fix config and setup script

.contentful.json.sample

@@ -1,11 +1,4 @@
 {
-  "development": {
-    "host": "preview.contentful.com",
-    "spaceId": "...",
-    "accessToken": "..."
-  },
-  "production": {
-    "spaceId": "...",
-    "accessToken": "..."
-  }
-}
+  "spaceId": "...",
+  "accessToken": "..."
+}

README.md

@@ -12,7 +12,7 @@ With Contentful and Gatsby you can connect your favorite static site generator w
 
 * Simple content model and structure. Easy to adjust to your needs.
 * Contentful integration using our [Sync API](https://www.contentful.com/developers/docs/references/content-delivery-api/#/reference/synchronization/initial-synchronization-of-entries-of-a-specific-content-type)
-* Using our [Preview API](https://www.contentful.com/developers/docs/references/content-preview-api/) for development and our [Delivery API](https://www.contentful.com/developers/docs/references/content-delivery-api/) for production.
+* Using our [Delivery API](https://www.contentful.com/developers/docs/references/content-delivery-api/).
 * Responsive/adaptive images via [gatsby-image](https://www.gatsbyjs.org/packages/gatsby-image/)
 
 ## Contribution
@@ -44,7 +44,7 @@ This project comes with a Contentful setup command `npm run setup`.
 
 ![Command line dialog of the npm run setup command](https://rawgit.com/contentful-userland/gatsby-contentful-starter/master/setup.jpg "Command line dialog of the npm run setup command")
 
-This command will ask you for a space ID, and access tokens for the Contentful Management, Preview and Delivery API and then import the needed content model into the space you define and write a config file (`./contentful.json`).
+This command will ask you for a space ID, and access tokens for the Contentful Management and Delivery API and then import the needed content model into the space you define and write a config file (`./contentful.json`).
 
 `npm run setup` automates that for you but if you want to do it yourself rename `.contentful.json.sample` to `.contentful.json` and add your configuration in this file.
 
@@ -54,7 +54,7 @@ This project comes with a few handy commands for linting and code fixing. The mo
 
 ### `npm run dev`
 
-Run in the project locally using the [Contentful Preview API](https://www.contentful.com/developers/docs/references/content-preview-api/). This can perfect to preview changes before they go into production.
+Run in the project locally.
 
 ### `npm run build`
 

gatsby-config.js

@@ -1,23 +1,22 @@
 let contentfulConfig
 
 try {
-  const configFile = require('./.contentful')
-  contentfulConfig = process.env.NODE_ENV === 'production'
-    ? configFile.production
-    : configFile.development
-} catch (_) {
-  contentfulConfig = {
-    spaceId: process.env.CONTENTFUL_SPACE_ID,
-    accessToken: process.env.CONTENTFUL_DELIVERY_TOKEN,
-  }
-} finally {
-  const { spaceId, accessToken } = contentfulConfig
+  // Load the Contentful config from the .contentful.json
+  contentfulConfig = require('./.contentful')
+} catch (_) {}
 
-  if (!spaceId || !accessToken) {
-    throw new Error(
-      'Contentful spaceId and the delivery token need to be provided.'
-    )
-  }
+// Overwrite the Contentful config with environment variables if they exist
+contentfulConfig = {
+  spaceId: process.env.CONTENTFUL_SPACE_ID || contentfulConfig.spaceId,
+  accessToken: process.env.CONTENTFUL_DELIVERY_TOKEN || contentfulConfig.accessToken,
+}
+
+const { spaceId, accessToken } = contentfulConfig
+
+if (!spaceId || !accessToken) {
+  throw new Error(
+    'Contentful spaceId and the delivery token need to be provided.'
+  )
 }
 
 module.exports = {