Set site environment variables in local dev

We'll want more control over this in the future, especially in terms of
distinguishing between dev context and production context.

For now this is a starting point.

With this change any locally defined environment variable will also take
precendence over any env var set in the site settings or from an addon

Author: biilmann

src/commands/dev/index.js

@@ -125,9 +125,19 @@ class DevCommand extends Command {
           addon.slug
         }`
         for (const key in addon.env) {
-          process.env[key] = addon.env[key]
+          process.env[key] = process.env[key] || addon.env[key]
         }
       })
+      const api = this.netlify.api
+      const apiSite = await api.getSite({site_id: site.id})
+      // TODO: We should move the environment outside of build settings and possibly have a
+      // `/api/v1/sites/:site_id/environment` endpoint for it that we can also gate access to
+      // In the future and that we could make context dependend
+      if (apiSite.build_settings && apiSite.build_settings.env) {
+        for (const key in apiSite.build_settings.env) {
+          process.env[key] = process.env[key] || apiSite.build_settings.env[key]
+        }
+      }
     }
     let settings = serverSettings()
     if (!(settings && settings.cmd)) {