Customizing the Dashboard View Source

Dashboard customization is done through a callback module that implements the Oban.Web.Resolver behaviour. Each of the callback functions are optional and will fall back to the default implementation, which is shown here as a starting point:

defmodule MyApp.Resolver do
  @behaviour Oban.Web.Resolver

  @impl true
  def resolve_user(_conn), do: nil

  @impl true
  def resolve_access(_user), do: :all

  @impl true
  def resolve_refresh(_user), do: 1

  @impl true
  def format_job_args(%Job{args: args}) do
    inspect(args, charlists: :as_lists, pretty: true)
  end

  @impl true
  def format_job_meta(%Job{meta: meta}) do
    inspect(meta, charlists: :as_lists, pretty: true)
  end
end

Jump to details for each of the callbacks:

• resolve_user/1
• resolve_access/1
• resolve_refresh/1
• format_job_args/1
• format_meta_args/1

Typespecs

📚 In order to bridge the gap between module level docs and a guide, here are the types and callbacks for the Resolver module.

@type user :: nil | map()
@type access :: :all | :read_only | [access_option()]
@type access_option ::
        {:pause_queues, boolean()}
        | {:scale_queues, boolean()}
        | {:cancel_jobs, boolean()}
        | {:delete_jobs, boolean()}
        | {:retry_jobs, boolean()}
@type refresh :: 1 | 2 | 5 | 15 | -1

@callback format_job_args(Job.t()) :: String.t()
@callback format_job_meta(Job.t()) :: String.t()
@callback resolve_user(Plug.Conn.t()) :: user()
@callback resolve_access(user()) :: access()
@callback resolve_refresh(user()) :: refresh()

Current User

With the resolve_user/1 callback you can extract the current user from a Plug.Conn when the dashboard mounts. The extracted user is passed to all of the other callback functions, allowing you to customize the dashboard per user or role.

In a typical plug based auth system the current user is stashed the private map:

@impl true
def resolve_user(conn) do
  conn.private.current_user
end

The resolve_user/1 callback is expected to return nil, a map or a struct. However, the resolved user is only passed to other functions in the Resolver and as part of the metadata for audit events, so you're free to use any data type you like.

Action Controls

During normal operation users can modify running queues and interact with jobs through the dashboard. In some situations actions such as pausing a queue may be undesired, or even dangerous for operations.

Through the resolve_access/1 callback you can tailor precisely which actions the current user can do. The default access level is :all, which permits all users to do any action.

To set the dashboard read only and prevent users from performing any actions at all:

@impl true
def resolve_access(_user), do: :read_only

Alternatively, you can use the resolved user to allow admins write access and keep all other users read only:

@impl true
def resolve_access(user) do
  if user.admin?, do: :all, else: :read_only
end

You can also specify fine grained access for each of the possible dashboard actions:

@impl true
def resolve_access(user) do
  if user.admin? do
    [cancel_jobs: true, delete_jobs: true, retry_jobs: true]
  else
    :read_only
  end
end

This configuration allows admins to cancel jobs, delete jobs and retry jobs. They still can't pause or scale queues because actions which aren't listed are considered disabled.

The available fine grained access controls are:

• :pause_queues
• :scale_queues
• :cancel_jobs
• :delete_jobs
• :retry_jobs

Default Refresh

The refresh rate controls how frequently the server pulls statistics from the database, and when data is pushed from the server. The default refresh rate is 1 second, but you can customize it with a resolve_refresh/0 callback.

For example, to set the default refresh to 5 seconds:

@impl true
def resolve_refresh(_user), do: 5

Possible values are: 1, 2, 5, 15 or -1 to disable refreshing.

Note that this only sets the default. Users may still choose a different refresh for themselves while viewing the dashboard.

Formatting Args

By default, all args are displayed in full in the table and detail views. If you desire more control, i.e. for for privacy or brevity, there is the format_job_args/1 callback.

For example, to redact the "email" for only the SecretJob worker:

@impl true
def format_job_args(%Oban.Job{worker: "MyApp.SecretJob", args: args}) do
  args
  |> Map.replace("email", "REDACTED")
  |> inspect(pretty: true)
end

def format_job_args(job), do: Oban.Web.Resolver.format_job_args(job)

Formatting Meta

Similarly to args, you can format meta using the format_job_meta/1 callback. Here we're using the callback to mask the batch_id for some secret batch jobs:

@impl Oban.Web.Resolver
def format_job_meta(%Oban.Job{meta: %{"batch_id" => _batch} = meta}) do
  meta
  |> Map.replace("batch_id", "SECRET BATCHES")
  |> inspect(pretty: true)
end

def format_job_meta(job), do: Oban.Web.Resolver.format_job_meta(job)