Added entrypoint.sh to support cluster and standalone

Dockerfile

+FROM alpine:3.9
+
+MAINTAINER Opstree Solutions
+
+LABEL VERSION=1.0 \
+      ARCH=AMD64 \
+      DESCRIPTION="A production grade performance tuned docker image created by Opstree Solutions"
+
+ARG REDIS_DOWNLOAD_URL="http://download.redis.io/"
+
+ARG REDIS_VERSION="stable"
+
+COPY redis.conf /etc/redis/redis.conf
+
+COPY entrypoint.sh /usr/bin/entrypoint.sh
+
+RUN addgroup -S -g 1000 redis && adduser -S -G redis -u 999 redis && \
+    apk add --no-cache su-exec tzdata make curl build-base linux-headers
+
+RUN curl -fL -Lo /tmp/redis-${REDIS_VERSION}.tar.gz ${REDIS_DOWNLOAD_URL}/redis-${REDIS_VERSION}.tar.gz && \
+    cd /tmp && \
+    tar xvzf redis-${REDIS_VERSION}.tar.gz && \
+    cd redis-${REDIS_VERSION} && \
+    make && \
+    make install && \
+    mkdir -p /etc/redis && \
+    cp -f *.conf /etc/redis && \
+    rm -rf /tmp/redis-${REDIS_VERSION}*
+
+VOLUME ["/data"]
+
+WORKDIR /data
+
+EXPOSE 6379
+
+ENTRYPOINT ["/usr/bin/entrypoint.sh"]

entrypoint.sh

+#!/bin/sh
+
+set -eu
+
+set_redis_password() {
+    if [ -z "${REDIS_PASSWORD}" ]; then
+        echo "Redis is running without password which is not recommended"
+    else
+        {
+            echo masterauth "${REDIS_PASSWORD}"
+            echo requirepass "${REDIS_PASSWORD}"
+        } >> /etc/redis/redis.conf
+    fi
+}
+
+redis_mode_setup() {
+    if [ "${SETUP_MODE}" = "cluster" ]; then
+        {
+            echo cluster-enabled yes
+            echo cluster-config-file nodes.conf
+            echo cluster-node-timeout 5000
+        } >> /etc/redis/redis.conf
+    else
+        echo "Setting up redis in standalone mode"
+    fi
+}
+
+start_redis() {
+    echo "Starting redis service "
+    redis-server /etc/redis/redis.conf
+}
+
+main_function() {
+    set_redis_password
+    redis_mode_setup
+    start_redis
+}
+
+main_function

redis.conf

+bind 0.0.0.0
+protected-mode yes
+tcp-backlog 511
+timeout 0
+tcp-keepalive 300
+daemonize no
+supervised no
+pidfile /var/run/redis.pid