layout: default
navsection: userguide
navmenu: Tutorials
-title: "Writing a Crunch script"
+title: "Writing a pipeline"
...
-h1. Writing a Crunch script
-
In this tutorial, we will write the "hash" script demonstrated in the first tutorial.
*This tutorial assumes that you are "logged into an Arvados VM instance":{{site.baseurl}}/user/getting_started/ssh-access.html#login, and have a "working environment.":{{site.baseurl}}/user/getting_started/check-environment.html*
~$ <span class="userinput">git config --global user.email <b>you</b>@example.com</span></code></pre>
</notextile>
-On the Arvados Workbench, navigate to "Compute %(rarr)→% Code repositories":http://{{site.arvados_workbench_host}}/repositiories . You should see a repository with your user name listed in the *name* column. Next to *name* is the column *push_url*. Copy the *push_url* value associated with your repository. This should look like <notextile><code>git@git.{{ site.arvados_api_host }}:<b>you</b>.git</code></notextile>.
+On the Arvados Workbench, navigate to "Compute %(rarr)→% Code repositories":http://{{site.arvados_workbench_host}}/repositories . You should see a repository with your user name listed in the *name* column. Next to *name* is the column *push_url*. Copy the *push_url* value associated with your repository. This should look like <notextile><code>git@git.{{ site.arvados_api_host }}:<b>you</b>.git</code></notextile>.
Next, on the Arvados virtual machine, clone your git repository:
notextile. <pre><code>~/<b>you</b>/crunch_scripts$ <span class="userinput">chmod +x hash.py</span></code></pre>
{% include 'notebox_begin' %}
-The steps below describe how to execute the script after committing changes to git. To test the script locally, please see the "debugging a crunch script":{{site.baseurl}}/user/topics/tutorial-job-debug.html page.
+The steps below describe how to execute the script after committing changes to git. To run a script locally for testing, please see "debugging a crunch script":{{site.baseurl}}/user/topics/tutorial-job-debug.html .
{% include 'notebox_end' %}
* [new branch] master -> master</code></pre>
</notextile>
-You should now be able to run your script using Crunch, as described in "running a crunch job on the command line.":tutorial-job1.html The field @"script_version"@ should be <notextile><code><b>you</b>:master</code></notextile> to tell Crunch to run the script at the head of the "master" git branch, which you just pushed to the repository.
+h2. Create a pipeline template
+
+Next, create a file that contains the pipeline definition:
<notextile>
-<pre><code>~/<b>you</b>/crunch_scripts$ <span class="userinput">cat >~/the_job <<EOF
-{
- "script": "hash.py",
- "script_version": "<b>you</b>:master",
- "script_parameters":
- {
- "input": "c1bad4b39ca5a924e481008009d94e32+210"
- }
-}
-EOF</span>
-~/<b>you</b>/crunch_scripts$ <span class="userinput">arv job create --job "$(cat ~/the_job)"</span>
-{
- ...
- "uuid":"qr1hi-xxxxx-xxxxxxxxxxxxxxx"
- ...
-}
-~/<b>you</b>/crunch_scripts$ <span class="userinput">arv job get --uuid qr1hi-xxxxx-xxxxxxxxxxxxxxx</span>
+<pre><code>~/<b>you</b>/crunch_scripts$ <span class="userinput">cd ~</span>
+~$ <span class="userinput">cat >the_pipeline <<EOF
{
- ...
- "output":"880b55fb4470b148a447ff38cacdd952+54",
- ...
+ "name":"My first pipeline",
+ "components":{
+ "do_hash":{
+ "script":"hash.py",
+ "script_parameters":{
+ "input":{
+ "required": true,
+ "dataclass": "Collection"
+ }
+ },
+ "script_version":"<b>you</b>:master"
+ }
+ }
}
-~/<b>you</b>/crunch_scripts$ <span class="userinput">arv keep get 880b55fb4470b148a447ff38cacdd952+54/md5sum.txt</span>
-44b8ae3fde7a8a88d2f7ebd237625b4f var-GS000016015-ASM.tsv.bz2
-</code></pre>
+EOF
+</span></code></pre>
</notextile>
-<hr>
+* @cat@ is a standard Unix utility that simply copies standard input to standard output
+* @<<EOF@ tells the shell to direct the following lines into the standard input for @cat@ up until it sees the line @EOF@
+* @>the_pipeline@ redirects standard output to a file called @the_pipeline@
+* @"name"@ is a human-readable name for the pipeline
+* @"components"@ is a set of scripts that make up the pipeline
+* The component is listed with a human-readable name (@"do_hash"@ in this example)
+* @"script"@ specifies the name of the script to run. The script is searched for in the "crunch_scripts/" subdirectory of the @git@ checkout specified by @"script_version"@.
+* @"script_version"@ specifies the version of the script that you wish to run. This can be in the form of an explicit @git@ revision hash, or in the form "repository:branch" (in which case it will take the HEAD of the specified branch). Arvados logs the script version that was used in the run, enabling you to go back and re-run any past job with the guarantee that the exact same code will be used as was used in the previous run. You can access a list of available @git@ repositories on the Arvados workbench under "Compute %(rarr)→% Code repositories":http://{{site.arvados_workbench_host}}//repositories .
+* @"script_parameters"@ describes the parameters for the script. In this example, there is one parameter called @input@ which is @required@ and is a @Collection@.
+
+Now, use @arv pipeline_template create@ tell Arvados about your pipeline template:
+
+<notextile>
+<pre><code>~$ <span class="userinput">arv pipeline_template create --pipeline-template "$(cat the_pipeline)"</span>
+</code></pre>
+</notextile>
-Next, "writing a crunch pipeline.":tutorial-new-pipeline.html
+Your new pipeline template will appear on the "Workbench %(rarr)→% Compute %(rarr)→% Pipeline templates":http://{{ site.arvados_workbench_host }}/pipeline_instances page. You can run the "pipeline using workbench":tutorial-pipeline-workbench.html
projects / arvados.git / blobdiff