Allow setting config URL with <link> (#1146)

* fix: allows for valid config types expansion

* feat: config url can now come through link tag

* fix: lints added coded

* fix: slims down code per review

* fix: expands query to find supported type

* fix: removes typo in test copy

* fix: changes validTypes to object

* fix: groups config functions into one getConfig func

* adds console message for config url

* adds to docs

* update docs

* fix test

* fix merge conflicts

contributor addition moved to #1241

* avoids empty path with link without href. changes link console message

* removes additional console

* fixes link path in console

* fix: remove superfluous .allcontributorsrc change

example/index.html

@@ -7,6 +7,15 @@
 
   <link href='https://fonts.googleapis.com/css?family=Roboto:300,400,500' rel='stylesheet' type='text/css'>
   <link rel="stylesheet" href="/cms.css"/>
+  <!--
+  Netlify CMS will automatically look for a "config.yml" file in the same directory
+  as this "index.html", but you can override this by providing a link tag like this
+  one:
+  
+  <link href="path/to/config.yml" type="text/yaml" rel="cms-config-url">
+-->
+
+
   <script>
   window.repoFiles = {
     _posts: {

src/actions/config.js

@@ -1,6 +1,6 @@
 import yaml from "js-yaml";
 import { Map, List, fromJS } from "immutable";
-import { trimStart, flow, isBoolean } from "lodash";
+import { trimStart, flow, isBoolean, get } from "lodash";
 import { authenticateUser } from "Actions/auth";
 import * as publishModes from "Constants/publishModes";
 
@@ -9,6 +9,19 @@ export const CONFIG_SUCCESS = "CONFIG_SUCCESS";
 export const CONFIG_FAILURE = "CONFIG_FAILURE";
 export const CONFIG_MERGE = "CONFIG_MERGE";
 
+
+const getConfigUrl = () => {
+  const validTypes = { 'text/yaml': 'yaml', 'application/x-yaml': 'yaml' };
+  const configLinkEl = document.querySelector('link[rel="cms-config-url"]');
+  const isValidLink = configLinkEl && validTypes[configLinkEl.type] && get(configLinkEl, 'href');
+  if (isValidLink) {
+    const link = get(configLinkEl, 'href');
+    console.log(`Using config file path: "${link}"`);
+    return link;
+  }
+  return 'config.yml';
+}
+
 const defaults = {
   publish_mode: publishModes.SIMPLE,
 };
@@ -130,7 +143,8 @@ export function loadConfig() {
 
     try {
       const preloadedConfig = getState().config;
-      const loadedConfig = await getConfig('config.yml', preloadedConfig && preloadedConfig.size > 1);
+      const configUrl = getConfigUrl();
+      const loadedConfig = await getConfig(configUrl, preloadedConfig && preloadedConfig.size > 1);
 
       /**
        * Merge any existing configuration so the result can be validated.

website/site/content/docs/configuration-options.md

@@ -7,6 +7,14 @@ position: 23
 
 All configuration options for Netlify CMS are specified in the `config.yml` file, in the folder where you access the editor UI (usually in the `/admin` folder).
 
+Alternatively, you can specify a custom config file using a link tag:
+
+```html
+<!-- Note the "type" and "rel" attribute values, which are required. -->
+
+<link href="path/to/config.yml" type="text/yaml" rel="cms-config-url">
+```
+
 To see working configuration examples, you can [start from a template](https://www.netlifycms.org/docs/start-with-a-template) or check out the [CMS demo site](https://cms-demo.netlify.com). (No login required: click the login button and the CMS will open.) You can refer to the demo [configuration code](https://github.com/netlify/netlify-cms/blob/master/example/config.yml) to see how each option was configured.
 
 You can find details about all configuration options below. Note that [YAML syntax](https://en.wikipedia.org/wiki/YAML#Basic_components) allows lists and objects to be written in block or inline style, and the code samples below include a mix of both.