Robust job processing in Elixir, backed by modern PostgreSQL or SQLite3. Reliable,
observable, and loaded with enterprise grade features.

## Table of Contents - [Features](#features) - [Oban Web+Pro](#oban-webpro) - Usage - [Installation](#installation) - [Requirements](#requirements) - [Running With SQLite3](#running-with-sqlite3) - [Configuring Queues](#configuring-queues) - [Defining Workers](#defining-workers) - [Enqueueing Jobs](#enqueueing-jobs) - [Scheduling Jobs](#scheduling-jobs) - [Prioritizing Jobs](#prioritizing-jobs) - [Unique Jobs](#unique-jobs) - [Pruning Historic Jobs](#pruning-historic-jobs) - [Periodic Jobs](#periodic-jobs) - [Error Handling](#error-handling) - [Instrumentation and Logging](#instrumentation-error-reporting-and-logging) - [Instance and Database Isolation](#instance-and-database-isolation) - [Community](#community) - [Contributing](#contributing) --- > [!NOTE] > > This README is for the unreleased main branch, please reference the > [official documentation on hexdocs][hexdoc] for the latest stable release. [hexdoc]: https://hexdocs.pm/oban/Oban.html --- ## Features Oban's primary goals are **reliability**, **consistency** and **observability**. Oban is a powerful and flexible library that can handle a wide range of background job use cases, and it is well-suited for systems of any size. It provides a simple and consistent API for scheduling and performing jobs, and it is built to be fault-tolerant and easy to monitor. Oban is fundamentally different from other background job processing tools because _it retains job data for historic metrics and inspection_. You can leave your application running indefinitely without worrying about jobs being lost or orphaned due to crashes. #### Advantages Over Other Tools - **Fewer Dependencies** — If you are running a web app there is a _very good_ chance that you're running on top of a [RDBMS][rdbms]. Running your job queue within a SQL database minimizes system dependencies and simplifies data backups. - **Transactional Control** — Enqueue a job along with other database changes, ensuring that everything is committed or rolled back atomically. - **Database Backups** — Jobs are stored inside of your primary database, which means they are backed up together with the data that they relate to. #### Advanced Features - **Isolated Queues** — Jobs are stored in a single table but are executed in distinct queues. Each queue runs in isolation, ensuring that a job in a single slow queue can't back up other faster queues. - **Queue Control** — Queues can be started, stopped, paused, resumed and scaled independently at runtime locally or across _all_ running nodes (even in environments like Heroku, without distributed Erlang). - **Resilient Queues** — Failing queries won't crash the entire supervision tree, instead a backoff mechanism will safely retry them again in the future. - **Job Canceling** — Jobs can be canceled in the middle of execution regardless of which node they are running on. This stops the job at once and flags it as `cancelled`. - **Triggered Execution** — Insert triggers ensure that jobs are dispatched on all connected nodes as soon as they are inserted into the database. - **Unique Jobs** — Duplicate work can be avoided through unique job controls. Uniqueness can be enforced at the argument, queue, worker and even sub-argument level for any period of time. - **Scheduled Jobs** — Jobs can be scheduled at any time in the future, down to the second. - **Periodic (CRON) Jobs** — Automatically enqueue jobs on a cron-like schedule. Duplicate jobs are never enqueued, no matter how many nodes you're running. - **Job Priority** — Prioritize jobs within a queue to run ahead of others with ten levels of granularity. - **Historic Metrics** — After a job is processed the row isn't deleted. Instead, the job is retained in the database to provide metrics. This allows users to inspect historic jobs and to see aggregate data at the job, queue or argument level. - **Node Metrics** — Every queue records metrics to the database during runtime. These are used to monitor queue health across nodes and may be used