Loggen

Simple NodeJS log generator app for Datadog logs experiments.

Dependencies

NodeJS 11.0 or superior

Architecture

This app generates logs based on some pre-defined templates.

Templates are divided in success templates and error templates. Both can be found in data/ folder under the respective type.

Success logs

A success log round selects, randomly, one log from each kind in the following order:

driverFound
paymentSubmitted
paymentAccepted
rideCreated

All the four logs are dispatched in the order above and all of them contains the same context_id, generated randomly by the system.

Error logs

An error log round selects, randomly, one log from each kind in the following order:

driverFound
paymentSubmitted
paymentFailed

... or ...

noDriverAvailable

All the logs are dispatched in the order above and all of them contains the same context_id, generated randomly by the system.

Configuration

This app requires two parameters, provided by environment variables:

LOG_INTERVAL_IN_MS: the interval (in ms) between the logs production. Interval honoring isn't guaranteed, but since the log generation process is simple, the log overhead can be ignored.
ERROR_RATE: the error rate (float between 0 and 1), defining the probabilistic occurrence of error logs. Setting to zero disables error logs, while setting to one generates exclusively error logs.

Running locally

$ LOG_INTERVAL_IN_MS=100 ERROR_RATE=0.25 npm start

Running with Docker

# Build the Docker image
$ docker build -t mauricioklein/loggen .
# ... or use the publicly available image: https://hub.docker.com/r/mauricioklein/loggen/

# Start the container
$ docker run \
    -e LOG_INTERVAL_IN_MS=100 \
    -e ERROR_RATE=0.25 \
    -it mauricioklein/loggen

Running in K8s

A public Docker image is available on DockerHub and can be used to deploy the app on K8s:

# Creates a single pod, not managed by a deployment
$ kubectl run loggen \
    --image mauricioklein/loggen:1.0.0 \
    --env LOG_INTERVAL_IN_MS=250 \
    --env ERROR_RATE=0.25 \
    --restart=Never