NoSql – Storage Backend

As an example for an NoSql database, MongoDB was chosen in order to evaluate write performance of NoSql databases.

Currently, only a Proof-of-Concept implementation exists and shall be used with caution.

Configuration

In order to use InfluxDB as a logging backend, the following configuration is necessary:

...
"EventLogging": {
    "PluginSearchPath": "/usr/lib/elos/backend",
    "Plugins": {
        "NoSQLBackend": {
            "File": "backend_nosql.so",
            "Run": "always",
            "Filter": [
                "1 1 EQ"
            ],
            "Config": {
                "ConnectionString": "mongodb://mongoadmin:secret@elos-mongo:27017"
            }
        }
    }
},
...

ConnectionString: define how to connect to mongoDB instance

Database Schema

The plugin creates a database elosd and stores all events in a table events. The event structure is flattened so that child fields of event.date and event.source becomes a member of the BSON object which is stored in the event table.

_id <OID>	messageCode <INT32>	classification <INT64>	severity <INT32>	date_s <INT64>	date_ns <INT64>	payload <UTF8>	pid <INT64>	appName <UTF8>	fileName <UTF8>
…	2000	0x01	0x01	1713187301	0	“custom payload”	42	“myApp”	“/bin/myApp”

Testing mongoDB backend

To run elos with mongodb plugin, a docker-mongodb-run.sh script is provided in the ./ci/ folder.

Configure elosd to mongoDB :

Copy the configuration snippet for NoSQLBackend from the example configuration above into the Plugins section of EventLogging in ./test/integration/service/config.json.

To start a mongoDB use :

./ci/docker-mongodb-run.sh

Then start elosd :

LINK_NOSQL=true ./ci/docker-target-run.sh