for analytics. - **Graceful Shutdown** — Queue shutdown is delayed so that slow jobs can finish executing before shutdown. When shutdown starts queues are paused and stop executing new jobs. Any jobs left running after the shutdown grace period may be rescued later. - **Telemetry Integration** — Job life-cycle events are emitted via [Telemetry][tele] integration. This enables simple logging, error reporting and health checkups without plug-ins. [rdbms]: https://en.wikipedia.org/wiki/Relational_database#RDBMS [tele]: https://github.com/beam-telemetry/telemetry ## Oban Web+Pro > [!TIP] > A web dashboard for managing Oban, along with an official set of extensions, plugins, and > workers that expand what Oban is capable are available as licensed packages: > > * [🧭 Oban Web](https://getoban.pro#oban-web) > * [🌟 Oban Pro](https://getoban.pro#oban-pro) > > Learn more at [getoban.pro][pro]! ## Requirements Oban requires Elixir 1.13+, Erlang 23+, and PostgreSQL 12.0+ or SQLite3 3.37.0+. ## Installation See the [installation guide](https://hexdocs.pm/oban/installation.html) for details on installing and configuring Oban in your application. ## Running with SQLite3 Oban ships with engines for PostgreSQL and SQLite3. Both engines support the same core functionality for a single node, while the Postgres engine is more advanced and designed to run in a distributed environment. Running with SQLite3 requires adding `ecto_sqlite3` to your app's dependencies and setting the `Oban.Engines.Lite` engine: ```elixir config :my_app, Oban, engine: Oban.Engines.Lite, queues: [default: 10], repo: MyApp.Repo ``` > #### High Concurrency Systems {: .warning} > > SQLite3 may not be suitable for high-concurrency systems or for systems that need to handle > large amounts of data. If you expect your background jobs to generate high loads, it would be > better to use a more robust database solution that supports horizontal scalability, like > Postgres. ## Configuring Queues Queues are specified as a keyword list where the key is the name of the queue and the value is the maximum number of concurrent jobs. The following configuration would start four queues with concurrency ranging from 5 to 50: ```elixir config :my_app, Oban, queues: [default: 10, mailers: 20, events: 50, media: 5], repo: MyApp.Repo ``` You may also use an expanded form to configure queues with individual overrides: ```elixir queues: [ default: 10, events: [limit: 50, paused: true] ] ``` The `events` queue will now start in a paused state, which means it won't process anything until `Oban.resume_queue/2` is called to start it. There isn't a limit to the number of queues or how many jobs may execute concurrently in each queue. Some additional guidelines: #### Caveats & Guidelines * Each queue will run as many jobs as possible concurrently, up to the configured limit. Make sure your system has enough resources (i.e. database connections) to handle the concurrent load. * Queue limits are local (per-node), not global (per-cluster). For example, running a queue with a local limit of one on three separate nodes is effectively a global limit of three. If you require a global limit you must restrict the number of nodes running a particular queue. * Only jobs in the configured queues will execute. Jobs in any other queue will stay in the database untouched. * Be careful how many concurrent jobs make expensive system calls (i.e. FFMpeg, ImageMagick). The BEAM ensures that the system stays responsive under load, but those guarantees don't apply when using ports or shelling out commands. ## Defining Workers Worker modules do the work of processing a job. At a minimum they must define a `perform/1` function, which is called with an `%Oban.Job{}` struct. Note that the `args` field of the job struct will _always_ have string keys, regardless of the key type when the job was enqueued. The `args` are stored as JSON and the serialization process automatically stringifies all keys. Also, because `args` are always encoded as JSON, you must ensure that all values are serializable, otherwise you'll have encoding errors when inserting jobs. Define a worker to