Debugging

Hydra provides a few options to improve debuggability.

Printing the configuration

Print the config for your app without running your function by adding --cfg or -c to the command line.

The --cfg option takes one argument indicating which part of the config to print:

• job: Your config
• hydra: Hydra's config
• all: The full config, which is a union of job and hydra.

# A normal run:
$ python my_app.py
MySQL connecting to localhost with user=root and password=1234

# just show the config without running your function:
$ python my_app.py --cfg job
db:
  host: localhost
  user: root
  password: 1234

The printed config includes any modifications done via the command line:

$ python my_app.py db.host=10.0.0.1 --cfg job
db:
  host: 10.0.0.1
  user: root
  password: 1234

You can use --package or -p to display a subset of the configuration:

python my_app.py --cfg hydra --package hydra.job
# @package hydra.job
name: my_app
config_name: config
...

By default, config interpolations are not resolved. To print resolved config use the --resolve flag in addition to the --cfg flag

Info

The --info flag can provide information about various aspects of Hydra and your application:

• --info all: Default behavior, prints everything
• --info config: Prints information useful to understanding the config composition:
  Config Search Path, Defaults Tree, Defaults List and the final config.
• --info defaults: Prints the Final Defaults List
• --info defaults-tree: Prints the Defaults Tree
• --info plugins: Prints information about installed plugins