VS Code: connect a docker container in a remote server

Question

I want to work in a container in a remote server. But it doesn't work.

Environment:

Local: Windows 10

Local Terminal for ssh: WSL in Windows 10

Server: Ubuntu 18.04

I checked these two articles.

https://code.visualstudio.com/docs/remote/containers-advanced https://code.visualstudio.com/docs/containers/ssh

I followed these steps.

1. I installed [Remote Development] extension in VS Code.
2. Remote-SSH: Connect to host. It works fine.
3. I Installed [Docker] extension on the remoter server.
4. Now I can see my containers and images in a docker tab.
5. I clicked one container and clicked [Attach Visual Studio Code] and it says There are no running containers to attach to.

Answer 1

I resolved this problem by switching to the remote server's Docker context on my local machine:

docker context create some-context-label --docker "host=ssh://user@remote_server_ip"

docker context use some-context-label

docker ps
# A list of remote containers on my local machine! It works!

After that:

1. Connect via Remote-SSH to the container server
2. Right click relevant container -> the "Attach Visual Studio Code"

That works for me.

(Note: One would think that I should be able to just use my local VSCode (skip step 1) to connect to said remote container after switching my local context, but VSCode complains Failed to connect. Is docker running? in the Docker control pane.)

Answer 2

This might sound very strange, but for me, I had to open a folder on the remote SSH server prior to using the Remote Containers extension in VS Code. If I didn't do that, then it would constantly try to find the docker service running locally, even though the terminal tab was connected to the remote SSH server.

This seems very weird, because if you're conncted via SSH in VS Code, then the extension should assume you're trying to attach to the container on the remote server. Shouldn't have to open a remote folder first.

By "opening a folder" on the remote server, the Remote Containers extension was then able to attach VS code to the container running on the remote SSH server. I didn't have to do any of the steps in any of those articles. Just simply use Remote SSH to connect VS Code remotely via SSH, open a folder, and then use Remote Containers.

Answer 3

I solve this issue using SSH tunneling following the steps found in https://florian-kriegel.de/blog/?p=234

Summarizing:

1. Set (or add) "docker.host": "tcp://localhost:23750" in settings.json in VSCode.
2. Open a SSH tunnel like this in your local machine changing the user and hostname by the remote machine (where the docker daemon is running) credentials: ssh -NL localhost:23750:/var/run/docker.sock user@hostname.
3. Now, in the docker tab, you will be able to see and attach to containers in the remote machine.

Note that the Remote SSH Extension is not used in this case.

Answer 4

Solution using the "Remote SSH" and the "Remote Explorer" extension in Visual Studio Code.

Following the steps above (https://stackoverflow.com/a/61728799/11687201) I figured out how to make use of the SSH Remote and Remote Explorer Extension. The first step is the same as above:

1. Open the settings.json file in VSCode, press F1 and select ">Preferences: Open Settings (JSON)" and add/edit the following line:
   "docker.host": "tcp://localhost:23750"
2. Open the ssh config file, click on the "Remote Explorer" Extension, then click on the "SSH Targets" "Configure" button and open the ssh config file. Add the following line to your ssh connection:
   LocalForward localhost:23750 /var/run/docker.sock

Remark: Previously I used the solution described earlier in this thread (https://stackoverflow.com/a/61728799/11687201). I had to reboot both machines the local machine and remote machine before the solution described below worked out.

Afterwards I have to use multiple VSCode Windows:

1. Local Machine: Start VSCode and use the "Remote Explorer" to connect to the remote machine using a new VSCode window

2. VSCode window connected to remote (SSH)
   → startup the Docker container of your choice
   (I was not able to "Attach Visual Studio Code" from this VSCode window)

3. VSCode window connected to local machine
   → Click on the "Docker" extension, the docker containers running on the remote get listed. Attach VSCode to a running container using one of the folling options:

   • Right-click on the desired container and chose "Attach Visual Studio Code"
   • Press F1 and chose">Remote-Containers: Attach to Running Container..." and select the container of your choice afterwards

   A third VSCode window will open being attached to the Docker container.