process jobs in the `events` queue: ```elixir defmodule MyApp.Business do use Oban.Worker, queue: :events @impl Oban.Worker def perform(%Oban.Job{args: %{"id" => id} = args}) do model = MyApp.Repo.get(MyApp.Business.Man, id) case args do %{"in_the" => "business"} -> IO.inspect(model) %{"vote_for" => vote} -> IO.inspect([vote, model]) _ -> IO.inspect(model) end :ok end end ``` The `use` macro also accepts options to customize `max_attempts`, `priority`, `tags`, `unique`, and `replace` options: ```elixir defmodule MyApp.LazyBusiness do use Oban.Worker, queue: :events, priority: 3, max_attempts: 3, tags: ["business"], unique: true, replace: [scheduled: [:scheduled_at]] @impl Oban.Worker def perform(_job) do # do business slowly :ok end end ``` Like all `use` macros, options are defined at compile time. Avoid using `Application.get_env/2` to define worker options. Instead, pass dynamic options at runtime by passing them to `MyWorker.new/2`: ```elixir MyApp.MyWorker.new(args, queue: dynamic_queue) ``` Successful jobs should return `:ok` or an `{:ok, value}` tuple. The value returned from `perform/1` is used to control whether the job is treated as a success, a failure, cancelled or deferred for retrying later. See the `Oban.Worker` docs for more details on failure conditions and `Oban.Telemetry` for details on job reporting. ## Enqueueing Jobs Jobs are simply Ecto structs and are enqueued by inserting them into the database. For convenience and consistency all workers provide a `new/2` function that converts an args map into a job changeset suitable for insertion: ```elixir %{id: 1, in_the: "business", of_doing: "business"} |> MyApp.Business.new() |> Oban.insert() ``` The worker's defaults may be overridden by passing options: ```elixir %{id: 1, vote_for: "none of the above"} |> MyApp.Business.new(queue: :special, max_attempts: 5) |> Oban.insert() ``` Unique jobs can be configured in the worker, or when the job is built: ```elixir %{email: "brewster@example.com"} |> MyApp.Mailer.new(unique: false) |> Oban.insert() ``` Job priority can be specified using an integer from 0 to 9, with 0 being the default and highest priority: ```elixir %{id: 1} |> MyApp.Backfiller.new(priority: 2) |> Oban.insert() ``` Any number of tags can be added to a job dynamically, at the time it is inserted: ```elixir id = 1 %{id: id} |> MyApp.OnboardMailer.new(tags: ["mailer", "record-#{id}"]) |> Oban.insert() ``` Multiple jobs can be inserted in a single transaction: ```elixir Ecto.Multi.new() |> Oban.insert(:b_job, MyApp.Business.new(%{id: 1})) |> Oban.insert(:m_job, MyApp.Mailer.new(%{email: "brewser@example.com"})) |> Repo.transaction() ``` Occasionally you may need to insert a job for a worker that exists in another application. In that case you can use `Oban.Job.new/2` to build the changeset manually: ```elixir %{id: 1, user_id: 2} |> Oban.Job.new(queue: :default, worker: OtherApp.Worker) |> Oban.insert() ``` `Oban.insert/2,4` is the preferred way of inserting jobs as it provides some of Oban's advanced features (i.e., unique jobs). However, you can use your application's `Repo.insert/2` function if necessary. See `Oban.Job.new/2` for a full list of job options. ## Scheduling Jobs Jobs may be scheduled down to the second any time in the future: ```elixir %{id: 1} |> MyApp.Business.new(schedule_in: 5) |> Oban.insert() ``` Jobs may also be scheduled at a specific datetime in the future: ```elixir %{id: 1} |> MyApp.Business.new(scheduled_at: ~U[2020-12-25 19:00:56.0Z]) |> Oban.insert() ``` Scheduling is _always_ in UTC. You'll have to shift timestamps in other zones to UTC before scheduling: ```elixir %{id: 1} |> MyApp.Business.new(scheduled_at: DateTime.shift_zone!