Oban.Web.Resolver behaviour (Oban Web v2.10.5)
Web customization is done through a callback module that implements the this behaviour.
Usage
Each callback is optional and resolution falls back to the default implementation when a callback is omittied. Here is an example implementation that defines all callbacks with their default values for reference:
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(%Oban.Job{args: args}) do
inspect(args, charlists: :as_lists, pretty: true)
end
@impl true
def format_job_meta(%Oban.Job{meta: meta}) do
inspect(meta, charlists: :as_lists, pretty: true)
end
@impl true
def format_recorded(recorded, _job) do
recorded
|> Oban.Web.Resolver.decode_recorded()
|> inspect(charlists: :as_lists, pretty: true)
end
@impl true
def jobs_query_limit(_state), do: 100_000
@impl true
def hint_query_limit(_qualifier), do: 10_000
end
To use a resolver such as MyApp.Resolver
defined above, you pass it through as an option to
oban_dashboard/2
in your application's router:
scope "/" do
pipe_through :browser
oban_dashboard "/oban", resolver: MyApp.Resolver
end
Overview
Details about each callback's functionality can be found in the callback docs. Here's a quick summary of each callback and its purpose:
Current User—Extract the current user for access controls when the dashboard mounts.
Action Controls—Restrict which operations users may perform or forbid access to the dashboard.
Jobs Query Limit—Control the maximum number of jobs to query when filtering, searching, and otherwise listing jobs.
Hint Query Limit—Control the maximum number of jobs to search for auto-complete hints.
Format Job Args—Override the default verbose args formatting.
Format Job Meta—Override the default verbose meta formatting.
Default Refresh—Set the default refresh interval for new sessions.
Authentication
By combining resolver_user/1
and resolve_access/1
callbacks it's possible to build an
authenticaiton solution around the dashboard. For example, this resolver extracts the
current_user
from the conn's assigns map and then scopes their access based on role. If it is
a standard user or nil
then they're redirected to /login
when the dashboard mounts.
defmodule MyApp.Resolver do
@behaviour Oban.Web.Resolver
@impl true
def resolve_user(conn) do
conn.assigns.current_user
end
@impl true
def resolve_access(user) do
case user do
%{admin?: true} -> :all
%{staff?: true} -> :read_only
_ -> {:forbidden, "/login"}
end
end
end
Summary
Callbacks
Customize the formatting of job args wherever they are displayed.
Customize the formatting of job meta wherever it is displayed.
Customize the formatting of recorded output wherever it is displayed.
The maximum number of jobs to query for auto-complete suggestions.
The maximum number of jobs to query when displaying jobs.
Determine the appropriate access level for a user.
Determine the initial refresh rate when the dashboard mounts.
Extract the current user from a Plug.Conn
when the dashboard mounts.
Functions
Decode a recorded job's output from a compressed, base64 binary into proper terms.
Types
access()
@type access() :: :all | :read_only | [access_option()] | {:forbidden, Path.t()}
access_option()
@type access_option() ::
:pause_queues | :scale_queues | :cancel_jobs | :delete_jobs | :retry_jobs
qualifier()
@type qualifier() :: :args | :meta | :nodes | :queues | :tags | :workers
refresh()
@type refresh() :: 1 | 2 | 5 | 15 | 60 | -1
user()
@type user() :: term()
Callbacks
@callback format_job_args(job :: Oban.Job.t()) :: iodata()
Customize the formatting of job args wherever they are displayed.
This callback allows for full over args formatting; whether for privacy, brevity, or clarity. By
default, all args
are preserved in table and detail views.
Examples
Redact the "email"
field for only the SecretJob
worker:
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)
@callback format_job_meta(job :: Oban.Job.t()) :: iodata()
Customize the formatting of job meta wherever it is displayed.
This callback behaves identically to format_job_args/1
, but is used for meta
.
Examples
Msk the batch_id
for some secret batch jobs:
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)
@callback format_recorded(recorded :: term(), job :: Oban.Job.t()) :: iodata()
Customize the formatting of recorded output wherever it is displayed.
This callback is similar to format_job_args/1
, but it accepts both the recorded binary and
the job to help augment the output.
Note that you must decode the recorded binary prior to inspecting it.
