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<p>For small clusters with simple setups that doesn't have a HDFS like file system, the SCP uploader
can be used to manage the package files. This uploader uses the <code>scp</code> linux command to upload the
files to a node accessible by all the worker nodes in the cluster. Then a scheduler like Aurora can
use the <code>scp</code> command again to download the content to each of the worker machines.</p>
<p>SCP Uploader requirements</p>
<ul>
<li>SCP uploader requires the <code>scp</code> and <code>ssh</code> linux utilities installed. Also it is better to have
passwordless ssh configured between the shared node and worker nodes in the cluster.</li>
</ul>
<h3><a class="anchor" aria-hidden="true" id="scp-uploader-configuration"></a><a href="#scp-uploader-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>SCP Uploader Configuration</h3>
<p>You can make Heron use SCP uploader by modifying the <code>uploader.yaml</code> config file specific
for the Heron cluster. You'll need to specify the following for each cluster:</p>
<ul>
<li><code>heron.class.uploader</code> --- Indicate the uploader class to be loaded. You should set this to
org.apache.heron.uploader.scp.ScpUploader</li>
<li><code>heron.uploader.scp.command.options</code> --- Part of the SCP command where you specify custom options.
i.e &quot;-i ~/.ssh/id_rsa&quot;</li>
<li><code>heron.uploader.scp.command.connection</code> --- The user name and host pair to be used by the SCP command.
i.e &quot;user@host&quot;</li>
<li><code>heron.uploader.ssh.command.options</code> --- Part of the SSH command where you specify custom options.
i.e &quot;-i ~/.ssh/id_rsa&quot;</li>
<li><code>heron.uploader.ssh.command.connection</code> --- The user name and host pair to be used by the SSH command.
i.e &quot;user@host&quot;</li>
<li><code>heron.uploader.scp.dir.path</code> --- The directory to be used to uploading the package.</li>
</ul>
<h3><a class="anchor" aria-hidden="true" id="example-scp-uploader-configuration"></a><a href="#example-scp-uploader-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 SCP Uploader Configuration</h3>
<p>Below is an example configuration (in <code>uploader.yaml</code>) for a SCP uploader:</p>
<pre><code class="hljs css language-yaml"><span class="hljs-comment"># uploader class for transferring the topology jar/tar files to storage</span>
<span class="hljs-attr">heron.class.uploader:</span>         <span class="hljs-string">org.apache.heron.uploader.scp.ScpUploader</span>
<span class="hljs-comment"># This is the scp command options that will be used by the uploader, this can be used to</span>
<span class="hljs-comment"># specify custom options such as the location of ssh keys.</span>
<span class="hljs-attr">heron.uploader.scp.command.options:</span>   <span class="hljs-string">"-i ~/.ssh/id_rsa"</span>
<span class="hljs-comment"># The scp connection string sets the remote user name and host used by the uploader.</span>
<span class="hljs-attr">heron.uploader.scp.command.connection:</span>   <span class="hljs-string">"user@host"</span>

<span class="hljs-comment"># The ssh command options that will be used when connecting to the uploading host to execute</span>
<span class="hljs-comment"># command such as delete files, make directories.</span>
<span class="hljs-attr">heron.uploader.ssh.command.options:</span>   <span class="hljs-string">"-i ~/.ssh/id_rsa"</span>
<span class="hljs-comment"># The ssh connection string sets the remote user name and host used by the uploader.</span>
<span class="hljs-attr">heron.uploader.ssh.command.connection:</span>   <span class="hljs-string">"user@host"</span>

<span class="hljs-comment"># the directory where the file will be uploaded, make sure the user has the necessary permissions</span>
<span class="hljs-comment"># to upload the file here.</span>
<span class="hljs-attr">heron.uploader.scp.dir.path:</span>   <span class="hljs-string">${HOME}/heron/repository/${CLUSTER}/${ROLE}/${TOPOLOGY}</span>
</code></pre>
<p>The uploader will use SSH to create the entire directory structure specified in <code>heron.uploader.scp.dir.path</code>
by running <code>mkdir -p</code> before using SCP to upload the topology package.</p>
<p>Below is an example <code>scp</code> command configuration in the <code>heron.aurora</code> file. The cmdline is run by every node
in the cluster to <strong>download</strong> the topology package.</p>
<pre><code class="hljs css language-bash">fetch_user_package = Process(
  name = <span class="hljs-string">'fetch_user_package'</span>,
  cmdline = <span class="hljs-string">'scp -i ~/.ssh/id_rsa user@host:%s %s &amp;&amp; tar zxf %s'</span> % (heron_topology_jar_uri, \
      topology_package_file, topology_package_file)
)
</code></pre>
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