(datetime, "Etc/UTC")) |> Oban.insert() ``` #### Caveats & Guidelines Usually, scheduled job management operates in `global` mode and notifies queues of available jobs via PubSub to minimize database load. However, when PubSub isn't available, staging switches to a `local` mode where each queue polls independently. Local mode is less efficient and will only happen if you're running in an environment where neither `Postgres` nor `PG` notifications work. That situation should be rare and limited to the following conditions: 1. Running with a connection pooler, i.e., `pg_bouncer`, in transaction mode. 2. Running without clustering, i.e., without Distributed Erlang If **both** of those criteria apply and PubSub notifications won't work, then staging will switch to polling in `local` mode. ## Prioritizing Jobs Normally, all available jobs within a queue are executed in the order they were scheduled. You can override the normal behavior and prioritize or de-prioritize a job by assigning a numerical `priority`. * Priorities from 0-9 are allowed, where 0 is the highest priority and 9 is the lowest. * The default priority is 0, unless specified all jobs have an equally high priority. * All jobs with a higher priority will execute before any jobs with a lower priority. Within a particular priority jobs are executed in their scheduled order. #### Caveats & Guidelines The default priority is defined in the jobs table. The least intrusive way to change it for all jobs is to change the column default: ```elixir alter table("oban_jobs") do modify :priority, :integer, default: 1, from: {:integer, default: 0} end ``` ## Unique Jobs The unique jobs feature lets you specify constraints to prevent enqueueing duplicate jobs. Uniqueness is based on a combination of job attribute based on the following options: * `:period` — The number of seconds until a job is no longer considered duplicate. You should always specify a period, otherwise Oban will default to 60 seconds. `:infinity` can be used to indicate the job be considered a duplicate as long as jobs are retained. * `:fields` — The fields to compare when evaluating uniqueness. The available fields are `:args`, `:queue`, `:worker`, and `:meta`. By default, fields is set to `[:worker, :queue, :args]`. * `:keys` — A specific subset of the `:args` or `:meta` to consider when comparing against historic jobs. This allows a job with multiple key/value pairs in the args to be compared using only a subset of them. * `:states` — The job states that are checked for duplicates. The available states are `:available`, `:scheduled`, `:executing`, `:retryable`, `:completed`, `:cancelled` and `:discarded`. By default all states except for `:discarded` and `:cancelled` are checked, which prevents duplicates even if the previous job has been completed. * `:timestamp` — Which timestamp to check the period against. The available timestamps are `:inserted_at` or `:scheduled_at`, and it defaults to `:inserted_at` for legacy reasons. The simplest form of uniqueness will configure uniqueness for as long as a matching job exists in the database, regardless of state: ```elixir use Oban.Worker, unique: true ``` Configure the worker to be unique only for 60 seconds: ```elixir use Oban.Worker, unique: [period: 60] ``` Check the `:scheduled_at` timestamp instead of `:inserted_at` for uniqueness: ```elixir use Oban.Worker, unique: [period: 120, timestamp: :scheduled_at] ``` Only consider the `:url` key rather than the entire `args`: ```elixir use Oban.Worker, unique: [keys: [:url]] ``` Use `Oban.Job.states/0` to specify uniqueness across _all_ states, including `cancelled` and `discarded`: ```elixir use Oban.Worker, unique: [period: :infinity, states: Oban.Job.states()] ``` #### Detecting Unique Conflicts When unique settings match an existing job, the return value of `Oban.insert/2` is still `{:ok, job}`. However, you can detect a unique conflict by checking the jobs' `:conflict?` field. If there was an existing job, the field is `true`; otherwise it is `false`. You can use the `:conflict?