<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Local Cluster · Apache Heron</title><meta name="viewport" content="width=device-width"/><meta name="generator" content="Docusaurus"/><meta name="description" content="&lt;!--"/><meta name="docsearch:version" content="0.20.4-incubating"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Local Cluster · Apache Heron"/><meta property="og:type" content="website"/><meta property="og:url" content="https://heron.apache.org/"/><meta property="og:description" content="&lt;!--"/><meta property="og:image" content="https://heron.apache.org/img/undraw_online.svg"/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://heron.apache.org/img/undraw_tweetstorm.svg"/><link rel="shortcut icon" href="/img/favicon-32x32.png"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/default.min.css"/><link rel="alternate" type="application/atom+xml" href="https://heron.apache.org/blog/atom.xml" title="Apache Heron Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://heron.apache.org/blog/feed.xml" title="Apache Heron Blog RSS Feed"/><script>
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<p>In addition to out-of-the-box schedulers for
<a href="schedulers-aurora-cluster">Aurora</a>, Heron can also be deployed in a local environment, which
stands up a mock Heron cluster on a single machine. This can be useful for
experimenting with Heron's features, testing a wide variety of possible cluster
events, and so on.</p>
<p>One of two state managers can be used for coordination when deploying locally:</p>
<ul>
<li><a href="state-managers-zookeeper">ZooKeeper</a></li>
<li><a href="state-managers-local-fs">Local File System</a></li>
</ul>
<p><strong>Note</strong>: Deploying a Heron cluster locally is not to be confused with Heron's
<a href="guides-simulator-mode">simulator mode</a>. Simulator mode enables
you to run topologies in a cluster-agnostic JVM process for the purpose of
development and debugging, while the local scheduler stands up a Heron cluster
on a single machine.</p>
<h2><a class="anchor" aria-hidden="true" id="how-local-deployment-works"></a><a href="#how-local-deployment-works" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>How Local Deployment Works</h2>
<p>Using the local scheduler is similar to deploying Heron on other schedulers.
The <a href="user-manuals-heron-cli">Heron</a> cli is used to deploy and manage topologies
as would be done using a distributed scheduler. The main difference is in
the configuration.</p>
<h2><a class="anchor" aria-hidden="true" id="local-scheduler-configuration"></a><a href="#local-scheduler-configuration" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Local Scheduler Configuration</h2>
<p>To configure Heron to use local scheduler, specify the following in <code>scheduler.yaml</code>
config file.</p>
<ul>
<li><p><code>heron.class.scheduler</code> --- Indicates the class to be loaded for local scheduler.
Set this to <code>org.apache.heron.scheduler.local.LocalScheduler</code></p></li>
<li><p><code>heron.class.launcher</code> --- Specifies the class to be loaded for launching
topologies. Set this to <code>org.apache.heron.scheduler.local.LocalLauncher</code></p></li>
<li><p><code>heron.scheduler.local.working.directory</code> --- Provides the working
directory for topology. The working directory is essentially a scratch pad where
topology jars, heron core release binaries, topology logs, etc are generated and kept.</p></li>
<li><p><code>heron.package.core.uri</code> --- Indicates the location of the heron core binary package.
The local scheduler uses this URI to download the core package to the working directory.</p></li>
<li><p><code>heron.directory.sandbox.java.home</code> --- Specifies the java home to
be used when running topologies in the containers. Set to <code>${JAVA_HOME}</code> to
use the value set in the bash environment variable $JAVA_HOME.</p></li>
</ul>
<h3><a class="anchor" aria-hidden="true" id="example-local-scheduler-configuration"></a><a href="#example-local-scheduler-configuration" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Example Local Scheduler Configuration</h3>
<pre><code class="hljs css language-yaml"><span class="hljs-comment"># scheduler class for distributing the topology for execution</span>
<span class="hljs-attr">heron.class.scheduler:</span> <span class="hljs-string">org.apache.heron.scheduler.local.LocalScheduler</span>

<span class="hljs-comment"># launcher class for submitting and launching the topology</span>
<span class="hljs-attr">heron.class.launcher:</span> <span class="hljs-string">org.apache.heron.scheduler.local.LocalLauncher</span>

<span class="hljs-comment"># working directory for the topologies</span>
<span class="hljs-attr">heron.scheduler.local.working.directory:</span> <span class="hljs-string">${HOME}/.herondata/topologies/${CLUSTER}/${TOPOLOGY}</span>

<span class="hljs-comment"># location of the core package</span>
<span class="hljs-attr">heron.package.core.uri:</span> <span class="hljs-string">file://${HERON_DIST}/heron-core.tar.gz</span>

<span class="hljs-comment"># location of java - pick it up from shell environment</span>
<span class="hljs-attr">heron.directory.sandbox.java.home:</span> <span class="hljs-string">${JAVA_HOME}</span>
</code></pre>
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