mirror of https://github.com/apache/druid.git
88 lines
4.1 KiB
Markdown
88 lines
4.1 KiB
Markdown
---
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layout: doc_page
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title: "Loading extensions"
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---
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<!--
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~ Licensed to the Apache Software Foundation (ASF) under one
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# Loading extensions
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## Loading core extensions
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Druid bundles all [core extensions](../development/extensions.html#core-extensions) out of the box.
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See the [list of extensions](../development/extensions.html#core-extensions) for your options. You
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can load bundled extensions by adding their names to your common.runtime.properties
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`druid.extensions.loadList` property. For example, to load the *postgresql-metadata-storage* and
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*druid-hdfs-storage* extensions, use the configuration:
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```
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druid.extensions.loadList=["postgresql-metadata-storage", "druid-hdfs-storage"]
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```
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These extensions are located in the `extensions` directory of the distribution.
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<div class="note info">
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Druid bundles two sets of configurations: one for the <a href="../tutorials/quickstart.html">quickstart</a> and
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one for a <a href="../tutorials/cluster.html">clustered configuration</a>. Make sure you are updating the correct
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common.runtime.properties for your setup.
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</div>
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<div class="note caution">
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Because of licensing, the mysql-metadata-storage extension does not include the required MySQL JDBC driver. For instructions
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on how to install this library, see the <a href="../development/extensions-core/mysql.html">MySQL extension page</a>.
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</div>
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## Loading community and third-party extensions (contrib extensions)
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You can also load community and third-party extensions not already bundled with Druid. To do this, first download the extension and
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then install it into your `extensions` directory. You can download extensions from their distributors directly, or
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if they are available from Maven, the included [pull-deps](../operations/pull-deps.html) can download them for you. To use *pull-deps*,
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specify the full Maven coordinate of the extension in the form `groupId:artifactId:version`. For example,
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for the (hypothetical) extension *com.example:druid-example-extension:1.0.0*, run:
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```
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java \
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-cp "lib/*" \
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-Ddruid.extensions.directory="extensions" \
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-Ddruid.extensions.hadoopDependenciesDir="hadoop-dependencies" \
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org.apache.druid.cli.Main tools pull-deps \
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--no-default-hadoop \
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-c "com.example:druid-example-extension:1.0.0"
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```
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You only have to install the extension once. Then, add `"druid-example-extension"` to
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`druid.extensions.loadList` in common.runtime.properties to instruct Druid to load the extension.
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<div class="note info">
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Please make sure all the Extensions related configuration properties listed <a href="../configuration/index.html#extensions">here</a> are set correctly.
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</div>
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<div class="note info">
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The Maven groupId for almost every <a href="../development/extensions.html#community-extensions">community extension</a> is org.apache.druid.extensions.contrib. The artifactId is the name
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of the extension, and the version is the latest Druid stable version.
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</div>
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## Loading extensions from classpath
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If you add your extension jar to the classpath at runtime, Druid will also load it into the system. This mechanism is relatively easy to reason about,
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but it also means that you have to ensure that all dependency jars on the classpath are compatible. That is, Druid makes no provisions while using
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this method to maintain class loader isolation so you must make sure that the jars on your classpath are mutually compatible.
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