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https://github.com/getnelson/helm
A native Scala client for interacting with Consul
https://github.com/getnelson/helm
Last synced: about 2 months ago
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A native Scala client for interacting with Consul
- Host: GitHub
- URL: https://github.com/getnelson/helm
- Owner: getnelson
- License: apache-2.0
- Fork: true (Verizon/helm)
- Created: 2018-12-23T03:59:45.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2021-09-14T13:58:32.000Z (about 3 years ago)
- Last Synced: 2024-06-17T07:32:46.202Z (3 months ago)
- Language: Scala
- Size: 188 KB
- Stars: 4
- Watchers: 1
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-consul - getnelson/helm
README
# Helm
[](https://travis-ci.org/getnelson/helm)
[](https://maven-badges.herokuapp.com/maven-central/io.getnelson.helm/core_2.11)
[](https://codecov.io/gh/getnelson/helm)
A native [Scala](http://scala-lang.org) client for interacting with [Consul](https://www.consul.io/). There is currently one supported client, which uses [http4s](http://http4s.org) to make HTTP calls to Consul. Alternative implementations could be added with relative ease by providing an additional free interpreter for the `ConsulOp` algebra.
## Getting Started
Add the following to your `build.sbt`:
libraryDependencies += "io.getnelson.helm" %% "http4s" % "x.y.z"
Where `x.y.z` is the desired Helm version. Check for the latest release [Maven Central](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22io.getnelson.helm%22).
### Algebra
Consul operations are specified by the `ConsulOp` algebra. Two
examples are `get` and `set`:
```
import ConsulOp.ConsulOpF
val setAlgebra: ConsulOpF[Unit] = ConsulOp.kvSet(key = "testKey", value = "testValue".getBytes)
val getAlgebra: ConsulOpF[QueryResponse[List[KVGetResult]]] = ConsulOp.kvGet(key = "testKey",
recurse = Some(false),
datacenter = None,
separator = None,
index = None,
maxWait = None)
```
These are however just descriptions of what operations the program might perform in the future, just creating these operations does not
actually execute the operations. In order to perform the gets and sets, we need to use the [http4s](http://http4s.org) interpreter.
### The http4s interpreter
First we create an interpreter, which requires an http4s client and
a base url for consul:
```
import scala.concurrent.ExecutionContext
import cats.effect.IO
import helm.http4s._
import org.http4s.Uri.uri
import org.http4s.client.blaze.BlazeClientBuilder
val ec = ExecutionContext.global
implicit val contextShift = IO.contextShift(ec)
// It's better to run everything inside of resource.use() where possible, but this makes for a simpler example
val client = BlazeClientBuilder[IO](ec).resource.allocated.unsafeRunSync()._1
val baseUrl = uri("http://127.0.0.1:8500")
val interpreter = new Http4sConsulClient(baseUrl, client)
```
Now we can apply commands to our http4s client to get back IOs
which actually interact with consul.
```
import helm._
import cats.effect.IO
val set: IO[Unit] = helm.run(interpreter, setAlgebra)
val get: IO[QueryResponse[List[KVGetResult]]] = helm.run(interpreter, getAlgebra)
// actually execute the calls
val setResult: Unit = set.unsafeRunSync()
val getResult: QueryResponse[List[KVGetResult]] = get.unsafeRunSync()
```
Typically, the *Helm* algebra would be a part of a `Coproduct` with other algebras in a larger program, so running the `IO` immediately after `helm.run` is not typical.
## Contributing
Contributions are welcome; particularly to expand the algebra with additional operations that are supported by Consul but not yet supported by *Helm*.