# Logstash Kafka Input Plugin Fails to Load OAUTHBEARER strimzi CallbackHandler Class

**URL:** https://discuss.elastic.co/t/logstash-kafka-input-plugin-fails-to-load-oauthbearer-strimzi-callbackhandler-class/379464
**Category:** Logstash
**Created:** [June 25, 2025, 11:30am UTC](https://discuss.elastic.co/t/logstash-kafka-input-plugin-fails-to-load-oauthbearer-strimzi-callbackhandler-class/379464 "2025-06-25T11:30:19Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![niveditakathal](https://avatars.discourse-cdn.com/v4/letter/n/e19b73/32.png) [@niveditakathal](https://discuss.elastic.co/u/niveditakathal)
#### Post date: [June 25, 2025, 11:30am UTC](https://discuss.elastic.co/t/logstash-kafka-input-plugin-fails-to-load-oauthbearer-strimzi-callbackhandler-class/379464/1 "2025-06-25T11:30:19Z")

</div>

Hi Experts,

I'm encountering a **Kafka OAuth setup issue in Logstash** where it fails to load the `JaasClientOauthLoginCallbackHandler` class from the Strimzi libraries.

**Error Message:**  
`ConfigException: Invalid value io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler for configuration sasl.login.callback.handler.class: Class ... could not be found.`

**Environment & Setup:**

**Jar files in** `/usr/share/logstash/jars` **:**

```auto
json-smart-2.5.0.jar
kafka-oauth-client-0.8.1.jar
kafka-oauth-common-0.8.1.jar
kafka-oauth-keycloak-authorizer-0.8.1.jar
kafka-oauth-server-0.8.1.jar
lang-tag-1.4.4.jar
nimbus-jose-jwt-9.37.3.jar
oauth2-oidc-sdk-10.8.jar
slf4j-api-1.7.36.jar 

```

**Kafka JAAS config (** `/usr/share/logstash/config/kafka-jaas.conf` **):**

```KafkaClient
  org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required
  oauth.client.id="kafka"
  oauth.client.secret="***"
  oauth.token.endpoint.uri="https://<auth-endpoint>"
  oauth.username="kafkatst"
  oauth.password="***";
};

```

**Logstash input config:**

```input
  kafka {
    bootstrap_servers => "il-kafka-tst.local:9093"
    topics => ["test"]
    group_id => "kafkatst"
    codec => "json"
    security_protocol => "SASL_PLAINTEXT"
    sasl_mechanism => "OAUTHBEARER"
    sasl_login_callback_handler_class => "io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler"
    jaas_path => "/usr/share/logstash/config/kafka-jaas.conf"
  }
}

```

Could someone help me fix this issue?

Thanks in advance !  
Nivedita

---

<div class="post-metadata">

### Author: ![niveditakathal](https://avatars.discourse-cdn.com/v4/letter/n/e19b73/32.png) [@niveditakathal](https://discuss.elastic.co/u/niveditakathal)
#### Post date: [July 1, 2025, 12:16pm UTC](https://discuss.elastic.co/t/logstash-kafka-input-plugin-fails-to-load-oauthbearer-strimzi-callbackhandler-class/379464/2 "2025-07-01T12:16:53Z")

</div>

The issue was resolved by updating the `deployment.yaml` file with the appropriate container configuration for `dev-logstash`, which includes a custom startup command and volume mount to ensure necessary JARs are available at runtime.

```auto
containers:
  - name: dev-logstash
    image: logstash:8.18.0
    imagePullPolicy: Always
    command:
      - "sh"
      - "-c"
      - > cp /usr/share/logstash/jars/* /usr/share/logstash/logstash-core/lib/jars/ &&
        exec /usr/local/bin/docker-entrypoint
    volumeMounts:
      - name: strimzi-kafka-oauth-client-jars-volume
        mountPath: /usr/share/logstash/jars

```

_Note : I used initContainers to download the jars first_