The Configuration File - Explained

This section will detail the different sections and fields of the configuration file and how they relate to a simulation. The configuration file is designed to let the user to easily set data items used by the framework, components, tasks, and the portal from run to run. There are user specific, platform specific, and component specific entries that need to be modified or verified before running the IPS in the given configuration. After a short overview of the syntax of the package used by the framework to make sense of the configuration file, a detailed explanation of each line of the configuration file is presented.

Syntax and the ConfigObj module

ConfigObj is a Python package for reading and writing config files. The syntax is similar to shell syntax (e.g., use of $ to reference variables), uses square brackets to create named sections and nested subsections, comma-separated lists and comments indicated by a “#”.

In the example configuration file below, curly braces ({}) are used to clarify references to variables with underscores (_). Any left-hand side value can be used as a variable after it is defined. Additionally, any platform configuration value can be referenced as a variable in the configuration file as well.

Configuration File - Line by Line

Platform Configuration Override Section It is possible for the configuration file to override entries in the platform configuration file. It is rare and users should use caution when overriding these values. See Platform Configuration File - Explained for details on these values.


User Data Section

The following items are specific to the user and should be changed accordingly. They will help you to identify your runs in the portal (USER), and also store the data from your runs in particular web-enabled locations for post-processing (USER_W3_DIR on the local machine, USER_W3_BASEURL on the portal). All of the items in this section are optional.

USER_W3_DIR = /project/projectdirs/m876/www/ssfoley
USER = ssfoley                # Optional, if missing the unix username is used

Simulation Information Section These items describe this configuration and is used for describing and locating its output, information for the portal, and location of the source code of the IPS.

** Mandatory items: SIM_ROOT, SIM_NAME, LOG_FILE

RUN_ID, TOKOMAK_ID, SHOT_NUMBER - identifiers for the simulation that are helpful for SWIM users. They are often used to form a hierarchical name for the simulation, identifying related runs.

OUTPUT_PREFIX - used to prevent collisions and overwriting of different simulations using the same SIM_ROOT.

SIM_NAME - used to identify the simulation on the portal, and often to name the output tree.

LOG_FILE - name of the log file for this simulation. The framework log file is specified at the command line.

LOG_LEVEL - sets the logging level for the simulation. If empty, the framework log level is used, which defaults to WARNING. See Logging for details on the logging capabilities in the IPS. Possible values: DEBUG, INFO, WARNING, ERROR, EXCEPTION, CRITICAL.

SIM_ROOT - location of output tree. This directory will be created if it does not exist. If the directory already exists, then data files will be added, possibly overwriting existing data.

RUN_ID = Model_seq             # Identifier for this simulation run
SHOT_NUMBER = 1              # Identifier for specific case for this tokamak
                             # (should be character integer)


LOG_FILE = ${RUN_ID}_sim.log
LOG_LEVEL = DEBUG             # Default = WARNING

# Simulation root - path of the simulation directory that will be constructed
# by the framework
SIM_ROOT = /scratch/scratchdirs/ssfoley/seq_example

# Description of the simulation for the portal
SIMULATION_DESCRIPTION = sequential model simulation using generic
RUN_COMMENT = sequential model simulation using generic
TAG = sequential_model                        # for grouping related runs

Simulation Mode

This section describes the mode in which to run the simulation. All values are optional.

SIMULATION_MODE - describes whether the simulation is starting from init (NORMAL) or restarting from a checkpoint (RESTART). The default is NORMAL. For RESTART, a restart time and directory must be specified. These values are used by the driver to control how the simulation is initialized. RESTART_TIME must coincide with a checkpoint save time. RESTART_DIRECTORY may be $SIM_ROOT if there is an existing current simulation there, and the new work will be appended, such that it looks like a seamless simulation.

NODE_ALLOCATION_MODE - sets the default execution mode for tasks in this simulation. If the value is EXCLUSIVE, then tasks are assigned whole nodes. If the value is SHARED, sub-node allocation is used so tasks can shared nodes thus using the allocation more efficiently. It is the users responsibility to understand how node sharing will impact the performance of their tasks.

RESTART_TIME = 12         # time step to restart from

Plasma State Section

The locations and names of the plasma state files are specified here, along with the directory where the global plasma state files are located in the simulation tree. It is common to specify groups of plasma state files for use in the component configuration sections. These files should contain all the shared data values for the simulation so that they can be managed by the driver.

