Initial commit of Go NPM

Allows you to distribute and install Go binaries through NPM.

.gitignore

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+.idea
+node_modules

README.md

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+# Go NPM
+### Distribute cross-platform Go binaries via NPM

example/package.json

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+{
+  "name": "app",
+  "version": "0.0.1",
+  "description": "Example App",
+  "main": "index.js",
+  "scripts": {
+    "install": "go-npm"
+  },
+  "bin": {
+    "myBinaryName": "./bin"
+  },
+  "goBinary": {
+    "name": "myBinaryName",
+    "path": "./bin",
+    "url": "https://github.com/user/myrepo/releases/download/v{{version}}/myBinaryName{{platform}}_{{arch}}.tar.gz"
+  }
+}

index.js

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+#!/usr/bin/env node
+
+"use strict"
+
+const request = require('request'),
+    path = require('path'),
+    tar = require('tar'),
+    zlib = require('zlib'),
+    mkdirp = require('mkdirp'),
+    fs = require('fs');
+
+// Mapping from Node's `process.arch` to Golang's `$GOARCH`
+const ARCH_MAPPING = {
+    "ia32": "386",
+    "x64": "amd64",
+    "arm": "arm"
+};
+
+// Mapping between Node's `process.platform` to Golang's 
+const PLATFORM_MAPPING = {
+    "darwin": "darwin",
+    "linux": "linux",
+    "win32": "windows",
+    "freebsd": "freebsd"
+};
+
+function verifyBinary(binName, binPath, callback) {
+    if (!fs.existsSync(path.join(binPath, binName))) return callback(`Downloaded binary does not contain the binary specified in configuration - ${binName}`);
+
+    return callback(null);
+}
+
+function validateConfiguration(packageJson) {
+
+    if (!packageJson.version) {
+        return "'version' property must be specified";
+    }
+
+    if (!packageJson.goBinary || typeof(packageJson.goBinary) !== "object") {
+        return "'goBinary' property must be defined and be an object";
+    }
+
+    if (!packageJson.goBinary.name) {
+        return "'name' property is necessary";
+    }
+
+    if (!packageJson.goBinary.path) {
+        return "'path' property is necessary";
+    }
+
+    if (!packageJson.goBinary.url) {
+        return "'url' property is required";
+    }
+
+    if (!packageJson.bin || typeof(packageJson.bin) !== "object") {
+        return "'bin' property of package.json must be defined and be an object";
+    }
+
+    if (packageJson.goBinary.path !== packageJson.bin[packageJson.goBinary.name]) {
+        return "'bin' property must be a map from 'name' to 'path'. This is necessary for NPM Global install to work";
+    }
+}
+
+/**
+ * Reads the configuration from application's package.json,
+ * validates properties, downloads the binary, untars, and stores at
+ * ./bin in the package's root. NPM already has support to install binary files
+ * specific locations when invoked with "npm install -g"
+ *
+ *  See: https://docs.npmjs.com/files/package.json#bin
+ */
+const INVALID_INPUT = "Invalid inputs";
+function install(callback) {
+    if (!(process.arch in ARCH_MAPPING)) {
+        console.error("Installation is not supported for this architecture: " + process.arch);
+        return callback(INVALID_INPUT);
+    }
+
+    if (!(process.platform in PLATFORM_MAPPING)) {
+        console.error("Installation is not supported for this platform: " + process.platform);
+        return callback(INVALID_INPUT);
+    }
+
+    const packageJsonPath = path.join(".", "package.json");
+    if (!fs.existsSync(packageJsonPath)) {
+        console.error("Unable to find package.json. " +
+            "Please run this script at root of the package you want to be installed");
+        return callback(INVALID_INPUT);
+    }
+
+    let packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
+    let error = validateConfiguration(packageJson);
+    if (error && error.length > 0) {
+        console.error("Invalid package.json: " + error);
+        return callback(INVALID_INPUT);
+    }
+
+    // We have validated the config. It exists in all its glory
+    let binName = packageJson.goBinary.name;
+    let binPath = packageJson.goBinary.path;
+    let url = packageJson.goBinary.url;
+    let version = packageJson.version;
+    if (version[0] === 'v') version = version.substr(1);  // strip the 'v' if necessary v0.0.1 => 0.0.1
+
+    // Interpolate variables in URL, if necessary
+    url = url.replace("{{arch}}", ARCH_MAPPING[process.arch]);
+    url = url.replace("{{platform}}", PLATFORM_MAPPING[process.platform]);
+    url = url.replace("{{version}}", version);
+    url = url.replace("{{bin_name}}", binName);
+
+
+    mkdirp.sync(binPath);
+    let ungz = zlib.createGunzip();
+    let untar = tar.Extract({path: binPath});
+
+    ungz.on('error', callback);
+    untar.on('error', callback);
+
+    // First we will Un-GZip, then we will untar. So once untar is completed,
+    // binary is downloaded into `binPath`. Verify the binary and call it good
+    untar.on('end', verifyBinary.bind(null, binName, binPath, callback));
+
+    console.log("Downloading from URL: " + url);
+    let req = request({uri: url});
+    req.on('error', callback.bind(null, "Error downloading from URL: " + url));
+    req.on('response', function(res) {
+        if (res.statusCode !== 200) return callback("Error downloading binary. HTTP Status Code: " + res.statusCode);
+
+        req.pipe(ungz).pipe(untar);
+    })
+}
+
+
+install(function(err) {
+    if (err) {
+        console.error(err);
+        process.exit(1);
+    } else {
+        process.exit(0);
+    }
+});
+

package.json

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+{
+  "name": "go-npm",
+  "version": "0.1.0",
+  "description": "Distribute and install Go binaries via NPM",
+  "main": "index.js",
+  "bin": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "Sanath Kumar Ramesh <dayanandasaraswati@gmail.com>",
+  "license": "Apache-2.0",
+  "dependencies": {
+    "mkdirp": "^0.5.1",
+    "request": "^2.81.0",
+    "tar": "^2.2.1"
+  }
+}