Run process with non-root user in docker container

Question

I'm building redis sentinal image that run.sh should run as non-rootuser

run.sh

  while true; do
    master=$(redis-cli -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1)
    if [[ -n ${master} ]]; then
      master="${master//\"}"
    else
      master=$(hostname -i)
    fi

    redis-cli -h ${master} INFO
    if [[ "$?" == "0" ]]; then
      break
    fi
    echo "Connecting to master failed.  Waiting..."
    sleep 10
  done

  sentinel_conf=/home/ubuntu/sentinel.conf

  echo "sentinel monitor mymaster ${master} 6379 2" > ${sentinel_conf}
  echo "sentinel down-after-milliseconds mymaster 60000" >> ${sentinel_conf}
  echo "sentinel failover-timeout mymaster 180000" >> ${sentinel_conf}
  echo "sentinel parallel-syncs mymaster 1" >> ${sentinel_conf}
  echo "bind 0.0.0.0" >> ${sentinel_conf}

  redis-sentinel ${sentinel_conf} --protected-mode no
}

function launchslave() {
  while true; do
    master=$(redis-cli -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1)
    if [[ -n ${master} ]]; then
      master="${master//\"}"
    else
      echo "Failed to find master."
      sleep 60
      exit 1
    fi
    redis-cli -h ${master} INFO
    if [[ "$?" == "0" ]]; then
      break
    fi
    echo "Connecting to master failed.  Waiting..."
    sleep 10
  done
  sed -i "s/%master-ip%/${master}/" /redis-slave/redis.conf
  sed -i "s/%master-port%/6379/" /redis-slave/redis.conf
  redis-server /redis-slave/redis.conf --protected-mode no

Dockerfile

FROM alpine:3.4

RUN apk add --no-cache redis sed bash busybox-suid
#su: must be suid to work properly
COPY redis-master.conf /redis-master/redis.conf
COPY redis-slave.conf /redis-slave/redis.conf
RUN adduser -D ubuntu
USER ubuntu
COPY run.sh /home/ubuntu/run.sh
CMD [ "sh", "/home/ubuntu/run.sh" ]
ENTRYPOINT [ "bash", "-c" ]

I deployed in Openshift. The container is continuously restarting and I dont see any logs also. I have seen the some logs before when the "run.sh" is root(default) ie not mentioned any adduser in Dockerfile .

Answer 1

According to the docker documentation :

 Both CMD and ENTRYPOINT instructions define what command gets executed when running a container. There are few rules that describe their co-operation: 1. Dockerfile should specify at least one of CMD or ENTRYPOINT commands. 2. CMD will be overridden when running the container with alternative arguments. 

CMD and ENTRYPOINT layers are completely different in the above Dockerfile , so ENTRYPOINT overrides CMD layer and that's why CMD layer is never executed.

Just delete ENTRYPOINT layer from the Dockerfile , it is not needed here:

FROM alpine:3.4

RUN apk add --no-cache redis sed bash busybox-suid
#su: must be suid to work properly
COPY redis-master.conf /redis-master/redis.conf
COPY redis-slave.conf /redis-slave/redis.conf
RUN adduser -D ubuntu
USER ubuntu
COPY run.sh /home/ubuntu/run.sh
CMD [ "sh", "/home/ubuntu/run.sh" ]

Update:

I see that [[ ]] is used in run.sh script. This construction works in bash , not in sh . That's why the Dockerfile should be the following:

FROM alpine:3.4

RUN apk add --no-cache redis sed bash busybox-suid
#su: must be suid to work properly
COPY redis-master.conf /redis-master/redis.conf
COPY redis-slave.conf /redis-slave/redis.conf
RUN adduser -D ubuntu
USER ubuntu
COPY run.sh /home/ubuntu/run.sh
CMD [ "bash", "/home/ubuntu/run.sh" ]