Workflows on demand!

For the impatient

Dependencies

• Python
• Singularity
• Git (to setup existing modules)
• Snakemake (to setup existing modules)

Setup

#!/bin/bash
pip install limes-x

git clone https://github.com/hallamlab/Limes-compute-modules.git
python ./Limes-compute-module/setup_modules.py ./lx_ref

Run

#!/bin/python3.10
import limes_x as lx

modules = lx.LoadComputeModules("./Limes-compute-modules/metagenomics")
wf = lx.Workflow(
    compute_modules=modules,
    reference_folder="./lx_ref",
)

wf.Run(
    workspace="./test_workspace",
    targets=[
        Item('metagenomic gzipped reads'),
        Item('metagenomic assembly'),
        Item("metagenomic bin"),
        Item("checkm stats"),
        Item('bin taxonomy table'),
        Item('assembly taxonomy table'),
        Item('genomic annotation'),
    ],
    given=[
        lx.InputGroup(  
            group_by=(Item("sra accession"), "SRR19573024"), 
            children={Item("username"): "Steven"}, # use "whoami" in bash
        )
    ],
    executor=lx.Executor(),
)

Dependencies

• Anaconda (optional, but recommended)
  • faster version (Mamba); Use "mamba" instead of "conda" below
  • plain Anaconda
• Python

  • NOTE: Most compute servers and linux distributions will have python installed already

  • install with Anaconda
    • conda create -n test_env python=3.10
    • feel free to pick a better name than "test_env"
• Singularity

  • NOTE: Most compute servers will have singularity installed already

  • install with Anaconda
    • activate the conda environment: conda activate test_env
    • conda install singularity
  • manual install
• Git
  • you may already have git
    • use git --version in the console to find out
  • otherwise, here's a tutorial

Setup

NOTE: We are working on a conda package. Meanwhile, this will work in a conda environment with python installed.

pip install limes-x

Running workflows

Compute Modules

Limes-x encapsulates the complexity of workflows by surfacing a declarative syntax that allows you to focus on what you want and worry less about how to achieve it. This is made possible by compute modules that provide conversions between datatypes such as changing the format of an image or assembling a metagenome from Illumina sequences.

Limes-x finds the set of compute modules required to convert the given inputs to the desired inputs. This set of modules is then joined together into an execution-ready workflow.

A list of available compute modules can be found at this repo
Use the setup_modules script to install each module's dependencies and reference databases using Singularity and Snakemake.

git clone https://github.com/hallamlab/Limes-compute-modules.git
python ./Limes-compute-module/setup_modules.py ./lx_ref

Minimal execution example

Create a workflow with the compute modules found in ./Limes-compute-modules/metagenomics

#!/bin/python3.10
import limes_x as lx

modules = lx.LoadComputeModules("./Limes-compute-modules/metagenomics")
wf = lx.Workflow(
    compute_modules=modules,
    reference_folder="./lx_ref",
)

Run the workflow by indicating the desired data products and giving an SRA accession string as the input. A sequence read archive (SRA) accession points to DNA sequnces hosted by the National Center for Biotechnology Information.

NOTE: While multiple InputGroups can be provided, each must have identical formats (same Items). This is a bug.

wf.Run(
    workspace="./test_workspace",
    targets=[
        Item('metagenomic gzipped reads'),
        Item('metagenomic assembly'),
        Item("metagenomic bin"),
        Item("checkm stats"),
        Item('bin taxonomy table'),
        Item('assembly taxonomy table'),
        Item('genomic annotation'),
    ],
    given=[
        lx.InputGroup(  
            group_by=(Item("sra accession"), "SRR19573024"), 
            children={Item("username"): "Steven"},
        )
    ],
    executor=lx.Executor(),
)

Workspace format:

├── ./test_workspace
    ├── comms.json
    ├── comms.lock
    ├── limesx_src.tgz
    ├── input_paths.tsv
    ├── workflow_state.json

    ├── <module name>--######
        ├── context.json
        ├── result.json
        ├── <module ouputs>

    ├── inputs
        ├── <soft links to each input file/folder>
        
    ├── outputs
        ├── <data type (Item)>
            ├── <each instance of Item produced>

