pixels

Disposable Linux containers for AI coding agents, powered by TrueNAS and Incus.

Spin up sandboxed Linux containers pre-loaded with AI coding tools (Claude Code, Codex, OpenCode via mise). Each container gets SSH access, ZFS snapshot-based checkpoints, and network egress policies that control what the agent can reach. Managed entirely from the CLI over TrueNAS WebSocket API.

Features

• Container lifecycle -- create, start, stop, destroy, and list Incus containers
• SSH access -- interactive console and remote command execution
• ZFS checkpoints -- snapshot, restore, delete, and clone containers from checkpoints
• AI agent provisioning -- automatically installs mise, Claude Code, Codex, and OpenCode
• Network egress policies -- restrict outbound traffic to AI APIs, package registries, and Git (or a custom allowlist)
• Configuration -- TOML config file, PIXELS_* environment variables, and CLI flags
• Network accessible -- each container gets its own IP, reachable from the host for running and accessing services
• Local caching -- disk cache avoids WebSocket round-trips for console/exec

Prerequisites

• TrueNAS SCALE with Incus virtualization enabled
• TrueNAS API key (create one in the TrueNAS web UI under Credentials > API Keys)
• Go 1.25+ (for building from source)
• SSH key pair (defaults to ~/.ssh/id_ed25519)

Installation

go install github.com/deevus/pixels@latest

Or build from source:

git clone https://github.com/deevus/pixels.git
cd pixels
go build

Quick Start

# Create a base container with agent egress restrictions
pixels create base --egress agent --console

# Set up your environment, install dependencies, etc.
# Then save a checkpoint
pixels checkpoint create base --label ready

# Spin up new containers from the checkpoint
pixels create task1 --from base:ready
pixels create task2 --from base:ready

# Or clone from a container's current state
pixels create task3 --from base

# Tear down when done
pixels destroy task1
pixels destroy task2

Commands

Command	Description
pixels create <name>	Create a new container
pixels start <name>	Start a stopped container
pixels stop <name>	Stop a running container
pixels destroy <name>	Permanently destroy a container and all its checkpoints
pixels list	List all containers with status and IP
pixels console <name>	Open an interactive SSH session
pixels exec <name> -- <command...>	Run a command via SSH
pixels checkpoint create <name>	Create a ZFS snapshot
pixels checkpoint list <name>	List checkpoints with sizes
pixels checkpoint restore <name> <label>	Restore to a checkpoint
pixels checkpoint delete <name> <label>	Delete a checkpoint
pixels network show <name>	Show current egress rules
pixels network set <name> <mode>	Set egress mode
pixels network allow <name> <domain>	Add a domain to the allowlist
pixels network deny <name> <domain>	Remove a domain from the allowlist

Global flags: --host, --api-key, -u/--username, -v/--verbose

Container Lifecycle

# Create with custom resources
pixels create mybox --image ubuntu/24.04 --cpu 4 --memory 4096

# Create with agent sandbox and open console when ready
pixels create mybox --egress agent --console

# Skip all provisioning (no SSH keys, devtools, or egress setup)
pixels create mybox --no-provision

# Clone from an existing container's checkpoint
pixels create newbox --from mybox:ready

# Clone from an existing container's current state
pixels create newbox --from mybox

All containers are prefixed px- internally. Commands accept bare names (e.g., mybox becomes px-mybox).

SSH Access

Console opens an interactive SSH session with zmx session persistence. Disconnecting and reconnecting re-attaches to the same session:

pixels console mybox                    # default "console" session
pixels console mybox -s build           # named session
pixels console mybox --no-persist       # plain SSH, no zmx

Inside a session, press Ctrl+\ to detach (works in TUIs too), or type detach.

Sessions lists zmx sessions in a container:

pixels sessions mybox

Exec runs a command and returns its exit code:

pixels exec mybox -- ls -la /home/pixel

Both commands check the local cache first for the container's IP, falling back to the TrueNAS API. SSH key auth is verified on connect -- if it fails, the current machine's public key is automatically written to the container.

Checkpoints

Checkpoints are ZFS snapshots of the container's root filesystem.