` field to customize responses after insert: ```elixir case Oban.insert(changeset) do {:ok, %Job{id: nil, conflict?: true}} -> {:error, :failed_to_acquire_lock} {:ok, %Job{conflict?: true}} -> {:error, :job_already_exists} result -> result end ``` Note that conflicts are only detected for jobs enqueued through `Oban.insert/2,3`. Jobs enqueued through `Oban.insert_all/2` _do not_ use per-job unique configuration. #### Replacing Values In addition to detecting unique conflicts, passing options to `replace` can update any job field when there is a conflict. Any of the following fields can be replaced per _state_: `args`, `max_attempts`, `meta`, `priority`, `queue`, `scheduled_at`, `tags`, `worker`. For example, to change the `priority` and increase `max_attempts` when there is a conflict with a job in a `scheduled` state: ```elixir BusinessWorker.new( args, max_attempts: 5, priority: 0, replace: [scheduled: [:max_attempts, :priority]] ) ``` Another example is bumping the scheduled time on conflict. Either `scheduled_at` or `schedule_in` values will work, but the replace option is always `scheduled_at`. ```elixir UrgentWorker.new(args, schedule_in: 1, replace: [scheduled: [:scheduled_at]]) ``` NOTE: If you use this feature to replace a field (e.g. `args`) in the `executing` state by doing something like: `UniqueWorker.new(new_args, replace: [executing: [:args]])` Oban will update the `args`, but the job will continue executing with the original value. #### Strong Guarantees Unique jobs are guaranteed through transactional locks and database queries: they _do not_ rely on unique constraints in the database. This makes uniqueness entirely configurable by application code, without the need for database migrations. ## Testing Find testing setup, helpers, and strategies in the [testing guide](https://hexdocs.pm/oban/testing.html). [pro]: https://getoban.pro ## Pruning Historic Jobs Job stats and queue introspection are built on keeping job rows in the database after they have completed. This allows administrators to review completed jobs and build informative aggregates, at the expense of storage and an unbounded table size. To prevent the `oban_jobs` table from growing indefinitely, Oban provides active pruning of `completed`, `cancelled` and `discarded` jobs. By default, the `Pruner` plugin retains jobs for 60 seconds. You can configure a longer retention period by providing a `max_age` in seconds to the `Pruner` plugin. ```elixir # Set the max_age for 5 minutes config :my_app, Oban, plugins: [{Oban.Plugins.Pruner, max_age: 300}] ... ``` #### Caveats & Guidelines * Pruning is best-effort and performed out-of-band. This means that all limits are soft; jobs beyond a specified age may not be pruned immediately after jobs complete. * Pruning is only applied to jobs that are `completed`, `cancelled` or `discarded`. It'll never delete a new job, a scheduled job or a job that failed and will be retried. ## Periodic Jobs Oban's `Cron` plugin registers workers a cron-like schedule and enqueues jobs automatically. Periodic jobs are declared as a list of `{cron, worker}` or `{cron, worker, options}` tuples: ```elixir config :my_app, Oban, repo: MyApp.Repo, plugins: [ {Oban.Plugins.Cron, crontab: [ {"* * * * *", MyApp.MinuteWorker}, {"0 * * * *", MyApp.HourlyWorker, args: %{custom: "arg"}}, {"0 0 * * *", MyApp.DailyWorker, max_attempts: 1}, {"0 12 * * MON", MyApp.MondayWorker, queue: :scheduled, tags: ["mondays"]}, {"@daily", MyApp.AnotherDailyWorker} ]} ] ``` The crontab would insert jobs as follows: * `MyApp.MinuteWorker` — Inserted once every minute * `MyApp.HourlyWorker` — Inserted at the first minute of every hour with custom args * `MyApp.DailyWorker` — Inserted at midnight every day with no retries * `MyApp.MondayWorker` — Inserted at noon every Monday in the "scheduled" queue * `MyApp.AnotherDailyWorker` — Inserted at midnight every day with no retries The crontab format respects all [standard rules][cron] and has one minute resolution. Jobs are considered unique for most of each minute, which prevents duplicate jobs with multiple nodes and across node restarts. Like other jobs, recurring jobs will use the `:queue` specified by the worker module (or `:default` if one is not specified). ### Cron Expressions Standard Cron expressions are composed of rules specifying the minutes, hours, days, months and weekdays. Rules for each field are comprised of literal values, wildcards, step values or ranges: * `*` — Wildcard, matches any value (0, 1, 2, ...) * `0` — Literal, matches only itself (only 0) * `*/15` — Step, matches any value that is a multiple (0, 15, 30, 45) * `0-5` — Range, matches any value