Update drone to use docker image

.drone.yml

@@ -1,11 +1,15 @@
 ---
 kind: pipeline
-type: exec
+type: docker
 name: dnscontrol
 
+workspace:
+  path: /dns
+
 steps:
 
  - name: preview
+   image: stackexchange/dnscontrol
    environment:
      PDNS_API_KEY:
        from_secret: PDNS_API_KEY   
@@ -15,6 +19,7 @@ steps:
     - dnscontrol preview
    
  - name: push
+   image: stackexchange/dnscontrol
    environment:
      PDNS_API_KEY:
        from_secret: PDNS_API_KEY   
@@ -24,3 +29,18 @@ steps:
     - dnscontrol push
    when:
      branch: master
+
+---
+kind: secret
+name: PDNS_API_KEY
+get:
+  path: burble.dn42/kv/data/drone/dns
+  name: PDNS_API_KEY
+
+---
+kind: secret
+name: CLOUDFLARE_API_KEY
+get:
+  path: burble.dn42/kv/data/drone/dns
+  name: CLOUDFLARE_API_KEY
+