Different execution environments

The default executor will run modules locally.

wf.Run(
    ...
    executor=lx.Executor(),
)

We can use the HpcExecutor to interface with high performance compute clusters (HPC) by specifying how to interact with the cluster's scheduler. Here, we write the callback function, schedule_job, which will be called when a compute module needs to be executed on the cluster. The executor will pass in a job object to our function that provides a shell, the run_command to execute the compute module.

from limes_x import Job

def schedule_job(job: Job) -> tuple[bool, str]:
    return job.Shell(f"""\
        <schedule a job with the following command>
        {job.run_command}
    """)

ex = lx.HpcExecutor(
    hpc_procedure=schedule_job,
    tmp_dir_name="TMP"
)
wf.Run(
    ...
    executor=ex,
)

tmp_dir_name is the environment variable that stores the path to the temporary directory on the worker node. The HpcExecutor will transfer all required files/folders there before running the job.

Below is an example with slurm, the scheduler used by the Digital Alliance of Canada's Cedar cluster.

def get_res(job: str, manifest: dict, cores, mem):
    _cores, _hrs, _mem = {
        "download_sra":             lambda: (cores, 4,  mem),
        "extract_mg-reads":         lambda: (cores, 4,  mem),
        "metagenomic_assembly":     lambda: (cores, 12, mem),
        "metagenomic_binning":      lambda: (cores, 24, mem),
        "taxonomy_bin":             lambda: (cores, 4,  mem),
        "taxonomy_assembly":        lambda: (cores, 4,  mem),
        "checkm_on_bin":            lambda: (cores, 1,  mem),
        "annotation_metapathways":  lambda: (cores, 8,  mem),
    }.get(job, lambda: (cores, 4, mem))()
    return (_cores, _hrs, _mem)

def slurm(job: lx.Job) -> tuple[bool, str]:
    p = job.context.params
    time.sleep(2*random.random())
    job_name = job.instance.step.name
    job_id = job.instance.GetID()
    cores, hrs, mem = get_res(
        job_name,
        job.context.manifest,
        p.threads,
        p.mem_gb
    )
    return job.Shell(f"""\
        sbatch --wait --account={ALLOC} \
            --job-name="lx-{job_name}:{job_id}" \
            --nodes=1 --ntasks=1 \
            --cpus-per-task={cores} --mem={mem}G --time={hrs}:00:00 \
            --wrap="{job.run_command}"\
    """)

ex = lx.HpcExecutor(
    hpc_procedure=slurm,
    tmp_dir_name="SLURM_TMPDIR"
)
wf.Run(
    ...
    executor=ex,
)

Making new modules

First, use Limes to generate a template in the folder where you want to keep all of your compute modules.

import limes_x as lx

lx.ModuleBuilder.GenerateTemplate(
    modules_folder = "./compute_modules",
    name = "a descriptive name",
)

├── ./compute_modules
    ├── <module name>
        ├── lib
            ├── definition.py
        ├── setup
            ├── setup.smk

    ├── <module name>
        ├── lib
        ├── setup
    .
    .
    .

The setup folder contains the snakemake workflow required to install the module. The lib folder must contain (or link to) all scripts required by the compute module. Limes will invoke the module by loading definition.py and looking for a MODULE variable that holds the compute module.

# template definition.py
from pathlib import Path
from limes_x import ModuleBuilder, Item, JobContext, JobResult

A = Item('a')
B = Item('b')

DEPENDENCY = "image.sif"

def procedure(context: JobContext) -> JobResult:
    input_path = context.manifest[A]
    output_path = context.output_folder.joinpath('copied_file')
    context.shell(f"cp {input_path} {output_path}")
    return JobResult(
        manifest = {
            B: Path(output_path)
        },
    )

MODULE = ModuleBuilder()\
    .SetProcedure(procedure)\
    .AddInput(A, groupby=None)\
    .PromiseOutput(B)\
    .Requires({DEPENDENCY})\
    .SuggestedResources(threads=1, memory_gb=4)\
    .SetHome(__file__, name=None)\
    .Build()

For some examples, take a look at this repo.