ExecRecipe

The ExecRecipe can be used to run the command on the service (see exec or wait)

exec_recipe = ExecRecipe(
    # The actual command to execute. 
    # Each item corresponds to one shell argument, so ["echo", "Hello world"] behaves as if you ran "echo 'Hello World'" in the shell.
    # MANDATORY
    command = ["echo", "Hello, World"],
        
    # The extract dictionary can be used for filtering specific parts of a response
    # assigning that output to a key-value pair, where the key is the reference 
    # variable and the value is the specific output. 
    # 
    # Specifically: the key is the way you refer to the extraction later on and
    # the value is a 'jq' string that contains logic to extract parts from response 
    # body that you get from the exec_recipe used
    # 
    # To lean more about jq, please visit https://devdocs.io/jq/
    # OPTIONAL (DEFAULT:{})
    extract = {
        "extractfield" : ".name.id",
    },
)

tip

If you are trying to run a complex command with |, you should prefix the command with /bin/sh -c and wrap the actual command in a string; for example: command = ["echo", "a", "|", "grep a"] should be rewritten as command = ["/bin/sh", "-c", "echo a | grep a"]. Not doing so makes everything after the echo as args of that command, instead of following the behavior you would expect from a shell.

tip

If the executed command returns a proper JSON formatted data structure, it's necessary to pass the output through jq's fromjson function to enable jq to parse the input. For more information on jq's built-in methods, plese refer to jq's documentation. The following is an example of how to parse the json formatted output using jq syntax:

Example:

def run(plan, args={}):
    plan.add_service(
        name = "service",
        config = ServiceConfig(
            image = "alpine",
            entrypoint = ["/bin/sh", "-c", "sleep infinity"],
        )
    )
    cmd = ''' echo '{"key": "value"}' '''
    result = plan.exec(
        service_name = "service",
        recipe = ExecRecipe(
            command = ["/bin/sh", "-c", cmd],
            extract = {
                "example_reference_key": "fromjson | .key"   # <----- Notice the use of `fromjson`
            }
        ),
    )
    plan.print(result["output"])
    plan.print(result["extract.example_reference_key"])

will output:

> print msg="{{kurtosis:1f60460f3eee4036af01b41fc2ecddc0:output.runtime_value}}"
{"key": "value"}


> print msg="{{kurtosis:1f60460f3eee4036af01b41fc2ecddc0:extract.example_reference_key.runtime_value}}"
value