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run

Kurtosis can be used to run a Starlark script or a runnable package in an enclave.

A single Starlark script can be ran with:

kurtosis run script.star

Adding the --dry-run flag will print the changes without executing them.

A Kurtosis package on your local machine can be run with:

kurtosis run /path/to/package/on/your/machine

A Kurtosis package published to GitHub can be run like so:

kurtosis run github.com/package-author/package-repo
tip

If you want to run a non-main branch, tag or commit use the following syntax kurtosis run github.com/package-author/package-repo@tag-branch-commit

Arguments

Package behaviour can be customized by passing in JSON/YAML-serialized arguments when calling kurtosis run.

For example, if your package's run function looks like this...

def run(plan, some_parameter, some_other_parameter="Default value"):

...then you can pass in values for some_parameter and some_other_parameter like so:

kurtosis run github.com/USERNAME/REPO '{"some_parameter": 5, "some_other_parameter": "New value"}'

Kurtosis deserializes the JSON, with each key treated as a separate parameter passed to the run function in Starlark.

This is the equivalent to the following Starlark:

run(plan, some_parameter = 5, some_other_parameter = "New value")
info

By default, Kurtosis deserializes JSON objects (anything in {}) as dictionaries in Starlark. However, sometimes you need to pass a struct as a parameter instead.

To have Kurtosis deserialize a JSON object as a struct instead of a dictionary, simply add "_kurtosis_parser": "struct" to the object.

For example, this command...

kurtosis run github.com/USERNAME/REPO '{"some_parameter": {"_kurtosis_parser": "struct", "some_property": "Property value"}}'

...is equivalent to this Starlark:

run(plan, some_parameter = struct(some_property = "Property value"))

Extra Configuration

kurtosis run has additional flags that can further modify its behaviour:

  1. The --args-file flag can be used to send in a JSON/YAML file, from a local file through the filepath or from remote using the URL, as an argument to the Kurtosis Package. Note that if you pass in package arguments as CLI arguments and via the flag, the CLI arguments will be the one used. For example:

    kurtosis run github.com/kurtosis-tech/ethereum-package --args-file "devnet-5.json"

    or

    kurtosis run github.com/kurtosis-tech/ethereum-package --args-file "https://www.myhost.com/devnet-5.json"
  2. The --dry-run flag can be used to print the changes proposed by the script without executing them

  3. The --parallelism flag can be used to specify to what degree of parallelism certain commands can be run. For example: if the script contains an add_services instruction and is run with --parallelism 100, up to 100 services will be run at one time.

  4. The --enclave flag can be used to instruct Kurtosis to run the script inside the specified enclave or create a new enclave (with the given enclave identifier) if one does not exist. If this flag is not used, Kurtosis will create a new enclave with an auto-generated name, and run the script or package inside it.

  5. The --verbosity flag can be used to set the verbosity of the command output. The options include BRIEF, DETAILED, or EXECUTABLE. If unset, this flag defaults to BRIEF for a concise and explicit output. Use DETAILED to display the exhaustive list of arguments for each command. Meanwhile, EXECUTABLE will generate executable Starlark instructions.

  6. The --main-function-name flag can be used to set the name of Starlark function inside the package that kurtosis run will call. The default value is run, meaning Starlark will look for a function called run in the file defined by the --main-file flag (which defaults to main.star). Regardless of the function, Kurtosis expects the main function to have a parameter called plan into which Kurtosis will inject the Kurtosis plan.

    For example:

    To run the start_node function in a main.star file, simple use:

    kurtosis run main.star --main-function-name start_node

    Where start_node is a function defined in main.star like so:

    # --------------- main.star --------------------
    def start_node(plan, args):
    # your code
  7. The --main-file flag sets the main file in which Kurtosis looks for the main function defined via the --main-function-name flag. This can be thought of as the entrypoint file. This flag takes a filepath relative to the package's root, and defaults to main.star. For example, if your package is github.com/my-org/my-package but your main file is located in subdirectories like github.com/my-org/my-package/src/internal/my-file.star, you should set this flag like --main-file src/internal/my-file.star.

    Example of using the --main-function-name flag

    For example, to run the start_node function in a main.star file, simple use:

    kurtosis run main.star --main-function-name start_node

    Where start_node is a function defined in main.star like so:

    # main.star code
    def start_node(plan,args):
    # your code
  8. The --production flag can be used to make sure services restart in case of failure (default behavior is not restart)

  9. The --no-connect flag can be used to disable user services port forwarding (default behavior is to forward the ports)

  10. The --image-download flag can be used to determine what is the behavior to fetch images tagged as latest during the package deployment. Use missing to fetch the latest image only if not available in local cache and use always to always fetch the latest image from remote repository (default behavior is missing).

  11. The --experimental flag can be used to enable experimental or incubating features. Please reach out to Kurtosis team if you wish to try any of those.