app with config/appsignal.rb config file" do
+              let(:root_path) { File.join(tmp_dir, "diagnose_test_app_#{SecureRandom.uuid}") }
+              let(:app_name) { "TestApp" }
+              let(:environment) { "test" }
+              # Set the environment option so it's more predictable which
+              # environment we should mock API requests for
+              let(:options) { { :environment => environment } }
+              before do
+                # Copy Rails project so we can require the same
+                # `config/appsignal.rb` file multiple times in one test suite
+                # from multiple locations.
+                FileUtils.cp_r(rails_project_with_config_rb_fixture_path, root_path)
+
+                # Workaround to not being able to require the railtie file
+                # multiple times and triggering the Rails initialization process.
+                # This will be used whtn the MyApp app has already been loaded.
+                if defined?(MyApp) && MyApp::Application.initialized?
+                  Appsignal::Integrations::Railtie.load_default_config
+                end
+              end
+              after { FileUtils.rm_rf(root_path) }
+
+              it "includes the Rails default config in the output and transmitted report" do
+                run_within_dir(root_path)
+
+                expect(output).to include(
+                  "  name: \"TestApp\"\n" \
+                    "    Sources:\n" \
+                    "      loaders: \"MyApp\"\n" \
+                    "      dsl:     \"TestApp\"\n"
+                )
+
+                expect(received_report["app"]["rails"]).to be(true)
+                expect(received_report["config"]["sources"]).to include(
+                  "loaders" => {
+                    "root_path" => root_path,
+                    "env" => "test",
+                    "log_path" => File.join(root_path, "log"),
+                    "name" => "MyApp",
+                    "ignore_actions" => ["Rails::HealthController#show"]
+                  }
+                )
                 # Includes values from the DSL
                 expect(received_report["config"]["sources"]).to include(
                   "dsl" => {
-                    "ignore_actions" => ["Action from DSL"]
+                    "active" => true,
+                    "name" => "TestApp",
+                    "push_api_key" => "abc",
+                    "enable_minutely_probes" => false
                   }
                 )
               end

spec/support/fixtures/projects/valid_with_rails_app/config/environment.rb

@@ -3,8 +3,3 @@
 
 # Initialize the Rails application.
 MyApp::Application.initialize!
-
-# Asserted from the diagnose spec
-Appsignal.configure do |config|
-  config.ignore_actions = ["Action from DSL"]
-end

spec/support/fixtures/projects/valid_with_rails_app_with_config_rb/config/application.rb

@@ -0,0 +1,16 @@
+require "rails"
+
+module MyApp
+  class Application < Rails::Application
+    config.active_support.deprecation = proc { |message, stack| }
+    config.eager_load = false
+
+    def self.initialize!
+      # Prevent errors about Rails being initialized more than once
+      return if defined?(@initialized)
+
+      super
+      @initialized = true
+    end
+  end
+end

spec/support/fixtures/projects/valid_with_rails_app_with_config_rb/config/appsignal.rb

@@ -0,0 +1,6 @@
+Appsignal.configure do |config|
+  config.activate_if_environment(:production, :development, :test)
+  config.name = "TestApp"
+  config.push_api_key = "abc"
+  config.enable_minutely_probes = false
+end

spec/support/fixtures/projects/valid_with_rails_app_with_config_rb/config/environment.rb

@@ -0,0 +1,5 @@
+# Load the Rails application.
+require_relative "application"
+
+# Initialize the Rails application.
+MyApp::Application.initialize!

spec/support/helpers/config_helpers.rb

@@ -13,6 +13,13 @@ def rails_project_fixture_path
   end
   module_function :rails_project_fixture_path
 
+  def rails_project_with_config_rb_fixture_path
+    File.expand_path(
+      File.join(File.dirname(__FILE__), "../fixtures/projects/valid_with_rails_app_with_config_rb")
+    )
+  end
+  module_function :rails_project_fixture_path
+
   def build_config(
     root_path: project_fixture_path,
     env: "production",