Configuration

vdb works with zero configuration — db/schema.rb is parsed automatically and auth is disabled by default. Use the initializer to customise behaviour.

Reference

Option	Type	Default	Description
username	String | nil	nil	HTTP Basic Auth username. Set both username and password to enable auth. Either one alone is ignored.
password	String | nil	nil	HTTP Basic Auth password. Compared using ActiveSupport::SecurityUtils.secure_compare.
databases	Hash<String, Pathname|String|nil>	{ 'primary' => nil }	Schema files to expose. Each key becomes a tab label. A nil value auto-resolves to db/schema.rb.
title	String	'Database ERD'	Text shown in the browser tab and page header.

Initializer

Create config/initializers/vdb.rb with a Vdb.configure block:

# config/initializers/vdb.rb

return unless Rails.env.development?

Vdb.configure do |c|
  c.username  = ENV.fetch('VDB_USER', nil)
  c.password  = ENV.fetch('VDB_PASS', nil)
  c.databases = { 'primary' => nil }
  c.title     = 'Database ERD'
end

---

Authentication

HTTP Basic Auth is enabled when both username and password are non-nil. The comparison uses Rails' secure_compare to prevent timing attacks.

Vdb.configure do |c|
  c.username = ENV.fetch('VDB_USER')   # e.g. "admin"
  c.password = ENV.fetch('VDB_PASS')   # e.g. "s3cr3t"
end

Set the environment variables in your shell or .env file:

export VDB_USER=admin
export VDB_PASS=s3cr3t

---

Multiple schema files

If your app uses multiple databases (e.g. primary + a separate audit database), expose each schema as a named tab:

Vdb.configure do |c|
  c.databases = {
    'primary' => nil,   # auto-resolves to db/schema.rb
    'audit'   => Rails.root.join('db', 'audit_schema.rb'),
    'shard'   => Rails.root.join('db', 'shard_schema.rb')
  }
end

Each key appears as a clickable tab in the header. The URL parameter ?database=audit selects the tab directly, which is useful for deep-linking from Slack or a wiki.

URL routing

URL	What it shows
/dev/erd	First (or only) database tab
/dev/erd?database=audit	audit tab
/dev/erd?database=shard	shard tab
/dev/erd/parse	JSON API — schema text → graph data

---

Custom title

The title appears in the browser tab and in the top-left header of the ERD page:

Vdb.configure do |c|
  c.title = 'Acme Corp — Database ERD'
end

---

Resetting config

In tests or when you need a clean slate:

Vdb.reset_config!

This restores all options to their defaults.

---

Ruby API

Method	Description
Vdb.configure { |c| ... }	Block-based configuration. Yields a Vdb::Config instance.
Vdb.config	Returns the current Vdb::Config object.
Vdb.reset_config!	Replaces the config with a fresh default instance.