nixos-servers/services/vault/default.nix

{ pkgs, ... }:
let
  unsealScript = pkgs.writeShellApplication {
    name = "openbao-unseal";
    runtimeInputs = with pkgs; [
      openbao
      coreutils
      gnugrep
      getent
    ];
    text = ''
      # Set environment to use Unix socket
      export BAO_ADDR='unix:///run/openbao/openbao.sock'
      SOCKET_PATH="/run/openbao/openbao.sock"
      CREDS_DIR="''${CREDENTIALS_DIRECTORY:-}"

      # Wait for socket to exist
      echo "Waiting for OpenBao socket..."
      for _ in {1..30}; do
        if [ -S "$SOCKET_PATH" ]; then
          echo "Socket exists"
          break
        fi
        sleep 1
      done

      # Wait for OpenBao to accept connections
      echo "Waiting for OpenBao to be ready..."
      for _ in {1..30}; do
        output=$(timeout 2 bao status 2>&1 || true)

        if echo "$output" | grep -q "Sealed.*false"; then
          # Already unsealed
          echo "OpenBao is already unsealed"
          exit 0
        elif echo "$output" | grep -qE "(Sealed|Initialized)"; then
          # Got a valid response, OpenBao is ready (sealed)
          echo "OpenBao is ready"
          break
        fi

        sleep 1
      done

      # Check if already unsealed
      if output=$(timeout 2 bao status 2>&1 || true); then
        if echo "$output" | grep -q "Sealed.*false"; then
          echo "OpenBao is already unsealed"
          exit 0
        fi
      fi

      # Unseal using the TPM-decrypted keys (one per line)
      if [ -n "$CREDS_DIR" ] && [ -f "$CREDS_DIR/unseal-key" ]; then
        echo "Unsealing OpenBao..."
        while IFS= read -r key; do
          # Skip empty lines
          [ -z "$key" ] && continue

          echo "Applying unseal key..."
          bao operator unseal "$key"

          # Check if unsealed after each key
          if output=$(timeout 2 bao status 2>&1 || true); then
            if echo "$output" | grep -q "Sealed.*false"; then
              echo "OpenBao unsealed successfully"
              exit 0
            fi
          fi
        done < "$CREDS_DIR/unseal-key"

        echo "WARNING: Applied all keys but OpenBao is still sealed"
        exit 0
      else
        echo "WARNING: Unseal key credential not found, OpenBao remains sealed"
        exit 0
      fi
    '';
  };

  bootstrapCertScript = pkgs.writeShellApplication {
    name = "bootstrap-vault-cert";
    runtimeInputs = with pkgs; [
      openbao
      jq
      openssl
      coreutils
    ];
    text = ''
      # Bootstrap vault01 with a proper certificate from its own PKI
      # This solves the chicken-and-egg problem where ACME clients can't trust
      # vault01's self-signed certificate.

      echo "=== Bootstrapping vault01 certificate ==="

      # Use Unix socket to avoid TLS issues
      export BAO_ADDR='unix:///run/openbao/openbao.sock'

      # ACME certificate directory
      CERT_DIR="/var/lib/acme/vault01.home.2rjus.net"

      # Issue certificate for vault01 with vault as SAN
      echo "Issuing certificate for vault01.home.2rjus.net (with SAN: vault.home.2rjus.net)..."
      OUTPUT=$(bao write -format=json pki_int/issue/homelab \
        common_name="vault01.home.2rjus.net" \
        alt_names="vault.home.2rjus.net" \
        ttl="720h")

      # Create ACME directory structure
      echo "Creating ACME certificate directory..."
      mkdir -p "$CERT_DIR"

      # Extract certificate components to temp files
      echo "$OUTPUT" | jq -r '.data.certificate' > /tmp/vault01-cert.pem
      echo "$OUTPUT" | jq -r '.data.private_key' > /tmp/vault01-key.pem
      echo "$OUTPUT" | jq -r '.data.issuing_ca' > /tmp/vault01-ca.pem

      # Create fullchain (cert + CA)
      cat /tmp/vault01-cert.pem /tmp/vault01-ca.pem > /tmp/vault01-fullchain.pem

      # Backup old certificates if they exist
      if [ -f "$CERT_DIR/fullchain.pem" ]; then
        echo "Backing up old certificate..."
        cp "$CERT_DIR/fullchain.pem" "$CERT_DIR/fullchain.pem.backup"
        cp "$CERT_DIR/key.pem" "$CERT_DIR/key.pem.backup"
      fi

      # Install new certificates
      echo "Installing new certificate..."
      mv /tmp/vault01-fullchain.pem "$CERT_DIR/fullchain.pem"
      mv /tmp/vault01-cert.pem "$CERT_DIR/cert.pem"
      mv /tmp/vault01-ca.pem "$CERT_DIR/chain.pem"
      mv /tmp/vault01-key.pem "$CERT_DIR/key.pem"

      # Set proper ownership and permissions (ACME-style)
      chown -R acme:acme "$CERT_DIR"
      chmod 750 "$CERT_DIR"
      chmod 640 "$CERT_DIR"/*.pem

      echo "Certificate installed successfully!"
      echo ""
      echo "Certificate details:"
      openssl x509 -in "$CERT_DIR/cert.pem" -noout -subject -issuer -dates
      echo ""
      echo "Subject Alternative Names:"
      openssl x509 -in "$CERT_DIR/cert.pem" -noout -ext subjectAltName

      echo ""
      echo "Now restart openbao service:"
      echo "  systemctl restart openbao"
      echo ""
      echo "After restart, verify ACME endpoint is accessible:"
      echo "  curl https://vault01.home.2rjus.net:8200/v1/pki_int/acme/directory"
      echo ""
      echo "Once working, ACME will automatically manage certificate renewals."
    '';
  };
in
{
  # Make bootstrap script available as a command
  environment.systemPackages = [ bootstrapCertScript ];

  services.openbao = {
    enable = true;

    settings = {
      ui = true;

      storage.file.path = "/var/lib/openbao";
      listener.default = {
        type = "tcp";
        address = "0.0.0.0:8200";
        tls_cert_file = "/run/credentials/openbao.service/cert.pem";
        tls_key_file = "/run/credentials/openbao.service/key.pem";
      };
      listener.socket = {
        type = "unix";
        address = "/run/openbao/openbao.sock";
      };
    };
  };

  systemd.services.openbao.serviceConfig = {
    LoadCredential = [
      "key.pem:/var/lib/acme/vault01.home.2rjus.net/key.pem"
      "cert.pem:/var/lib/acme/vault01.home.2rjus.net/fullchain.pem"
    ];
    # TPM2-encrypted unseal key (created manually, see setup instructions)
    LoadCredentialEncrypted = [
      "unseal-key:/var/lib/openbao/unseal-key.cred"
    ];
    # Auto-unseal on service start
    ExecStartPost = "${unsealScript}/bin/openbao-unseal";
    # Add openbao user to acme group to read certificates
    SupplementaryGroups = [ "acme" ];
  };

  # ACME certificate management
  # Bootstrapped with bootstrap-vault-cert, now managed by ACME
  security.acme.certs."vault01.home.2rjus.net" = {
    server = "https://vault01.home.2rjus.net:8200/v1/pki_int/acme/directory";
    listenHTTP = ":80";
    reloadServices = [ "openbao" ];
    extraDomainNames = [ "vault.home.2rjus.net" ];
  };
}