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Monitoring MySQLd with Prometheus

The Prometheus ecosystem contains a multitude of integrations, both officially supported and third party. Let’s have a look at how to use the mysqld_exporter.

 

MySQL is a popular database system, which exposes a wide variety of metrics but not in a format Prometheus can directly consume. The mysqld_exporter bridges this gap.

I’m going to assume you already have a working MySQLd installed. We first need to create a user that can connect locally with appropriate permissions:

CREATE USER 'mysqld_exporter'@'localhost' IDENTIFIED BY 'a_password';
GRANT PROCESS, REPLICATION CLIENT, SELECT ON *.* TO 'mysqld_exporter'@'localhost'
  WITH MAX_USER_CONNECTIONS 3;

Then download and run the mysqld_exporter:

wget https://github.com/prometheus/mysqld_exporter/releases/download/v0.9.0/mysqld_exporter-0.9.0.linux-amd64.tar.gz
tar -xzf mysqld_exporter-0.9.0.linux-amd64.tar.gz
export DATA_SOURCE_NAME='mysqld_exporter:a_password@unix(/var/run/mysqld/mysqld.sock)/'
./mysqld_exporter

You may need to adjust the location of the Unix socket.

If you visit http://localhost:9104/metrics you’ll see your metrics!

 

Let’s setup a Prometheus to scrape the exporter:

wget https://github.com/prometheus/prometheus/releases/download/v2.0.0/prometheus-2.0.0.linux-amd64.tar.gz
tar -xzf prometheus-2.0.0.linux-amd64.tar.gz
cd prometheus-*
cat <<'EOF' > prometheus.yml
global:
 scrape_interval: 10s
 evaluation_interval: 10s
scrape_configs:
 - job_name: 'mysqld'
   static_configs:
    - targets:
      - localhost:9104
EOF
./prometheus &

From there you can go to http://localhost:9090/graph and plot expressions such as irate(mysql_global_status_queries[1m]) to get the query rate.

The mysqld_exporter can provide a wide wealth of information, however for performance reasons most of this is disabled by default. The official docs have the flags you can use to enable more metrics.

 

Have questions about monitoring databases with Prometheus? Contact us.

Brian BrazilMonitoring MySQLd with Prometheus
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