Phoenix LiveDashboard

LiveDashboard provides several real-time monitoring modules:

• Home: General system information.
• OS Data: CPU, Memory, and Disk usage.
• Metrics: Real-time charts visualizing :telemetry events.
• Request logging: Logs associated with specific requests.
• Applications: Supervision trees, filtering, and searching for applications in the current node.
• Processes: Search and filter processes in the current node.
• Ports: I/O port monitoring.
• Sockets: TCP/UDP socket monitoring.
• ETS: In-memory ETS table monitoring.
• Ecto Stats: Usage statistics for Ecto Repo storage (indexes, tables, etc.).

Distributed Monitoring: If your nodes are connected via Distributed Erlang, you can access information from remote nodes while viewing the dashboard on your local node.

A metrics history provider is a module used by LiveDashboard to retrieve historical data points. When LiveDashboard requests history for a specific metric, it calls the configured function.

Data Format Requirements:

• The function must return a list of maps.
• Each map must contain exactly these keys: :label, :measurement, and :time.
• If no data is available, return an empty list [].
• If Phoenix.LiveDashboard.extract_datapoint_for_metric/4 returns nil for a specific data point, that point should not be included in the history.

Example Implementation Pattern: Using a GenServer with a circular buffer is a common way to store transient metrics in memory. You can also use Redis, an ETS table, or a database.

LiveDashboard integrates with :telemetry by converting different Telemetry.Metrics types into specific chart visualizations:

LiveDashboard requires LiveView to be configured. You must update your endpoint configuration to include a signing_salt and declare a socket for LiveView.

In your config/config.exs:

config :my_app, MyAppWeb.Endpoint,
  live_view: [signing_salt: "SECRET_SALT"]

In your endpoint file (e.g., lib/my_app_web/endpoint.ex):

socket "/live", Phoenix.LiveView.Socket

# config/config.exs
config :my_app, MyAppWeb.Endpoint,
  live_view: [signing_salt: "SECRET_SALT"]

socket "/live", Phoenix.LiveView.Socket

To enable Ecto repository statistics for MySQL or MariaDB in LiveDashboard, add the ecto_mysql_extras dependency to your mix.exs file.

Configuration Notes:

• The database user must have access to specific system-level databases (see ecto_mysql_extras documentation).
• For MariaDB, ensure performance_schema=ON is set in your my.cnf file and restart the server.

  {:ecto_mysql_extras, "~> 0.3"}

To enable Ecto repository statistics for PostgreSQL in LiveDashboard, add the ecto_psql_extras dependency to your mix.exs file. Note that some queries like 'Calls' and 'Outliers' require the PostgreSQL pg_stat_statements extension to be installed on your database server to function.

  {:ecto_psql_extras, "~> 0.6"}

To install Phoenix LiveDashboard, follow these three steps:

1. Add the dependency: Add {:phoenix_live_dashboard, "~> 0.7"} to your mix.exs file and run mix deps.get.
2. Configure LiveView: Ensure your endpoint has a signing_salt configured and a Phoenix.LiveView.Socket declaration.
3. Add dashboard access: Update your router to include the Phoenix.LiveDashboard.Router and define a live_dashboard route.

def deps do
  [
    {:phoenix_live_dashboard, "~> 0.7"}
  ]
end

To enable the dashboard only during development, import Phoenix.LiveDashboard.Router in your router and wrap the live_dashboard route in a Mix.env() == :dev check.

# lib/my_app_web/router.ex
use MyAppWeb, :router
import Phoenix.LiveDashboard.Router

...

if Mix.env() == :dev do
  scope "/" do
    pipe_through :browser
    live_dashboard "/dashboard"
  end
end

To install the request logger, add the Phoenix.LiveDashboard.RequestLogger plug to your lib/my_app_web/endpoint.ex file. It should be placed immediately before Plug.RequestId.

For standard web applications, use both param_key and cookie_key. If your application is an API-only application that does not use cookies, you should omit the cookie_key option.

plug Phoenix.LiveDashboard.RequestLogger,
  param_key: "request_logger",
  cookie_key: "request_logger"

To enable Ecto repository statistics for SQLite in LiveDashboard, add the ecto_sqlite3_extras dependency to your mix.exs file.

  {:ecto_sqlite3_extras, "~> 1.2.0"}

LiveDashboard retrieves OS-level metrics via the Erlang os_mon application. To enable this data, you must add :os_mon to the extra_applications list in your project's mix.exs file.

Note: On some operating systems where Erlang is split into multiple packages, you may need to install the specific Erlang package for os_mon (e.g., erlang-os-mon) via your system's package manager.

  def application do
    [
      ...,
      extra_applications: [:logger, :runtime_tools, :os_mon]
    ]
  end