allow pid creation as ruby user

Dockerfile

@@ -9,6 +9,8 @@ RUN <<EOT
   apk upgrade --no-cache
 EOT
 
+RUN mkdir -p /run/app
+
 
 FROM base AS build
 
@@ -39,6 +41,8 @@ FROM base
 RUN adduser ruby -h /app -D
 USER ruby:ruby
 
+RUN mkdir -p /run/app
+
 COPY --from=build /usr/local/bundle /usr/local/bundle
 COPY --from=build --chown=ruby:ruby /app /app
 

config/puma.rb

@@ -1,3 +1,3 @@
 # workers 3
-pidfile '/run/pid'
+pidfile '/run/app/pid'
 preload_app!