---
checkId: check.docker.network
plugin: stellaops.doctor.docker
severity: warn
tags: [docker, network, connectivity]
---
# Docker Network

## What It Checks
Validates Docker network configuration and connectivity. The check connects to the Docker daemon and lists all networks, then verifies:

1. **Required networks exist**: Checks that each network listed in `Docker:RequiredNetworks` configuration is present. Defaults to `["bridge"]` if not configured.
2. **Bridge driver available**: Verifies at least one network using the `bridge` driver exists.

Evidence collected includes: total network count, available network drivers, found/missing required networks, and bridge network name.

If the Docker daemon is unreachable, the check is skipped.

## Why It Matters
Docker networks provide isolated communication channels between containers. Stella Ops services communicate over dedicated networks for:

- **Service-to-service communication**: Platform, Authority, Gateway, and other services need to reach each other.
- **Database access**: PostgreSQL and Valkey are on specific networks.
- **Network isolation**: Separating frontend, backend, and data tiers.

Missing networks cause container DNS resolution failures and connection refused errors between services.

## Common Causes
- Required network not found (not yet created or was deleted)
- No bridge network driver available (Docker networking misconfigured)
- Docker Compose network not created (compose project not started)
- Network name mismatch between configuration and actual Docker networks

## How to Fix

### Docker Compose
Docker Compose normally creates networks automatically. If missing:

```bash
# List existing networks
docker network ls

# Start compose to create networks
docker compose -f devops/compose/docker-compose.stella-ops.yml up -d

# Create a network manually if needed
docker network create stellaops-network

# Inspect a network
docker network inspect <network-name>
```

Configure required networks for the check:
```yaml
environment:
  Docker__RequiredNetworks__0: "stellaops-network"
  Docker__RequiredNetworks__1: "bridge"
```

### Bare Metal / systemd
For bare metal deployments, Docker networks must be created manually:

```bash
# Create required networks
docker network create --driver bridge stellaops-frontend
docker network create --driver bridge stellaops-backend
docker network create --driver bridge stellaops-data

# List networks
docker network ls

# Inspect network details
docker network inspect stellaops-backend
```

### Kubernetes / Helm
Docker networks are not used in Kubernetes; instead, Kubernetes networking (Services, NetworkPolicies) handles inter-pod communication. Configure the check to skip Docker network requirements:

```yaml
doctor:
  docker:
    requiredNetworks: []  # Not applicable in Kubernetes
```

Or verify Kubernetes networking:
```bash
# Check services
kubectl get svc -n stellaops

# Check network policies
kubectl get networkpolicy -n stellaops

# Test connectivity between pods
kubectl exec -it <pod-a> -- curl http://<service-b>:5000/health
```

## Verification
```
stella doctor run --check check.docker.network
```

## Related Checks
- `check.docker.daemon` — Docker daemon must be running to query networks
- `check.docker.socket` — Docker socket must be accessible to communicate with the daemon