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Using the Redis Client

This guide demonstrates how your Quarkus application can connect to a Redis server using the Redis Client extension.

This technology is considered preview.

In preview, backward compatibility and presence in the ecosystem is not guaranteed. Specific improvements might require changing configuration or APIs, and plans to become stable are under way. Feedback is welcome on our mailing list or as issues in our GitHub issue tracker.

For a full list of possible statuses, check our FAQ entry.

Prerequisites

To complete this guide, you need:

  • Roughly 15 minutes

  • An IDE

  • JDK 11+ installed with JAVA_HOME configured appropriately

  • Apache Maven 3.8.6

  • Optionally the Quarkus CLI if you want to use it

  • Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

  • A working Docker environment

Architecture

In this guide, we are going to expose a simple Rest API to increment numbers by using the INCRBY command. Along the way, we’ll see how to use other Redis commands like GET, SET (from the string group), DEL and KEYS (from the key group).

We’ll be using the Quarkus Redis extension to connect to interact with Redis.

Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

Clone the Git repository: git clone https://github.com/quarkusio/quarkus-quickstarts.git, or download an archive.

The solution is located in the redis-quickstart directory.

Creating the Maven Project

First, we need a new project. Create a new project with the following command:

CLI
quarkus create app org.acme:redis-quickstart \
    --extension='redis-client,resteasy-reactive-jackson' \
    --no-code
cd redis-quickstart

To create a Gradle project, add the --gradle or --gradle-kotlin-dsl option.

For more information about how to install the Quarkus CLI and use it, please refer to the Quarkus CLI guide.

Maven
mvn io.quarkus.platform:quarkus-maven-plugin:2.14.2.Final:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=redis-quickstart \
    -Dextensions='redis-client,resteasy-reactive-jackson' \
    -DnoCode
cd redis-quickstart

To create a Gradle project, add the -DbuildTool=gradle or -DbuildTool=gradle-kotlin-dsl option.

This command generates a new project, importing the Redis extension.

If you already have your Quarkus project configured, you can add the redis-client extension to your project by running the following command in your project base directory:

CLI
quarkus extension add 'redis-client'
Maven
./mvnw quarkus:add-extension -Dextensions='redis-client'
Gradle
./gradlew addExtension --extensions='redis-client'

This will add the following to your build file:

pom.xml
<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-redis-client</artifactId>
</dependency>
build.gradle
implementation("io.quarkus:quarkus-redis-client")

Creating the Increment POJO

We are going to model our increments using the Increment POJO. Create the src/main/java/org/acme/redis/Increment.java file, with the following content:

package org.acme.redis;

public class Increment {
    public String key; (1)
    public long value; (2)

    public Increment(String key, long value) {
        this.key = key;
        this.value = value;
    }

    public Increment() {
    }
}
1 The key that will be used as the Redis key
2 The value held by the Redis key

Creating the Increment Service

We are going to create an IncrementService class which will play the role of a Redis client. With this class, we’ll be able to perform the SET, GET , DEL, KEYS and INCRBY Redis commands.

Create the src/main/java/org/acme/redis/IncrementService.java file, with the following content:

package org.acme.redis;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;

import io.quarkus.redis.datasource.ReactiveRedisDataSource;
import io.quarkus.redis.datasource.RedisDataSource;
import io.quarkus.redis.datasource.keys.KeyCommands;
import io.quarkus.redis.datasource.keys.ReactiveKeyCommands;
import io.quarkus.redis.datasource.string.StringCommands;
import io.smallrye.mutiny.Uni;

@ApplicationScoped
public class IncrementService {

    // This quickstart demonstrates both the imperative
    // and reactive Redis data sources
    // Regular applications will pick one of them.

    private ReactiveKeyCommands<String> keyCommands; (1)
    private ValueCommands<String, Long> countCommands; (2)

    public IncrementService(RedisDataSource ds, ReactiveRedisDataSource reactive) { (3)
        countCommands = ds.value(Long.class); (4)
        keyCommands = reactive.key();  (5)