STATE_WORK_DIR = ${SIM_ROOT}/work/plasma_state

# Config variables defining simulation specific names for plasma state files
NEXT_STATE = ${SIM_NAME}_psn.cdf

# List of files that constitute the plasma state

Ports Section

The ports section identifies which ports and their associated implementations that are to be used for this simulation. The ports section is defined by [PORTS]. NAMES is a list of port names, where each needs to appear as a subsection (e.g., [[DRIVER]]). Each port definition section must contain the entry IMPLEMENTATION whose value is the name of a component definition section. These are case sensitive names and should be named such that someone familiar the components of this project has an understanding of what is being modeled. The only mandatory port is DRIVER. It should be named DRIVER, but the implementation can be anything, as long as it is defined. If no INIT port is defined, then the framework will produce a warning to that effect. There may be more port definitions than listed in NAMES.


# Required ports - DRIVER and INIT

      IMPLEMENTATION = minimal_state_init

# Physics ports


      IMPLEMENTATION = minority_model_FP




      IMPLEMENTATION = monitor_comp_4

Component Configuration Section

Component definition and configuration is done in this “section.” Each component configuration section is defined as a section (e.g., [model_RF_IC]). Each entry in the component configuration section is available to the component at runtime using that name (e.g., self.NPROC), thus these values can be used to create specific simulation cases using generic components. Variables defined within a component configuration section are local to that section, but values may be defined in terms of the simulation values defined above (e.g., STATE_FILES).

** Mandatory entries: SCRIPT, NAME, BIN_PATH, INPUT_DIR

CLASS - commonly this is the port name or the first directory name in the path to the component implementation in ips/components/.

SUB_CLASS - commonly this is the name of the code or method used to model this port, or the second directory name in the path to the component implementation in ips/components/.

NAME - name of the class in the Python script that implements this component.

MODULE - module name to use instead of script e.g. package.component, see Create a component package for an example.

NPROC - number of processes on which to launch tasks.

BIN_PATH - path to script and any other helper scripts and binaries. This is used by the framework and component to find and execute helper scripts and binaries.

BINARY - the binary to launch as a task. Typically, these binaries are found in the

PHYS_BIN or some subdirectory therein. Otherwise, you can make your own variable and put the directory where the binary is located there.

INPUT_DIR - directory where the input files (listed below) are found. This is used during initialization to copy the input files to the work directory of the component.

INPUT_FILES - list of files (relative to INPUT_DIR) that need to be copied to the component work directory on initialization. OUTPUT_FILES - list of output files that are produced that need to be protected and archived on a call to services.ServicesProxy.stage_output_files().

STATE_FILES - list of plasma state files used and modified by this component. If not present, then the files specified in the simulation entry STATE_FILES is used.

RESTART_FILES - list of files that need to be archived as the checkpoint of this component.

NODE_ALLOCATION_MODE - sets the default execution mode for tasks in this component. If the value is EXCLUSIVE, then tasks are assigned whole nodes. If the value is SHARED, sub-node allocation is used so tasks can share nodes thus using the allocation more efficiently. If no value or entry is present, the simulation value for NODE_ALLOCATION_MODE is used. It is the users responsibility to understand how node sharing will impact the performance of their tasks. This can be overridden using the whole_nodes and whole_sockets arguments to services.ServicesProxy.launch_task().

Additional values that are specific to the component may be added as needed, for example certain data values like PPN, paths to and names of other executables used by the component or alternate NPROC values are examples. It is the responsibility of the component writer to make sure users know what values are required by the component and what the valid values are for each.

    CLASS = epa
    SUB_CLASS = model_epa
    NAME = model_EPA
    NPROC = 1
    BIN_PATH = /path/to/bin
    INPUT_DIR = ${DATA_TREE_ROOT}/model_epa/ITER/hy040510/t20.0
        INPUT_STATE_FILE = hy040510_002_ps_epa__tsc_4_20.000.cdf
        INPUT_EQDSK_FILE = hy040510_002_ps_epa__tsc_4_20.000.geq
        INPUT_FILES = model_epa_input.nml ${INPUT_STATE_FILE} ${INPUT_EQDSK_FILE}
        OUTPUT_FILES = internal_state_data.nml
        RESTART_FILES = ${INPUT_FILES} internal_state_data.nml

