Moved LD_PRELOAD variable initialization to the Dockerfile from the entrypoint

Author: igor-alexandrov

railties/lib/rails/generators/rails/app/templates/Dockerfile.tt

@@ -17,13 +17,15 @@ WORKDIR /rails
 # Install base packages
 RUN apt-get update -qq && \
     apt-get install --no-install-recommends -y <%= dockerfile_base_packages.join(" ") %> && \
+    ln -s /usr/lib/$(uname -m)-linux-gnu/libjemalloc.so.2 /usr/local/lib/libjemalloc.so && \
     rm -rf /var/lib/apt/lists /var/cache/apt/archives
 
-# Set production environment
+# Set production environment variables and enable jemalloc for reduced memory usage and latency.
 ENV RAILS_ENV="production" \
     BUNDLE_DEPLOYMENT="1" \
     BUNDLE_PATH="/usr/local/bundle" \
-    BUNDLE_WITHOUT="development"
+    BUNDLE_WITHOUT="development" \
+    LD_PRELOAD=/usr/local/lib/libjemalloc.so
 
 # Throw-away build stage to reduce size of final image
 FROM base AS build

railties/lib/rails/generators/rails/app/templates/docker-entrypoint.tt

@@ -1,11 +1,5 @@
 #!/bin/bash -e
 
-# Enable jemalloc for reduced memory usage and latency.
-if [ -z "${LD_PRELOAD+x}" ]; then
-    LD_PRELOAD=$(find /usr/lib -name libjemalloc.so.2 -print -quit)
-    export LD_PRELOAD
-fi
-
 <% unless skip_active_record? -%>
 # If running the rails server then create or migrate existing database
 if [ "${@: -2:1}" == "./bin/rails" ] && [ "${@: -1:1}" == "server" ]; then