Pros and cons of this solution

(+) Using the "Remote Explorer" extension I can directly connect and open a previously used project folder on my remote machine with one click

(-) 3 VSCode windows (local machine, remote ssh and remote container) are needed instead of 2 VSCode windows

Answer 5

Do you see the error message as of following?

Failed to connect. Is Docker running?
  Error: connect EACCES /var/run/docker.sock

Error Message on VSCode

It's because VSCode uses /var/run/docker.sock of remote host to communicate with the Docker service.

There're two methods.

Method 1. (Secure, Need reboot or logging out) After executing following code of dockerode npm getting error "connect EACCES /var/run/docker.sock" on ubuntu 14.04

Method 2. (Instant effect. Use it if you're not dealing with production server) Run the following command on SSH console.

sudo chmod o+rw /var/run/docker.sock

Answer 6

For some reason, this problem is fixed for me when I open a folder in the remote window before trying to attach to a container.

Answer 7

I found Daniel's answer really helpful but didn't work for me. I put my two cents.

TL;DR

1. Create a new docker context for the remote machine where remote container is running.

docker context create some-context-label --docker "host=ssh://user@remote_server_ip"

docker context use some-context-label

2. Just open VSC, go to Docker (you should have installed the extension) tab and you'll see listed all running containers from the remote context you recently created.
3. Right click on your desired container and attach visual studio code

You can also use the remote-explorer tab, just select containers from the dropdown at the top left.

Why not to ssh remote host

When attaching visual studio code to a container, you can check logs by clicking the notification Setting up Remote-Containers (show log) at the bottom left. There, you can check that:

...
[26154 ms] Start: Run: ssh some-remote-host /bin/sh
[26160 ms] Start: Run in host: id -un

Here, my guess is that it's trying to ssh to the remote host from itself ,since we already connected via remote-ssh.

Answer 8

If you can reach the remote node running Docker engine via SSH why you need yet another SSH server inside the container? From the host running your container, it is possible and safe to use tty, i.e. attach.

I don't think that this is not a good idea to use SSHD running inside the container although it is possible. To be useful SSHD has to listen to non-conflict port in every container. Otherwise, 2 containers occasionally exposing the same port on the same node will conflict like any other service running on same the node.

Of course, ports can be randomized using -P option but it is not so convenient. It is also less convenient to manage keys and users at the container level than at host level where all machinery is provided by the Host software.

Loading every container with SSHD increases the container size. In Kubernetes, every container is reachable without any SSHD running inside containers via pass Pod->Container because Pod, has IP and containers are attachable by id, i.e. "Docker-host->container"

Answer 9

Step 1 - Docker daemon on the remote machine

• make sure your remote Docker daemon can accept connections from your host
• for testing purposes, I use the following command on the remote machine to force Docker daemon to listen on port 4243 on all IPs, beware this is not secure

There is no support for reading a file from /etc/sysconfig or elsewhere to modify the command line. Fortunately, systemd gives us the tools we need to change this behavior. The simplest solution is probably to create the file /etc/systemd/system/docker.service.d/docker-external.conf (the exact filename doesn't matter; it just needs to end with .conf) with the following contents:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock

And then:

systemctl daemon-reload
systemctl restart docker

Step 3 - Opening Docker Ports Using FirewallD

firewall-cmd --permanent --zone=public --change-interface=docker0
firewall-cmd --permanent --zone=public --add-port=4243/tcp
firewall-cmd --reload

Step 4 - Set (or add) "docker.host": "tcp://localhost:4243" in settings.json in VSCode.

Answer 10

Here's what worked for me...
(I'm specifically connecting to docker running on Unraid Server)

1. Install the Remote SSH extension.
2. Install the Docker extension.
3. Enable the Docker extension for use when connected via SSH.
   Go to the VSCode Settings UI > Remote SSH: Default Extensions > Add Item
   Add ms-azuretools.vscode-docker
   
4. Use the Remote SSH extension to connect to the remote server.
5. Click on the Docker extension in the sidebar and it works!