Observability with Prometheus

Observability with Prometheus

You can monitor your local YugabyteDB cluster with a local instance of Prometheus, a popular standard for time-series monitoring of cloud native infrastructure. YugabyteDB services and APIs expose metrics in the Prometheus format at the /prometheus-metrics endpoint.

For details on the metrics targets for YugabyteDB, see Monitoring with Prometheus.

If you haven’t installed YugabyteDB yet, do so first by following the Quick Start guide.

Prerequisite

Prometheus is installed on your local machine. If you have not done so already, follow the links below.

1. Create universe

If you have a previously running local universe, destroy it using the following.

$ ./bin/yb-ctl destroy

Start a new local YugabyteDB cluster - by default, this will create a three-node universe with a replication factor of 3.

$ ./bin/yb-ctl create

2. Run the YugabyteDB workload generator

Download the YugabyteDB workload generator JAR file (yb-sample-apps.jar) by running the following command.

$ wget https://github.com/yugabyte/yb-sample-apps/releases/download/v1.2.0/yb-sample-apps.jar?raw=true -O yb-sample-apps.jar

Run the CassandraKeyValue workload in a separate shell.

$ java -jar ./yb-sample-apps.jar \
    --workload CassandraKeyValue \
    --nodes 127.0.0.1:9042 \
    --num_threads_read 1 \
    --num_threads_write 1

3. Prepare Prometheus configuration file

Copy the following into a file called yugabytedb.yml.

global:
  scrape_interval:     5s # Set the scrape interval to every 5 seconds. Default is every 1 minute.
  evaluation_interval: 5s # Evaluate rules every 5 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).
# YugabyteDB configuration to scrape Prometheus time-series metrics
scrape_configs:
  - job_name: 'yugabytedb'
    metrics_path: /prometheus-metrics
    static_configs:
      - targets: ['127.0.0.1:7000', '127.0.0.2:7000', '127.0.0.3:7000']
        labels:
          group: 'yb-master'
      - targets: ['127.0.0.1:9000', '127.0.0.2:9000', '127.0.0.3:9000']
        labels:
          group: 'yb-tserver'
      - targets: ['127.0.0.1:11000', '127.0.0.2:11000', '127.0.0.3:11000']
        labels:
          group: 'yedis'
      - targets: ['127.0.0.1:12000', '127.0.0.2:12000', '127.0.0.3:12000']
        labels:
          group: 'ycql'
      - targets: ['127.0.0.1:13000', '127.0.0.2:13000', '127.0.0.3:13000']
        labels:
          group: 'ysql'

4. Start Prometheus server

Go to the directory where Prometheus is installed and start the Prometheus server as below.

$ ./prometheus --config.file=yugabytedb.yml

Open the Prometheus UI at http://localhost:9090 and then navigate to the Targets page under Status.

5. Analyze key metrics

On the Prometheus Graph UI, you can now plot the read IOPS and write IOPS for the CassandraKeyValue sample app. As we can see from the source code of the app, it uses only SELECT statements for reads and INSERT statements for writes (aside from the initial CREATE TABLE). This means we can measure throughput and latency by simply using the metrics corresponding to the SELECT and INSERT statements.

Paste the following expressions into the Expression box and click Execute followed by Add Graph.

Throughput

Read IOPS

sum(irate(handler_latency_yb_cqlserver_SQLProcessor_SelectStmt_count[1m]))

Write IOPS

sum(irate(handler_latency_yb_cqlserver_SQLProcessor_InsertStmt_count[1m]))

Latency

Read Latency (in microseconds)

avg(irate(handler_latency_yb_cqlserver_SQLProcessor_SelectStmt_sum[1m])) / avg(irate(handler_latency_yb_cqlserver_SQLProcessor_SelectStmt_count[1m]))

Write Latency (in microseconds)

avg(irate(handler_latency_yb_cqlserver_SQLProcessor_InsertStmt_sum[1m])) / avg(irate(handler_latency_yb_cqlserver_SQLProcessor_InsertStmt_count[1m]))

6. [Optional] Clean up

Optionally, you can shut down the local cluster created in Step 1.

$ ./bin/yb-ctl destroy