Add support for SENTRY_URL (fixes GH-29)

Author: dcramer

Diff for: README.md

@@ -9,6 +9,14 @@ It is based on [Cloudflare's work towards remote MCPs](https://blog.cloudflare.c
 
 ## Getting Started
 
+### Self-Hosted Sentry
+
+You can override the `SENTRY_URL` env variable to set your base Sentry url:
+
+```shell
+SENTRY_URL=https://sentry.mycompany.com
+```
+
 ### MCP Inspector
 
 MCP includes an [Inspector](https://modelcontextprotocol.io/docs/tools/inspector), to easily test the service:

Diff for: src/lib/sentry-api.ts

@@ -1,7 +1,7 @@
 import { z } from "zod";
 import { logError } from "./logging";
 
-const API_BASE_URL = "https://sentry.io/api/0";
+const API_BASE_URL = new URL("/api/0", process.env.SENTRY_URL || "https://sentry.io");
 
 export const SentryOrgSchema = z.object({
   id: z.string(),

Diff for: src/routes/auth.ts

@@ -4,8 +4,8 @@ import { exchangeCodeForAccessToken, getUpstreamAuthorizeUrl } from "../lib/oaut
 import type { Props } from "../types";
 import { SentryApiService } from "../lib/sentry-api";
 
-export const SENTRY_AUTH_URL = "https://sentry.io/oauth/authorize/";
-export const SENTRY_TOKEN_URL = "https://sentry.io/oauth/token/";
+export const SENTRY_AUTH_URL = "/oauth/authorize/";
+export const SENTRY_TOKEN_URL = "/oauth/token/";
 // https://docs.sentry.io/api/permissions/
 export const SCOPES = "org:read project:read project:write team:read team:write event:read";
 
@@ -14,6 +14,7 @@ export default new Hono<{
     OAUTH_PROVIDER: OAuthHelpers;
     SENTRY_CLIENT_ID: string;
     SENTRY_CLIENT_SECRET: string;
+    SENTRY_URL: string;
   };
 }>()
   /**
@@ -34,7 +35,7 @@ export default new Hono<{
 
     return Response.redirect(
       getUpstreamAuthorizeUrl({
-        upstream_url: SENTRY_AUTH_URL,
+        upstream_url: new URL(SENTRY_AUTH_URL, c.env.SENTRY_URL || "https://sentry.io").href,
         scope: SCOPES,
         client_id: c.env.SENTRY_CLIENT_ID,
         redirect_uri: new URL("/callback", c.req.url).href,
@@ -60,7 +61,7 @@ export default new Hono<{
 
     // Exchange the code for an access token
     const [payload, errResponse] = await exchangeCodeForAccessToken({
-      upstream_url: SENTRY_TOKEN_URL,
+      upstream_url: new URL(SENTRY_TOKEN_URL, c.env.SENTRY_URL || "https://sentry.io").href,
       client_id: c.env.SENTRY_CLIENT_ID,
       client_secret: c.env.SENTRY_CLIENT_SECRET,
       code: c.req.query("code"),