    CLASS = monitor
    NAME = monitor
    NPROC = 1
    W3_DIR = ${USER_W3_DIR}              # Note this is user specific
    W3_BASEURL = ${USER_W3_BASEURL}      # Note this is user specific
    TEMPLATE_FILE= basic_time_traces.xml
    BIN_PATH = /path/to/bin
    INPUT_DIR = /path/to/components/monitor/monitor_4
    INPUT_FILES = basic_time_traces.xml
    RESTART_FILES = ${INPUT_FILES} monitor_restart

Checkpoint Section

This section describes when checkpoints should be taken by the simulation. Drivers should be written such that at the end of each step there is a call to services.ServicesProxy.checkpoint_components(). This way the services use the settings in this section to either take a checkpoint or not.

Selectively checkpoint components in comp_id_list based on the configuration section CHECKPOINT. If Force is True, the checkpoint will be taken even if the conditions for taking the checkpoint are not met. If Protect is True, then the data from the checkpoint is protected from clean up. Force and Protect are optional and default to False.

The CHECKPOINT_MODE option controls determines if the components checkpoint methods are invoked. Possible MODE options are:


checkpoints are saved upon invocation of the service call checkpoint_components(), when a time interval greater than, or equal to, the value of the configuration parameter WALLTIME_INTERVAL had passed since the last checkpoint. A checkpoint is assumed to have happened (but not actually stored) when the simulation starts. Calls to checkpoint_components() before WALLTIME_INTERVAL seconds have passed since the last successful checkpoint result in a NOOP.


checkpoints are saved when the simulation wall clock time exceeds one of the (ordered) list of time values (in seconds) specified in the variable WALLTIME_VALUES. Let [t_0, t_1, …, t_n] be the list of wall clock time values specified in the configuration parameter WALLTIME_VALUES. Then checkpoint(T) = True if T >= t_j, for some j in [0,n] and there is no other time T_1, with T > T_1 >= T_j such that checkpoint(T_1) = True. If the test fails, the call results in a NOOP.


checkpoints are saved at regularly spaced “physics time” intervals, specified in the configuration parameter PHYSTIME_INTERVAL. Let PHYSTIME_INTERVAL = PTI, and the physics time stamp argument in the call to checkpoint_components() be pts_i, with i = 0, 1, 2, … Then checkpoint(pts_i) = True if pts_i >= n PTI , for some n in 1, 2, 3, … and pts_i - pts_prev >= PTI, where checkpoint(pts_prev) = True and pts_prev = max (pts_0, pts_1, ..pts_i-1). If the test fails, the call results in a NOOP.


checkpoints are saved when the physics time equals or exceeds one of the (ordered) list of physics time values (in seconds) specified in the variable PHYSTIME_VALUES. Let [pt_0, pt_1, …, pt_n] be the list of physics time values specified in the configuration parameter PHYSTIME_VALUES. Then checkpoint(pt) = True if pt >= pt_j, for some j in [0,n] and there is no other physics time pt_k, with pt > pt_k >= pt_j such that checkpoint(pt_k) = True. If the test fails, the call results in a NOOP.

The configuration parameter NUM_CHECKPOINT controls how many checkpoints to keep on disk. Checkpoints are deleted in a FIFO manner, based on their creation time. Possible values of NUM_CHECKPOINT are:

  • NUM_CHECKPOINT = n, with n > 0 –> Keep the most recent n checkpoints

  • NUM_CHECKPOINT = 0 –> No checkpoints are made/kept (except when Force = True)

  • NUM_CHECKPOINT < 0 –> Keep ALL checkpoints

Checkpoints are saved in the directory ${SIM_ROOT}/restart


Time Loop Section

The time loop specifies how time progresses for the simulation in the driver. It is not required by the framework, but may be required by the driver. Most simulations use the time loop section to specify the number and frequency of time steps for the simulation as opposed to hard coding it into the driver. It is a helpful tool to control the runtime of each step and the overall simulation. It can also be helpful when looking at a small portion of time in the simulation for debugging purposes.

MODE - defines the following entries. If mode is REGULARSTART, FINISH and NSTEP are used to generate a list of times of length NSTEP starting at START and ending at FINISH. If mode is EXPLICITVALUES contains the (whitespace separated) list of times that are are to be modeled.

    START = 0.0
    FINISH = 20.0
    NSTEP = 5