5 title: "Crunch utility libraries"
9 h1. Crunch utility libraries
11 Several utility libraries are included with Arvados. They are intended to make it quicker and easier to write your own crunch scripts.
13 * "Python SDK extras":#pythonsdk
14 * "Toolkit wrappers":#toolkit_wrappers
16 h2(#pythonsdk). Python SDK extras
18 The Python SDK adds some convenience features that are particularly useful in crunch scripts, in addition to the standard set of API calls.
20 In a crunch job, the environment variables @ARVADOS_API_HOST@ and @ARVADOS_API_TOKEN@ will be set up so the job has the privileges of the user who submitted the job.
25 my_user = arvados.api().users().current().execute()
26 my_uuid = my_user['uuid']
29 h3. Get the current job and task parameters
31 @arvados.current_job()@ and @arvados.current_task()@ are convenient ways to retrieve the current Job and Task, using the @JOB_UUID@ and @TASK_UUID@ environment variables provided to each crunch task process.
34 this_job = arvados.current_job()
35 this_task = arvados.current_task()
36 this_job_input = this_job['script_parameters']['input']
37 this_task_input = this_task['parameters']['input']
40 h3(#one_task_per_input). Queue a task for each input file
42 A common pattern for a crunch job is to run one task to scan the input, and one task per input file to do the work.
44 The @one_task_per_input_file()@ function implements this pattern. Pseudocode:
47 if this is the job's first (default) task:
48 for each file in the 'input' collection:
49 queue a new task, with parameters['input'] = file
59 arvados.job_setup.one_task_per_input_file(if_sequence=0, and_end_task=True)
61 # Now do the work on a single file
62 my_input = this_task['parameters']['input']
65 h3. Set the current task's output and success flag
67 Each task in a crunch job must make an API call to record its output and set its @success@ attribute to True. The object returned by @current_task()@ has a @set_output()@ method to make the process more succinct.
70 arvados.current_task().set_output(my_output_locator)
75 Manage child processes and FIFOs (pipes).
78 This module makes it easier to check the exit status of every child process you start, and close the unused end of each FIFO at the appropriate time.
81 from arvados_ipc import *
86 pipe_setup(pipes, 'hellopipe')
87 if 0 == named_fork(children, 'child_a'):
88 pipe_closeallbut(pipes, ('hellopipe', 'w'))
89 os.write(pipes['hellopipe', 'w'], "Hello, parent.")
92 pipe_closeallbut(pipes, ('hellopipe', 'r'))
93 with os.fdopen(pipes['hellopipe', 'r'], 'rb') as f:
95 sys.stderr.write("Child says: " + message + "\n")
97 if not waitpid_and_check_children(children):
98 raise Exception("Child process exited non-zero.")
101 The "crunch scripts" included with Arvados include some more examples of using the arvados_ipc module.
103 h2(#toolkit_wrappers). Toolkit wrappers
105 The following *arvados-∗.py* modules provide "extract, build, run" helpers to make it easy to incorporate common analysis tools in your crunch scripts.
109 Build and run the "bwa":http://bio-bwa.sourceforge.net/bwa.shtml program.
111 The module retrieves the bwa source code from Keep, using the job's @bwa_tbz@ parameter.
115 arvados_bwa.run('aln', [ref_basename, '-'],
116 stdin=open(fastq_filename,'rb'),
117 stdout=open(aln_filename,'wb'))
120 On qr1hi.arvadosapi.com, the source distribution @bwa-0.7.5a.tar.bz2@ is available in the collection @8b6e2c4916133e1d859c9e812861ce13+70@.
124 "script_parameters":{
125 "bwa_tbz":"8b6e2c4916133e1d859c9e812861ce13+70",
134 Extract and run the "Genome Analysis Toolkit":http://www.broadinstitute.org/gatk/ programs.
136 The module retrieves the binary distribution tarball from Keep, using the job's @gatk_tbz@ parameter.
142 '-T', 'BaseRecalibrator',
143 '-R', ref_fasta_files[0],
144 '-I', input_bam_files[0],
149 On qr1hi.arvadosapi.com, the binary distribution @GenomeAnalysisTK-2.6-4.tar.bz2@ is available in the collection @5790482512cf6d5d6dfd50b7fd61e1d1+86@.
151 The GATK data bundle is available in the collection @d237a90bae3870b3b033aea1e99de4a9+10820@.
155 "script_parameters":{
156 "gatk_tbz":"7e0a277d6d2353678a11f56bab3b13f2+87",
157 "gatk_bundle":"d237a90bae3870b3b033aea1e99de4a9+10820",
164 h3. arvados_samtools.py
166 Build and run the "samtools":http://samtools.sourceforge.net/samtools.shtml program.
169 The module retrieves the samtools source code from Keep, using the job's @samtools_tgz@ parameter.
172 import arvados_samtools
173 arvados_samtools.run('view', ['-S', '-b', '-'],
174 stdin=open(sam_filename,'rb'),
175 stdout=open(bam_filename,'wb'))
178 On qr1hi.arvadosapi.com, the source distribution @samtools-0.1.19.tar.gz@ is available in the collection @c777e23cf13e5d5906abfdc08d84bfdb+74@.
182 "script_parameters":{
183 "samtools_tgz":"c777e23cf13e5d5906abfdc08d84bfdb+74",
191 h3. arvados_picard.py
193 Build and run the "picard":http://picard.sourceforge.net/command-line-overview.shtml program.
196 The module retrieves the picard binary distribution from Keep, using the job's @picard_zip@ parameter.
199 import arvados_picard
201 'FixMateInformation',
207 'validation_stringency': 'LENIENT',
208 'compression_level': 0
210 stdout=open('out.bam','wb'))
213 On qr1hi.arvadosapi.com, the binary distribution @picard-tools-1.82.zip@ is available in the collection @687f74675c6a0e925dec619cc2bec25f+77@.
217 "script_parameters":{
218 "picard_zip":"687f74675c6a0e925dec619cc2bec25f+77",