Docker Nix Build Slave

start-docker-nix-build-slave

#!/usr/bin/env bash

# Requires: curl, docker, grep

# To clean up:
#  * Remove ~/.nix-docker-build-slave.
#  * Remove entries from ~/.ssh/config for nix-docker-build-slave.


working_dir="$HOME/.nix-docker-build-slave"
mkdir -p "$working_dir"

ssh_id_file="$working_dir/insecure_rsa"
remote_sys_conf="$working_dir/remote-systems.conf"

ssh_config="$HOME/.ssh/config"

docker_machine_name="nix-docker-build-slave"

# -- Download SSH credentials for docker machine --
echo ">>> Downloading SSH credentials for the docker machine"
rm -f "$ssh_id_file" "$ssh_id_file.pub"
curl https://raw.githubusercontent.com/LnL7/nix-docker/master/ssh/insecure_rsa > "$ssh_id_file"
curl https://raw.githubusercontent.com/LnL7/nix-docker/master/ssh/insecure_rsa.pub > "$ssh_id_file.pub"
chmod 600 "$ssh_id_file"

# -- Set up SSH configuration --
[ -f "$ssh_config" ] || touch "$ssh_config"
if ! grep "$docker_machine_name" "$HOME/.ssh/config"; then
  echo ">>> Adding an entry to $ssh_config for $docker_machine_name"
  cat >> "$ssh_config" <<CONF

Host "$docker_machine_name"
  User root
  HostName 127.0.0.1
  Port 3022
  IdentityFile "$ssh_id_file"
CONF
else
  echo ">>> SSH configuration already contains an entry for $docker_machine_name in $ssh_config"
  echo "(If you're having trouble using the build slave, try removing this entry and starting over.)"
fi

# -- Start docker machine --
echo ">>> Starting docker machine: $docker_machine_name"
docker run --restart always --name "$docker_machine_name" -d -p 3022:22 lnl7/nix:ssh

# -- Write remote systems confugration --
echo ">>> Writing remote systems configuration to $remote_sys_conf"
rm -f "$remote_sys_conf"
cat > "$remote_sys_conf" <<CONF
$docker_machine_name x86_64-linux "$ssh_id_file" 1
CONF

# -- Test connection --
echo ">>> Running SSH test"
ssh "$docker_machine_name" echo "SSH connection is working." || echo "SSH connection failed."

# -- Export environment --
echo ">>> Setting \$NIX_REMOTE_SYSTEMS to use $remote_sys_conf"
export NIX_REMOTE_SYSTEMS="$remote_sys_conf"