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https://issues.apache.org/jira/browse/KAFKA-7208?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sean Policarpio resolved KAFKA-7208.
------------------------------------
Resolution: Not A Problem
Oops, realised I misunderstood how this API request works; ConfigEntries
represents the entire map of overrides you want to apply for the resource
(topic in this case). So to delete an override, it just needs to not be
specified in the map submitted by the API, in which case the default value will
take over.
The only issue here is that the documentation is still wrong, in that it says
the config value is a nullable String.
> AlterConfigsRequest with null config value throws NullPointerException
> ----------------------------------------------------------------------
>
> Key: KAFKA-7208
> URL: https://issues.apache.org/jira/browse/KAFKA-7208
> Project: Kafka
> Issue Type: Bug
> Components: admin, config, core
> Affects Versions: 1.1.1
> Reporter: Sean Policarpio
> Priority: Major
>
> The following exception is thrown from the Kafka server when an
> AlterConfigsRequest API request is made via the binary protocol where the
> CONFIG_ENTRY's CONFIG_VALUE is set to null:
> {noformat}
> [2018-07-26 15:53:01,487] ERROR [Admin Manager on Broker 1000]: Error
> processing alter configs request for resource Resource(type=TOPIC,
> name='foo'}, config
> org.apache.kafka.common.requests.AlterConfigsRequest$Config@692d8300
> (kafka.server.AdminManager)
> java.lang.NullPointerException
> at java.util.Hashtable.put(Hashtable.java:459)
> at java.util.Properties.setProperty(Properties.java:166)
> at
> kafka.server.AdminManager$$anonfun$alterConfigs$1$$anonfun$apply$18.apply(AdminManager.scala:357)
> at
> kafka.server.AdminManager$$anonfun$alterConfigs$1$$anonfun$apply$18.apply(AdminManager.scala:356)
> at scala.collection.Iterator$class.foreach(Iterator.scala:891)
> at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
> at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
> at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
> at
> kafka.server.AdminManager$$anonfun$alterConfigs$1.apply(AdminManager.scala:356)
> at
> kafka.server.AdminManager$$anonfun$alterConfigs$1.apply(AdminManager.scala:339)
> at
> scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
> at
> scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
> at scala.collection.Iterator$class.foreach(Iterator.scala:891)
> at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
> at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
> at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
> at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
> at scala.collection.AbstractTraversable.map(Traversable.scala:104)
> at kafka.server.AdminManager.alterConfigs(AdminManager.scala:339)
> at
> kafka.server.KafkaApis.handleAlterConfigsRequest(KafkaApis.scala:1994)
> at kafka.server.KafkaApis.handle(KafkaApis.scala:143)
> at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:69)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> As a first guess, I'd say the issue is happening
> [here|https://github.com/apache/kafka/blob/49db5a63c043b50c10c2dfd0648f8d74ee917b6a/core/src/main/scala/kafka/server/AdminManager.scala#L361],
> since HashTable/Property can't take a null value.
> The reason I'm sending a null for the configuration value is I assumed that
> since the API documentation says that the value is nullable (see
> [here|http://kafka.apache.org/protocol.html#The_Messages_AlterConfigs] and
> [here|https://github.com/apache/kafka/blob/49db5a63c043b50c10c2dfd0648f8d74ee917b6a/clients/src/main/java/org/apache/kafka/common/requests/AlterConfigsRequest.java#L53]),
> this meant the (override) configuration itself would be deleted when a null
> value was received.
> Contradictory to that, I did notice null checks throughout the code, like
> [here|https://github.com/apache/kafka/blob/49db5a63c043b50c10c2dfd0648f8d74ee917b6a/clients/src/main/java/org/apache/kafka/common/requests/AlterConfigsRequest.java#L92].
> If null is in fact not meant to be accepted by the binary API, this probably
> needs to be addressed at the protocol level. Further to that, can someone
> show me how to then remove a configuration override via the binary API?
> For clarity sake, here's what my request looked like (pseudo/Rust):
> {noformat}
> AlterConfigsRequest {
> resources: [
> Resource
> {
> resource_type: 2,
> resource_name: "foo",
> config_entries: [
> ConfigEntry
> {
> config_name: "file.delete.delay.ms",
> config_value: None // serialized as a 16-bit '-1'
> }
> ]
> }
> ],
> validate_only: false
> }
> {noformat}
>
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