ArmoredGate/volt
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
main
volt/docs/networking.md
Karl Clinger 0ebe75b2ca Volt CLI: source-available under AGPSL v5.0 
Complete infrastructure platform CLI:
- Container runtime (systemd-nspawn)
- VoltVisor VMs (Neutron Stardust / QEMU)
- Stellarium CAS (content-addressed storage)
- ORAS Registry
- GitOps integration
- Landlock LSM security
- Compose orchestration
- Mesh networking

Copyright (c) Armored Gates LLC. All rights reserved.
Licensed under AGPSL v5.0
2026-03-21 02:08:15 -05:00

558 lines
14 KiB
Markdown
Raw Permalink Blame History

# Volt Networking
Volt networking provides a unified interface for all workload connectivity. It is built on Linux bridge interfaces and nftables, supporting containers and VMs on the same L2 network.
## Architecture Overview
```
┌──────────────────────────────┐
│ Host Network │
│ (eth0, etc.) │
└──────────────┬────────────────┘
│ NAT / routing
┌──────────────┴────────────────┐
│ volt0 (bridge) │
│ 10.0.0.1/24 │
├───────┬───────┬───────┬───────┤
│ veth │ veth │ tap │ veth │
│ ↓ │ ↓ │ ↓ │ ↓ │
│ web │ api │ db │ cache │
│(con) │(con) │ (vm) │(con) │
└───────┴───────┴───────┴───────┘
```
### Key Concepts
- **Bridges**: Linux bridge interfaces that act as virtual switches
- **veth pairs**: Virtual ethernet pairs connecting containers to bridges
- **TAP interfaces**: Virtual network interfaces connecting VMs to bridges
- **L2 peers**: Containers and VMs on the same bridge communicate directly at Layer 2
## Default Bridge: volt0
When Volt initializes, it creates the `volt0` bridge with a default subnet of `10.0.0.0/24`. All workloads connect here unless assigned to a different network.
The bridge IP (`10.0.0.1`) serves as the default gateway for workloads. NAT rules handle outbound traffic to the host network and beyond.
```bash
# View bridge status
volt net bridge list
# View all network status
volt net status
```
## Creating Networks
### Basic Network
```bash
volt net create --name backend --subnet 10.30.0.0/24
```
This creates:
1. A Linux bridge named `volt-backend`
2. Assigns `10.30.0.1/24` to the bridge interface
3. Configures NAT for outbound connectivity
4. Updates internal DNS for name resolution
### Internal (Isolated) Network
```bash
volt net create --name internal --subnet 10.50.0.0/24 --no-nat
```
Internal networks have no NAT rules and no outbound connectivity. Workloads on internal networks can only communicate with each other.
### Inspecting Networks
```bash
volt net inspect backend
volt net list
volt net list -o json
```
## Connecting Workloads
### Connect to a Network
```bash
# Connect a container
volt net connect backend api-server
# Connect a VM
volt net connect backend db-primary
```
When connected, the workload gets:
- A veth pair (container) or TAP interface (VM) attached to the bridge
- An IP address from the network's subnet via DHCP or static assignment
- DNS resolution for all other workloads on the same network
### Disconnect
```bash
volt net disconnect api-server
```
### Cross-Type Communication
A key feature of Volt networking: containers and VMs on the same network are L2 peers. There is no translation layer.
```bash
# Both on "backend" network
volt net connect backend api-server # container
volt net connect backend db-primary # VM
# From inside api-server container:
psql -h db-primary -U app -d myapp # just works
```
This works because:
- The container's veth and the VM's TAP are both bridge ports on the same bridge
- Frames flow directly between them at L2
- Internal DNS resolves `db-primary` to its bridge IP
## Firewall Rules
Volt firewall wraps `nftables` with a workload-aware interface. Rules can reference workloads by name.
### Listing Rules
```bash
volt net firewall list
```
### Adding Rules
```bash
# Allow HTTP to a workload
volt net firewall add --name allow-http \
--source any --dest 10.0.0.5 --port 80,443 --proto tcp --action accept
# Allow DB access from specific subnet
volt net firewall add --name db-access \
--source 10.0.0.0/24 --dest 10.30.0.10 --port 5432 --proto tcp --action accept
# Block SSH from everywhere
volt net firewall add --name block-ssh \
--source any --dest 10.0.0.5 --port 22 --proto tcp --action drop
```
### Deleting Rules
```bash
volt net firewall delete --name allow-http
```
### Flushing All Rules
```bash
volt net firewall flush
```
### How It Works Internally
Volt manages a dedicated nftables table called `volt` with chains for:
| Chain | Purpose |
|-------|---------|
| `volt-input` | Traffic destined for the host |
| `volt-forward` | Traffic between workloads (inter-bridge) |
| `volt-nat-pre` | DNAT rules (port forwarding inbound) |
| `volt-nat-post` | SNAT rules (masquerade for outbound) |
Rules added via `volt net firewall add` are inserted into the appropriate chain based on source/destination. The chain is determined automatically — you don't need to know whether traffic is "input" or "forward".