within the range (0, 1, 2, 3, 4, 5) * `0-9/2` - Step values can be used in conjunction with ranges (0, 2, 4, 6, 8) Each part may have multiple rules, where rules are separated by a comma. The allowed values for each field are as follows: * `minute` — 0-59 * `hour` — 0-23 * `days` — 1-31 * `month` — 1-12 (or aliases, `JAN`, `FEB`, `MAR`, etc.) * `weekdays` — 0-6 (or aliases, `SUN`, `MON`, `TUE`, etc.) The following Cron extensions are supported: * `@hourly` — `0 * * * *` * `@daily` (as well as `@midnight`) — `0 0 * * *` * `@weekly` — `0 0 * * 0` * `@monthly` — `0 0 1 * *` * `@yearly` (as well as `@annually`) — `0 0 1 1 *` * `@reboot` — Run once at boot across the entire cluster Some specific examples that demonstrate the full range of expressions: * `0 * * * *` — The first minute of every hour * `*/15 9-17 * * *` — Every fifteen minutes during standard business hours * `0 0 * DEC *` — Once a day at midnight during December * `0 7-9,4-6 13 * FRI` — Once an hour during both rush hours on Friday the 13th For more in depth information see the man documentation for `cron` and `crontab` in your system. Alternatively you can experiment with various expressions online at [Crontab Guru][guru]. #### Caveats & Guidelines * All schedules are evaluated as UTC unless a different timezone is provided. See `Oban.Plugins.Cron` for information about configuring a timezone. * Workers can be used for regular _and_ scheduled jobs so long as they accept different arguments. * Duplicate jobs are prevented through transactional locks and unique constraints. Workers that are used for regular and scheduled jobs _must not_ specify `unique` options less than `60s`. * Long running jobs may execute simultaneously if the scheduling interval is shorter than it takes to execute the job. You can prevent overlap by passing custom `unique` opts in the crontab config: ```elixir custom_args = %{scheduled: true} unique_opts = [ period: 60 * 60 * 24, states: [:available, :scheduled, :executing] ] config :my_app, Oban, repo: MyApp.Repo, plugins: [ {Oban.Plugins.Cron, crontab: [ {"* * * * *", MyApp.SlowWorker, args: custom_args, unique: unique_opts} ]} ] ``` [cron]: https://en.wikipedia.org/wiki/Cron#Overview [guru]: https://crontab.guru ## Error Handling When a job returns an error value, raises an error, or exits during execution the details are recorded within the `errors` array on the job. When the number of execution attempts is below the configured `max_attempts` limit, the job will automatically be retried in the future. The retry delay has an exponential backoff, meaning the job's second attempt will be after 16s, third after 31s, fourth after 1m 36s, etc. See the `Oban.Worker` documentation on "Customizing Backoff" for alternative backoff strategies. ### Error Details Execution errors are stored as a formatted exception along with metadata about when the failure occurred and which attempt caused it. Each error is stored with the following keys: * `at` The UTC timestamp when the error occurred at * `attempt` The attempt number when the error occurred * `error` A formatted error message and stacktrace See the [Instrumentation](#instrumentation-error-reporting-and-logging) docs for an example of integrating with external error reporting systems. ### Limiting Retries By default, jobs are retried up to 20 times. The number of retries is controlled by the `max_attempts` value, which can be set at the Worker or Job level. For example, to instruct a worker to discard jobs after three failures: ```elixir use Oban.Worker, queue: :limited, max_attempts: 3 ``` ### Limiting Execution Time By default, individual jobs may execute indefinitely. If this is undesirable you may define a timeout in milliseconds with the `timeout/1` callback on your worker module. For example, to limit a worker's execution time to 30 seconds: ```elixir def MyApp.Worker do use Oban.Worker @impl Oban.Worker def perform(_job) do something_that_may_take_a_long_time() :ok end @impl Oban.Worker def timeout(_job), do: :timer.seconds(30) end ``` The `timeout/1` function accepts an `Oban.Job` struct, so you can customize the timeout using any job