# Create with auto-generated label
pixels checkpoint create mybox

# Create with a custom label
pixels checkpoint create mybox --label ready

# List checkpoints
pixels checkpoint list mybox
# LABEL       SIZE
# ready       42.0 MiB

# Restore (stops container, rolls back, restarts)
pixels checkpoint restore mybox ready

# Delete
pixels checkpoint delete mybox ready

Clone a new container from a checkpoint to get identical copies:

pixels create worker1 --from mybox:ready
pixels create worker2 --from mybox:ready

The checkpoint command can also be abbreviated as cp.

Agent Provisioning

By default, new containers are provisioned with:

• SSH public key injection (root + pixel user)
• DNS configuration via systemd-resolved
• Environment variables from config written to /etc/environment
• Dev tools: mise, Node.js LTS, Claude Code, Codex, and OpenCode (installed via a background systemd service)

Dev tools install asynchronously after container creation. Use --console to wait for them to finish before dropping into a shell, or monitor progress with:

pixels exec mybox -- sudo journalctl -fu pixels-devtools

Disable provisioning entirely with --no-provision, or just dev tools via config:

[provision]
devtools = false

Network Egress

Control outbound network access with three modes:

Mode	Description
unrestricted	No filtering (default)
agent	Preset allowlist: AI APIs, package registries, Git/GitHub, Ubuntu repos, plus any custom domains
allowlist	Custom domain list only

Setting Egress at Creation

pixels create mybox --egress agent

Changing Egress on a Running Container

# Switch to agent mode
pixels network set mybox agent

# Switch to unrestricted
pixels network set mybox unrestricted

# Show current rules
pixels network show mybox

Managing the Allowlist

# Add a domain
pixels network allow mybox api.example.com

# Remove a domain
pixels network deny mybox api.example.com

The agent preset includes domains for Anthropic, OpenAI, Google AI, npm, PyPI, crates.io, Go proxy, GitHub (including release CDN), mise, Node.js, and Ubuntu package repos. CIDR ranges are included for Google and GitHub/Azure CDN IPs.

Egress is enforced via nftables rules inside the container with restricted sudo access. See SECURITY.md for known limitations and mitigations.

Configuration

Create ~/.config/pixels/config.toml:

[truenas]
host = "truenas.local"
# api_key: prefer PIXELS_TRUENAS_API_KEY env var over storing here
# username = "root"           # default
# insecure_skip_verify = false # default; set true for self-signed certs

[defaults]
# image = "ubuntu/24.04"     # default
# cpu = "2"                  # default
# memory = 2048              # MiB, default
# pool = "tank"              # discovered from server; override if needed
# dns = ["1.1.1.1"]          # optional; nameservers to inject into containers

[ssh]
# user = "pixel"             # default
# key = "~/.ssh/id_ed25519"  # default

[provision]
# enabled = true             # default
# devtools = true            # default

[network]
# egress = "unrestricted"    # default
# allow = ["api.example.com"]  # additional domains for agent/allowlist modes

[env]
# ANTHROPIC_API_KEY = "sk-ant-..."
# OPENAI_API_KEY = "sk-..."

Priority Order

1. TOML config file (~/.config/pixels/config.toml)
2. Environment variables (PIXELS_TRUENAS_HOST, PIXELS_TRUENAS_API_KEY, etc.)
3. CLI flags (--host, --api-key, -u)

Environment Variables

Variable	Config key
PIXELS_TRUENAS_HOST	truenas.host
PIXELS_TRUENAS_USERNAME	truenas.username
PIXELS_TRUENAS_API_KEY	truenas.api_key
PIXELS_TRUENAS_PORT	truenas.port
PIXELS_TRUENAS_INSECURE	truenas.insecure_skip_verify
PIXELS_DEFAULT_IMAGE	defaults.image
PIXELS_DEFAULT_CPU	defaults.cpu
PIXELS_DEFAULT_MEMORY	defaults.memory
PIXELS_DEFAULT_POOL	defaults.pool
PIXELS_SSH_USER	ssh.user
PIXELS_SSH_KEY	ssh.key
PIXELS_CHECKPOINT_DATASET_PREFIX	checkpoint.dataset_prefix
PIXELS_PROVISION_ENABLED	provision.enabled
PIXELS_PROVISION_DEVTOOLS	provision.devtools
PIXELS_NETWORK_EGRESS	network.egress

Security

Container egress filtering uses nftables rules inside the container. A root process with cap_net_admin could bypass these rules. The pixel user has restricted sudo that only permits safe-apt, dpkg-query, systemctl, journalctl, and nft list.

See SECURITY.md for the full threat model, known issues, and mitigations.

License

MIT