ProcBlocks Syntax

YAML Basics:

Mind your margins. YAML syntax depends on margins to identify grouping.

# Comments: Everything right of a # is ignored.
- block: # Blocks begin the line with a hyphen and a space to denote a YAML list.
    key: "value" # Children indented deeper than the text above.
    section: # A block is broken into sections
      key: "value" # Section items require one further indent level (same size as your block indent).

- block:
  key: # invalid. must be indented more than the text above.

Important: YAML List items, denoted by a hyphen, must be indented at least 3 spaces to be recognized as children. This applies to all blocks.

For more on YAML

Blocks, Sections, and Key-value Pairs:

- block:
    key: "value" # Key-value pair
    section: # List of items
      key: "value" # Key-value pair

---

Blocks

Each block represents a "step" in the pipeline and is defined at the outermost indent.

Blocks can be one of three types:

- assign:  # Define vars, init, and overrides
    params: # Indent
      myparam: "value" # Indent 2+ more spaces

- processor: ""  # Perform image processing
    ...
- job:  # Nested job block
    ...

Standard Block Properties

Property	Required?	Description
step	No	Identifier for this block (defaults to block type name)
condition	No	Skip block if false

---

Assign Blocks

Assign blocks let you define variables, route files, and declare overrides for subsequent steps.

- assign:
    step: "prepare-assets"
    inputs:
      src: "input/photo.png" # vars.src = "input/photo.png"
      meta: "input/photo.json"
    outputs:
      src: "mem/photo.png" # copy input/photo.png → mem/photo.png
      meta: "mem/photo.json"
    vars:
      src_width: "{width:src}" # inline‐parsed metadata from the `src` image
      retries: "3"
    init:
      quality: "85" # only if `quality` not already set
    overrides:
      - key: "size"
        value: "1024"

Assign Block Properties

Property	Required?	Description
step	No	Block identifier (defaults to "assign")
condition	No	Expression to skip block if false (e.g. "True", "0")
inputs	No	key: "filepath" → sets vars[key] = filepath
outputs	No	key: "filepath" → copies inputs[key] → outputs[key]
vars	No	var: "expr" → inline‐parsed, assigned to vars[var]
init	No	Like vars, but only if not already defined
overrides	No	List of {step?, section?, key, value} scoped overrides

---

Processor Blocks

Processor blocks perform image processing and include sections for inputs, params, outputs, and optional var assignments.

- processor:
    processor: "trim"
    step: "trimmed" # Optional name; defaults to processor name.
    condition: "True" # Block is skipped if condition is false.
    inputs:
      source: "input/input.png"
    params:
      padding: "10"
      trim_color: "transparent"
    outputs:
      target: "mem/trimmed.png"
    assigns: # Optional; assigns values to variables.
      left: "trim_left"
      top: "trim_top"
      right: "trim_right"
      bottom: "trim_bottom"
      width: "trim_width"
      height: "trim_height"

Processor Block Properties

Property	Required?	Description
processor	Yes	Processor name (e.g. "trim")
step	No	Identifier (defaults to processor name)
condition	No	Skip block if false
inputs	No	Input file mappings
params	No	Processor-specific parameters
outputs	No	Output file mappings
assigns	No	Map processor results back into variables (optional)

---

Job Blocks (Nested Jobs)

Job blocks enable nesting of job definitions, allowing reuse of pipelines or job fragments as subjobs. Nested jobs inherit copies of the parent job's variables and overrides so changes in the nested context do not affect the parent.

- job:
    job: "somejob" # Specifies the external job definition.
    step: "nested" # Optional; defaults to "nestedjob" if omitted.
    condition: "True" # Block is skipped if condition is false.

Job Block Properties

Property	Required?	Description
job	Yes	Name of nested job definition
step	No	Identifier (defaults to "nestedjob")
condition	No	Skip block if false