Skip to main content

ServiceConfig

The ServiceConfig is used to configure a service when it is added to an enclave (see add_service).

config = ServiceConfig(
    # The name of the container image that Kurtosis will use to create and start the service's container.
    # This image can be pulled from a remote container registry, picked up from the local cache, or built by Kurtosis using
    # the underlying container engine.
    # If a string is provided, Kurtosis will by default detect if images exists locally, or pull from container registry if not.
    # The string form is syntactic sugar for ImageSpec with only image set
    # ImageSpec referring to private registries limited to Docker
    # Reach out to the team if you want to run Kurtosis with private images on Kubernetes
    # If an ImageBuildSpec is provided, Kurtosis will build the image.
    # MANDATORY
    image = "kurtosistech/example-datastore-server",

    OR

    image = ImageSpec(
        #  The name of the image that needs to be pulled qualified with the registry
        # MANDATORY
        image = "my.registry.io/my-user/my-image",

        # The username that will be used to pull the image from the given registry
        # OPTIONAL
        username = "my-user",

        # The password that will be used to pull the image from the given registry
        # OPTIONAL
        password = "password",

        # The URL of the registry
        # OPTIONAL
        registry = "http://my.registry.io/"
    )

    OR

    image = ImageBuildSpec(
        # Name to give built image
        # MANDATORY
        image_name="kurtosistech/example-datastore-server"

        # Locator to build context within the Kurtosis package
        # As of now, Kurtosis expects a Dockerfile at the root of the build context
        # MANDATORY
        build_context_dir="./server"

        # Name of the build file
        # The default value is "Dockerfile"
        # OPTIONAL
        build_file=""

        # Stage of image build to target for multi-stage container image
        # OPTIONAL
        target_stage=""

        # Arguments passed at build-time
        # OPTIONAL (Default: {})
        build_args={
            "BUILD_ARG_1": "VALUE_1",
            "BUILD_ARG_2": "VALUE_2",
        }
    )

    OR

    image = NixBuildSpec(
        #  The name of the container image that should be used
        # MANDATORY
        image_name = "hello-world-server",

        # Locator to build context within the Kurtosis package
        # This allows to select a sub-package where the context is going be used to build the image
        # MANDATORY
        build_context_dir = "./"

        #  The relative path (from the `build_context_dir`) to the folder containing the flake.nix file
        # MANDATORY
        flake_location_dir = "./hello-go",

        #  The selector for the Flake output with the image derivation. Fallbacks to the default package.
        flake_output = "containerImage",
    )

    # The ports that the container should listen on, identified by a user-friendly ID that can be used to select the port again in the future.
    # Kurtosis will automatically perform a check to ensure all declared UDP and TCP ports are open and ready for traffic and connections upon startup.
    # You may specify a custom wait timeout duration or disable the feature entirely, learn more via PortSpec docs
    # If no ports are provided, no ports will be exposed on the host machine, unless there is an EXPOSE in the Dockerfile.
    # OPTIONAL (Default: {})
    ports = {
        "grpc": PortSpec(
            # The port number which we want to expose
            # MANDATORY
            number = 3000,

            # Transport protocol for the port (can be either "TCP" or "UDP")
            # Optional (DEFAULT:"TCP")
            transport_protocol = "TCP",

            # Application protocol for the port
            # Optional
            application_protocol = "http",

            # Kurtosis will automatically perform a check to ensure all declared UDP and TCP ports are open and ready for traffic and connections upon startup.
            # You may specify a custom wait timeout duration or disable the feature entirely.
            # You may specify a custom wait timeout duration with a string:
            #  wait = "2m"
            # Or, you can disable this feature by setting the value to None:
            #  wait = None
            # The feature is enabled by default with a default timeout of 15s
            # OPTIONAL (DEFAULT:"15s")
            wait = "4s"
        ),
    },
    
    # The deterministic public ports that Kurtosis will expose from the container to the machine
    # This only applies to Docker; the port ids here must be a subset of `ports`
    # If no ports are provided; normal ports behavior will happen and the exposed ports will be randomly allocated
    # This doesn't work on Kubernetes!!!
    # OPTIONAL (Default: {})
    public_ports = {
        "grpc": PortSpec(
            # The port number which we want to expose
            # MANDATORY
            number = 3000,

            # Transport protocol for the port (can be either "TCP" or "UDP")
            # Optional (DEFAULT:"TCP")
            transport_protocol = "TCP",

            # Application protocol for the port
            # Optional
            application_protocol = "http"
        )
    },

    # A mapping of path_on_container_where_contents_will_be_mounted -> Directory object or file artifact name
    # For more info on what a Directory object is, see below
    #
    # OPTIONAL (Default: {})
    files = {
        "path/to/files/artifact_1/": files_artifact_1,
        "path/to/files/artifact_2/": Directory(
            artifact_names=[files_artifact_2],
        ),
        "path/to/persistent/directory/": Directory(
            persistent_key="data-directory",
        ),
    },

    # The ENTRYPOINT statement hardcoded in a container image's Dockerfile might not be suitable for your needs.
    # This field allows you to override the ENTRYPOINT when the container starts.
    # OPTIONAL (Default: [])
    entrypoint = [
        "bash",
    ],

    # The CMD statement hardcoded in a container image's Dockerfile might not be suitable for your needs.
    # This field allows you to override the CMD when the container starts.
    # OPTIONAL (Default: [])
    cmd = [
        "-c",
        "sleep 99",
    ],

