use drone cache

.drone.yml

@@ -3,6 +3,20 @@ type: docker
 name: default
 
 steps:
+- name: restore-cache-with-filesystem
+  image: meltwater/drone-cache
+  settings:
+    backend: "filesystem"
+    restore: true
+    cache_key: "{{ .Repo.Name }}"
+    archive_format: "gzip"
+    filesystem_cache_root: "/tmp/cache"
+    mount:
+      - '.pipcache'
+  volumes:
+  - name: cache
+    path: /tmp/cache
+
 - name: static_analysis
   image: python:3
   commands:
@@ -34,6 +48,21 @@ steps:
   - cd docs
   - make html
 
+- name: rebuild-cache-with-filesystem
+  image: meltwater/drone-cache
+  pull: true
+  settings:
+    backend: "filesystem"
+    rebuild: true
+    cache_key: "{{ .Repo.Name }}"
+    archive_format: "gzip"
+    filesystem_cache_root: "/tmp/cache"
+    mount:
+      - '.pipcache'
+  volumes:
+  - name: cache
+    path: /tmp/cache
+
 - name: build_docs
   image: docker:stable-dind
   volumes:
@@ -73,3 +102,6 @@ services:
 volumes:
 - name: dockersock
   temp: {}
+- name: cache
+  host:
+    path: "/tmp/cache"