Add condensed #inspect for Pool, Adapter, Config

Previously, it was very easy to accidentally leak a database password in
production logs if an error ends up calling inspect on a ConnectionPool
or an individual connection (Adapter). This is due to the default
`#inspect` output for Pools and Adapters being unnecessarily large, and
both currently including passwords (through the DatabaseConfig of a
Pool, and the internal configuration of an Adapter).

This commit addresses these issues by defining a custom `#inspect` for
ConnectionPool, AbstractAdapter, and DatabaseConfig. The condensed
`#inspect` only includes a few valuable fields instead of all of the
internals, which prevents both the large output and passwords from being
included.

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Add condensed `#inspect` for `ConnectionPool`, `AbstractAdapter`, and
+    `DatabaseConfig`.
+
+    *Hartley McGuire*
+
 *   Add `.shard_keys`, `.sharded?`, & `.connected_to_all_shards` methods.
 
     ```ruby

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -263,6 +263,13 @@ module ActiveRecord
         @reaper.run
       end
 
+      def inspect # :nodoc:
+        name_field = " name=#{db_config.name.inspect}" unless db_config.name == "primary"
+        shard_field = " shard=#{@shard.inspect}" unless @shard == :default
+
+        "#<#{self.class.name} env_name=#{db_config.env_name.inspect}#{name_field} role=#{role.inspect}#{shard_field}>"
+      end
+
       def schema_cache
         @schema_cache ||= BoundSchemaReflection.new(schema_reflection, self)
       end

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -172,6 +172,13 @@ module ActiveRecord
         @verified = false
       end
 
+      def inspect # :nodoc:
+        name_field = " name=#{pool.db_config.name.inspect}" unless pool.db_config.name == "primary"
+        shard_field = " shard=#{shard.inspect}" unless shard == :default
+
+        "#<#{self.class.name}:#{'%#016x' % (object_id << 1)} env_name=#{pool.db_config.env_name.inspect}#{name_field} role=#{role.inspect}#{shard_field}>"
+      end
+
       def lock_thread=(lock_thread) # :nodoc:
         @lock =
         case lock_thread

activerecord/lib/active_record/database_configurations/database_config.rb

@@ -18,6 +18,10 @@ module ActiveRecord
         @adapter_class ||= ActiveRecord::ConnectionAdapters.resolve(adapter)
       end
 
+      def inspect # :nodoc:
+        "#<#{self.class.name} env_name=#{@env_name} name=#{@name} adapter_class=#{adapter_class}>"
+      end
+
       def new_connection
         adapter_class.new(configuration_hash)
       end

activerecord/test/cases/adapter_test.rb

@@ -323,6 +323,12 @@ module ActiveRecord
     test "type_to_sql returns a String for unmapped types" do
       assert_equal "special_db_type", @connection.type_to_sql(:special_db_type)
     end
+
+    test "inspect does not show secrets" do
+      output = @connection.inspect
+
+      assert_match(/ActiveRecord::ConnectionAdapters::\w+:0x[\da-f]+ env_name="\w+" role=:writing>/, output)
+    end
   end
 
   class AdapterForeignKeyTest < ActiveRecord::TestCase

activerecord/test/cases/connection_pool_test.rb

@@ -984,6 +984,16 @@ module ActiveRecord
         assert_equal ActiveSupport::Concurrency::NullLock, @pool.lease_connection.lock
       end
 
+      def test_inspect_does_not_show_secrets
+        assert_match(/#<ActiveRecord::ConnectionAdapters::ConnectionPool env_name="\w+" role=:writing>/, @pool.inspect)
+
+        db_config = ActiveRecord::Base.connection_pool.db_config
+        pool_config = ActiveRecord::ConnectionAdapters::PoolConfig.new(ActiveRecord::Base, db_config, :reading, :shard_one)
+        pool = ConnectionPool.new(pool_config)
+
+        assert_match(/#<ActiveRecord::ConnectionAdapters::ConnectionPool env_name="\w+" role=:reading shard=:shard_one>/, pool.inspect)
+      end
+
       private
         def active_connections(pool)
           pool.connections.find_all(&:in_use?)

activerecord/test/cases/database_configurations/hash_config_test.rb

@@ -174,6 +174,11 @@ module ActiveRecord
           config.validate!
         end
       end
+
+      def test_inspect_does_not_show_secrets
+        config = HashConfig.new("default_env", "primary", { adapter: "abstract", password: "hunter2" })
+        assert_equal "#<ActiveRecord::DatabaseConfigurations::HashConfig env_name=default_env name=primary adapter_class=ActiveRecord::ConnectionAdapters::AbstractAdapter>", config.inspect
+      end
     end
   end
 end