Provision NixOS Server

Workflow Overview

1. Gather requirements from user
2. Create Proxmox container
3. Set up SSH access
4. Create Colmena init configuration
5. Deploy init config and update to static IP
6. Copy infrastructure key for SOPS
7. Configure application (if applicable)
8. Deploy full configuration

Step 1: Gather Requirements

Ask user for:

• Hostname: Server name (e.g., woodpecker)
• Container ID: Proxmox container ID (e.g., 122)
• Proxmox server: Target Proxmox host (e.g., thrall)
• Storage: local-lvm (fast) or cephpool1 (distributed, slower)
• Memory: RAM in MB (default: 4096)
• Disk size: In GB (default: 100)
• Application: What will run on this server

Verify soft-secrets exist for the new host (host.<hostname>.admin_ip_address, etc.) or ask user to create them.

Step 2: Create Proxmox Container

PROXMOX_SERVER=<server>
HOSTNAME=<hostname>
CONTAINER_ID=<id>
STORAGE=local-lvm
MEMORY=4096
DISK_SIZE_IN_GB=100

ssh $PROXMOX_SERVER "pct create $CONTAINER_ID \
    --arch amd64 local:vztmpl/nixos-system-x86_64-linux.tar.xz \
    --ostype unmanaged \
    --description nixos \
    --hostname $HOSTNAME \
    --net0 name=eth0,bridge=vmbr3,ip=dhcp,firewall=1 \
    --storage $STORAGE \
    --memory $MEMORY \
    --rootfs $STORAGE:$DISK_SIZE_IN_GB \
    --unprivileged 1 \
    --features nesting=1 \
    --cmode console \
    --onboot 1 \
    --start 1"

Timeout note: Use longer timeouts (5+ minutes) for cephpool1 storage.

Step 3: Set Up SSH Access

Fresh NixOS containers require full paths. Run via pct exec:

ssh $PROXMOX_SERVER "pct exec $CONTAINER_ID -- /run/current-system/sw/bin/bash -c '\
  mkdir -p ~/.ssh && \
  curl -s https://github.com/fred-drake.keys > ~/.ssh/authorized_keys && \
  chmod 700 ~/.ssh && chmod 600 ~/.ssh/authorized_keys'"

Get DHCP IP address:

ssh $PROXMOX_SERVER "pct exec $CONTAINER_ID -- /run/current-system/sw/bin/ip addr show eth0 | grep 'inet '"

Step 4: Create Colmena Init Configuration

Create these files (see references/colmena-host-template.md and references/nixos-config-template.md):

1. mkdir -p modules/nixos/host/<hostname>
2. Create modules/nixos/host/<hostname>/configuration.nix
3. Create colmena/hosts/<hostname>.nix
4. Update colmena/default.nix with imports

Initial deploy config: Use DHCP IP and root user:

deployment = {
  targetHost = "<DHCP_IP>";
  targetUser = "root";
};

Stage files and build:

git add colmena/hosts/<hostname>.nix modules/nixos/host/<hostname>/ colmena/default.nix
colmena build --impure --on <hostname>-init

Step 5: Deploy Init and Update IP

Deploy (will hang when network restarts due to IP change):

colmena apply --impure --on <hostname>-init

Kill the hanging command, then update colmena/hosts/<hostname>.nix:

deployment = {
  targetHost = soft-secrets.host.<hostname>.admin_ip_address;
  targetUser = "default";
};

Verify with another deploy:

colmena apply --impure --on <hostname>-init

Step 6: Copy Infrastructure Key

Required for SOPS secret decryption:

ssh default@<NEW_IP> "mkdir -p ~/.ssh && chmod 700 ~/.ssh"
scp ~/.ssh/id_infrastructure default@<NEW_IP>:~/id_infrastructure
ssh default@<NEW_IP> "chmod 600 ~/id_infrastructure"

Age public key (for .sops.yaml): age1rnarwmx5yqfhr3hxvnnw2rxg3xytjea7dhtg00h72t26dn6csdxqvsryg5

If secrets fail to decrypt, user needs to add this key to .sops.yaml and run sops updatekeys on the secret files.

Step 7: Configure Application

See references/app-templates.md for patterns.

Add Container Images

1. Edit apps/fetcher/containers.toml
2. Run just update-container-digests
3. Stage: git add apps/fetcher/containers.toml apps/fetcher/containers-sha.nix

Create Application Config

Create apps/<appname>.nix with:

• Nginx proxy with SSL (if web-facing)
• PostgreSQL container (if database needed)
• Application container(s)
• tmpfiles rules for data directories

Create Secrets Config

Create modules/secrets/<hostname>.nix referencing SOPS files.

User must create SOPS files in secrets repo with:

• postgresql-env.sops (POSTGRES_PASSWORD, POSTGRES_USER, POSTGRES_DB)
• <appname>-env.sops (app-specific secrets)

Update Colmena Full Config

In colmena/hosts/<hostname>.nix, add to full configuration imports:

../../modules/secrets/<hostname>.nix
../../apps/<appname>.nix

Step 8: Deploy Full Configuration

just update-secrets  # Get latest secrets
git add <all-new-files>
colmena apply --impure --on <hostname>

Common Issues

SOPS decrypt fails: Age key not in .sops.yaml – user must add key and re-encrypt

Nginx duplicate directive: Don’t add proxy_http_version when using proxyWebsockets = true

PostgreSQL 18 fails: Mount at /var/lib/postgresql not /var/lib/postgresql/data

Container can’t reach postgres: Use 0.0.0.0:5432:5432 for port binding, host.containers.internal in connection string