An upstream is a real MCP server vMCP connects to.

Field	Meaning
slug	Identifier in URLs and tool names ([a-z0-9-])
name, description	Display text
url	Endpoint, http:// or https://
fallbackUrls	Up to 5 more URLs of the same server, tried in order (failover)
transport	streamable_http (default) or sse (legacy HTTP+SSE)
enabled	Disabled upstreams are not served
headers	Sent on every upstream request, typically Authorization. Encrypted at rest, write-only, never returned; the API only lists headerNames
tls	Custom CA, server name override, mTLS (Upstream TLS)

The Upstreams table opens a dedicated page at /upstreams/<slug>. Saved configuration opens read-only, with node health and stored discovery snapshots. Choose Edit upstream at the top to change connection settings, credentials, TLS or OAuth. Save writes the versioned configuration and returns to read-only mode; Cancel restores saved values after confirming any unsaved changes. Viewers cannot enter edit mode. Add upstream opens a full-page creation form.

Test stored credentials uses the saved configuration. In edit mode, Test edited connection uses the draft and only credentials entered in this session; stored secret values remain write-only. Reloading discovery snapshots reads the cache. Use Refresh capabilities in the upstream table for fresh discovery. Existing ?inspect=<slug> links redirect to the dedicated detail page.

POST /api/v1/upstreams/{slug}/refresh-tools connects, lists the tools and caches them. The response reports added, removed, changed and orphaned selections (virtual-server entries whose upstream tool vanished). POST /api/v1/connection-tests tries a connection without saving anything (the UI's "Test connection").

Tool schemas are cached, so virtual servers keep working while an upstream is briefly down. Refresh when an upstream changes its tools, resources or prompts. Discovery also caches advertised resources, URI templates, prompts and capability metadata. See catalogs. A saved upstream can be tested with POST /api/v1/upstreams/{slug}/connection-test without returning its credentials.

PUT with headers omitted keeps the stored headers; {} clears them. With PATCH, a header set to null is deleted and others are merged. Exported configuration never contains header values.

Deleting an upstream used by virtual servers returns 409 unless you pass ?force=true, which also removes those selections.

Only HTTP endpoints are supported. Before upgrading an existing deployment, remove any upstream whose transport is neither streamable_http nor sse, or replace it with an actual HTTP MCP endpoint. Remove or update its virtual-server selections as needed. Migration 26 enforces the HTTP-only database constraint and refuses to proceed while unsupported configurations exist; it does not delete configurations. Migration version 24 is retained as a no-op for migration-history compatibility. Run the migration command before restarting the control and data planes.