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feat(core): honor HTTPS_PROXY/HTTP_PROXY/NO_PROXY in the Node transport (closes #1563)

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Wrap the Node transport's fetch with an undici EnvHttpProxyAgent dispatcher
when a standard proxy env var is set, so the CLI and web backend can reach
remote MCP servers through corporate proxies with zero new flags. undici is
imported lazily (only when a proxy var is present) and added as a dependency
at the repo root and in the CLI client; a missing undici raises an actionable
error. Documents the behavior and dependency in the CLI README.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S3fTN8H3R8YV4yUGvZjYnX
This commit is contained in:
cliffhall 2026-07-01 18:25:16 -04:00
commit d5be4929e9
3 changed files with 215 additions and 14 deletions
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28
clients/cli/README.md
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@ -80,6 +80,12 @@ npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com --tr
When a server is loaded from a `--catalog`/`--config` file, its per-server settings (headers, connection/request timeouts, and OAuth) are applied to the connection — the same resolution the TUI uses. A `--header` flag overrides the file's headers for that run while leaving the file's timeouts and OAuth in place.
### HTTP proxy support
Connections to remote HTTP/SSE servers honor the conventional proxy environment variables: `HTTPS_PROXY` / `HTTP_PROXY` (and their lowercase forms) select the proxy, and `NO_PROXY` exempts hosts. This applies to the Node transport shared by the CLI and the web backend — no inspector-specific flag is needed. When a proxy variable is set, outbound requests are routed through undici's `EnvHttpProxyAgent`.
Proxy routing is powered by the [`undici`](https://www.npmjs.com/package/undici) package (`^8.5.0`, which requires Node `>= 22.7.5` — the inspector's supported floor). It is imported lazily only when a proxy variable is set, so runs without a proxy configured pay no cost.
## Options
### MCP server (which server to connect to)
@ -115,23 +121,23 @@ The CLI does **not** start a local callback server or retry connect on 401. If t
#### OAuth callback URL
| Surface | Default callback |
| ------- | ---------------- |
| **Web** | `http://localhost:6274/oauth/callback` |
| **TUI** | `http://127.0.0.1:6276/oauth/callback` (interactive — callback server) |
| Surface | Default callback |
| ------- | ----------------------------------------------------------------------------------------- |
| **Web** | `http://localhost:6274/oauth/callback` |
| **TUI** | `http://127.0.0.1:6276/oauth/callback` (interactive — callback server) |
| **CLI** | `http://127.0.0.1:6276/oauth/callback` (redirect URI in OAuth metadata only; no listener) |
Register `http://127.0.0.1:6276/oauth/callback` on static or enterprise IdPs that require pre-registered redirect URIs before using the **TUI** (or when your OAuth app expects that URI). Override with `--callback-url` or `MCP_OAUTH_CALLBACK_URL`. The CLI passes this value as `redirect_uri` when an OAuth flow runs, but does not listen on the port.
#### Flags
| Option | Env | Description |
| ------ | --- | ----------- |
| `--client-config <path>` | `MCP_CLIENT_CONFIG_PATH` | Install-level client config (default: `~/.mcp-inspector/storage/client.json`). |
| `--client-id <id>` | — | OAuth client ID (static client); overrides `client.json`. |
| `--client-secret <secret>` | — | OAuth client secret; overrides `client.json`. |
| `--client-metadata-url <url>` | — | CIMD metadata URL; overrides `client.json`. |
| `--callback-url <url>` | `MCP_OAUTH_CALLBACK_URL` | Redirect URI sent to the authorization server (default: `http://127.0.0.1:6276/oauth/callback`). |
| Option | Env | Description |
| ----------------------------- | ------------------------ | ------------------------------------------------------------------------------------------------ |
| `--client-config <path>` | `MCP_CLIENT_CONFIG_PATH` | Install-level client config (default: `~/.mcp-inspector/storage/client.json`). |
| `--client-id <id>` | — | OAuth client ID (static client); overrides `client.json`. |
| `--client-secret <secret>` | — | OAuth client secret; overrides `client.json`. |
| `--client-metadata-url <url>` | — | CIMD metadata URL; overrides `client.json`. |
| `--callback-url <url>` | `MCP_OAUTH_CALLBACK_URL` | Redirect URI sent to the authorization server (default: `http://127.0.0.1:6276/oauth/callback`). |
**Example** — list tools on an OAuth-protected server using stored tokens and CIMD from the command line:

10
clients/cli/package-lock.json generated
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@ -15,6 +15,7 @@
"atomically": "^2.1.1",
"commander": "^13.1.0",
"pino": "^9.14.0",
"undici": "^8.5.0",
"zod": "^4.3.6",
"zustand": "^5.0.13"
},
@ -5378,6 +5379,15 @@
"dev": true,
"license": "MIT"
},
"node_modules/undici": {
"version": "8.5.0",
"resolved": "https://registry.npmjs.org/undici/-/undici-8.5.0.tgz",
"integrity": "sha512-xamtWoB1EshgjpmlXd7GGm2VfdDtw1+rD8uhry8pSNW3If6S8E0m2T2+orSKeZXEn/aPJMviCpDBA65WJt8zhg==",
"license": "MIT",
"engines": {
"node": ">=22.19.0"
}
},
"node_modules/undici-types": {
"version": "7.18.2",
"resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.18.2.tgz",

1
clients/cli/package.json
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@ -38,6 +38,7 @@
"atomically": "^2.1.1",
"commander": "^13.1.0",
"pino": "^9.14.0",
"undici": "^8.5.0",
"zod": "^4.3.6",
"zustand": "^5.0.13"
},