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SmallRye Health

This guide demonstrates how your Quarkus application can use SmallRye Health an implementation of the MicroProfile Health specification.

SmallRye Health allows applications to provide information about their state to external viewers which is typically useful in cloud environments where automated processes must be able to determine whether the application should be discarded or restarted.

Requisitos previos

To complete this guide, you need:

  • Roughly 15 minutes

  • An IDE

  • JDK 17+ installed with JAVA_HOME configured appropriately

  • Apache Maven 3.9.6

  • 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)

Arquitectura

In this guide, we build a simple REST application that exposes MicroProfile Health functionalities at the /q/health/live and /q/health/ready endpoints according to the specification.

Solución

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 el repositorio Git: git clone https://github.com/quarkusio/quarkus-quickstarts.git o descargue un archivo.

The solution is located in the microprofile-health-quickstart directory.

Creación del proyecto Maven

En primer lugar, necesitamos un nuevo proyecto. Cree un nuevo proyecto con el siguiente comando:

CLI
quarkus create app org.acme:microprofile-health-quickstart \
    --extension='smallrye-health' \
    --no-code
cd microprofile-health-quickstart

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

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven
mvn io.quarkus.platform:quarkus-maven-plugin:3.10.0:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=microprofile-health-quickstart \
    -Dextensions='smallrye-health' \
    -DnoCode
cd microprofile-health-quickstart

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

For Windows users:

  • If using cmd, (don’t use backward slash \ and put everything on the same line)

  • If using Powershell, wrap -D parameters in double quotes e.g. "-DprojectArtifactId=microprofile-health-quickstart"

This command generates a project, importing the smallrye-health extension.

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

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

Esto añadirá lo siguiente a su archivo de construcción:

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

Running the health check

Importing the smallrye-health extension directly exposes three REST endpoints:

  • /q/health/live - The application is up and running.

  • /q/health/ready - The application is ready to serve requests.

  • /q/health/started - The application is started.

  • /q/health - Accumulating all health check procedures in the application.

To check that the smallrye-health extension is working as expected:

All health REST endpoints return a simple JSON object with two fields:

  • status — the overall result of all the health check procedures

  • checks — an array of individual checks

The general status of the health check is computed as a logical AND of all the declared health check procedures. The checks array is empty as we have not specified any health check procedure yet so let’s define some.

Management interface

By default, the health checks are exposed on the main HTTP server. You can expose them on a separate network interface and port by enabling the management interface with the quarkus.management.enabled=true property. Refer to the management interface reference for more information.

Creating your first health check

In this section, we create our first simple health check procedure.

Create the org.acme.microprofile.health.SimpleHealthCheck class:

package org.acme.microprofile.health;

import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;
import org.eclipse.microprofile.health.Liveness;

import jakarta.enterprise.context.ApplicationScoped;

@Liveness
@ApplicationScoped (1) (2)
public class SimpleHealthCheck implements HealthCheck {

    @Override
    public HealthCheckResponse call() {
        return HealthCheckResponse.up("Simple health check");
    }
}
1 It’s recommended to annotate the health check class with @ApplicationScoped or the @Singleton scope so that a single bean instance is used for all health check requests.
2 If a bean class annotated with one of the health check annotations declares no scope then the @Singleton scope is used automatically.

As you can see, the health check procedures are defined as CDI beans that implement the HealthCheck interface and are annotated with one of the health check qualifiers, such as:

  • @Liveness - the liveness check accessible at /q/health/live

  • @Readiness - the readiness check accessible at /q/health/ready

HealthCheck is a functional interface whose single method call returns a HealthCheckResponse object which can be easily constructed by the fluent builder API shown in the example.

As we have started our Quarkus application in dev mode simply repeat the request to http://localhost:8080/q/health/live by refreshing your browser window or by using curl http://localhost:8080/q/health/live. Because we defined our health check to be a liveness procedure (with @Liveness qualifier) the new health check procedure is now present in the checks array.

Congratulations! You’ve created your first Quarkus health check procedure. Let’s continue by exploring what else can be done with SmallRye Health.