### Default Policy
- **Inbound to host**: deny all (except established connections)
- **Inter-workload (same network)**: allow
- **Inter-workload (different network)**: deny
- **Outbound from workloads**: allow (via NAT)
- **Host access from workloads**: deny by default
## Port Forwarding
Forward host ports to workloads:
### Adding Port Forwards
```bash
# Forward host:80 to container web-frontend:80
volt net port add --host-port 80 --target web-frontend --target-port 80
# Forward host:5432 to VM db-primary:5432
volt net port add --host-port 5432 --target db-primary --target-port 5432
```
### Listing Port Forwards
```bash
volt net port list
```
Output:
```
HOST-PORT TARGET TARGET-PORT PROTO STATUS
80 web-frontend 80 tcp active
443 web-frontend 443 tcp active
5432 db-primary 5432 tcp active
```
### How It Works
Port forwards create DNAT rules in nftables:
1. Incoming traffic on `host:port` is DNATed to `workload-ip:target-port`
2. Return traffic is tracked by conntrack and SNATed back
## DNS Resolution
Volt runs an internal DNS resolver (`volt-dns.service`) that provides automatic name resolution for all workloads.
### How It Works
1. When a workload starts, Volt registers its name and IP in the internal DNS
2. All workloads are configured to use the bridge gateway IP as their DNS server
3. Lookups for workload names resolve to their bridge IPs
4. Unknown queries are forwarded to upstream DNS servers
### Upstream DNS
Configured in `/etc/volt/config.yaml`:
```yaml
network:
dns:
enabled: true
upstream:
- 1.1.1.1
- 8.8.8.8
search_domains:
- volt.local
```
### DNS Management
```bash
# List DNS entries
volt net dns list
# Flush DNS cache
volt net dns flush
```
### Name Resolution Examples
Within any workload on the same network:
```bash
# Resolve by name
ping db-primary # resolves to 10.30.0.10
curl http://api-server:8080/health
psql -h db-primary -U app -d myapp
```
## Network Policies
Policies define allowed communication patterns between specific workloads. They provide finer-grained control than firewall rules.
### Creating Policies
```bash
# Only app-server can reach db-primary on port 5432
volt net policy create --name app-to-db \
--from app-server --to db-primary --port 5432 --action allow
```
### Listing Policies
```bash
volt net policy list
```
### Testing Connectivity
Before deploying, test whether traffic would be allowed:
```bash
# This should succeed
volt net policy test --from app-server --to db-primary --port 5432
# ✓ app-server → db-primary:5432 — ALLOWED (policy: app-to-db)
# This should fail
volt net policy test --from web-frontend --to db-primary --port 5432
# ✗ web-frontend → db-primary:5432 — DENIED
```
### Deleting Policies
```bash
volt net policy delete --name app-to-db
```
## VLANs
### Listing VLANs
```bash
volt net vlan list
```
VLAN management is available for advanced network segmentation. VLANs are created on top of physical interfaces and can be used as bridge uplinks.
## Ingress Proxy
Volt includes a built-in reverse proxy for routing external HTTP/HTTPS traffic to workloads by hostname and path prefix. It supports automatic TLS via ACME (Let's Encrypt), manual certificates, WebSocket passthrough, health checks, and zero-downtime route reloading.
### Creating Routes
Route external traffic to workloads by hostname:
```bash
# Simple HTTP route
volt ingress create --name web \
--hostname app.example.com \
--backend web:8080
# Route with path prefix
volt ingress create --name api \
--hostname api.example.com \
--path /v1 \
--backend api:3000
# Route with automatic TLS (Let's Encrypt)
volt ingress create --name secure-web \
--hostname app.example.com \
--backend web:8080 \
--tls auto
# Route with manual TLS certificate
volt ingress create --name cdn \
--hostname cdn.example.com \
--backend static:80 \
--tls manual \
--cert /etc/certs/cdn.pem \
--key /etc/certs/cdn.key
```
### TLS Termination
Three TLS modes are available:
| Mode | Description |
|------|-------------|
| `auto` | ACME (Let's Encrypt) — automatic certificate issuance, renewal, and storage |
| `manual` | User-provided certificate and key files |
| `passthrough` | Forward TLS directly to the backend without termination |
```bash
# Auto ACME — Volt handles everything
volt ingress create --name web --hostname app.example.com --backend web:8080 --tls auto
# Manual certs
volt ingress create --name web --hostname app.example.com --backend web:8080 \
--tls manual --cert /etc/certs/app.pem --key /etc/certs/app.key
# TLS passthrough — backend handles TLS
volt ingress create --name web --hostname app.example.com --backend web:443 --tls passthrough
```
For ACME to work, the ingress proxy must be reachable on port 80 from the internet (for HTTP-01 challenges). Ensure your DNS records point to the server running the proxy.
