Parsing DATABASE_URI, use URI#hostname: it's smarter about IPv6

Fixes #15705.

3 files changed, 20 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index b3df23c623..f15bd6261b 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Correctly extract IPv6 addresses from `DATABASE_URI`: the square brackets
+    are part of the URI structure, not the actual host.
+
+    Fixes #15705.
+
+    *Andy Bakun*, *Aaron Stone*
+
 *   Ensure both parent IDs are set on join records when both sides of a
     through association are new.
 
diff --git a/activerecord/lib/active_record/connection_adapters/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
index b79d1a4458..2fcb085ab2 100644
--- a/activerecord/lib/active_record/connection_adapters/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
@@ -85,7 +85,7 @@ module ActiveRecord
               "password" => uri.password,
               "port"     => uri.port,
               "database" => database_from_path,
-              "host"     => uri.host })
+              "host"     => uri.hostname })
           end
         end
 
diff --git a/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
index da852aaa02..e1b2804a18 100644
--- a/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
+++ b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
@@ -144,6 +144,18 @@ module ActiveRecord
         assert_equal nil,      actual[:test]
       end
 
+      def test_database_url_with_ipv6_host_and_port
+        ENV['DATABASE_URL'] = "postgres://[::1]:5454/foo"
+
+        config   = {}
+        actual   = resolve_config(config)
+        expected = { "adapter"  => "postgresql",
+                     "database" => "foo",
+                     "host"     => "::1",
+                     "port"     => 5454 }
+        assert_equal expected, actual["default_env"]
+      end
+
       def test_url_sub_key_with_database_url
         ENV['DATABASE_URL'] = "NOT-POSTGRES://localhost/NOT_FOO"