    # Defines environment variables that should be set inside the Docker container running the service.
    # This can be necessary for starting containers from Docker images you don’t control, as they’ll often be parameterized with environment variables.
    # OPTIONAL (Default: {})
    env_vars = {
        "VAR_1": "VALUE_1",
        "VAR_2": "VALUE_2",
    },

    # ENTRYPOINT, CMD, and ENV variables sometimes need to refer to the container's own IP address.
    # If this placeholder string is referenced inside the 'entrypoint', 'cmd', or 'env_vars' properties, the Kurtosis engine will replace it at launch time
    # with the container's actual IP address.
    # OPTIONAL (Default: "KURTOSIS_IP_ADDR_PLACEHOLDER")
    private_ip_address_placeholder = "KURTOSIS_IP_ADDRESS_PLACEHOLDER",

    # The maximum amount of CPUs the service can use, in millicpu/millicore.
    # OPTIONAL (Default: no limit)
    max_cpu = 1000,

    # The minimum amout of CPUs the service must have, in millicpu/millicore.
    # CAUTION: This is only available for Kubernetes, and will be ignored for Docker.
    # OPTIONAL (Default: no limit)
    min_cpu = 500,

    # The maximum amount of memory, in megabytes, the service can use.
    # OPTIONAL (Default: no limit)
    max_memory = 1024,

    # The minimum amount of memory, in megabytes, the service must have.
    # CAUTION: This is only available for Kubernetes, and will be ignored for Docker.
    # OPTIONAL (Default: no limit)
    min_memory = 512,

    # This field can be used to check the service's readiness after the service has started,
    # to confirm that it is ready to receive connections and traffic
    # OPTIONAL (Default: no ready conditions)
    ready_conditions = ReadyCondition(...),

    # This field is used to specify custom labels at the container level in Docker and Pod level in Kubernetes.
    # For Docker, the label syntax and format will follow: "com.kurtosistech.custom.key": "value"
    # For Kubernetes, the label syntax & format will follow: kurtosistech.com.custom/key=value

    # Labels must follow the label standards outlined in [RFC-1035](https://datatracker.ietf.org/doc/html/rfc1035),
    # meaning that both the label key and label value must contain at most 63 characters, contain only lowercase
    # alphanumeric characters, dashes (-), underscores (_) or dots (.), start with an alphabetic character, and end with an alphanumeric character.
    # Empty value and capital letters are valid on label values.
    # OPTIONAL
    labels = {
        "key": "value",
        # Examples
        "name": "alice",
    }

    # The user id and group id to start the container with
    # Some containers are configured to start with users other than root by default; this allows you to override to root or other
    # users if you choose to.
    # Note that the `gid` field is optional
    # OPTIONAL
    user = User(uid=0, gid=0),

    # An array of Toleration
    # This refers to Kubernetes Tolerations https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/
    # This has no effect on Docker
    # As of 2024-01-24 Taints and Tolerations to work with Kubernetes you need at least one untainted node
    # Refer to the Toleration docs linked near the end of the page to learn more
    # OPTIONAL
    tolerations = [
        Toleration(
            key = "test-key",
            value = "test-value",
            operator = "Equal",
            effect = "NoSchedule",
            toleration_seconds = 64,
        )
    ],

    # A map of node selectors
    # This refers to Node Selectors in Kubernetes https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#nodeselector
    # This has no effect on Docker
    # This is an experimental feature that might get replaced with a better abstraction suited for Kurtosis
    # OPTIONAL
    node_selectors = {
        "disktype": "ssd",
    },
    
    # The tini_enabled field allows you to set the `--init` options when a container is started in Docker.
    # OPTIONAL
    # Default (true)
    tini_enabled = True
)

Note that ImageBuildSpec can only be used in packages and not standalone scripts as it relies on build context in package. More info on ImageBuildSpec here. More info can be found on locators referring to local resources here and how to turn your script into a Kurtosis package here.

The ports dictionary argument accepts a key value pair, where key is a user defined unique port identifier and value is a PortSpec object.

The files dictionary argument accepts a key value pair, where key is the path where the contents of the artifact will be mounted to and value is a Directory object or files artifact name. Using a Directory object with artifact_name is strictly equivalent to directly using the files artifact name as the value of the dictionary. This is just to simplify usage.

See NixBuildSpec for more information on how to use the Nix and Kurtosis together.

You can view more information on configuring the ReadyCondition type here.

tip

If you are trying to use a more complex versions of cmd and are running into issues, we recommend using cmd in combination with entrypoint. You can set the entrypoint to ["/bin/sh", "-c"] and then set the cmd to the command as you would type it in your shell. For example, cmd = ["echo foo | grep foo"]

Example of a rendered label

If you have defined the pod label key:value pair in ServiceConfig to be:

config = ServiceConfig(
    ...
    labels = {
        "name": "alice",
    "age": "20",
    "height": "175"
    }
)

then the labels for the pods on Kubernetes will look like:

labels:
    kurtosistech.com.custom/name=alice
    kurtosistech.com.custom/age=20
    kurotsistech.com.custom/height=175

while on Docker, the container labels will look like:

labels:
    "com.kurtosistech.custom.name": "alice"
    "com.kurtosistech.custom.age": "20"
    "com.kurtosistech.custom.height": "175"

The user field expects a User object being passed.

The tolerations field expects a list of Toleration objects being passed.