MigrationsRunner.java
package de.dlr.shepard.neo4j;
import org.neo4j.driver.AuthTokens;
import org.neo4j.driver.Driver;
import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.exceptions.ServiceUnavailableException;
import ac.simons.neo4j.migrations.core.Migrations;
import ac.simons.neo4j.migrations.core.MigrationsConfig;
import ac.simons.neo4j.migrations.core.MigrationsException;
import de.dlr.shepard.util.PropertiesHelper;
import lombok.extern.slf4j.Slf4j;
@Slf4j
public class MigrationsRunner {
private Migrations migrations;
private Driver driver;
public MigrationsRunner() {
var pHelper = new PropertiesHelper();
String username = pHelper.getProperty("neo4j.username");
String password = pHelper.getProperty("neo4j.password");
String host = "neo4j://" + pHelper.getProperty("neo4j.host");
var path = this.getClass().getClassLoader().getResource("neo4j/migrations");
driver = GraphDatabase.driver(host, AuthTokens.basic(username, password));
var config = MigrationsConfig.builder().withTransactionMode(MigrationsConfig.TransactionMode.PER_STATEMENT)
.withPackagesToScan("de.dlr.shepard.neo4j.migrations").withLocationsToScan("file://" + path.toString())
.build();
migrations = new Migrations(config, driver);
}
public void waitForConnection() {
while (true) {
try {
driver.verifyConnectivity();
break;
} catch (Exception e) {
log.warn("Cannot connect to neo4j database. Retrying...");
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
log.error("Cannot sleep while waiting for neo4j Connection");
Thread.currentThread().interrupt();
}
}
}
public void apply() {
try {
migrations.apply();
} catch (ServiceUnavailableException e) {
log.error("Migrations cannot be executed because the neo4j database is not available");
} catch (MigrationsException e) {
log.error("An error occurred during the execution of the migrations: ", e);
}
}
}