Get node deps with npm install.

node server.js

Debug mode:

node server.js debug

grunt test

Sentinel uses the changes feed on a CouchDB database and runs a set of transitions on a document. It also manages some scheduled tasks like message schedules.

Export a COUCH_URL env variable so sentinel knows what database to use. e.g.

export COUCH_URL='http://root:123qwe@localhost:5984/medic'

Throughout this document we will be refering to ddoc. Here we mean the currently deployed _design/medic ddoc from medic-webapp.

Default settings values are in defaults.js. On initial start, and when there are changes to the ddoc, sentinel reads ddoc.app_settings to determine configuration.

By default all transitions are disabled, to enable a transition modify the transitions property on ddoc.app_settings.

A transition is enabled if the value associated with its name is truthy.

In both of these examples all three transitions are enabled:

{
  "transitions": {
    "registrations": true,
    "default_responses": true,
    "update_clinics": true
  }
}

{
  "transitions": {
    "registrations": {
      "param": "val"
    },
    "default_responses": {},
    "update_clinics": {}
  }
}

A transition is disabled if either the value associated with its name is falsey, or it has "disable" set to true, or the transition is missing.

In all three examples below the registrations transition is disabled.

{
  "transitions": {}
}

{
  "transitions": {
    "registrations": false
  }
}

{
  "transitions": {
    "registrations": {
      "disable": true
    }
  }
}

A transition does async processing of a document once per rev/change, and obeys the following rules:

• has a filter function that determines if it needs to run/be applied to a document.

• accepts a document as a reference and makes changes using that reference, copying is discouraged.

• does not have side effects outside of the document passed in. This might be extended in the future to manage changes to multiple documents, but for now the transition is responsible for these types of changes.

• guarantees the consistency of a document.

• runs serially in any order.

• is repeatable, it can run multiple times on the same document without negative effect. You can use the transitions property on a document to determine if a transition has run.

Callback arguments:

• callback(err, true)

  The document is saved and ok property value is false if err is truthy.

• callback(err)

  The document is saved and ok property value is false if err is truthy. Use this when a transition fails and should be re-run.

• callback()

  Nothing to be done, the document is not saved and next transition continues. Transitions will run again on next change.