lantern-rails

Postgres health monitoring for Rails apps. Collects database metrics and sends them to Lantern — a hosted dashboard that scores your database health and surfaces actionable recommendations.

Add to your Gemfile:

gem "lantern-rails"

Then run:

bundle install

1. Sign up for a free API key at uselantern.dev
2. Run the installer:

rails generate lantern:install

3. Add your API key to the generated initializer (config/initializers/lantern.rb) via environment variable or Rails credentials:

LANTERN_API_KEY=lnt_your_key_here

4. Deploy — Lantern starts collecting automatically.

That's it. Open uselantern.dev to see your dashboard.

Lantern::Rails.configure do |config|
  config.api_key                  = ENV["LANTERN_API_KEY"]
  config.host                     = "https://uselantern.dev"  # default
  config.interval                 = 300                       # seconds, default 5 min
  config.collect_in_environments  = %w[production staging]   # default
end

To correlate deploys with health score changes, call this from your deploy pipeline or a Rails initializer that runs after deploy:

Lantern::Rails.report_deploy

Or pass explicit values:

Lantern::Rails.report_deploy(
  git_sha:    ENV["GIT_SHA"],
  git_author: ENV["GIT_AUTHOR"],
  deployer:   "github-actions"
)

Every collection interval, the gem queries your Postgres instance for:

• Buffer and index cache hit ratios
• Unused index count and total size
• Table bloat ratio
• Long-running queries (> 30 seconds)
• Dead tuple counts and vacuum status
• Active connections vs. max_connections
• pg_stat_bgwriter stats_reset timestamp (to detect false positives)

No query text, no table data, no PII. Only aggregate pg_stat_* metrics.

• Ruby >= 3.1
• Rails >= 7.0
• PostgreSQL (any version with pg_stat_statements)

MIT