Once you start to manage microservices using a cloud infrastructure, there are various monitoring tools that can help you to manage your servers.

Amazon CloudWatch is the built-in monitoring tool for AWS. No agent installation is needed; it automatically gathers metrics from AWS instances and allows the user to visualize these in order to carry out DevOps tasks. It also supports the ability to set an alert based on the criteria that you set. The following screenshot shows the Amazon CloudWatch metrics for an EC2 instance:

Amazon CloudWatch also supports the gathering of an application log. This requires us to install an agent on an EC2 instance. Centralized log management is useful when you need to start managing multiple microservice instances.

ELK is a popular combination of stacks that stands for Elasticsearch (https://www.elastic.co/products/elasticsearch), Logstash (https://www.elastic.co/products/logstash), and Kibana (https://www.elastic.co/products/kibana). Logstash aggregates the application log, transforms it to JSON format, and then sends it to Elasticsearch. Elasticsearch is a distributed JSON database. Kibana can visualize the data that's stored on Elasticsearch. The following Kibana example shows an nginx access log:

Grafana (https://grafana.com) is another popular visualization tool. It used to be connected with time series databases such as Graphite (https://graphiteapp.org) or InfluxDB (https://www.influxdata.com). A time series database is designed to store data that's flat, de-normalized, and numeric, such as CPU usage or network traffic. Unlike RDBMS, a time series database has some optimization in order to save data space and can carry out faster queries on historical numeric data. Most DevOps monitoring tools use time series databases in the backend.

The following Grafana screenshot shows some Message Queue Server statistics: