use node_modules by default, clarify README

README.md

@@ -17,15 +17,24 @@ You have many options to install wrangler!
 
 ### Install with `npm`
 
-We strongly recommend you install `npm` with a Node version manager like [`nvm`](https://github.com/nvm-sh/nvm#installing-and-updating), which will allow `wrangler` to install configuration data in a global `node_modules` directory in your user's home directory, without requiring that you run as `root`. 
+We strongly recommend you install `npm` with a Node version manager like [`nvm`](https://github.com/nvm-sh/nvm#installing-and-updating), which puts the global `node_modules` in your home directory to eliminate permissions issues with `npm install -g`. Distribution-packaged `npm` installs often use `/usr/lib/node_modules` (which is root) for globally installed `npm` packages, and running `npm install -g` as `root` prevents `wrangler` from installing properly.
 
-Once you've installed `nvm`, run:
+
+Once you've installed `nvm` and configured your system to use the `nvm` managed node install, run:
 
 ```bash
 npm i @cloudflare/wrangler -g
 ```
+
 If you are running an ARM based system (eg Raspberry Pi, Pinebook) you'll need to use the `cargo` installation method listed below to build wrangler from source.
 
+#### Specify binary location
+
+In case you need `wrangler`'s npm installer to place the binary in a non-default location (such as when using `wrangler` in CI), you can use the following configuration options to specify an install location:
+
+- Environment variable: `WRANGLER_INSTALL_PATH`
+- NPM configuration: `wrangler_install_path`
+
 #### Specify binary site URL
 
 In case you need to store/mirror binaries on premise you will need to specify where wrangler should search for them by providing any of the following:

npm/binary.js

@@ -32,10 +32,10 @@ const getBinary = () => {
   const version = require("./package.json").version;
   const url = getBinaryURL(version, platform);
 
-  const useCwd = !!process.env.WRANGLER_USE_CWD;
-  const customPath = process.env.WRANGLER_INSTALL_PATH;
-  const altPath = useCwd ? process.cwd() : !!customPath ? customPath : false;
-  const installDirectory = join(altPath || os.homedir(), ".wrangler");
+  const customPath =
+    process.env.WRANGLER_INSTALL_PATH ||
+    process.env.npm_config_wrangler_install_path;
+  const installDirectory = join(customPath || __dirname, "wrangler");
   return new Binary(url, { name: "wrangler", installDirectory });
 };