Docker Testing Environment for Remote LSP

August 4, 2025 · View on GitHub

This Docker container provides a complete testing environment for remote LSP functionality with multiple language servers and test projects.

Quick Start

Method 1: Using Docker Compose (Recommended)

# Build and start the container
docker-compose up -d --build

# Set up passwordless SSH access
./setup-ssh-keys.sh

# Connect to the container
ssh testuser@localhost

Method 2: Using the Build Script

# Make script executable (first time only)
chmod +x build-docker.sh

# Build and run everything
./build-docker.sh full

# Or just start (if already built)
./build-docker.sh run

# Connect via SSH
./build-docker.sh connect

# Show status
./build-docker.sh status

# View logs
./build-docker.sh logs

# Clean everything
./build-docker.sh clean

Manual SSH Setup

If automated setup fails, you can configure SSH keys manually:

# Generate SSH key if you don't have one
ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa

# Copy the key to the container (password: testpassword)
ssh-copy-id testuser@localhost

# Test the connection
ssh testuser@localhost

Container Details

SSH User: testuser
SSH Password: testpassword (for initial setup)
SSH Port: 22
Root Password: rootpassword

Available Tools

The container includes:

Language Servers: rust-analyzer, clangd, pylsp
Development Tools: git, cmake, build-essential
System Tools: rsync, find, tree, htop, vim, nano
Network Tools: netcat, telnet, ping

Test Repositories

The container includes several real-world projects for comprehensive LSP testing:

C++ Projects (`/home/testuser/repos/`)

llvm-project: LLVM/Clang subset
Catch2: Modern C++ testing framework
json: nlohmann/json library

Python Projects (`/home/testuser/repos/`)

django: Web framework
flask: Micro web framework
fastapi: Async web framework
requests: HTTP library

Rust Projects (`/home/testuser/repos/`)

tokio: Async runtime
serde: Serialization framework
clap: Command line parser
actix-web: Web framework
Rocket: Web framework

Custom Test Files (`/home/testuser/test-files`)

Minimal but complete projects for each language
Designed to trigger specific LSP features
Includes proper build configurations

Neovim Remote Development

Once SSH keys are set up, you can use this container for remote development:

-- Example: Edit a complex Rust file
vim.cmd("edit scp://testuser@localhost//home/testuser/repos/tokio/tokio/src/lib.rs")

-- Example: Edit a Django model
vim.cmd("edit scp://testuser@localhost//home/testuser/repos/django/django/db/models/base.py")

Test with Real-World Codebases

-- Large C++ files with complex dependencies
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/llvm-project/clang/lib/Basic/Targets.cpp')
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/Catch2/src/catch2/catch_test_macros.hpp')

-- Complex Python frameworks
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/django/django/db/models/base.py')
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/fastapi/fastapi/main.py')

-- Advanced Rust async and macro code
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/tokio/tokio/src/lib.rs')
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/repos/serde/serde/src/lib.rs')

-- Or use the simple test files
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/test-files/main.cpp')
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/test-files/main.py')
vim.cmd('edit rsync://testuser@localhost:2222/home/testuser/test-files/main.rs')

Test Features

Once connected, you can test:

Go-to-definition: Jump to function/variable definitions
Hover: Get type information and documentation
Code completion: IntelliSense-style completions
Diagnostics: Syntax errors and warnings
Workspace symbols: Search for symbols across the project
File watching: Changes detected across the workspace

SSH Configuration

Add to your ~/.ssh/config:

Host docker-lsp-test
    HostName localhost
    Port 2222
    User testuser
    PasswordAuthentication yes

Then connect with: ssh docker-lsp-test

Test Scenarios

C++ with clangd

# Connect and test
ssh -p 2222 testuser@localhost
cd /home/testuser/test-files
clangd --version

Test files include:

main.cpp - Main application with includes
utils.cpp - Implementation file
include/utils.h - Header file
CMakeLists.txt - Build configuration
build/compile_commands.json - Clangd database

Python with pylsp

cd /home/testuser/test-files
pylsp --version
python3 main.py

Test files include:

main.py - Main script with type hints
utils.py - Utility module with classes
Full type annotation support

Rust with rust-analyzer

cd /home/testuser/test-files
rust-analyzer --version
cargo build
cargo run

Test files include:

main.rs - Main application
utils.rs - Utility module
Cargo.toml - Project configuration
Built dependencies in target/

Troubleshooting

SSH Connection Issues

Ensure the container is running: docker ps
Check container logs: docker logs remote-lsp-test
Verify SSH service: docker exec remote-lsp-test systemctl status ssh

Missing Tools

Install additional tools: docker exec remote-lsp-test apt update && apt install -y <package-name>
Or modify the Dockerfile and rebuild

Port Conflicts

If port 22 is in use, modify docker-compose.yml to use a different port:
```
ports:
  - "2222:22"
```

Container Management

# Stop container
docker-compose down

# Rebuild container
docker-compose up -d --build --force-recreate

# Access container shell
docker exec -it remote-lsp-test bash

# View container logs
docker-compose logs -f remote-lsp-test

Language Server Issues

# Test language servers directly
docker exec -it remote-lsp-test bash
su - testuser
clangd --version
pylsp --version
rust-analyzer --version

Advanced Usage

Custom Test Files

You can mount additional test files:

# Create local test directory
mkdir -p test-workspace

# Mount it in docker-compose.yml (already configured)
# Files will appear at /home/testuser/workspace in the container

Network Configuration

The container uses a custom bridge network. You can inspect it:

docker network inspect remote-ssh-nvim_lsp-network

Performance Testing

For performance testing, you can:

Create large projects in the container
Test with multiple simultaneous connections
Monitor resource usage with docker stats

Cleanup

# Stop and remove container
docker-compose down

# Remove built image
docker rmi remote-ssh-nvim_remote-lsp-test

# Remove volumes (if any)
docker volume prune