Docker (compose): connection refused without sudo - linux

Question

All was fine until "something". After that "something", I could use docker and docker-compose with sudo but without it the docker would hang indefinitely and the docker-compose would return connection stack traces.
Doesn't work:
Running docker without sudo hangs indefinitely. Temporarily fixed by exporting DOCKER_HOST=tcp://127.0.0.1:2375.
docker-compose without sudo returns with connection refused. It's not about connecting to specific container but for all basic commands such as docker-compose ps.
Proof that user belongs to docker group:
kretyn#junk$ groups kretyn
kretyn : kretyn adm cdrom sudo dip plugdev lpadmin lxd sambashare docker
Solution hints
I had a docker context activated that was pointing at existing but inactive host. Removing that context and unsetting DOCKER_HOST allowed the docker command to work correctly. That's a surprise since I reinstalled (purged everything I could find) the docker before writing this question.
Removing context isn't sufficient. Docker Compose required explicit docker context use default otherwise it wouldn't understand.
The problem with docker-compose ps is still present.
Stack trace on docker-compose
kretyn#junk$ docker-compose ps
Traceback (most recent call last):
File "urllib3/connection.py", line 159, in _new_conn
File "urllib3/util/connection.py", line 84, in create_connection
File "urllib3/util/connection.py", line 74, in create_connection
ConnectionRefusedError: [Errno 111] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "urllib3/connectionpool.py", line 670, in urlopen
File "urllib3/connectionpool.py", line 392, in _make_request
File "http/client.py", line 1255, in request
File "http/client.py", line 1301, in _send_request
File "http/client.py", line 1250, in endheaders
File "http/client.py", line 1010, in _send_output
File "http/client.py", line 950, in send
File "urllib3/connection.py", line 187, in connect
File "urllib3/connection.py", line 171, in _new_conn
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f762c4e3e20>: Failed to establish a new connection: [Errno 111] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "requests/adapters.py", line 439, in send
File "urllib3/connectionpool.py", line 726, in urlopen
File "urllib3/util/retry.py", line 446, in increment
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=2375): Max retries exceeded with url: /version (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f762c4e3e20>: Failed to establish a new connection: [Errno 111] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "docker/api/client.py", line 214, in _retrieve_server_version
File "docker/api/daemon.py", line 181, in version
File "docker/utils/decorators.py", line 46, in inner
File "docker/api/client.py", line 237, in _get
File "requests/sessions.py", line 543, in get
File "requests/sessions.py", line 530, in request
File "requests/sessions.py", line 643, in send
File "requests/adapters.py", line 516, in send
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=2375): Max retries exceeded with url: /version (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f762c4e3e20>: Failed to establish a new connection: [Errno 111] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "docker-compose", line 3, in <module>
File "compose/cli/main.py", line 80, in main
File "compose/cli/main.py", line 189, in perform_command
File "compose/cli/command.py", line 60, in project_from_options
File "compose/cli/command.py", line 152, in get_project
File "compose/cli/docker_client.py", line 41, in get_client
File "compose/cli/docker_client.py", line 170, in docker_client
File "docker/api/client.py", line 197, in __init__
File "docker/api/client.py", line 221, in _retrieve_server_version
docker.errors.DockerException: Error while fetching server API version: HTTPConnectionPool(host='127.0.0.1', port=2375): Max retries exceeded with url: /version (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f762c4e3e20>: Failed to establish a new connection: [Errno 111] Connection refused'))
[46145] Failed to execute script docker-compose
Versions/builds
Linux distro
kretyn#junk$ uname -a
Linux junk 5.8.0-43-generic #49~20.04.1-Ubuntu SMP Fri Feb 5 09:57:56 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Docker
kretyn#junk$ sudo docker system info
Client:
Context: default
Debug Mode: false
Plugins:
app: Docker App (Docker Inc., v0.9.1-beta3)
buildx: Build with BuildKit (Docker Inc., v0.5.1-docker)
Server:
Containers: 9
Running: 8
Paused: 0
Stopped: 1
Images: 44
Server Version: 20.10.3
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Cgroup Version: 1
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: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 269548fa27e0089a8b8278fc4fc781d7f65a939b
runc version: ff819c7e9184c13b7c2607fe6c30ae19403a7aff
init version: de40ad0
Security Options:
apparmor
seccomp
Profile: default
Kernel Version: 5.8.0-43-generic
Operating System: Ubuntu 20.04.2 LTS
OSType: linux
Architecture: x86_64
CPUs: 12
Total Memory: 15.29GiB
Name: meland
ID: 3PE6:4AWU:LGRR:HOBJ:XUCJ:ER4H:ZEF5:MWUJ:COEG:WPK5:YH2U:FKUF
Docker Root Dir: /var/lib/docker
Debug Mode: false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: No blkio weight support
WARNING: No blkio weight_device support
Docker-compose
kretyn#junk$ sudo docker-compose version
docker-compose version 1.28.0, build d02a7b1a
docker-py version: 4.4.1
CPython version: 3.9.0
OpenSSL version: OpenSSL 1.1.1d 10 Sep 2019

Answer 1

The problem was a dead context entry.
Solution
Removed the dead context named remote using docker context rm remote.
Even though docker context ls was pointing default as default, it was necessary to do docker context use default for the context to be properly updated.
As a partial fix I had previously set DOCKER_HOST to tcp://127.0.0.1:2375. After updating context the env variable had to be unset, i.e. unset DOCKER_HOST.
Lazy commands, assuming context remote:
$ docker context rm remote
$ docker context use default
$ unset DOCKER_HOST
Background
Had a remote context that was based on ssh endpoint. My ssh config was set that the name points at my domain but recently the host behind it was removed.
Interestingly, I've been "fixing" this for a while and one of the steps was to completely purge docker from my local Ubuntu host, including apt, /var/lib/docker, /etc/docker and random scripts in ~/.local/. The context, however, wasn't cleaned.

Answer 2

The solution by Dawid was perfect for me.
I wanna mention that even when your sudo docker context ls only shows default context, your docker context ls might show different (and potentially broken) contexts. You wanna delete them.
But the problem is that your docker ps hangs.
So before you try docker rm, you need to override the context by DOCKER_HOST=tcp://127.0.0.1:2375.
As a result, the full solution is
DOCKER_HOST=tcp://127.0.0.1:2375
docker context ls
docker context rm <broken context name>
docker context use <valid context name(maybe default?)>
unset DOCKER_HOST
and then make sure all docker commands work without sudo.
docker ps

Answer 3

You don't have the necessary rights to use docker or docker-compose without sudo, check the documentation.
sudo usermod -aG docker
sudo chmod +x /usr/local/bin/docker-compose
You have to restart your terminal after that.