    }


    long get(String key) {
        Long value = countCommands.get(key); (6)
        if (value == null) {
            return 0L;
        }
        return value;
    }

    void set(String key, Long value) {
        countCommands.set(key, value); (7)
    }

    void increment(String key, Long incrementBy) {
        countCommands.incrby(key, incrementBy); (8)
    }

    Uni<Void> del(String key) {
        return keyCommands.del(key) (9)
            .replaceWithVoid();
    }

    Uni<List<String>> keys() {
        return keyCommands.keys("*"); (10)
    }
}
1 The field use to manipulate keys
2 The field use to manipulate the counter
3 Inject both the imperative and reactive data sources
4 Retrieve the commands to manipulate the counters
5 Retrieve the commands to manipulate the keys
6 Retrieve the value associated with the given key. It null, returns 0.
7 Set the value associated with the given key
8 Increment the value associated with the given key
9 Delete a key (and its associated value)
10 List all the keys

Creating the Increment Resource

Create the src/main/java/org/acme/redis/IncrementResource.java file, with the following content:

package org.acme.redis;

import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.POST;
import javax.ws.rs.DELETE;
import java.util.List;

import io.smallrye.mutiny.Uni;

@Path("/increments")
public class IncrementResource {

    @Inject
    IncrementService service;

    @GET
    public Uni<List<String>> keys() {
        return service.keys();
    }

    @POST
    public Increment create(Increment increment) {
        service.set(increment.key, increment.value);
        return increment;
    }

    @GET
    @Path("/{key}")
    public Increment get(String key) {
        return new Increment(key, service.get(key));
    }

    @PUT
    @Path("/{key}")
    public void increment(String key, long value) {
        service.increment(key, value);
    }

    @DELETE
    @Path("/{key}")
    public Uni<Void> delete(String key) {
        return service.del(key);
    }
}

Creating the test class

Edit the pom.xml file to add the following dependency:

<dependency>
    <groupId>io.rest-assured</groupId>
    <artifactId>rest-assured</artifactId>
    <scope>test</scope>
</dependency>

Create the src/test/java/org/acme/redis/IncrementResourceTest.java file with the following content:

package org.acme.redis;

import static org.hamcrest.Matchers.is;

import org.junit.jupiter.api.Test;

import io.quarkus.test.junit.QuarkusTest;

import static io.restassured.RestAssured.given;

import io.restassured.http.ContentType;

@QuarkusTest
public class IncrementResourceTest {

    @Test
    public void testRedisOperations() {
        // verify that we have nothing
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments")
                .then()
                .statusCode(200)
                .body("size()", is(0));

        // create a first increment key with an initial value of 0
        given()
                .contentType(ContentType.JSON)
                .accept(ContentType.JSON)
                .body("{\"key\":\"first-key\",\"value\":0}")
                .when()
                .post("/increments")
                .then()
                .statusCode(200)
                .body("key", is("first-key"))
                .body("value", is(0));

        // create a second increment key with an initial value of 10
        given()
                .contentType(ContentType.JSON)
                .accept(ContentType.JSON)
                .body("{\"key\":\"second-key\",\"value\":10}")
                .when()
                .post("/increments")
                .then()
                .statusCode(200)
                .body("key", is("second-key"))
                .body("value", is(10));

        // increment first key by 1
        given()
                .contentType(ContentType.JSON)
                .body("1")
                .when()
                .put("/increments/first-key")
                .then()
                .statusCode(204);

        // verify that key has been incremented
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments/first-key")
                .then()
                .statusCode(200)
                .body("key", is("first-key"))
                .body("value", is(1));

        // increment second key by 1000
        given()
                .contentType(ContentType.JSON)
                .body("1000")
                .when()
                .put("/increments/second-key")
                .then()
                .statusCode(204);

        // verify that key has been incremented
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments/second-key")
                .then()
                .statusCode(200)
                .body("key", is("second-key"))
                .body("value", is(1010));

