SLALite

Description

The SLALite is a lightweight implementation of an SLA system, inspired by the WS-Agreement standard. Its features are:

• REST interface to manage creation and update of agreements
• Agreements evaluation on background; any breach in the agreement terms generates an SLA violation.
• Configurable monitoring: a monitoring has to be provided externally.
• Configurable repository: a memory repository (for developing purposes) and a mongodb repository are provided, but more can be added.

An agreement is represented by a simple JSON structure (see examples in resources/samples):

{
    "id": "2018-000234",
    "name": "an-agreement-name",
    "details":{
        "id": "2018-000234",
        "type": "agreement",
        "name": "an-agreement-name",
        "provider": { "id": "a-provider", "name": "A provider" },
        "client": { "id": "a-client", "name": "A client" },
        "creation": "2018-01-16T17:09:45Z",
        "expiration": "2019-01-17T17:09:45Z",
        "guarantees": [
            {
                "name": "TestGuarantee",
                "constraint": "[execution_time] < 100"
            }
        ]
    }
}

Quick usage guide

Installation

Build the Docker image:

make docker

Run the container:

docker run -ti -p 8090:8090 slalite:<version>

Stop execution pressing CTRL-C

To run the service under HTTPs, you must change supply a different configuration file and the certificate files. You will find these files in docker/https for debugging purposes. DO NOT USE THE CERT.PEM and KEY.PEM in production!!

docker run -ti -p 8090:8090 -v $PWD/docker/https:/etc/slalite slalite

Configuration

The SLALite can be configured with a configuration file and with environment variables. The configuration file is read by default from /etc/slalite and the current working directory. The -f parameter can be used to set the config file location.

$ ./SLALite -h
Usage of SLALite:
  -b string
        Filename (w/o extension) of config file (default "slalite")
  -d string
        Directories where to search config files (default "/etc/slalite:.")
  -f string
        Path of configuration file. Overrides -b and -d

File settings

General settings

• singlefile (default: false). Sets if all file settings are read from a single file or from several files. For example, when singlefile=false, the MongoDB settings are read from the file mongodb.yml.
• repository (default: memory). Sets the repository type to use. Set this value to mongodb to use a MongoDB database.
• externalIDs (default: false). Set this to true if the repository auto assign the IDs of the saved entities.
• checkPeriod (default: 60). Sets the period in seconds of assessments executions.
• CAPath. Sets the value of a file path containing certificates of trusted CAs; to be used to connect as client to SSL servers whose certificate is not trusted by default (e.g. self-signed certificates)

REST interface settings

• port (default: 8090). Port of REST interface.
• enableSsl (default: false). Enables the use of SSL on the REST interface. The two following variables should be set.
• sslCertPath (default: cert.pem). Sets the certificate path.
• sslKeyPath (default: key.pem). Sets the private key path to access the certificate.

MongoDB settings (default file: /etc/slalite/mongodb.yml)

• connection (default: localhost). Sets the MongoDB host.
• database (default: slalite). Sets the MongoDB database name to use.
• clear_on_boot (default: false). Sets if the database is cleared on startup (useful for tests).

Env vars

Every file setting can be overriden with the use of environment variables. The name of the var is the uppercase setting name prefixed with SLA_. For example, to override the check period, set the env var SLA_CHECKPERIOD.

Usage

SLALite offers a usual REST API, with an endpoint on /agreements

Add an agreement (agreement below is stopped):

curl -k -X POST -d @resources/samples/agreement.json http://localhost:8090/agreements

Change agreement state:

curl -k http://localhost:8090/agreements/a02 -X PUT -d'{"state":"started"}'

Get agreements:

curl -k http://localhost:8090/agreements
curl -k http://localhost:8090/agreements/a02

Add a template:

curl -k -X POST -d @resources/samples/template.json http://localhost:8090/templates

Get templates:

curl -k http://localhost:8090/templates
curl -k http://localhost:8090/templates/t01

Create agreement from template:

curl -k -X POST -d @resources/samples/create-agreement.json http://localhost:8090/create-agreement

{"template_id":"t01","agreement_id":"9be511e8-347f-4a40-b784-e80789e4c65b","parameters":{"M":1,"N":100,"agreementname":"An agreement name","client":{"id":"client01","name":"A name of a client"},"provider":{"id":"provider01","name":"A name of a provider"}}}