Adding a readiness health check procedure

In the previous section, we created a simple liveness health check procedure which states whether our application is running or not. In this section, we will create a readiness health check which will be able to state whether our application is able to process requests.

We will create another health check procedure that simulates a connection to an external service provider such as a database. For starters, we will always return the response indicating the application is ready.

Create org.acme.microprofile.health.DatabaseConnectionHealthCheck class:

package org.acme.microprofile.health;

import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;
import org.eclipse.microprofile.health.Readiness;

import jakarta.enterprise.context.ApplicationScoped;

@Readiness
@ApplicationScoped
public class DatabaseConnectionHealthCheck implements HealthCheck {

    @Override
    public HealthCheckResponse call() {
        return HealthCheckResponse.up("Database connection health check");
    }
}

If you now rerun the health check at http://localhost:8080/q/health/live the checks array will contain only the previously defined SimpleHealthCheck as it is the only check defined with the @Liveness qualifier. However, if you access http://localhost:8080/q/health/ready (in the browser or with curl http://localhost:8080/q/health/ready) you will see only the Database connection health check as it is the only health check defined with the @Readiness qualifier as the readiness health check procedure.

If you access http://localhost:8080/q/health you will get back both checks.

More information about which health check procedures should be used in which situation is detailed in the MicroProfile Health specification. Generally, the liveness procedures determine whether the application should be restarted while readiness procedures determine whether it makes sense to contact the application with requests.

Adding a startup health check procedure

The third and final type of health check procedures is startup. Startup procedures are defined as an option for slow starting containers (should not be needed in Quarkus) to delay the invocations of liveness probe which will take over from startup once the startup responds UP for the first time. Startup health checks are defined with the @Startup qualifier.

Please make sure that you import the microprofile org.eclipse.microprofile.health.Startup annotation since there is an unfortunate clash with io.quarkus.runtime.Startup.

Create org.acme.microprofile.health.StartupHealthCheck class:

package org.acme.microprofile.health;

import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;
import org.eclipse.microprofile.health.Startup;

import jakarta.enterprise.context.ApplicationScoped;

@Startup
@ApplicationScoped
public class StartupHealthCheck implements HealthCheck {

    @Override
    public HealthCheckResponse call() {
        return HealthCheckResponse.up("Startup health check");
    }
}

The startup health check will be available either at http://localhost:8080/q/health/started or together with other health check procedure at http://localhost:8080/q/health.

Negative health check procedures

In this section, we extend our Database connection health check with the option of stating that our application is not ready to process requests as the underlying database connection cannot be established. For simplicity reasons, we only determine whether the database is accessible or not by a configuration property.

Update the org.acme.microprofile.health.DatabaseConnectionHealthCheck class:

package org.acme.microprofile.health;

import org.eclipse.microprofile.config.inject.ConfigProperty;
import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;
import org.eclipse.microprofile.health.HealthCheckResponseBuilder;
import org.eclipse.microprofile.health.Readiness;

import jakarta.enterprise.context.ApplicationScoped;

@Readiness
@ApplicationScoped
public class DatabaseConnectionHealthCheck implements HealthCheck {

    @ConfigProperty(name = "database.up", defaultValue = "false")
    private boolean databaseUp;

    @Override
    public HealthCheckResponse call() {

        HealthCheckResponseBuilder responseBuilder = HealthCheckResponse.named("Database connection health check");

        try {
            simulateDatabaseConnectionVerification();
            responseBuilder.up();
        } catch (IllegalStateException e) {
            // cannot access the database
            responseBuilder.down();
        }

        return responseBuilder.build();
    }

    private void simulateDatabaseConnectionVerification() {
        if (!databaseUp) {
            throw new IllegalStateException("Cannot contact database");
        }
    }
}
Until now, we used a simplified method of building a HealthCheckResponse through the HealthCheckResponse#up(String) (there is also HealthCheckResponse#down(String)) which will directly build the response object. From now on, we utilize the full builder capabilities provided by the HealthCheckResponseBuilder class.

If you now rerun the readiness health check (at http://localhost:8080/q/health/ready) the overall status should be DOWN. You can also check the liveness check at http://localhost:8080/q/health/live which will return the overall status UP because it isn’t influenced by the readiness checks.

