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https://issues.apache.org/jira/browse/KAFKA-9170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16972187#comment-16972187
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Oleg Muravskiy commented on KAFKA-9170:
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Hi [~guozhang],
And this is exactly the problem.
if this "by-design" declares its input type as *Properties*, it must support
any object of this type, no matter how it was constructed.
If does not support *Properties*, but only *Map*, then it should declare the
input type as a *Map*.
> KafkaStreams constructor fails to read configuration from Properties object
> created with default values
> -------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-9170
> URL: https://issues.apache.org/jira/browse/KAFKA-9170
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.3.0
> Reporter: Oleg Muravskiy
> Priority: Major
>
> When the *Properties* object passed in to the *KafkaStreams* constructor is
> created like
>
> {code:java}
> new Properties(defaultProperties){code}
>
> KafkaStreams fails to read properties properly, which in my case results in
> an error:
>
> {noformat}
> org.apache.kafka.common.config.ConfigException: Missing required
> configuration "bootstrap.servers" which has no default
> value.org.apache.kafka.common.config.ConfigException: Missing required
> configuration "bootstrap.servers" which has no default value. at
> org.apache.kafka.common.config.ConfigDef.parseValue(ConfigDef.java:476) at
> org.apache.kafka.common.config.ConfigDef.parse(ConfigDef.java:466) at
> org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:108)
> at
> org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:142)
> at org.apache.kafka.streams.StreamsConfig.<init>(StreamsConfig.java:844) at
> org.apache.kafka.streams.StreamsConfig.<init>(StreamsConfig.java:839) at
> org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:544)
> {noformat}
> This is due to the fact that the constructor that receives the *Properties*
> class:
>
> {code:java}
> public KafkaStreams(final Topology topology,
> final Properties props) {
> this(topology.internalTopologyBuilder, new StreamsConfig(props), new
> DefaultKafkaClientSupplier());
> {code}
> passes *props* into *StreamsConfig*, which ignores the *Properties*
> interface, and only uses the *Map* interface:
>
> {code:java}
> public StreamsConfig(final Map<?, ?> props) {
> this(props, true);
> }
> {code}
> (Note that if you do
> {{props.getProperty(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG)}}, it returns the
> correct value).
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