Native SSH Tunnel support for database connections #6573

[pyjams]

Native SSH Tunnel support for database connections

Addresses #6573

Problem

Currently, Apache Hop has no built-in way to connect to databases that sit inside private networks behind an SSH bastion host. Users are forced to set up external SSH tunnels manually (e.g. via ssh -L) before running pipelines, which complicates deployment and is error-prone in automated/containerised environments.

Solution

This PR adds native SSH tunnel support directly in the database connection metadata, so that Hop can transparently open an SSH tunnel before establishing the JDBC connection — no external tooling required.

What changed

• SshTunnelManager (new class): manages JSch SSH sessions with local port forwarding. Supports three authentication methods: password, keyboard-interactive, and private key (with optional passphrase). Includes a 30-second keepalive interval to prevent VPN/firewall idle-connection drops.
• IDatabase / BaseDatabaseMeta: added SSH tunnel configuration fields (sshEnabled, sshHost, sshPort, sshUsername, sshPassword, sshPrivateKey, sshPassphrase) persisted via @HopMetadataProperty.
• DatabaseMeta: delegate getters/setters for the new SSH fields.
• Database: opens the SSH tunnel before the JDBC connect and rewrites the JDBC URL to point to localhost:<localPort>. The tunnel is closed in closeConnectionOnly() (not disconnect()) to avoid premature teardown when connections are shared across a pipeline connection group.
• DatabaseMetaEditor (UI): new "SSH Tunnel" tab in the database connection dialog, with fields that enable/disable dynamically based on the selected authentication method.
• i18n: English and Italian labels.

Testing

• 5 unit tests for SshTunnelManager (session creation, port forwarding, authentication modes, error handling)
• 5 unit tests for Database SSH tunnel integration (tunnel open/close lifecycle, URL rewriting, grouped connections)
• Manual testing verified with MySQL over SSH tunnel

Checklist

• mvn clean install apache-rat:check passes
• Single commit, no squash needed
• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004

Dependencies

Added com.jcraft:jsch:0.1.55 to core/pom.xml (widely used, Apache-compatible BSD license).

Note: pre-existing LDAP build failure

The hop-transform-ldap module fails to compile on current main due to commit 859d0dbc (PR #6665 — LDAP XML cleanup) which changed several methods in LdapOutputMeta and LdapInputMeta to private that are still called by external converter classes (LdapOutputOperationTypeConverter, LdapOutputDerefAliasesTypeConverter, LdapOutputReferralTypeConverter, LdapInputSearchScopeConverter). This is unrelated to the changes in this PR.

[hansva]

Thanks for this @pyjams!

[hansva]

We removed the vintage Junit engine and migrated all our tests to Junit 5+. I can take a look at that if you want

[pyjams]

We removed the vintage Junit engine and migrated all our tests to Junit 5+. I can take a look at that if you want

Thank you, I’ve just updated the files. There shouldn’t be any errors now.

[hansva]

I removed the LDAP changes and added integration tests.
Looking very good, thanks for the work @pyjams