Allow hostless MySQL JDBC TC URLs

[Copilot]

The MySQL JDBC Testcontainers URL parser wrongly treated a leading slash as a hostname, forcing users to add a fake host (e.g., jdbc:tc:mysql:5.7.12://hostname/...). This enables hostless URLs like jdbc:tc:mysql:5.7.12:///mydatabase, consistent with other JDBC modules.

• Parsing
  • Tightened the DB instance regex to ignore leading /, preventing it from being misread as a hostname for MySQL JDBC URLs.
• Verification
  • Added a MySQL driver test asserting jdbc:tc:mysql:8.0.36:///databasename starts correctly and selects the expected database.

Example:

String url = "jdbc:tc:mysql:8.0.36:///databasename";
try (Connection conn = DriverManager.getConnection(url)) {
    try (ResultSet rs = conn.createStatement().executeQuery("SELECT DATABASE()")) {
        rs.next();
        // returns "databasename"
    }
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• ge.testcontainers.org
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx2g -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-8.14.3-all/10utluxaxniiv4wxiphsi49nj/gradle-8.14.3/lib/gradle-daemon-main-8.14.3.jar (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

According to testcontainers#4121, the testcontainers-mysql module cannot use JDBC URLs like jdbc:tc:mysql:5.7.12:///mydatabase; a custom hostname must be added. However, other modules' JDBC URLs do not require a custom hostname. Please diagnose and fix this.

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[linghengqian]

• Fixed by dynamic-datasource/dynamic-datasource-samples#56 and testcontainers#4121 (comment) .