attributes. Define the `timeout` value through job args: ```elixir def timeout(%_{args: %{"timeout" => timeout}}), do: timeout ``` Define the `timeout` based on the number of attempts: ```elixir def timeout(%_{attempt: attempt}), do: attempt * :timer.seconds(5) ``` ## Instrumentation, Error Reporting, and Logging Oban provides integration with [Telemetry][tele], a dispatching library for metrics. It is easy to report Oban metrics to any backend by attaching to `:oban` events. Here is an example of a sample unstructured log handler: ```elixir defmodule MyApp.ObanLogger do require Logger def handle_event([:oban, :job, :start], measure, meta, _) do Logger.warning("[Oban] :started #{meta.worker} at #{measure.system_time}") end def handle_event([:oban, :job, event], measure, meta, _) do Logger.warning("[Oban] #{event} #{meta.worker} ran in #{measure.duration}") end end ``` Attach the handler to success and failure events in `application.ex`: ```elixir events = [[:oban, :job, :start], [:oban, :job, :stop], [:oban, :job, :exception]] :telemetry.attach_many("oban-logger", events, &MyApp.ObanLogger.handle_event/4, []) ``` The `Oban.Telemetry` module provides a robust structured logger that handles all of Oban's telemetry events. As in the example above, attach it within your `application.ex` module: ```elixir :ok = Oban.Telemetry.attach_default_logger() ``` For more details on the default structured logger and information on event metadata see docs for the `Oban.Telemetry` module. ### Reporting Errors Another great use of execution data is error reporting. Here is an example of integrating with [Honeybadger][honeybadger] to report job failures: ```elixir defmodule MyApp.ErrorReporter do def attach do :telemetry.attach( "oban-errors", [:oban, :job, :exception], &__MODULE__.handle_event/4, [] ) end def handle_event([:oban, :job, :exception], measure, meta, _) do Honeybadger.notify(meta.reason, stacktrace: meta.stacktrace) end end MyApp.ErrorReporter.attach() ``` You can use exception events to send error reports to Sentry, AppSignal, Honeybadger, Rollbar, or any other application monitoring platform. Some of these services support reporting Oban errors out of the box: - Sentry — [Oban integration documentation](https://docs.sentry.io/platforms/elixir/integrations/oban) - AppSignal - [Oban integration documentation](https://docs.appsignal.com/elixir/integrations/oban.html) [tele]: https://hexdocs.pm/telemetry [honeybadger]: https://www.honeybadger.io ## Instance and Database Isolation You can run multiple Oban instances with different prefixes on the same system and have them entirely isolated, provided you give each supervisor a distinct id. Here we configure our application to start three Oban supervisors using the "public", "special" and "private" prefixes, respectively: ```elixir def start(_type, _args) do children = [ Repo, Endpoint, {Oban, name: ObanA, repo: Repo}, {Oban, name: ObanB, repo: Repo, prefix: "special"}, {Oban, name: ObanC, repo: Repo, prefix: "private"} ] Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor) end ``` ### Umbrella Apps If you need to run Oban from an umbrella application where more than one of the child apps need to interact with Oban, you may need to set the `:name` for each child application that configures Oban. For example, your umbrella contains two apps: `MyAppA` and `MyAppB`. `MyAppA` is responsible for inserting jobs, while only `MyAppB` actually runs any queues. Configure Oban with a custom name for `MyAppA`: ```elixir config :my_app_a, Oban, name: MyAppA.Oban, repo: MyApp.Repo ``` Then configure Oban for `MyAppB` with a different name: ```elixir config :my_app_b, Oban, name: MyAppB.Oban, repo: MyApp.Repo, queues: [default: 10] ``` Now, use the configured name when calling functions like `Oban.insert/2`, `Oban.insert_all/2`, `Oban.drain_queue/2`, etc., to reference the correct Oban process for the current application. ```elixir Oban.insert(MyAppA.Oban, MyWorker.new(%{})) Oban.insert_all(MyAppB.Oban, multi, :multiname, [MyWorker.new(%{})]) Oban.drain_queue(MyAppB.Oban, queue: :default) ``` ### Database Prefixes Oban supports namespacing through