Example sshd and HTTP server App

DISCLAIMER: This image is solely for example purposes, it may not be maintained or continue working.

This project contains the following:

• a Dockerfile which builds a container which:
  • is based on https://hub.docker.com/r/linuxserver/openssh-server
  • is configured for ssh connections in GitLab Workspaces
  • contains ruby installed
  • a /usr/local/bin/server.sh script which starts a simple ruby HTTP server on port 8000 using HTTP::Server::Brick via ruby:
  • ruby -run -ehttpd . -p8000
• a .devfile.yaml to run this project in GitLab Workspaces

Developer notes

Building the image

• Create a buildx builder for multiplatform builds (linux and MacOS) docker buildx create --use
• Create a multiplatform build (for publishing to registry): docker buildx build --platform linux/amd64,linux/arm64 -t example-sshd-http-app .
• Also create a single-platform arm64 (MacOS) build, with --load option, to support local testing: docker buildx build --platform linux/arm64 -t example-sshd-http-app-arm64 --load .

Testing the image locally

• Run the container locally: docker run -it -p 8022:22 -p 8000:8000 --name local-sshd-http-app example-sshd-http-app-arm64 /bin/bash
  • -p 8022:22 maps the container's port 22 (sshd) to the host's port 8022
  • -p 8000:8000 maps the container's port 8000 (web server) to the host's port 8000
• Connect to the container via bash: docker exec -it local-sshd-http-app /bin/bash
  • Run sshd daemonized: /usr/sbin/sshd
  • Run the HTTP server in the background: nohup /usr/local/bin/server.sh > /tmp/server.log 2>&1 &
  • Tail the http server log: tail -f /tmp/server.log
• Test connecting to container via SSH from docker host machine: ssh -p 8022 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null gitlab-workspaces@localhost
  • Connection should be successful with no password required.
• Test connecting to the container via HTTP from docker host machine. Access http://localhost:8000 in a browser
• Remove the container: docker rm -f local-sshd-http-app

Publish the image to registry and verify

• docker login registry.gitlab.com (See https://docs.gitlab.com/ee/user/packages/container_registry/authenticate_with_container_registry.html for details)
• Tag and push the multiplatform build: docker buildx build --platform linux/amd64,linux/arm64 -t registry.gitlab.com/gitlab-org/workspaces/examples/example-sshd-http-app:latest --push .
• Verify the image was successfully pushed: https://gitlab.com/groups/gitlab-org/workspaces/examples/-/container_registries

Running the image in GitLab Workspaces

• Open this project from https://gitlab.com/gitlab-org/workspaces/examples/example-sshd-http-app, or...
• ...push it to a new project in your local GDK:
  • Create example-sshd-http-app project in GDK under gitlab-org, with no repo (no README)
  • From local machine: git remote add gdk ssh://[email protected]:2222/gitlab-org/example-sshd-http-app.git
  • Push to GDK: git push gdk main:main
• Create a new workspace for the project.
• NOTE: Currently, the gitlab-workspaces-tools container image does not support ARM64 (MacOS) architecture. To work around this in local GDK, you can locally edit tools_injector_image in ee/lib/remote_development/settings/default_settings.rb to have the following value: registry.gitlab.com/gitlab-org/workspaces/testing/gitlab-workspaces-tools-arm-fork:arm64-latest. Then, gdk restart rails-web, and create a new workspace for the example-sshd-http-app project.

Debugging SSH connection issues

In the tooling container

• Get workspace's namespace name: kubectl get namespace
• Get pod name: kubectl get pods -n <namespace name>
• Exec into workspaces tooling container: kubectl exec -it <pod name> -n <namespace name> -- /bin/bash
• ps -ef | grep sshd to check if sshd is running
• To see logs, kill -9 the /usr/bin/sshd PID, then run /usr/sbin/sshd -d -D to see sshd server output to console (TODO: Not sure where default logs go, find them and update this).

In the gitlab-workspaces-proxy container

• Get gitlab-workspaces-proxy pod name: kubectl get pods -n gitlab-workspaces
• Tail the logs of the container: kubectl logs -f gitlab-workspaces-proxy-79d845b49-hlxnv -c gitlab-workspaces-proxy -n gitlab-workspaces