Configuration file

The configuration file is used to store information used by the backend, the frontend, and the build system. It is a fairly standard ‘INI’ file, containing section titles in square brackets (e.g. [general]) and key-value pairs within the sections, either of the form ‘foo: bar’ or ‘foo = bar’.

The example file below defines the configuration for a fictional ‘ModFoo’ service:

socket: /modbase1/home/modfoo/modfoo.socket
service_name: ModFoo

user: modfoo
state_file: /modbase1/home/modfoo/modfoo.state
check_minutes: 10

running: 5

db: modfoo
backend_config: backend.conf
frontend_config: frontend.conf

install: /modbase1/home/modfoo/
incoming: /modbase1/home/modfoo/incoming/
preprocessing: /wynton/home/sali/modfoo/running/
completed: /modbase1/home/modfoo/completed/
failed: /modbase1/home/modfoo/failed/

archive: 7d
expire: 30d

Each section in the configuration file is described below.



The email address of the administrator of this web service. This is used to notify the admin if a job fails with a technical error or the entire web service encounters an unrecoverable error and cannot continue.


The full path to a socket file that is used for the frontend to send messages to the backend.


The name of the service (human-readable). This is used in emails to the owners of jobs and the server admin, and as the title of web pages.


The URL under which the service’s web pages live. This is used to construct URLs containing job results, for example.


If set to “True” then the hostname or IP address of each web service user is stored in the database.


For web services that are open source and are hosted on GitHub, this should be filled in with the GitHub URL.



The system user that the backend runs as. For security, robustness and easier monitoring, each web service has its own system user (e.g. the ModLoop web service runs as the ‘modloop’ system user). Note that the system user is distinct from the MySQL users set up to access the database.


The full path to a file that is used by the backend to store state between calls. In normal operation this is simply used as a lock file to ensure that only one copy of the backend is running at a time. After an unrecoverable error, this file continues information on the nature of the failure and must be manually removed by the admin before the backend will run again.


Typically, when new jobs are submitted the backend is notified and they start running immediately; once jobs are started the backend waits for them to finish and collects the results as soon as this happens. However, if a job is submitted from the frontend while the backend is not running, or the backend is restarted or the machine it is on is rebooted while jobs are running, the backend must fall back to a less efficient polling method to look for newly submitted or completed jobs. ‘check_minutes’ is the time, in minutes, to wait between checks for these jobs. An interval of 10 minutes is recommended. Note that archived and expired jobs are also checked for periodically, but this interval is fixed at 10% of the shorter of the archive and expiry times.



The maximum number of jobs that will run simultaneously. Defaults to 5.


The maximum number of tasks in each job that will run simultaneously. This is not enforced by the framework, but a service that runs a job on more than one machine can use this value to limit the parallelism. For example, services that run SGE array jobs can use this value to populate the -tc qsub parameter. Default is no limit.



The name of the database in which the service’s data are stored.

backend_config, frontend_config

Filenames of additional INI files containing the MySQL username and password used by the backend and frontend to communicate with the database (in sections called [backend_db] and [frontend_db] respectively). (The frontend and backend should use different MySQL users, since they should have different access rights set up for the job tables.) If these filenames are not absolute paths, they are taken to be relative to the directory containing the main configuration file. The database authentication information has to stored in separate files so that file permissions can be set appropriately so that the frontend cannot read the backend configuration. An example backend.conf is shown below.

user: modfoo_backend
passwd: Ra1Echoh4uim



The top-level directory in which the web service files are installed.

incoming, preprocessing, etc.

Each job state except EXPIRED can be given a directory in which the job data are placed. Only the INCOMING and PREPROCESSING directories are required; others, if not specified, will default to the directory for the previous state (i.e. the RUNNING directory will default to that for PREPROCESSING, that for POSTPROCESSING will default to RUNNING, FINALIZING to POSTPROCESSING, COMPLETED to FINALIZING, and ARCHIVED to COMPLETED). If the FAILED directory is not given, it will default to the same as the COMPLETED directory.


This section controls what happens to old jobs after they have completed.


Completed job results, after this time, will no longer be available for the end user to download from the frontend. The time is either NEVER to indicate that job results are available forever, or a number with a single character suffix (h for hours, d for days, w for weeks, m for months or y for years). For example, ‘90d’ will archive job results after 90 days.


Completed job results will be deleted from disk after this time. Times are specified in the same way as for archive. Note that the archive time cannot be longer than the expire time.