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new de75dcd [FLINK-27097] Document custom validator implementations
de75dcd is described below
commit de75dcdc51ef3ee8e0477a8799ffe000088546f1
Author: SteNicholas <programg...@163.com>
AuthorDate: Wed May 4 14:07:28 2022 +0800
[FLINK-27097] Document custom validator implementations
This closes #192.
---
docs/content/docs/operations/validator.md | 91 +++++++++++++++++++++++++++++++
1 file changed, 91 insertions(+)
diff --git a/docs/content/docs/operations/validator.md
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+---
+title: "Validator"
+weight: 5
+type: docs
+aliases:
+- /operations/validator.html
+---
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements. See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership. The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied. See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+# Custom `FlinkResourceValidator` implementation
+
+`FlinkResourceValidator`, an interface for validating the resources of
`FlinkDeployment` and `FlinkSessionJob`, is a pluggable component based on the
[Plugins](https://nightlies.apache.org/flink/flink-docs-master/docs/deployment/filesystems/plugins)
mechanism. During development, we can customize the implementation of
`FlinkResourceValidator` and make sure to retain the service definition in
`META-INF/services`.
+The following steps demonstrate how to develop and use a custom validator.
+
+1. Implement `FlinkResourceValidator` interface:
+ ```java
+ package org.apache.flink.kubernetes.operator.validation;
+
+ import org.apache.flink.kubernetes.operator.crd.FlinkDeployment;
+ import org.apache.flink.kubernetes.operator.crd.FlinkSessionJob;
+
+ import java.util.Optional;
+
+ /** Custom validator implementation of {@link FlinkResourceValidator}. */
+ public class CustomValidator implements FlinkResourceValidator {
+
+ @Override
+ public Optional<String> validateDeployment(FlinkDeployment deployment)
{
+ if (deployment.getSpec().getFlinkVersion() == null) {
+ return Optional.of("Flink Version must be defined.");
+ }
+ return Optional.empty();
+ }
+
+ @Override
+ public Optional<String> validateSessionJob(
+ FlinkSessionJob sessionJob, Optional<FlinkDeployment>
session) {
+ if (sessionJob.getSpec().getJob() == null) {
+ return Optional.of("The job spec should not be empty");
+ }
+ return Optional.empty();
+ }
+ }
+ ```
+
+2. Create service definition file
`org.apache.flink.kubernetes.operator.validation.FlinkResourceValidator` in
`META-INF/services`. With custom `FlinkResourceValidator` implementation, the
service definition describes as follows:
+ ```text
+ org.apache.flink.kubernetes.operator.validation.CustomValidator
+ ```
+
+3. Use the Maven tool to package the project and generate the custom validator
JAR.
+
+4. Create Dockerfile to build a custom image from the
`apache/flink-kubernetes-operator` official image and copy the generated JAR to
custom validator plugin directory.
+ `/opt/flink/plugins` is the value of `FLINK_PLUGINS_DIR` environment
variable in the flink-kubernetes-operator helm chart. The structure of custom
validator directory under `/opt/flink/plugins` is as follows:
+ ```text
+ /opt/flink/plugins
+ ├── custom-validator
+ │ ├── custom-validator.jar
+ └── ...
+ ```
+
+ With the custom validator directory location, the Dockerfile is defined as
follows:
+ ```shell script
+ FROM apache/flink-kubernetes-operator
+ ENV FLINK_PLUGINS_DIR=/opt/flink/plugins
+ ENV CUSTOM_VALIDATOR_DIR=custom-validator
+ RUN mkdir $FLINK_PLUGINS_DIR/$CUSTOM_VALIDATOR_DIR
+ COPY custom-validator.jar $FLINK_PLUGINS_DIR/$CUSTOM_VALIDATOR_DIR/
+ ```
+
+5. Install the flink-kubernetes-operator helm chart with the custom image and
verify the `deploy/flink-kubernetes-operator` log has:
+ ```text
+ 2022-05-04 14:01:46,551 o.a.f.k.o.u.FlinkUtils [INFO ] Discovered
resource validator from plugin directory[/opt/flink/plugins]:
org.apache.flink.kubernetes.operator.validation.CustomValidator.
+ ```
