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Pipestat

Starting with version 1.4.0, looper supports additional functionality for pipestat-compatible pipelines. Pipestat-compatible pipelines will allow you to use looper to do 2 things:

  1. monitor the status of pipeline runs
  2. summarize the results of pipelines

For non-pipestat-compatible pipelines, you can still use looper to run pipelines, but you won't be able to use looper report or looper check to manage their output.

Pipestat configuration overview

Starting with version 1.6.0 configuring looper to work with pipestat has changed.

Now, Looper will obtain pipestat configurations data from two sources: 1. pipeline interface 2. looper_config file

Looper will combine the necessary configuration data and write a new pipestat configuration for each pipeline interface.

Briefly, the Looper config file must contain a pipestat field. A project name must be supplied if running a project level pipeline. The user must also supply a file path for a results file if using a local file backend or database credentials if using a postgresql database backend. 

pep_config: project_config_pipestat.yaml # pephub registry path or local path
output_dir: output
sample_table: annotation_sheet.csv
pipeline_interfaces:
  sample:  ./pipeline_interface1_sample_pipestat.yaml
  project: ./pipeline_interface1_project_pipestat.yaml
pipestat:
  project_name: TEST_PROJECT_NAME
  results_file_path: tmp_pipestat_results.yaml
  flag_file_dir: output/results_pipeline
  database:
    dialect: postgresql
    driver: psycopg2
    name: pipestat-test
    user: postgres
    password: pipestat-password
    host: 127.0.0.1
    port: 5432
And the pipeline interface must include information required by pipestat such as pipeline_name, pipeline_type, and an output schema path: 
pipeline_name: example_pipestat_pipeline
pipeline_type: sample
output_schema: pipeline_pipestat/pipestat_output_schema.yaml
command_template: >
  python {looper.piface_dir}/count_lines.py {sample.file} {sample.sample_name} {pipestat.results_file}

Pipestat Configuration for Looper Versions 1.4.0-1.5.0

Note: The instructions below are for older versions of Looper.

Generally, pipestat configuration comes from 3 sources, with the following priority:

  1. PipestatManager constructor
  2. Pipestat configuration file
  3. Environment variables

In looper, only 1 and 2 are available, and can be specified via the project or sample attributes. Pipestat environment variables are intentionally not supported to ensure looper runs are reproducible -- otherwise, jobs configured in one computing environment could lead to totally different configuration and errors in other environments.

Usage

The PipestatManager constructor attributes mentioned in the previous section are sourced from either sample attributes (for looper run) or project attributes ( forlooper runp). One of the attributes can be used to specify the pipestat configuration file, which is the other way of configuring pipestat.

The names of the attributes can be adjusted in the PEP configuration file. Let's take a pipestat namespace as an example: by default the value for the namespace is taken from Sample.sample_name but can be changed with looper.pipestat.sample.namespace_attribute in the PEP configuration file, like so:

looper:
  pipestat:
    sample:
      namespace_attribute: custom_attribute

Now the value for the pipestat namespace will be sourced from Sample.custom_attribute rather than Sample.sample_name.

Similarly, a project-level pipestat namespace can be configured with looper.pipestat.project.namespace_attribute:

looper:
  pipestat:
    project:
      namespace_attribute: custom_attribute

Now the value for the pipestat namespace will be sourced from Project.custom_attribute rather than Project.name.

Naturally, this configuration procedure can be applied to other pipestat options. The only exception is pipestat results schema, which is never specified here, since it's sourced from the output_schema attribute of the pipeline interface.

looper:
  pipestat:
    sample:
      results_file_attribute: pipestat_results_file
      config_attribute: pipestat_config
      namespace_attribute: sample_name
    project:
      results_file_attribute: pipestat_results_file
      config_attribute: pipestat_config
      namespace_attribute: name

Again, the values above are defaults -- not needed, but configurable.

Examples

To make the pipestat configuration rules more clear let's consider the following pipestat configuration setups.

Example 1: All configuration as sample attributes

In this case the pipestat configuration options are sourced only from the sample attributes. Namely, pipestat_results_file and custom_namespace.

PEP config

pep_version: 2.0.0
sample_table: sample_table.csv
sample_modifiers:
  append:
    pipestat_results_file: $HOME/my_results_file.yaml
  derive:
    attributes: [custom_namespace]
    sources:
      namespace: "{sample_name}_pipelineX"
looper:
  pipestat:
    sample:
      namespace_attribute: "custom_namespace"

PEP sample table (sample_table.csv)

sample_name,custom_namespace
sample1,namespace

Example 2: A mix of pipestat configuration sources

In this case the pipestat configuration options are sourced from both sample attributes and pipestat configuration file.

Looper sourced the value for pipestat namespace from Sample.sample_name and database login credentials from the pipestat configuration file.

PEP config

pep_version: 2.0.0
sample_table: sample_table.csv
sample_modifiers:
  append:
    pipestat_config: pipestat_config.yaml

PEP sample table (sample_table.csv)

sample_name
sample1

Pipestat configuration file (pipestat_config.yaml)

database:
  name: database_name
  user: user_name
  password: user_password
  host: localhost
  port: 5432
  dialect: postgresql
  driver: psycopg2