I was trying to test my recent docker install on Debian 9 but the following error appeared:

root@gsdpuma:~# docker run hello-world
Unable to find image 'hello-world:latest' locally
docker: Error response from daemon: Get https://registry-1.docker.io/v2/: dial tcp: lookup registry-1.docker.io on 76.248.127.8:53: no such host.
See 'docker run --help'.

I had clear it was related to our corporate proxy and I was focused on that.

I’ve tried searching for the error but it had multiple solutions, reading the comments I’ve started digging in the filesystem looking for any docker related file, and I found this one:

/etc/systemd/system/multi-user.target.wants/docker.service
#which is just a symlink to:
lrwxrwxrwx 1 root root 34 Feb 10 14:53 docker.service -> /lib/systemd/system/docker.service

And added this on the file under the [Service] section:

[Service]

#proxy added by mortiz
Environment=HTTP_PROXY=http://12345.66.777:1234

After that restarted docker:

root@grrrrrr:/etc/systemd/system# service docker restart

Executed docker info to see that the proxy had been loaded correctly:

root@grrrrrr:/etc/systemd/system# docker info
Client:
Debug Mode: false

Server:
Containers: 1
Running: 0
Paused: 0
Stopped: 1
Images: 1
Server Version: 19.03.5
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: asdasd
runc version: asdasdasd
init version: asdasdsad
Security Options:
seccomp
Profile: default
Kernel Version: 4.9.0-7-amd64
Operating System: Debian GNU/Linux 9 (stretch)
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 7.701GiB
Name: grrrrr.domain
ID: XXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXX
Docker Root Dir: /var/lib/docker
Debug Mode: false
HTTP Proxy: http://12345.66.777:1234
HTTPS Proxy: http://12345.66.777:1234
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false

And I succeeded running the test:

root@grrrrrrrrr:/etc/systemd/system# docker run hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly