Composing tasks

Composing tasks into sequences

You can compose tasks into a new task that runs them in order by declaring a sequence task.

For example:

[tool.poe.tasks]

_publish = "poetry publish"
release = [
  { cmd = "pytest --cov=src" },
  { script = "devtasks:build" },
  { ref = "_publish" },
]

And here’s an example that uses the sequence task type explicitly in a task definition:

[tool.poe.tasks._publish]
cmd = "poetry publish"

[tool.poe.tasks.release]
sequence = [
  { cmd = "pytest --cov=src" },
  { script = "devtasks:build" },
  { ref = "_publish" }
]

See also

See sequence tasks specifics for more information on the sequence task type.

Composing tasks into graphs

You can define tasks that depend on other tasks, and optionally capture and reuse the output of those tasks, thus defining an execution graph of tasks. This is done by using the deps task option, or if you want to capture the output of the upstream task to pass it to the present task then specify the uses option, as demonstrated below.

[tool.poe.tasks]
_website_bucket_name.shell = """
  aws cloudformation describe-stacks \
    --stack-name $AWS_SAM_STACK_NAME \
    --query "Stacks[0].Outputs[?(@.OutputKey == 'FrontendS3Bucket')].OutputValue" \
  | jq -cr 'select(0)[0]'
"""

[tool.poe.tasks.build-backend]
help = "Build the backend"
sequence = [
  {cmd = "poetry export -f requirements.txt --output src/requirements.txt"},
  {cmd = "sam build"},
]

[tool.poe.tasks.build-frontend]
help = "Build the frontend"
cmd = "npm --prefix client run build"

[tool.poe.tasks.shipit]
help = "Build and deploy the app"
sequence = [
  "sam deploy --config-env $SAM_ENV_NAME",
  "aws s3 sync --delete ./client/build s3://${BUCKET_NAME}"
]
default_item_type = "cmd"
deps = ["build-frontend", "build-backend"]
uses = { BUCKET_NAME = "_website_bucket_name" }

In this example the shipit task depends on the build-frontend build-backend, which means that these tasks get executed before the shipit task. It also declares that it uses the output of the hidden _website_bucket_name task, which means that this also gets executed, but its output it captured and then made available to the shipit task as the environment variable BUCKET_NAME.

Important

Note that captured output that is exposed as an environment variable via the uses is compacted to have new lines removed. This is similar to how interpolated command output is treated by bash.