Add container registry settings to app settings

What does this MR do?

Adds columns to the application settings table for storing information about an instance's container registry (vendor, version, features). These settings will be used to tell if a given instance is using the GitLab container registry, or an external container registry in order to allows us to toggle specific features based on the registry type.

How will the columns be used

A rake task (not yet created), will ping the container registry anytime an instance is reconfigured to find out its vendor/version/features and fill in the table.

Database

Migrations

AddRegistrySettingsToApplicationSettings

Up migration

== 20200505164958 AddRegistrySettingsToApplicationSettings: migrating =========
-- transaction_open?()
   -> 0.0000s
-- execute("SET statement_timeout TO 0")
   -> 0.0003s
-- transaction()
-- add_column(:application_settings, :container_registry_vendor, :text, {:default=>nil})
   -> 0.0020s
-- change_column_default(:application_settings, :container_registry_vendor, "")
   -> 0.0291s
   -> 0.0318s
-- columns(:application_settings)
   -> 0.0289s
-- transaction_open?()
   -> 0.0000s
-- exec_query("SELECT COUNT(*) AS count FROM \"application_settings\"")
   -> 0.0015s
-- exec_query("SELECT \"application_settings\".\"id\" FROM \"application_settings\" ORDER BY \"application_settings\".\"id\" ASC LIMIT 1")
   -> 0.0005s
-- exec_query("SELECT \"application_settings\".\"id\" FROM \"application_settings\" WHERE \"application_settings\".\"id\" >= 1 ORDER BY \"application_settings\".\"id\" ASC LIMIT 1 OFFSET 1")
   -> 0.0004s
-- execute("UPDATE \"application_settings\" SET \"container_registry_vendor\" = '' WHERE \"application_settings\".\"id\" >= 1")
   -> 0.0008s
-- change_column_null(:application_settings, :container_registry_vendor, false)
   -> 0.0006s
-- execute("RESET ALL")
   -> 0.0002s
-- transaction_open?()
   -> 0.0000s
-- execute("SET statement_timeout TO 0")
   -> 0.0001s
-- transaction()
-- add_column(:application_settings, :container_registry_version, :text, {:default=>nil})
   -> 0.0011s
-- change_column_default(:application_settings, :container_registry_version, "")
   -> 0.0314s
   -> 0.0330s
-- columns(:application_settings)
   -> 0.0299s
-- transaction_open?()
   -> 0.0000s
-- exec_query("SELECT COUNT(*) AS count FROM \"application_settings\"")
   -> 0.0005s
-- exec_query("SELECT \"application_settings\".\"id\" FROM \"application_settings\" ORDER BY \"application_settings\".\"id\" ASC LIMIT 1")
   -> 0.0004s
-- exec_query("SELECT \"application_settings\".\"id\" FROM \"application_settings\" WHERE \"application_settings\".\"id\" >= 1 ORDER BY \"application_settings\".\"id\" ASC LIMIT 1 OFFSET 1")
   -> 0.0003s
-- execute("UPDATE \"application_settings\" SET \"container_registry_version\" = '' WHERE \"application_settings\".\"id\" >= 1")
   -> 0.0007s
-- change_column_null(:application_settings, :container_registry_version, false)
   -> 0.0007s
-- execute("RESET ALL")
   -> 0.0002s
== 20200505164958 AddRegistrySettingsToApplicationSettings: migrated (0.1325s)

Down migration

== 20200505164958 AddRegistrySettingsToApplicationSettings: reverting =========
-- remove_column(:application_settings, :container_registry_vendor)
   -> 0.0019s
-- remove_column(:application_settings, :container_registry_version)
   -> 0.0007s
== 20200505164958 AddRegistrySettingsToApplicationSettings: reverted (0.0027s)

AddTextLimitToContainerRegistryVendor

Up migration

== 20200505171834 AddTextLimitToContainerRegistryVendor: migrating ============
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE application_settings\nADD CONSTRAINT check_d03919528d\nCHECK ( char_length(container_registry_vendor) <= 255 )\nNOT VALID;\n")
   -> 0.0011s
-- execute("SET statement_timeout TO 0")
   -> 0.0001s
-- execute("ALTER TABLE application_settings VALIDATE CONSTRAINT check_d03919528d;")
   -> 0.0007s
-- execute("RESET ALL")
   -> 0.0003s
== 20200505171834 AddTextLimitToContainerRegistryVendor: migrated (0.0200s) ===

Down migration

== 20200505171834 AddTextLimitToContainerRegistryVendor: reverting ============
-- execute("ALTER TABLE application_settings\nDROP CONSTRAINT IF EXISTS check_d03919528d\n")
   -> 0.0015s
== 20200505171834 AddTextLimitToContainerRegistryVendor: reverted (0.0087s) ===

AddTextLimitToContainerRegistryVersion

Up migration

== 20200505172405 AddTextLimitToContainerRegistryVersion: migrating ===========
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE application_settings\nADD CONSTRAINT check_e5aba18f02\nCHECK ( char_length(container_registry_version) <= 255 )\nNOT VALID;\n")
   -> 0.0011s
-- execute("SET statement_timeout TO 0")
   -> 0.0002s
-- execute("ALTER TABLE application_settings VALIDATE CONSTRAINT check_e5aba18f02;")
   -> 0.0008s
-- execute("RESET ALL")
   -> 0.0002s
== 20200505172405 AddTextLimitToContainerRegistryVersion: migrated (0.0059s) ==

Down migration

== 20200505172405 AddTextLimitToContainerRegistryVersion: reverting ===========
-- execute("ALTER TABLE application_settings\nDROP CONSTRAINT IF EXISTS check_e5aba18f02\n")
   -> 0.0012s
== 20200505172405 AddTextLimitToContainerRegistryVersion: reverted (0.0086s) ==

AddContainerRegistryFeaturesToApplicationSettings

Up migration

== 20200507221434 AddContainerRegistryFeaturesToApplicationSettings: migrating
-- add_column(:application_settings, :container_registry_features, :text, {:array=>true, :default=>[], :null=>false})
   -> 0.0016s
== 20200507221434 AddContainerRegistryFeaturesToApplicationSettings: migrated (0.0017s)

Down migration

== 20200507221434 AddContainerRegistryFeaturesToApplicationSettings: reverting
-- remove_column(:application_settings, :container_registry_features)
   -> 0.0025s
== 20200507221434 AddContainerRegistryFeaturesToApplicationSettings: reverted (0.0026s)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related #204839 (closed)