Dockerfile: Docker build can't download packages: centos->yum, debian/ubuntu->apt-get behind intranet

PROBLEM

Talking to some developers at #docker@freenode, the problem was clear to everyone: DNS and the environment. The build works just fine at a regular Internet connection at home.

SOLUTION:

This problem occurs in an environment that has a private DNS server, or the network blocks the Google's DNS servers. Even if the docker container can ping 8.8.8.8, the build still needs to have access to the same private DNS server behind your firewall or Data Center.

Start the Docker daemon with the --dns switch to point to your private DNS server, just like your host OS is configured. That was found by trial and error.

Details

My MAC OS X, host OS, had a different DNS configured on my /etc/resolv.conf:

mdesales@Marcello-Work ~ (mac) $ cat /etc/resolv.confsearch corp.my-private-company.netnameserver 172.18.20.13nameserver 172.20.100.29

My host might be dropping the packets to the Google's IP address 8.8.8.8 while building... I just took those 2 IP addresses and placed under the Ubuntu's docker daemon configuration:

mdesales@ubuntu ~ $ cat /etc/default/docker......# Use DOCKER_OPTS to modify the daemon startup options.DOCKER_OPTS="--dns 172.18.20.13 --dns 172.20.100.29 --dns 8.8.8.8"...

The build now works as expected!

$ sudo ./build.sh Sending build context to Docker daemon 7.168 kBSending build context to Docker daemon Step 0 : FROM centos ---> b157b77b1a65Step 1 : MAINTAINER Marcello_deSales@intuit.com ---> Running in 49bc6e233e4c ---> 2a380810ffdaRemoving intermediate container 49bc6e233e4cStep 2 : RUN yum install -y curl; yum upgrade -y; yum update -y;  yum clean all ---> Running in 5f11b65c87b8Loaded plugins: fastestmirrorDetermining fastest mirrors * base: mirror.supremebytes.com * extras: centos.mirror.ndchost.com * updates: mirrors.tummy.comResolving Dependencies--> Running transaction check---> Package systemd.x86_64 0:208-11.el7 will be updated---> Package systemd.x86_64 0:208-11.el7_0.2 will be an update---> Package systemd-libs.x86_64 0:208-11.el7 will be updated---> Package systemd-libs.x86_64 0:208-11.el7_0.2 will be an update--> Finished Dependency Resolution

Thanks to @BrianF and others who helped in the IRC channel!

Permanent VM Solution - UPDATE JULY 2, 2015

We now have GitHub Enterprise and CoreOS Enterprise Docker Registry in the mix... So, it was important for me to add the corporate DNS servers from the HOST machine in order to get the VM also to work.

Replacing the /etc/resolv.conf from the guest OS with the Host's /etc/resolv.conf also resolved the problem! Docker 1.7.0. I just created a new VM using Ubuntu 15.04 on VMWare Fusion and I had this problem again...

/etc/resolv.conf BEFORE

~/dev/github/public/stackedit on ⭠ master ⌚ 20:31:02$ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTENnameserver 127.0.1.1search localdomain

/etc/resolv.conf AFTER*

~/dev/github/public/stackedit on ⭠ master ⌚ 20:56:09$ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTENsearch corp.mycompany.netnameserver 10.180.194.35nameserver 10.180.194.36nameserver 192.168.1.1

I had pretty the same problem. The provided solution didn't help in my case. But it worked as soon I updated my Dockerfile adding environment variables for the proxy in it.

ENV HTTP_PROXY http://<proxy_host>:<port>ENV HTTPS_PROXY http://<proxy_host>:<port>ENV http_proxy http://<proxy_host>:<port>ENV https_proxy http://<proxy_host>:<port>

It's likely due to your local caching name server listening on 127.0.1.1 which is not accessible from within the container.

Try putting the following into your Dockerfile:

CMD "sh" "-c" "echo nameserver 8.8.8.8 > /etc/resolv.conf"