subscription system<\/a> that manages subscriptions for various lottery brands, creates invoices, handles the payments and eventually provisions the tickets. <\/p>\n\n\n\nThe system consists of ca. 10 different services, which all connect to a database, which in our case is a managed PostgreSQL running on AWS. This database makes a lot of metrics available out of the box.<\/p>\n\n\n\n
Who Are You? (who who, who who)<\/h1>\n\n\n\n
When you start to drill down into some of these metrics, you\u2019ll notice that metrics like postgresql.queries.duration<\/code> and postgresql.transactions.duration<\/code> contain a tag named \u201capp\u201d, which represents the application connecting to the DB. However, by default for the Boot apps this is set to \u201cPostgreSQL JDBC Driver\u201d:<\/p>\n\n\n\n![](\"https:\/\/lh7-us.googleusercontent.com\/dNsSxDuCgmeCDSjEfsCQHZCTO-FE3GGe58QGC5_LcYEpcpCBWlFcMGAUyFWaujQtMjC1sZL5__aKiCIEEE_6msIxcjZQm1ptykvqaqw-trVIgxfyZDf-jhvFLGL_cWMeeSJ3m4R9WzVwmsa9kxDOAFA\")
<\/p>\n\n\n\n
We have around 10 different services. One contains Batch jobs, others are handling OLTP concerns like creating a new subscription, or create business reports. We don\u2019t really want to see those lumped together as one app in the DB metrics.
Fortunately it\u2019s easy to change this: you can simply configure the database connection to use the application\u2019s service name instead. This is how we do that in YML:<\/p>\n\n\n
\nspring:\n datasource:\n hikari:\n data-source-properties:\n # see https:\/\/jdbc.postgresql.org\/documentation\/use\/#connection-parameters\n ApplicationName: ${spring.application.name}\n<\/pre><\/div>\n\n\nWith that simple change, it suddenly becomes possible to distinguish between the apps in the PostgreSQL metrics:<\/p>\n\n\n\n
![](\"https:\/\/lh7-us.googleusercontent.com\/Ce2o1R1fKhJ6YNrl1GvOxDErauzw2_siKTr3wlRuoDQMAet3i2tau4CG1j4s3bjQJJQXjX_hcnwmt_igHmpYkaOstpjCYwygxVxQ3eKqH8Pglo0EMtHi9DuYdUzwW91IXbhmlqnl8kngfHcuwY70X5Q\")
<\/p>\n\n\n\n
These names are the same values that our application metrics use for a \u201cservice\u201d tag that we add. This is done by using a Micrometer meter registry customizer:<\/p>\n\n\n
\n@Bean\nMeterRegistryCustomizer<MeterRegistry> commonTags(Environment env) {\n String serviceName = env.getProperty("spring.application.name", "unknown-service");\n String hostName = Objects.requireNonNullElse(System.getenv("HOSTNAME"), "localhost");\n return registry -> registry.config().commonTags(\n "service", serviceName,\n "instance", hostName\n );\n}\n<\/pre><\/div>\n\n\nThat means that we can now create a database calls-related dashboard with template variables to allow all widgets to filter on the selected service. In that dashboard we also include built-in metrics from the Hikari connection pool and the Spring Data JPA repositories. Note how this allows to see what info displayed in the widgets correlates to the same service, and how we can filter (best watched full-screen):<\/p>\n\n\n\n