# faktory\_worker\_haskell
[](https://github.com/freckle/faktory_worker_haskell/actions/workflows/ci.yml)
Haskell client and worker process for the Faktory background job server.
Architecture overview from [Ruby client README](https://github.com/contribsys/faktory_worker_ruby#readme):
```
+--------------------+
| |
| Faktory |
| Server |
+---------->>>>| +>>>>--------+
| | | |
| | | |
| +--------------------+ |
+-----------------+ +-------------------+
| | | |
| Client | | Worker |
| pushes | | pulls |
| jobs | | jobs |
| | | |
| | | |
+-----------------+ +-------------------+
```
- Client - an API any process can use to push jobs to the Faktory server.
- Worker - a process that pulls jobs from Faktory and executes them.
- Server - the Faktory daemon which stores background jobs in queues to be
processed by Workers.
This package contains only the client and worker parts. The server part is
[here](https://github.com/contribsys/faktory/)
## Installation
- Hackage: http://hackage.haskell.org/package/faktory
- Stackage: *Coming soon*
## Faktory Documentation
See the [wiki](//github.com/contribsys/faktory/wiki) for more
details.
## Usage
<!--
```haskell
import Data.Aeson
import Prelude
import Faktory.Producer
import Faktory.Job
import Faktory.Worker
import GHC.Generics
import Text.Markdown.Unlit ()
{- Don't actually run anything -}
main :: IO ()
main = if True then pure () else (workerMain >> producerMain)
workerMain :: IO ()
producerMain :: IO ()
```
-->
### Job
Any value can be a "Job" that is pushed and pulled to and from Faktory via its
`ToJSON` and `FromJSON` instances:
```haskell
newtype MyJob = MyJob
{ myJobMessage :: String
}
deriving stock Generic
deriving anyclass (ToJSON, FromJSON)
```
### Worker
```haskell
workerMain = runWorkerEnv $ \job -> do
-- Process your Job here
putStrLn $ jobJid job
putStrLn $ myJobMessage $ jobArg job
-- If any exception is thrown, the job will be marked as Failed in Faktory
-- and retried. Note: you will not otherwise hear about any such exceptions,
-- unless you catch-and-rethrow them yourself.
```
### Producer
`Producer` wraps `Client` for push-only usage.
```haskell
producerMain = do
producer <- newProducerEnv
jobId <- perform mempty producer $ MyJob "Hello world"
print jobId
closeProducer producer
```
### Configuration
When using `envSettings`, the following variables will be used:
- `FAKTORY_PROVIDER`: the name of another environment variable where the
connection string can be found. Defaults to `FAKTORY_URL`.
- `FAKTORY_URL` (or whatever you named in `FAKTORY_PROVIDER`): connection string
to the Faktory server. Format is
`tcp(+tls)://(:password@)host:port(/namespace)`. Defaults to
`tcp://localhost:4719`. `namespace` is prependend to queue names on job
submission and worker consumption.
When using `envWorkerSettings`, the following variables are also used:
- `FAKTORY_QUEUE`: the name of the queue to consume from. Default is "default".
- `FAKTORY_WORKER_ID`: the Id to use for this Worker. Default is to assign a
random one.
## Examples
See the [examples](./examples). To run them:
1. Run a local Faktory server
```console
docker run --rm \
--publish 7419:7419 \
--publish 7420:7420 \
contribsys/faktory
```
1. Run the consumer example
```console
% stack exec faktory-example-consumer
Starting consumer loop
```
(Assumes you've built the project.)
1. Submit a Job through the producer example
```console
% stack exec faktory-example-producer hello world
Pushed job: "ljcjlbexbgun"
```
*NOTE*: if you submit "BOOM" as a Job, the processing loop will raise an
exception, so you can see how a Failed Job looks in Faktory.
1. See that your Job was processed back in the consumer
```console
% stack exec faktory-example-consumer
Starting consumer loop
hello world
```
## Development & Tests
```console
stack build --dependencies-only --test --no-run-tests
stack build --pedantic --test --no-run-tests
stack build --pedantic --test
```
- `FactorySpec` requires a local Faktory server is running, and it will flush
all Jobs from this server as part of running the tests.
- The tests for `BATCH` require testing against an Enterprise Faktory image
---
[CHANGELOG](./CHANGELOG.md) | [LICENSE](./LICENSE)
