SLA4OAI (SLA for Open API Initiative) Library

SLA4OAI is an open source library for applying SLA in your node application.

SLA4OAI is Express-compatible SLA Checking and Monitoring middleware for Node.js.

SLA4OAI is based on SLA for Open API Initiative Specification. And follows the Basic SLA Management Service proposal.

Install

$ npm install sla4aoi

Basic Usage

You can simply use the library by registering it with the Express app and backend connections for Supervisor & Monitor:

var app = express();

var supervisorConnection = {
    url: 'http://supervisor.oai.governify.io/api/v1'
};

var monitorConnection = {
    url: 'http://monitor.oai.governify.io/api/v1'
};

slaManager.register(app, supervisorConnection, monitorConnection);

API Reference

1. SlaManager

register

Register all library components as express middlewares. Called once when the server getting up.

Parameters:

Name	Type	Description
app	Express	Required - The express app.
supervisorConnection	ConnectionObject	Required - The connection details of the Supervisor.
monitorConnection	ConnectionObject	Optional - The connection details of the Monitor. In case of missing, the Reporter component will be disabled.

ConnectionObject:

Name	Type	Description
host	string	Host url.
port	integer	Port number.
username	string	Credentials username.
password	string	Credentials password.

Example:

var app = express();

var supervisorConnection = {
    url: 'http://supervisor.oai.governify.io/api/v1',
    port: 80,
    username: 'marck',
	password: 'm4321'
};

slaManager.register(app, supervisorConnection);

2. Scope Resolver

configure

Use this method to set the configuration parameters of the Scope Resolver.

Configuration parameters:

Name	Type	Description
defaultOAuthProvider	string	The default provider when oauthprovider is missing in the request header.
config	<provider, OAuthConfigObject>	OAuth provider configurations.

OAuthConfigObject:

Name	Type	Description
clientId	string	The provider application id.
clientSecret	string	The provider application secret.
callbackURL	string	The callback registered in the provider application.

Example:

var options = {
	defaultOAuthProvider: 'google',
    config: {
        google: {
	        clientId: '6076-d1m.apps.googleusercontent.com',
            clientSecret: '1lWx9DDDaPo9kxF4yu6t_loJ',
            callbackURL: 'https://app.myservice.com/google/callback'
        }
    }
};
slaManager.scopeResolver.configure(options);

getAccountName

Use this method to get the account name from the OAuth provider by the specified token.

Example:

slaManager.scopeResolver.getAccountName(oauthProvider, token, function (err, accountName) {
    // get accountName
});

getAccountScope

Using this method to get the scope object from the supervisor by the specifying the apikey or the account name.

Example:

slaManager.scopeResolver.getAccountScope('apikey', 'NbfiS7wjwjwb=', function (err, result) {
	// get result.scope
});
//or
slaManager.scopeResolver.getAccountScope('account', 'john@tenant.com', function (err, result) {
	// get result.scope
});

OAuth Providers

Using the powerful PassportJS framework and family of plugins SLA4OAI can be configured to support the following providers:

• Google
• Facebook
• WindowsLive
• Github

3. Bouncer

configure

Use this method to set the configuration parameters of the Bouncer.

Configuration parameters:

Name	Type	Description
environment	string	The deploying environment (devel, qa, or production).

Example:

var options = {
	environment: 'qa'
};
slaManager.bouncer.configure(options);

needChecking

By default, all incoming requests are verified by SLA Check, but you can customize this behaviour and specify which requests need checking in both bouncer and scopeResolver components.

Example:

slaManager.bouncer.needChecking = function(req) {
    if (req.originalUrl.startsWith('/api/')) {
        return true;
    }
    return false;
}

slaManager.scopeResolver.needChecking = function(req) {
     if (req.originalUrl.startsWith('/api/')) {
        return true;
    }
    return false;
}

decline

By default, bouncer declines all not accepted requested with status code 403 and the body that comes from the Supervisor. But you can customize the decline response message.

Example:

slaManager.bouncer.decline = function(req, res, next, supervisorPayload) {
    if(supervisorPayload.reason === 'Too many requests') {
        res.status(429).json(supervisorPayload.reason).end();
    }
    else {
        res.status(403).json(supervisorPayload).end();
    }
}

resolveMetrics

In order to resolve the required metrics for the check API, you need to define resolveMetrics function and return all metrics in single object.

Example:

slaManager.bouncer.resolveMetrics = function (requestedMetrics, req) {
    return {
        nameLegth: 12
    };
};

3. Reporter

configure

Use this method to set the configuration parameters of the Reporter.

Configuration parameters:

Name	Type	Description
autoReport	boolean	In case of true, all API calls will be reported one by one, else the developer can aggregate multiple API calls in one report (default = true).
aggregate	boolean	Aggregate multiple measures in one report, this aggregated measures will be frequently sended based on the aggregationPeriod (default = false). This features is disabled if the autoReport = false.
aggregationPeriod	double	All requests during this period will be aggregated in one report. It is calculated in milliseconds.
cluster	string	The cluster that process this API.
environment	string	The deploying environment (devel, qa, or production).

Example:

var options = {
	autoReport: true,
	aggregate: true,
	aggregationPeriod: 100,
	cluster: 'cl1.acme.com',
    environment: 'qa'
};

slaManager.reporter.configure(options);

reportMetrics

In case of autoReport=false, the developer will have the responsibility to call this method to report the aggregated metrics.

Example:

slaManager.reporter.reportMetrics();

setMetric

At any stage of the API logic, the developer can set a custom metric by simply passing its name and value.

Example:

slaManager.reporter.setMetric(req, 'animalTypes', records.length);

preCalculateMetrics

This method enables the developer to set the metrics that need to be calculated before the API logic.

Example:

slaManager.reporter.preCalculateMetrics = function(requestedMetrics, req, next) {
    req.sla.metrics['x-origin'] = req.headers['origin'];
    next();
};

postCalculateMetrics

This method enables the developer to set the metrics that need to be calculated after the API logic.

Example:

slaManager.reporter.postCalculateMetrics = function(requestedMetrics, req, res, next) {
    req.sla.metrics['x-animalType'] = getAnimalTypes(res.Body);
    next();
};

Predefined metrics

• responseTime: The API processing time.
• requestBody: The body of the request.
• responseHeaders: The headers of the request.
• responseBody: The body of the response.
• userAgent: Some information about the browser and operating system of the API consumer.

4. Winston

SLA4OAI uses Winston to log all SLA connection activities. You can customize the Winston logging behaviour by accessing slaManager.winston object.

Example: In the following example we change the logging from the Console to the file system:

slaManager.winston.add(slaManager.winston.transports.File, { filename: 'somefile.log' });
slaManager.winston.remove(slaManager.winston.transports.Console);