apt-get not working inside docker

burgas · 11-14-2020, 05:13 PM

I want to start something based on ubuntu:xenial but apt-get not working
most strange in my case that any command for buzybox like nslookup, ping gateway and so on, working fine.
Can anybody advice for me? How to fix this issue inside docker container?

jmgibson1981 · 11-15-2020, 11:38 AM

How did you install Docker. If you installed as per the instructions on https://docs.docker.com/engine/install/ubuntu/ then did you follow the final configuration? Namely https://docs.docker.com/engine/insta...x-postinstall/ . Most of it I find useless or already done in my configuration. This part however is necessary.

Quote:

Specify DNS servers for Docker
The default location of the configuration file is /etc/docker/daemon.json. You can change the location of the configuration file using the --config-file daemon flag. The documentation below assumes the configuration file is located at /etc/docker/daemon.json.

Create or edit the Docker daemon configuration file, which defaults to /etc/docker/daemon.json file, which controls the Docker daemon configuration.

$ sudo nano /etc/docker/daemon.json
Add a dns key with one or more IP addresses as values. If the file has existing contents, you only need to add or edit the dns line.

{
"dns": ["8.8.8.8", "8.8.4.4"]
}
If your internal DNS server cannot resolve public IP addresses, include at least one DNS server which can, so that you can connect to Docker Hub and so that your containers can resolve internet domain names.

Save and close the file.

Restart the Docker daemon.

$ sudo service docker restart
Verify that Docker can resolve external IP addresses by trying to pull an image:

$ docker pull hello-world
If necessary, verify that Docker containers can resolve an internal hostname by pinging it.

$ docker run --rm -it alpine ping -c4 <my_internal_host>

PING google.com (192.168.1.2): 56 data bytes
64 bytes from 192.168.1.2: seq=0 ttl=41 time=7.597 ms
64 bytes from 192.168.1.2: seq=1 ttl=41 time=7.635 ms
64 bytes from 192.168.1.2: seq=2 ttl=41 time=7.660 ms
64 bytes from 192.168.1.2: seq=3 ttl=41 time=7.677 ms

Here is mine with my local dns.

Code:

{
        "dns": ["192.168.1.2", "8.8.8.8", "8.8.4.4"]
}

burgas · 11-15-2020, 03:24 PM

Thank you, jmgibson1981, for answer
But in docker documentation I don't see anything information about file /etc/docker/daemon.json
I see documentation about file /etc/default/docker
Of course I tune this file and set up DNS in this file

# Use DOCKER_OPTS to modify the daemon startup options.
DOCKER_OPTS="--dns 8.8.8.8 --dns 1.1.1.1"

also DNS information can be set for each container creation, I use portainer, and in portainer I see overriding DNS parameters for each container creation

in my case /etc/docker/ now contains file key.json

{
"crv":"P-256",
"d":"M3232wECpwzHLRhXG4H-mTUjw7fGA3o0noJ2siLBiZDr4",
"kid":"6Q1GY:G2FY:N754:NLP7:KYLD:YH4P:LvBL:GD6Z:WZ2T:7S5V:NX45:ZTX5",
"kty":"EC",
"x":"zl2xyZR_ETQQW131312EgC3SssdDVy29Di7HnnTxjFZ2JU",
"y":"X2ZxqpEbbAV82xDz567566F4JRj0lGm3Kw7Akl8hW4NUmc"
}

However, I try you idea - add additional DNS definition and restart docker.
Unfortunately nothing changing....

In my case Hello-world docker working correctly, Portainer working correctly, even Busybox working absolutely correctly (any network utilities working fine), only Ubuntu don't working at all. In CentOS in my case working only ping.

berndbausch · 11-16-2020, 05:50 AM

Quote:

Originally Posted by burgas

But in docker documentation I don't see anything information about file /etc/docker/daemon.json

See https://docs.docker.com/engine/refer...iguration-file.

burgas · 11-16-2020, 03:25 PM

hmmm. interesting, at common my datacenter working with special MTU size, maybe problem close to there.