Simplify setup required for remote DOCKER_HOST over SSH #3045
Description
Description
When connecting to a remote host over ssh, by configuring the DOCKER_HOST environment variable, or by using the docker context functionality and specifying the host= parameter, some Linux/Unix environments require additional setup because the docker CLI assumes that the host it is SSHing into has docker located in the PATH.
Unfortunately while docker is almost always installed into the user PATH, it is not always installed into the system path. This causes the docker CLI to fail when attempting to use these systems as a remote host without additional setup.
One system that this occurs on is macOS. The default installation directory of docker on Mac's is /usr/local/bin but that path is not in the system PATH that sshd configures for the ssh session.
As an example, this is what the default PATH is on macOS:
% ssh <host> 'echo $PATH'
/usr/bin:/bin:/usr/sbin:/sbin
To work around this issue a user must run the following commands on macOS and other systems that have the same setup.
echo 'PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin' >> ~/.ssh/environment
sudo sh -c 'echo "PermitUserEnvironment PATH" >> /private/etc/ssh/sshd_config'
Steps to reproduce the issue:
DOCKER_HOST=ssh://<host> docker ps
Describe the results you received:
error during connect: Get http://docker/v1.24/containers/json: command [ssh -- Gigantor.local docker system dial-stdio] has exited with exit status 127, please make sure the URL is valid, and Docker 18.09 or later is installed on the remote host: stderr=zsh:1: command not found: docker
Describe the results you expected:
I expected it to be relatively straight forward to provide an SSH host address for another machine running docker and that docker could find itself.
I think it would significantly simplify using docker remotely across machines if docker didn't only rely on PATH but searched some common paths that Docker typically installs itself, such as /usr/local/bin/.
Additional information you deem important (e.g. issue happens only occasionally):
Issue happens consistently.
Output of docker version:
Client: Docker Engine - Community
Cloud integration: 1.0.9
Version: 20.10.5
API version: 1.41
Go version: go1.13.15
Git commit: 55c4c88
Built: Tue Mar 2 20:13:00 2021
OS/Arch: darwin/amd64
Context: default
Experimental: true
Server: Docker Engine - Community
Engine:
Version: 20.10.5
API version: 1.41 (minimum version 1.12)
Go version: go1.13.15
Git commit: 363e9a8
Built: Tue Mar 2 20:15:47 2021
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.4.3
GitCommit: 269548fa27e0089a8b8278fc4fc781d7f65a939b
runc:
Version: 1.0.0-rc92
GitCommit: ff819c7e9184c13b7c2607fe6c30ae19403a7aff
docker-init:
Version: 0.19.0
GitCommit: de40ad0
Output of docker 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)
scan: Docker Scan (Docker Inc., v0.5.0)
Server:
Containers: 2
Running: 1
Paused: 0
Stopped: 1
Images: 3
Server Version: 20.10.5
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.runtime.v1.linux runc io.containerd.runc.v2
Default Runtime: runc
Init Binary: docker-init
containerd version: 269548fa27e0089a8b8278fc4fc781d7f65a939b
runc version: ff819c7e9184c13b7c2607fe6c30ae19403a7aff
init version: de40ad0
Security Options:
seccomp
Profile: default
Kernel Version: 4.19.121-linuxkit
Operating System: Docker Desktop
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 1.942GiB
Name: docker-desktop
ID: BTMT:FQ3F:RCNB:IDF5:W7AP:7NRK:XSTI:7ERE:62JZ:3ODT:IARG:OQWC
Docker Root Dir: /var/lib/docker
Debug Mode: false
HTTP Proxy: gateway.docker.internal:3128
HTTPS Proxy: gateway.docker.internal:3129
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
Additional environment details (AWS, VirtualBox, physical, etc.):
This is all running on physical machines. I had the same problem with one flavor of Linux a little while ago on AWS, but I didn't note the details of which distro and version and don't remember.