### WebSocket Passthrough
WebSocket connections are passed through automatically. When a client sends an HTTP Upgrade request, the ingress proxy upgrades the connection and proxies frames bidirectionally to the backend. No additional configuration is needed.
### Health Checks
The ingress proxy monitors backend health. If a backend becomes unreachable, it is temporarily removed from the routing table until it recovers. Configure backend timeouts per route:
```bash
volt ingress create --name api --hostname api.example.com \
--backend api:3000 --timeout 60
```
The `--timeout` flag sets the backend timeout in seconds (default: 30).
### Hot Reload
Update routes without restarting the proxy or dropping active connections:
```bash
volt ingress reload
```
Existing connections are drained gracefully while new connections immediately use the updated routes. This is safe to call from CI/CD pipelines or GitOps workflows.
### Managing Routes
```bash
# List all routes
volt ingress list
# Show proxy status
volt ingress status
# Delete a route
volt ingress delete --name web
```
### Running the Proxy
**Foreground (testing):**
```bash
volt ingress serve
volt ingress serve --http-port 8080 --https-port 8443
```
**Production (systemd):**
```bash
systemctl enable --now volt-ingress.service
```
### Example: Full Ingress Setup
```bash
# Create routes for a web application
volt ingress create --name web \
--hostname app.example.com \
--backend web:8080 \
--tls auto
volt ingress create --name api \
--hostname api.example.com \
--path /v1 \
--backend api:3000 \
--tls auto
volt ingress create --name ws \
--hostname ws.example.com \
--backend realtime:9000 \
--tls auto
# Start the proxy
systemctl enable --now volt-ingress.service
# Verify
volt ingress list
volt ingress status
```
---
## Bridge Management
### Listing Bridges
```bash
volt net bridge list
```
Output:
```
NAME SUBNET MTU CONNECTED STATUS
volt0 10.0.0.0/24 1500 8 up
backend 10.30.0.0/24 1500 3 up
```
### Creating a Bridge
```bash
volt net bridge create mybridge --subnet 10.50.0.0/24
```
### Deleting a Bridge
```bash
volt net bridge delete mybridge
```
## Network Configuration
### Config File
Network settings in `/etc/volt/config.yaml`:
```yaml
network:
default_bridge: volt0
default_subnet: 10.0.0.0/24
dns:
enabled: true
upstream:
- 1.1.1.1
- 8.8.8.8
search_domains:
- volt.local
mtu: 1500
```
### Per-Network Settings in Compose
```yaml
networks:
frontend:
driver: bridge
subnet: 10.20.0.0/24
options:
mtu: 9000
backend:
driver: bridge
subnet: 10.30.0.0/24
internal: true # No external access
```
## Network Tuning
For high-throughput workloads, tune network buffer sizes and offloading:
```bash
# Increase buffer sizes
volt tune net buffers --rmem-max 16M --wmem-max 16M
# Show current tuning
volt tune net show
```
Relevant sysctls:
```bash
volt tune sysctl set net.core.somaxconn 65535
volt tune sysctl set net.ipv4.ip_forward 1
volt tune sysctl set net.core.rmem_max 16777216
volt tune sysctl set net.core.wmem_max 16777216
```
## Troubleshooting Network Issues
### Container Can't Reach the Internet
1. Check bridge exists: `volt net bridge list`
2. Check NAT is configured: `volt net firewall list`
3. Check IP forwarding: `volt tune sysctl get net.ipv4.ip_forward`
4. Verify the container has an IP: `volt container inspect <name>`
### Workloads Can't Reach Each Other
1. Verify both are on the same network: `volt net inspect <network>`
2. Check firewall rules aren't blocking: `volt net firewall list`
3. Check network policies: `volt net policy list`
4. Test connectivity: `volt net policy test --from <src> --to <dst> --port <port>`
### DNS Not Resolving
1. Check DNS service: `volt net dns list`
2. Flush DNS cache: `volt net dns flush`
3. Verify upstream DNS: check `/etc/volt/config.yaml` network.dns.upstream
### Port Forward Not Working
1. List active forwards: `volt net port list`
2. Check the target workload is running: `volt ps`
3. Verify the target port is listening inside the workload
4. Check firewall rules aren't blocking inbound traffic
See [troubleshooting.md](troubleshooting.md) for more.
Reference in New Issue View Git Blame Copy Permalink