        // verify that we have two keys in registered
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments")
                .then()
                .statusCode(200)
                .body("size()", is(2));

        // delete first key
        given()
                .accept(ContentType.JSON)
                .when()
                .delete("/increments/first-key")
                .then()
                .statusCode(204);

        // verify that we have one key left after deletion
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments")
                .then()
                .statusCode(200)
                .body("size()", is(1));

        // delete second key
        given()
                .accept(ContentType.JSON)
                .when()
                .delete("/increments/second-key")
                .then()
                .statusCode(204);

        // verify that there is no key left
        given()
                .accept(ContentType.JSON)
                .when()
                .get("/increments")
                .then()
                .statusCode(200)
                .body("size()", is(0));
    }
}

Get it running

If you followed the instructions, you should have the Redis server running. Then, you just need to run the application using:

CLI
quarkus dev
Maven
./mvnw quarkus:dev
Gradle
./gradlew --console=plain quarkusDev

Open another terminal and run the curl http://localhost:8080/increments command.

Interacting with the application

As we have seen above, the API exposes five Rest endpoints. In this section we are going to see how to initialise an increment, see the list of current increments, incrementing a value given its key, retrieving the current value of an increment, and finally deleting a key.

Creating a new increment

curl -X POST -H "Content-Type: application/json" -d '{"key":"first","value":10}' http://localhost:8080/increments (1)
1 We create the first increment, with the key first and an initial value of 10.

Running the above command should return the result below:

{
  "key": "first",
  "value": 10
}

See current increments keys

To see the list of current increments keys, run the following command:

curl http://localhost:8080/increments

The above command should return ["first"] indicating that we have only one increment thus far.

Retrieve a new increment

To retrieve an increment using its key, we will have to run the below command:

curl http://localhost:8080/increments/first (1)
1 Running this command, should return the following result:
{
  "key": "first",
  "value": 10
}

Increment a value given its key

To increment a value, run the following command:

curl -X PUT -H "Content-Type: application/json" -d '27' http://localhost:8080/increments/first (1)
1 Increment the first value by 27.

Now, running the command curl http://localhost:8080/increments/first should return the following result:

{
  "key": "first",
  "value": 37 (1)
}
1 We see that the value of the first key is now 37 which is exactly the result of 10 + 27, quick maths.

Deleting a key

Use the command below, to delete an increment given its key.

curl -X DELETE  http://localhost:8080/increments/first (1)
1 Delete the first increment.

Now, running the command curl http://localhost:8080/increments should return an empty list []

Configuring for production

At this point, Quarkus uses the Redis Dev Service to run a Redis server and configure the application. However, in production, you will run your own Redis (or used a Cloud offering).

Let’s start a Redis server on the port 6379 using:

docker run --ulimit memlock=-1:-1 -it --rm=true --memory-swappiness=0 --name redis_quarkus_test -p 6379:6379 redis:5.0.6

Then, open the src/main/resources/application.properties file and add:

%prod.quarkus.redis.hosts=redis://localhost:6379

Packaging and running in JVM mode

You can run the application as a conventional jar file.

First, we will need to package it:

CLI
quarkus build
Maven
./mvnw install
Gradle
./gradlew build
This command will start a Redis instance to execute the tests.

Then run it:

java -jar target/quarkus-app/quarkus-run.jar

Running Native

You can also create a native executable from this application without making any source code changes. A native executable removes the dependency on the JVM: everything needed to run the application on the target platform is included in the executable, allowing the application to run with minimal resource overhead.

Compiling a native executable takes a bit longer, as GraalVM performs additional steps to remove unnecessary codepaths. Use the native profile to compile a native executable:

CLI
quarkus build --native
Maven
./mvnw install -Dnative
Gradle
./gradlew build -Dquarkus.package.type=native

Once the build is finished, you can run the executable with:

./target/redis-quickstart-1.0.0-SNAPSHOT-runner

Going further

To learn more about the Quarkus Redis extension, check the Redis extension reference guide.