Initial version

.gitignore

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+*.swp
+
+node_modules/

LICENSE

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+The MIT License (MIT)
+Copyright (c) 2016 Arts Alliance Media
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is furnished
+to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE.

Readme.md

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+MkConf
+======
+Generate configuration files dynamically.
+
+`MkConf` is a tool to generate configuration files out of templates
+and environment variables.
+
+
+Quick start
+-----------
+```bash
+npm install -g github:artsalliancemedia/mk-config
+mkconf --help
+# Usage: node mkconf
+#
+# -h, --help           display this help
+# -e, --env-map=FILE   JSON map from environment variables to template variables
+# -d, --defaults=FILE  JSON file with the default data to pass to the template
+# -i, --input=FILE     Read the template from FILE, defaults to stdin
+# -o, --output=FILE    Write the rendered data to FILE, defaults to stdout
+
+mkconf --defaults=config.json --env-map=overrides.json --input=config.template > out.config
+mkconf --defaults=config.json --env-map=overrides.json --input=config.template --output=out.config
+```
+
+### Examples
+The following examples are based on the input files listed here:
+
+  * `config.json`:
+    ```json
+    {
+      "db-name": "myapp",
+      "bind-ip": "127.0.0.1"
+    }
+    ```
+
+  * `overrides.json`:
+    ```json
+    {
+      "db-name": "DB_NAME"
+    }
+    ```
+
+  * `config.template`:
+    ```text
+    [app]
+    bind = {{ bind-ip }}
+
+    [db]
+    name = {{ db-name }}
+    ```
+
+#### Clean environment
+In this example the environment variable `DB_NAME` is not set.
+```bash
+mkconf --defaults=config.json --env-map=overrides.json --input=config.template --output=out.config
+cat out.config
+[app]
+bind = 127.0.0.1
+
+[db]
+name = myapp
+```
+
+#### Environment override
+If the environment variable `DB_NAME` is instead set,
+the value in it will be used instead of the default:
+```bash
+export DB_NAME="mytest"
+mkconf --defaults=config.json --env-map=overrides.json --input=config.template --output=out.config
+cat out.config
+[app]
+bind = 127.0.0.1
+
+[db]
+name = mytest
+```

bin/mkconf

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+#!/bin/env node
+
+// Build CLI parser.
+var getopt = require("node-getopt");
+var parser = getopt.create([
+  ["h", "help", "display this help"],
+
+  ["e", "env-map=FILE", "JSON map from environment variables to template variables"],
+  ["d", "defaults=FILE", "JSON file with the default data to pass to the template"],
+
+  ["i", "input=FILE", "Read the template from FILE, defaults to stdin"],
+  ["o", "output=FILE", "Write the rendered data to FILE, defaults to stdout"]
+
+]).bindHelp();
+
+
+// Parse options.
+var opts = parser.parseSystem();
+var options = {
+  "env-map":  opts.options["env-map"],
+  "defaults": opts.options.defaults,
+  "input":  opts.options.input,
+
+  "output": opts.options.output || "-"
+}
+
+if (!options.defaults) {
+  console.error("Missing required --defaults option.");
+  process.exit(1)
+}
+if (!options["env-map"]) {
+  console.error("Missing required --env-map option.");
+  process.exit(1)
+}
+if (!options.input) {
+  console.error("Missing required --input option.");
+  process.exit(1)
+}
+
+var MkConf = require("../lib/mkconf");
+var mkconf = new MkConf(options);
+mkconf.make();

lib/mkconf.js

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+var fs = require("fs");
+var Handlebars = require("handlebars");
+
+
+// Create a new template processor.
+var MkConf = module.exports = function MkConf(options) {
+  this._options = options;
+  this._engine = Handlebars.create();
+};
+
+
+// Read and parse JSON defaults.
+MkConf.prototype._getDefaults = function _getDefaults() {
+  var raw = fs.readFileSync(this._options.defaults);
+  return JSON.parse(raw);
+};
+
+// Read and parse JSON env-map, then update template data.
+MkConf.prototype._getEnvironment = function _getEnvironment(data) {
+  var raw = fs.readFileSync(this._options["env-map"]);
+  var env = JSON.parse(raw);
+
+  Object.keys(env).forEach(function(data_name) {
+    var env_name = env[data_name];
+    if (process.env.hasOwnProperty(env_name)) {
+      data[data_name] = process.env[env_name];
+    }
+  });
+
+  return data;
+};
+
+
+// Read the template from file or stdin.
+MkConf.prototype._getTemplate = function _getTemplate(callback) {
+  return fs.readFileSync(this._options.input, { encoding: "utf-8" });
+};
+
+// Compile the template and render it with the data.
+MkConf.prototype._render = function _render(source, data) {
+  var template = this._engine.compile(source, { noEscape: true });
+  return template(data);
+};
+
+
+// Write the output to stdout/stderr.
+MkConf.prototype._write = function _write(data) {
+  if (this._options.output === "-") {
+    process.stdout.write(data);
+
+  } else {
+    fs.writeFileSync(this._options.output, data);
+  }
+};
+
+
+// Load template and render it.
+MkConf.prototype.make = function make() {
+  // Load data.
+  var data = this._getDefaults();
+  this._getEnvironment(data);
+
+  // Render template.
+  var template = this._getTemplate();
+  var output = this._render(template, data);
+
+  // Write output.
+  this._write(output);
+};

package.json

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+{
+  "name": "mkconf",
+  "version": "0.0.0",
+  "description": "Generate configuration files dynamically",
+  "author": "Stefano Pogliani <[email protected]",
+
+  "bin": {
+    "mkconf": "./bin/mkconf"
+  },
+
+  "main": "lib/mkconf.js",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/artsalliancemedia/mk-config.git"
+  },
+
+  "keywords": [
+    "configuration",
+    "handlebars",
+    "template"
+  ],
+
+  "dependencies": {
+    "handlebars": "~4.0.5",
+    "node-getopt": "~0.2.3"
+  },
+
+  "license": "MIT"
+}