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When i include the following command in my Docker file, I'm getting an error. I am trying to create a docker file for creating my base image for Redis, and this command helps with redis performance.

RUN echo 4096 > /writable-proc/sys/net/core/somaxconn

The error i am getting when i try to build the docker file to create an image is:

/bin/sh: 1: cannot create /writable-proc/sys/net/core/somaxconn: Directory nonexistent

Any suggestions on how i can run this command? I would actually like to run the following commands in my Dockerfile:

RUN echo 4096 > /writable-proc/sys/net/core/somaxconn RUN echo 'vm.overcommit_memory = 1' >> /etc/sysctl.conf RUN echo never > /sys/kernel/mm/transparent_hugepage/enabled

Below is the entire Docker file for my Redis image:

#Download base image ubuntu 16.04 FROM ubuntu:14.04 MAINTAINER George Chilumbu ENV HOME /root ENV DEBIAN_FRONTEND noninteractive #ENV /writable-proc/sys/net/core/somaxconn /proc:/writable-proc # Set the working directory to /app WORKDIR ~/ # Redis Cache Server Tuning RUN mkdir -p /writable-proc/sys/net/core/somaxconn RUN echo 4096 > /writable-proc/sys/net/core/somaxconn #RUN echo 'vm.overcommit_memory = 1' >> /etc/sysctl.conf #RUN echo never > /sys/kernel/mm/transparent_hugepage/enabled # Install some necessary software/tools RUN apt-get update && apt-get install -y \ wget \ vim \ unzip \ inetutils-ping \ inetutils-tools \ net-tools \ dnsutils \ software-properties-common \ python-software-properties \ ntp \ rsyslog \ curl RUN add-apt-repository ppa:gaod/redis-server \ && apt-get update \ && apt-get install -y redis-server \ redis-sentinel \ && rm /etc/redis/redis.conf \ && rm /etc/redis/sentinel.conf RUN mkdir -p /opt/redis/redis_dump RUN chown redis:redis -R /opt/redis/redis_dump/
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  • have you tried running it as privileged? stackoverflow.com/questions/26177059/… Commented May 5, 2017 at 10:50
  • 2
    Try to run the base image and check if the directory /writable-proc/sys/net/core/ exsits? Otherwise first create that directory before adding a file and text. Commented May 5, 2017 at 11:25
  • posting your full Dockerfile could help. Otherwise it's a guessing game. My guess you called USER something prior to that echo... Commented May 5, 2017 at 14:54
  • I have added my entire Dockerfile. Commented May 6, 2017 at 12:57

1 Answer 1

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Setting sysctl's is only possible at runtime with the --sysctl option. From the docker-run(1) manual:

 Configure namespaced kernel parameters at runtime IPC Namespace - current sysctls allowed: kernel.msgmax, kernel.msgmnb, kernel.msgmni, kernel.sem, kernel.shmall, kernel.shmmax, kernel.shmmni, kernel.shm_rmid_forced Sysctls beginning with fs.mqueue.* If you use the --ipc=host option these sysctls will not be allowed. Network Namespace - current sysctls allowed: Sysctls beginning with net.* If you use the --network=host option these sysctls will not be allowed.

For example, for /proc/sys/net/core/somaxconn you may use --sysctl net.core.somaxconn=4096.

Other kernel parameters in procfs and sysfs may be inherited (though others are not), so you should set them on the host.

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3 Comments

Thanks Ricardo. That worked. How can do similar thing for "echo 'vm.overcommit_memory = 1' >> /etc/sysctl.conf" and "echo never > /sys/kernel/mm/transparent_hugepage/enabled"?
Try setting them in the host to see whether these parameters are inherited. As a last resort I would try to run the container in privileged mode (possibly with apparmor/selinux & seccomp disabled). Also try the last version of Docker and tell us about the results.
I found a lot of discussions on this topic on Docker forums. Apparently, this cannot be done, and if you did it on the host level, it "might" apply to all docker containers on that host. I guess i can run these commands manually inside a container. Thanks Ricardo.

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