Added the cookie-suffix flag and environment variable.

Fixes #7544 but is it the best way?

src/common/http.ts

@@ -24,6 +24,6 @@ export class HttpError extends Error {
   }
 }
 
-export enum CookieKeys {
-  Session = "code-server-session",
+export const CookieKeys = {
+  Session: `code-server-session${process.env?.COOKIE_SUFFIX ? "-" + process.env?.COOKIE_SUFFIX : ""}`,
 }

src/node/cli.ts

@@ -53,6 +53,7 @@ export interface UserProvidedCodeArgs {
   "disable-getting-started-override"?: boolean
   "disable-proxy"?: boolean
   "session-socket"?: string
+  "cookie-suffix"?: string
   "link-protection-trusted-domains"?: string[]
   // locale is used by both VS Code and code-server.
   locale?: string
@@ -172,6 +173,12 @@ export const options: Options<Required<UserProvidedArgs>> = {
   "session-socket": {
     type: "string",
   },
+  "cookie-suffix": {
+    type: "string",
+    description:
+      "Adds a suffix to the cookie. This can prevent a collision of cookies for subdomains, making them explixit. \n" +
+      "Without this flag, no suffix is used. This can also be set with COOKIE_SUFFIX set to any string.",
+  },
   "disable-file-downloads": {
     type: "boolean",
     description:
@@ -616,6 +623,10 @@ export async function setDefaults(cliArgs: UserProvidedArgs, configArgs?: Config
     usingEnvPassword = false
   }
 
+  if (process.env.COOKIE_SUFFIX) {
+    args["cookie-suffix"] = process.env.COOKIE_SUFFIX
+  }
+
   if (process.env.GITHUB_TOKEN) {
     args["github-auth"] = process.env.GITHUB_TOKEN
   }