Many projects that use data require connections to a database. The main way of obtaining connections to a database is to use a datasource.
In Quarkus, the out of the box datasource and connection pooling implementation is Agroal.
This guide will explain how to:
-
configure a datasource, or multiple datasources
-
how to obtain a reference to those datasources in code
Prerequisites
To complete this guide, you need:
-
less than 10 minutes
-
an IDE
-
JDK 1.8+ installed with
JAVA_HOME
configured appropriately -
Apache Maven 3.5.3+
Creating the Maven project
First, we need a new project. Create a new project with the following command:
mvn io.quarkus:quarkus-maven-plugin:0.27.0:create \
-DprojectGroupId=org.acme \
-DprojectArtifactId=agroal-datasources\
-DclassName="org.acme.datasource.GreetingResource" \
-Dpath="/hello"
It generates:
-
the Maven structure
-
a landing page accessible on
http://localhost:8080
-
example
Dockerfile
files for bothnative
andjvm
modes -
the application configuration file
-
an
org.acme.datasource.GreetingResource
resource -
an associated test
Adding maven dependencies
Next, you will need to add the quarkus-agroal
dependency to your project.
You can add it using a simple Maven command:
./mvnw quarkus:add-extension -Dextensions="agroal"
Agroal comes as a transitive dependency of the Hibernate ORM extension so if you are using Hibernate ORM, you don’t need to add the Agroal extension dependency explicitly. |
You will also need to add the database connector library of choice.
Quarkus provides driver extensions for:
-
H2 - jdbc-h2
-
PostgreSQL - jdbc-postgresql
-
MariaDB - jdbc-mariadb
-
MySQL - jdbc-mysql
-
Microsoft SQL Server - jdbc-mssql
-
Derby - jdbc-derby
In JVM mode, simply adding your driver of choice is sufficient. Extensions are mostly useful to support GraalVM native images. |
As usual, you can install the extension using add-extension
.
To install the PostgreSQL driver dependency for instance, just run the following command:
./mvnw quarkus:add-extension -Dextensions="jdbc-postgresql"
Configuring the datasource
Once the dependencies are added to your pom.xml file, you’ll need to configure Agroal.
This is done in the src/main/resources/application.properties
file.
A viable configuration file would be:
quarkus.datasource.url=jdbc:h2:tcp://localhost/mem:default
quarkus.datasource.driver=org.h2.Driver
quarkus.datasource.username=username-default
quarkus.datasource.min-size=3
quarkus.datasource.max-size=13
There are other configuration options, detailed below.
For more information about the Agroal extension configuration please refer to the Configuration Reference. |
JDBC URL configurations
Each of the supported databases contains different JDBC URL configuration options. Going into each of those options is beyond the scope of this document, but it gives an overview of each database URL and link to the official documentation.
H2
jdbc:h2:{ {.|mem:}[name] | [file:]fileName | {tcp|ssl}:[//]server[:port][,server2[:port]]/name }[;key=value…]
- Example
-
jdbc:h2:tcp://localhost/~/test
,jdbc:h2:mem:myDB
H2 is an embedded database. It can run as a server, based on a file, or live completely in memory. All of these options are available as listed above. You can find more information at the official documentation.
PostgreSQL
PostgreSQL only runs as a server, as do the rest of the databases below. As such, you must specify connection details, or use the defaults.
jdbc:postgresql:[//][host][:port][/database][?key=value…]
- Example
-
jdbc:postgresql://localhost/test
Defaults for the different parts are as follows:
host
-
localhost
port
-
5432
database
-
same name as the username
The official documentation go into more detail and list optional parameters as well.
MariaDB
jdbc:mariadb:[replication:|failover:|sequential:|aurora:]//<hostDescription>[,<hostDescription>…]/[database][?<key1>=<value1>[&<key2>=<value2>]]
hostDescription:: <host>[:<portnumber>] or address=(host=<host>)[(port=<portnumber>)][(type=(master|slave))]
- Example
-
jdbc:mariadb://localhost:3306/test
You can find more information about this feature and others detailed in the official documentation.
MySQL
jdbc:mysql:[replication:|failover:|sequential:|aurora:]//<hostDescription>[,<hostDescription>…]/[database][?<key1>=<value1>[&<key2>=<value2>]]
hostDescription:: <host>[:<portnumber>] or address=(host=<host>)[(port=<portnumber>)][(type=(master|slave))]
- Example
-
jdbc:mysql://localhost:3306/test
You can find more information about this feature and others detailed in the official documentation.
Microsoft SQL Server
Microsoft SQL Server takes a connection URL in the following form:
jdbc:sqlserver://[serverName[\instanceName][:portNumber]][;property=value[;property=value]]
- Example
-
jdbc:sqlserver://localhost:1433;databaseName=AdventureWorks
The Microsoft SQL Server JDBC driver works essentially the same as the others. More details can be found in the official documentation.
Derby
jdbc:derby:[//serverName[:portNumber]/][memory:]databaseName[;property=value[;property=value]]
- Example
-
jdbc:derby://localhost:1527/myDB
,jdbc:derby:memory:myDB;create=true
Derby is an embedded database. It can run as a server, based on a file, or live completely in memory. All of these options are available as listed above. You can find more information at the official documentation.
