Useful things to know about yaml

https://www.yaml.info/learn/bestpractices.html

Indentation

YAML can use indented, or zero-indented lists (sequences), where the hyphen is at the same level of indentation as the previous line.

top_level_key:
- zero_indented_item
- another_zero_indented_item

different_top_level_key:
  - indented_list_item
  - another_indented_list_item

The creators recommend the zero-indented approach, but you can use either. It can help to view the indentation by considering the text rather than the hyphen. As ever, it’s best to stick to one convention within the same file, for reasons of clarity.

Splitting a long path

If you have a long path that you want to split over more than one line, the best approach is to use a quoted string, and use a backslash to concatenate lines without spaces e.g.

script: "<<script:/really/long/full/path/to/wherever/you/keep/your/matflow/script/\
        that/you/want/to/run/my_script.py>>"

Multi-line strings

Block scalars using the literal style (“|”) are useful for multi-line strings e.g.

environments:
- name: abaqus_env
setup: |
  source /mnt/iusers01/support/mbexegc2/scratch/Abaqus_bayesian_matflow/.venv/bin/activate
  module load apps/binapps/abaqus/2022

Null = None

In YAML, you use Null if you want to set a (python) value of None.

Checking your YAML file

If you’re struggling to understand a new error from MatFlow, it’s worth checking you’re using valid syntax in your yaml file(s) using something like https://www.yamllint.com/.