As we shouldn’t leave this application with a readiness check in a DOWN state and because we are running Quarkus in dev mode you can add database.up=true in src/main/resources/application.properties and rerun the readiness health check again — it should be up again.

Adding user-specific data to the health check response

In previous sections, we saw how to create simple health checks with only the minimal attributes, namely, the health check name and its status (UP or DOWN). However, the MicroProfile Health specification also provides a way for the applications to supply arbitrary data in the form of key-value pairs sent to the consuming end. This can be done by using the withData(key, value) method of the health check response builder API.

Let’s create a new health check procedure org.acme.microprofile.health.DataHealthCheck:

package org.acme.microprofile.health;

import org.eclipse.microprofile.health.Liveness;
import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;

import jakarta.enterprise.context.ApplicationScoped;

@Liveness
@ApplicationScoped
public class DataHealthCheck implements HealthCheck {

    @Override
    public HealthCheckResponse call() {
        return HealthCheckResponse.named("Health check with data")
                .up()
                .withData("foo", "fooValue")
                .withData("bar", "barValue")
                .build();
    }
}

If you rerun the liveness health check procedure by accessing the /q/health/live endpoint you can see that the new health check Health check with data is present in the checks array. This check contains a new attribute called data which is a JSON object consisting of the properties we have defined in our health check procedure.

This functionality is specifically useful in failure scenarios where you can pass the error along with the health check response.

        try {
            simulateDatabaseConnectionVerification();
            responseBuilder.up();
        } catch (IllegalStateException e) {
            // cannot access the database
            responseBuilder.down()
                    .withData("error", e.getMessage()); // pass the exception message
        }

Context propagation into the health check invocations

For performance reasons, the context (e.g., CDI or security context) is not propagated into each health check invocation. However, if you need to enable this functionality you can set the config property quarkus.smallrye-health.context-propagation=true to allow the context propagation into every health check call.

Reactive health checks

MicroProfile Health currently doesn’t support returning reactive types, but SmallRye Health does.

If you want to provide a reactive health check, you can implement the io.smallrye.health.api.AsyncHealthCheck interface instead of the org.eclipse.microprofile.health.HealthCheck one. The io.smallrye.health.api.AsyncHealthCheck interface allows you to return a Uni<HealthCheckResponse>.

The following example shows a reactive liveness check:

import io.smallrye.health.api.AsyncHealthCheck;

import org.eclipse.microprofile.health.Liveness;
import org.eclipse.microprofile.health.HealthCheckResponse;

import jakarta.enterprise.context.ApplicationScoped;

@Liveness
@ApplicationScoped
public class LivenessAsync implements AsyncHealthCheck {

    @Override
    public Uni<HealthCheckResponse> call() {
        return Uni.createFrom().item(HealthCheckResponse.up("liveness-reactive"))
                .onItem().delayIt().by(Duration.ofMillis(10));
    }
}

Extension health checks

Some extension may provide default health checks, including the extension will automatically register its health checks.

For example, quarkus-agroal that is used to manage Quarkus datasource(s) automatically register a readiness health check that will validate each datasource: Datasource Health Check.

You can disable extension health checks via the property quarkus.health.extensions.enabled so none will be automatically registered.

IU de la Salud

Experimental - not included in the MicroProfile specification

health-ui allows you to see your Health Checks in a Web GUI.

The Quarkus smallrye-health extension ships with health-ui and enables it by default in dev and test modes, but it can also be explicitly configured for production mode as well.

health-ui can be accessed from http://localhost:8080/q/health-ui/ .

Health UI

Management interface

By default, the health checks are exposed on the main HTTP server. You can expose them on a separate network interface and port by setting quarkus.management.enabled=true in your application configuration. Note that this property is a build-time property. The value cannot be overridden at runtime.

If you enable the management interface without customizing the management network interface and port, the health checks are exposed under: http://0.0.0.0:9000/q/health. You can configure the path (the health segment in the previous URL) using the quarkus.smallrye-health.root-path property.

Refer to the management interface reference for more information.