Injecting a Datasource
Because Quarkus uses CDI, injecting a datasource is very simple:
@Inject
AgroalDataSource defaultDataSource;
In the above example, the type is AgroalDataSource
which is a subtype of javax.sql.DataSource
.
Because of this, you can also use javax.sql.DataSource
.
Multiple Datasources
Agroal allows you to configure multiple datasources. It works exactly the same way as a single datasource, with one important change: a name.
quarkus.datasource.driver=org.h2.Driver
quarkus.datasource.url=jdbc:h2:tcp://localhost/mem:default
quarkus.datasource.username=username-default
quarkus.datasource.min-size=3
quarkus.datasource.max-size=13
quarkus.datasource.users.driver=org.h2.Driver
quarkus.datasource.users.url=jdbc:h2:tcp://localhost/mem:users
quarkus.datasource.users.username=username1
quarkus.datasource.users.min-size=1
quarkus.datasource.users.max-size=11
quarkus.datasource.inventory.driver=org.h2.Driver
quarkus.datasource.inventory.url=jdbc:h2:tcp://localhost/mem:inventory
quarkus.datasource.inventory.username=username2
quarkus.datasource.inventory.min-size=2
quarkus.datasource.inventory.max-size=12
Notice there’s an extra bit in the key.
The syntax is as follows: quarkus.datasource.[optional name.][datasource property]
.
Named Datasource Injection
When using multiple datasources, each DataSource
also has the io.quarkus.agroal.DataSource
qualifier with the name of the datasource in the property as the value.
Using the above properties to configure three different datasources, you can also inject each one as follows:
@Inject
AgroalDataSource defaultDataSource;
@Inject
@DataSource("users")
AgroalDataSource dataSource1;
@Inject
@DataSource("inventory")
AgroalDataSource dataSource2;
Datasource Health Check
If you are using the quarkus-smallrye-health
extension, quarkus-agroal
will automatically add a readiness health check
to validate the datasource.
So when you access the /health/ready
endpoint of your application you will have information about the datasource validation status.
If you have multiple datasources, all datasources will be checked and the status will be DOWN
as soon as there is one datasource validation failure.
This behavior can be disabled via the property quarkus.datasource.health.enabled
.
Agroal Configuration Reference
Configuration property fixed at build time - ️ Configuration property overridable at runtime
Type |
Default |
|
---|---|---|
The datasource driver class name |
string |
|
Whether we want to use regular JDBC transactions, XA, or disable all transactional capabilities.
When enabling XA you will need a driver implementing |
|
|
Whether or not an healtcheck is published in case the smallrye-health extension is present (default to true). |
boolean |
|
The datasource URL |
string |
|
The datasource username |
string |
|
The datasource password |
string |
|
The credentials provider name |
string |
|
The credentials provider type.
It is the |
string |
|
The initial size of the pool. Usually you will want to set the initial size to match at least the minimal size, but this is not enforced so to allow for architectures which prefer a lazy initialization of the connections on boot, while being able to sustain a minimal pool size after boot. |
int |
|
The datasource pool minimum size |
int |
|
The datasource pool maximum size |
int |
|
The interval at which we validate idle connections in the background.
Set to |
|
|
The timeout before cancelling the acquisition of a new connection |
|
|
The interval at which we check for connection leaks. |
||
The interval at which we try to remove idle connections. |
|
|
The max lifetime of a connection. |
||
The transaction isolation level. |
|
|
Enable datasource metrics collection. |
boolean |
|
When enabled Agroal will be able to produce a warning when a connection is returned to the pool without the application having closed all open statements. This is unrelated with tracking of open connections. Disable for peak performance, but only when there’s high confidence that no leaks are happening. |
boolean |
|
Query executed when first using a connection. |
string |
|
The datasource driver class name |
string |
|
Whether we want to use regular JDBC transactions, XA, or disable all transactional capabilities.
When enabling XA you will need a driver implementing |
|
|
The datasource URL |
string |
|
The datasource username |
string |
|
The datasource password |
string |
|
The credentials provider name |
string |
|
The credentials provider type.
It is the |
string |
|
The initial size of the pool. Usually you will want to set the initial size to match at least the minimal size, but this is not enforced so to allow for architectures which prefer a lazy initialization of the connections on boot, while being able to sustain a minimal pool size after boot. |
int |
|
The datasource pool minimum size |
int |
|
The datasource pool maximum size |
int |
|
The interval at which we validate idle connections in the background.
Set to |
|
|
The timeout before cancelling the acquisition of a new connection |
|
|
The interval at which we check for connection leaks. |
||
The interval at which we try to remove idle connections. |
|
|
The max lifetime of a connection. |
||
The transaction isolation level. |
|
|
Enable datasource metrics collection. |
boolean |
|
When enabled Agroal will be able to produce a warning when a connection is returned to the pool without the application having closed all open statements. This is unrelated with tracking of open connections. Disable for peak performance, but only when there’s high confidence that no leaks are happening. |
boolean |
|
Query executed when first using a connection. |
string |
About the Duration format
The format for durations uses the standard You can also provide duration values starting with a number.
In this case, if the value consists only of a number, the converter treats the value as seconds.
Otherwise, |