feat: add SFTP monitor type with password and private key authentication

[eXtgmA]

Summary

In this pull request, the following changes are made:

• New monitor type added for SFTP connections
• Resolves SFTP/FTP as a new monitor #2877
• No Breaking changes
• Added new testcases, but without a testcontainer, since I couldn't find an sftp container for node. If there is a better solution here, I'll be happy to correct this
• english translation

Please follow this checklist to avoid unnecessary back and forth (click to expand)

• ⚠️ If there are Breaking change (a fix or feature that alters existing functionality in a way that could cause issues) I have called them out
• 🧠 I have disclosed any use of LLMs/AI in this contribution and reviewed all generated content.
  I understand that I am responsible for and able to explain every line of code I submit.
• 🔍 Any UI changes adhere to visual style of this project.
• 🛠️ I have self-reviewed and self-tested my code to ensure it works as expected.
• 📝 I have commented my code, especially in hard-to-understand areas (e.g., using JSDoc for methods).
• 🤖 I added or updated automated tests where appropriate.
• 📄 Documentation updates are included (if applicable).
• 🧰 Dependency updates are listed and explained.
• ⚠️ CI passes and is green.

For the private key, I decided against a hidden input because it is much more readable with a text area.

New dependencies

• ssh2-sftp-client v12.0.1

Screenshots for Visual Changes

[github-actions]

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[Copilot]

Pull request overview

Adds a new SFTP monitor type to Uptime Kuma, including backend connectivity checks (password or SSH private key auth), UI configuration fields, persistence via DB migration, and backend unit tests.

Changes:

• Implemented a new backend monitor type (sftp) using ssh2-sftp-client, including optional remote path existence checks.
• Added SFTP configuration UI to the monitor editor and new i18n strings.
• Added DB columns + serialization/persistence wiring and backend tests for SFTP scenarios.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
server/monitor-types/sftp.js	New SFTP monitor type implementation.
server/uptime-kuma-server.js	Registers the new sftp monitor type.
server/server.js	Persists SFTP fields when saving a monitor.
server/model/monitor.js	Serializes/deserializes SFTP fields (incl. sensitive fields).
db/knex_migrations/2026-02-23-0000-add-sftp-monitor.js	Adds DB columns for SFTP configuration.
src/pages/EditMonitor.vue	Adds SFTP to monitor type list and renders SFTP-specific form fields.
src/lang/en.json	Adds English translations for SFTP UI strings.
test/backend-test/monitors/test-sftp.js	Adds backend unit tests for SFTP monitor behavior.
package.json / package-lock.json	Adds ssh2-sftp-client dependency.

[louislam]

Except sftp_path, I think it should called ssh_*. In case someone implement ssh monitor in the future, they can reuse the fields.

[CommanderStorm]

we also likely already have username and password fields for monitors -> reuse those

[louislam]

Added new testcases, but without a testcontainer, since I couldn't find an sftp container for node. If there is a better solution here, I'll be happy to correct this

This package seems to provide a basic working sftp server, not tested, but feel free to add to devDependencies.
https://www.npmjs.com/package/@micham/sftp-mock-server