Jenkins not able to access internet when running as docker container

Question

I am running the jenkins docker image. When starting, it complains that it is not possible to access the internet.

This is how I run it:

docker pull jenkins
mkdir jenkins-shared-volume
docker run -d -p 49001:8080 -p 50000:50000 -v jenkins-shared-volume:/var/jenkins_home -t --name jenkins jenkins

The jenkins instance is then running on http://localhost:49001. But it has connectivity issues:

Offline This Jenkins instance appears to be offline.

For information about installing Jenkins without an internet connection, see the Offline Jenkins Installation Documentation.

You may choose to continue by configuring a proxy or skipping plugin installation.

I have no proxy in my system (home laptop). I guess this is probably an obscure docker problem but:

1. I can not find any references to this issue
2. Since this is the usual way in which people would be running the jenkins docker image, I find it surprising that this is not working out of the box

Am I doing something wrong?

EDIT

Just to make sure that indeed the docker container has direct access to the internet:

docker exec -it jenkins /bin/bash
jenkins@4ef4944a7cb7:/$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=44 time=29.859 ms

EDIT2

Running the container connected to the host network solves the problem and lets jenkins access the internet:

docker run -d --net host -v jenkins-shared-volume:/var/jenkins_home -t --name jenkins jenkins

But I can not map ports: jenkins is directly reachable on http://localhost:8080, which can be a source of conflicts whenever other services are using the 8080 port.

Answer 1

Strangely I ran into the same issue last night using the official Jenkins image:

 docker run -p 8080:8080 --rm jenkins/jenkins

Though I have not figured out why yet or how to permanently fix it, I did find a work around.

Launch the image with the older un-supported image jenkins... do the initial setup.. then shut it down, swap the image and startup the official.

For reference here is my docker-compose.yml:

version: "2"

services:
  app:
    image: jenkins #after booting and initial setup swap to jenkins/jenkins
    ports:
      - "50000:50000"
      - "8080:8080"
    volumes:
      - home:/var/jenkins_home
volumes:
  home:

Answer 2

When you run 'ping 8.8.8.8', you are testing internet connection but not DNS resolution.

Try 'ping www.google.com', I think you are having a DNS issue, thats why Jenkins can't reach the plugins packages.

Edit /etc/docker/daemon.json and set your local DNS servers to avoid Docker using default Google Public DNS. Docker Docs - Daemon configuration file .