PostgreSQL schemas, also called "prefixes" in Ecto. With prefixes your jobs table can reside outside of your primary schema (usually public) and you can have multiple separate job tables. To use a prefix you first have to specify it within your migration: ```elixir defmodule MyApp.Repo.Migrations.AddPrefixedObanJobsTable do use Ecto.Migration def up do Oban.Migrations.up(prefix: "private") end def down do Oban.Migrations.down(prefix: "private") end end ``` The migration will create the "private" schema and all tables, functions and triggers within that schema. With the database migrated you'll then specify the prefix in your configuration: ```elixir config :my_app, Oban, prefix: "private", repo: MyApp.Repo, queues: [default: 10] ``` Now all jobs are inserted and executed using the `private.oban_jobs` table. Note that `Oban.insert/2,4` will write jobs in the `private.oban_jobs` table, you'll need to specify a prefix manually if you insert jobs directly through a repo. Not only is the `oban_jobs` table isolated within the schema, but all notification events are also isolated. That means that insert/update events will only dispatch new jobs for their prefix. ### Dynamic Repositories Oban supports [Ecto dynamic repositories][dynamic] through the `:get_dynamic_repo` option. To make this work, you need to run a separate Oban instance per each dynamic repo instance. Most often it's worth bundling each Oban and repo instance under the same supervisor: ```elixir def start_repo_and_oban(instance_id) do children = [ {MyDynamicRepo, name: nil, url: repo_url(instance_id)}, {Oban, name: instance_id, get_dynamic_repo: fn -> repo_pid(instance_id) end} ] Supervisor.start_link(children, strategy: :one_for_one) end ``` The function `repo_pid/1` must return the pid of the repo for the given instance. You can use `Registry` to register the repo (for example in the repo's `init/2` callback) and discover it. If your application exclusively uses dynamic repositories and doesn't specify all credentials upfront, you must implement an `init/1` callback in your Ecto Repo. Doing so provides the Postgres notifier with the correct credentials on init, allowing jobs to process as expected. [dynamic]: https://hexdocs.pm/ecto/replicas-and-dynamic-repositories.html#dynamic-repositories ### Ecto Multi-tenancy If you followed the Ecto guide on setting up multi-tenancy with foreign keys, you need to add an exception for queries originating from Oban. All of Oban's queries have the custom option `oban: true` to help you identify them in `prepare_query/3` or other instrumentation: ```elixir # Sample code, only relevant if you followed the Ecto guide on multi tenancy with foreign keys. defmodule MyApp.Repo do use Ecto.Repo, otp_app: :my_app require Ecto.Query @impl true def prepare_query(_operation, query, opts) do cond do opts[:skip_org_id] || opts[:schema_migration] || opts[:oban] -> {query, opts} org_id = opts[:org_id] -> {Ecto.Query.where(query, org_id: ^org_id), opts} true -> raise "expected org_id or skip_org_id to be set" end end end ``` ## Community There are a few places to connect and communicate with other Oban users: - Ask questions and discuss *#oban* on the [Elixir Forum][forum] - [Request an invitation][invite] and join the *#oban* channel on [Slack][slack] - Learn about bug reports and upcoming features in the [issue tracker][issues] - Follow [@sorentwo][twitter] (Twitter) [invite]: https://elixir-slack.community/ [slack]: https://elixir-lang.slack.com/ [forum]: https://elixirforum.com/ [issues]: https://github.com/sorentwo/oban/issues [twitter]: https://twitter.com/sorentwo ## Contributing To run the Oban test suite you must have PostgreSQL 12+ and SQLite3 3.37+ running. Follow these steps to create the database, create the database and run all migrations: ```bash mix test.setup ``` To ensure a commit passes CI you should run `mix test.ci` locally, which executes the following commands: * Check formatting (`mix format --check-formatted`) * Check deps (`mix deps.unlock --check-unused`) * Lint with Credo (`mix credo --strict`) * Run all tests (`mix test --raise`) * Run Dialyzer (`mix dialyzer`)