Examples
Disable pretty printing and change the output width to 98 characters:
def format_recorded(recorded, _job) do
recorded
|> Oban.Web.Resolver.decode_recorded()
|> inspect(pretty: false, width: 98)
end
Decode the recorded value without the :safe
flag set, to allow decoding terms with unknown
atoms:
def format_recorded(recorded, _job) do
recorded
|> Oban.Web.Resolver.decode_recorded([])
|> inspect(pretty: false, width: 98)
end
Display job args alongside recorded output:
def format_recorded(recorded, %Oban.Job{args: args}) when is_map(recorded) do
recorded
|> Oban.Web.Resolver.decode_recorded()
|> Map.put(:args, args)
|> inspect(charlists: :as_lists, pretty: true)
end
@callback hint_query_limit(qualifier()) :: :infinity | pos_integer()
The maximum number of jobs to query for auto-complete suggestions.
The limit may be determined by qualifier, e.g. :args
or :worker
, to fine-tune the impact of
suggestion queries. Limiting may be disabled with :infinity
.
Without a callback implemented it defaults to 10,000 for all qualifiers.
Example
Increase the limit to 20k for all qualifiers:
def hint_query_limit(_qualifier), do: 20_000
Customize the limit for args
and meta
, falling back to 10k for everything else.
def hint_query_limit(:args), do: 5_000
def hint_query_limit(:meta), do: 2_000
def hint_query_limit(_qualifier), do: 10_000
@callback jobs_query_limit(Oban.Job.unique_state()) :: :infinity | pos_integer()
The maximum number of jobs to query when displaying jobs.
Ordering is applied after limiting the query. That means the "oldest" job displayed will always be within the filter limit. For example, with a limit of 100k jobs and 200k completed jobs, only the latest 100k are queryable and the oldest 100k are effectively invisible.
In the interest of speed, limits are only approximate.
The limit may be determined by state, e.g. :completed
or :cancelled
, to fine-tune query
performance for larger states. Limiting may be disabled with :infinity
.
Without a callback impleted, the :completed
state defaults to a conservative 100k jobs and all
other states are :infinite
.
Example
Restrict the limit for all states:
def jobs_query_limit(_qualifier), do: 50_000
Use a conservative the limit for :completed
without any limit for other states (this is the
default):
def jobs_query_limit(:completed), do: 100_000
def jobs_query_limit(_state), do: :infinity
Determine the appropriate access level for a user.
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 this 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.
Returning {:forbidden, path}
prevents loading the dashboard entirely and redirects the user to
the provided path.
The available fine grained access controls are:
:pause_queues
:scale_queues
:cancel_jobs
:delete_jobs
:retry_jobs
Actions which aren't listed are considered disabled.
Examples
To set the dashboard read only and prevent users from performing any actions at all:
def resolve_access(_user), do: :read_only
Forbid any user that isn't an admin and redirect them to the root:
def resolve_access(user) do
if user.admin?, do: :all, else: {:forbidden, "/"}
end
Alternatively, you can use the resolved user
to allow admins write access and keep all other
users read only:
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.
def resolve_access(user) do
if user.admin? do
[cancel_jobs: true, delete_jobs: true, retry_jobs: true]
else
:read_only
end
end
Determine the initial refresh rate when the dashboard mounts.
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.
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 and their chosen value will stick for future sessions.
Examples
Default to 5 seconds:
def resolve_refresh(_user), do: 5
@callback resolve_user(conn :: Plug.Conn.t()) :: user()
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.
This 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.
Examples
Extract the user from the assigns
map in a typical plug based auth setup:
def resolve_user(conn) do
conn.assigns.current_user
end
Functions
decode_recorded(bin, opts \\ [:safe])
Decode a recorded job's output from a compressed, base64 binary into proper terms.
By default, decoding uses the :safe
flag to prevent decoding unsafe data that can be used to
attack the Erlang runtime.
Example
Decode a recorded binary:
iex> Oban.Web.Resolver.decode_recorded("g3QAAAABdwRuYW1lbQAAAARvYmFu")
%{name: "oban"}
Decode without safety:
iex> Oban.Web.Resolver.decode_recorded("g3QAAAABdwRhdG9tdwd1bmtub3du", [])
%{atom: :unknown}