S3-compatible object storage API (#2720)

* s3 active_storage

* updated readme

config/environments/production.rb

@@ -63,6 +63,8 @@ Rails.application.configure do
   # Store uploaded files on the local file system (see config/storage.yml for options)
   config.active_storage.service = if ENV["AWS_ACCESS_KEY_ID"].present?
                                     :amazon
+                                  elsif ENV["S3_ACCESS_KEY_ID"].present?
+                                    :s3
                                   elsif ENV["GCS_PRIVATE_KEY_ID"].present?
                                     :google
                                   else

config/storage.yml

@@ -13,6 +13,13 @@ amazon:
   secret_access_key: <%= ENV['AWS_SECRET_ACCESS_KEY'] %>
   region: <%= ENV['AWS_REGION'] %>
   bucket: <%= ENV['AWS_BUCKET'] %>
+s3:
+  service: S3
+  endpoint: <%= ENV['S3_ENDPOINT'] %>
+  access_key_id: <%= ENV['S3_ACCESS_KEY_ID'] %>
+  secret_access_key: <%= ENV['S3_SECRET_ACCESS_KEY'] %>
+  region: <%= ENV['S3_REGION'] %>
+  bucket: <%= ENV['S3_BUCKET'] %>
 
 # Remember not to checkin your GCS keyfile to a repository
 google:

sample.env

@@ -326,6 +326,13 @@ DEFAULT_REGISTRATION=open
 # AWS_REGION=
 # AWS_BUCKET=
 #
+# For S3-compatible API:
+# S3_ENDPOINT=
+# S3_ACCESS_KEY_ID=
+# S3_SECRET_ACCESS_KEY=
+# S3_REGION=
+# S3_BUCKET=
+#
 # For GCS Storage:
 # GCS_PROJECT_ID=
 # GCS_PRIVATE_KEY_ID=