Conclusion

SmallRye Health provides a way for your application to distribute information about its healthiness state to state whether it is able to function properly. Liveness checks are utilized to tell whether the application should be restarted and readiness checks are used to tell whether the application is able to process requests.

All that is needed to enable the SmallRye Health features in Quarkus is:

  • adding the smallrye-health Quarkus extension to your project using the quarkus-maven-plugin:

    CLI
    quarkus extension add smallrye-health
    Maven
    ./mvnw quarkus:add-extension -Dextensions='smallrye-health'
    Gradle
    ./gradlew addExtension --extensions='smallrye-health'
  • or simply adding the following Maven dependency:

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

Referencia de configuración

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property

Tipo

Por defecto

Whether extensions published health check should be enabled.

Environment variable: QUARKUS_HEALTH_EXTENSIONS_ENABLED

Show more

boolean

true

Whether to include the Liveness and Readiness Health endpoints in the generated OpenAPI document

Environment variable: QUARKUS_HEALTH_OPENAPI_INCLUDED

Show more

boolean

false

Root path for health-checking endpoints. By default, this value will be resolved as a path relative to ${quarkus.http.non-application-root-path}. If the management interface is enabled, the value will be resolved as a path relative to ${quarkus.management.root-path}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_ROOT_PATH

Show more

string

health

The relative path of the liveness health-checking endpoint. By default, this value will be resolved as a path relative to ${quarkus.smallrye-health.rootPath}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_LIVENESS_PATH

Show more

string

live

The relative path of the readiness health-checking endpoint. By default, this value will be resolved as a path relative to ${quarkus.smallrye-health.rootPath}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_READINESS_PATH

Show more

string

ready

The relative path of the health group endpoint. By default, this value will be resolved as a path relative to ${quarkus.smallrye-health.rootPath}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_GROUP_PATH

Show more

string

group

The relative path of the wellness health-checking endpoint. By default, this value will be resolved as a path relative to ${quarkus.smallrye-health.rootPath}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_WELLNESS_PATH

Show more

string

well

The relative path of the startup health-checking endpoint. By default, this value will be resolved as a path relative to ${quarkus.smallrye-health.rootPath}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_STARTUP_PATH

Show more

string

started

Whether the context should be propagated to each health check invocation.

Environment variable: QUARKUS_SMALLRYE_HEALTH_CONTEXT_PROPAGATION

Show more

boolean

false

The number of the maximum health groups that can be created.

Environment variable: QUARKUS_SMALLRYE_HEALTH_MAX_GROUP_REGISTRIES_COUNT

Show more

int

The name of the default health group used when no other health group is defined on the health check.

Environment variable: QUARKUS_SMALLRYE_HEALTH_DEFAULT_HEALTH_GROUP

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string

If management interface is turned on the health endpoints and ui will be published under the management interface. This allows you to exclude Health from management by setting the value to false

Environment variable: QUARKUS_SMALLRYE_HEALTH_MANAGEMENT_ENABLED

Show more

boolean

true

If Health UI should be enabled. By default, Health UI is enabled if it is included (see always-include).

Environment variable: QUARKUS_SMALLRYE_HEALTH_UI_ENABLE

Show more

boolean

true

Additional top-level properties to be included in the resulting JSON object.

Environment variable: QUARKUS_SMALLRYE_HEALTH_ADDITIONAL_PROPERTY

Show more

Map<String,String>

Whether the HealthCheck should be enabled.

Environment variable: QUARKUS_SMALLRYE_HEALTH_CHECK__CHECK__ENABLED

Show more

boolean

false

SmallRye Health UI configuration

Tipo

Por defecto

The path where Health UI is available. The value / is not allowed as it blocks the application from serving anything else. By default, this value will be resolved as a path relative to ${quarkus.http.non-application-root-path}.

Environment variable: QUARKUS_SMALLRYE_HEALTH_UI_ROOT_PATH

Show more

string

health-ui

Always include the UI. By default, this will only be included in dev and test. Setting this to true will also include the UI in Prod

Environment variable: QUARKUS_SMALLRYE_HEALTH_UI_ALWAYS_INCLUDE

Show more

boolean

false