k7
Self-hosted secure VM sandboxes for AI compute at scale
πΈ
πΈ
k7 aims to make it easy to create, manage and orchestrate lightweight safe VM sandboxes for executing untrusted code, at scale. It is built on battle-tested VM isolation with Kata, Firecracker, QEMU, Longhorn, and Kubernetes β plus k7's own k7d runtime. It is orignally motivated by AI agents that need to run arbitrary code at scale but it is also great for:
- Custom serverless (like AWS Fargate, but yours)
- Hardened CI/CD runners (no Docker-in-Docker risks)
- Blockchain execution layers for AI dApps
> 100% openβsource (Apacheβ2.0). For technical support, write us at: hi@katakate.org
The Tech Stack
k7 is built on:
- Kubernetes for orchestration, with K3s which is prod-ready and a great choice for edge nodes,
- Kata to encapsulate containers into light-weight virtual-machines,
- Firecracker (`kfd`) for super-fast boots, light footprints and minimal attack surface (with the jailer),
- Devmapper Snapshotter with thin-pool provisioning of logical volumes for efficient disk use across many Firecracker VMs per node,
- QEMU (`kql`) via Kata when you want a fuller VMM and durable sandbox disks,
- Longhorn for replicated PVC-backed root disks on the QEMU path β named snapshots, restore, disk-only fork, and cross-node mobility,
- k7d β k7's own microVM runtime daemon (Katakate/k7d) with VM-level warm fork (CoW disk+memory) and in-place pause/resume.
Sandbox backends
`k7 install --backend ` provisions those backends (required; there is no default). `none` installs the cluster with no sandbox runtime β typical for scheduling-only masters (`k7_backends=none` in inventory). Each sandbox picks one runtime (`k7 create --backend β¦`). See [docs/BACKENDS.md](docs/BACKENDS.md) for the architecture and [PERFORMANCE.md](PERFORMANCE.md) for the full measurements (Hetzner AX41 node, medians).
| | `kfd` (kata-firecracker-devmapper) | `kql` (kata-qemu-longhorn) | `k7d` | `k7d-fc` |
|---|---|---|---|---|
| VMM | Firecracker (Kata) | QEMU (Kata) | k7d (custom KVM VMM) | k7d + Firecracker jailer |
| RuntimeClass | `kata` | `kata-qemu` | `k7` | `k7-fc` |
| Sandbox storage | devmapper thin-pool (needs a spare raw disk) | Longhorn PVC (replicated, persistent) | erofs images + reflink XFS + guest tmpfs | same as k7d (no virtiofs / hostPath) |
| Create β Ready* | not re-measuredβ | 17.1s | **2.1s** | **2.1s** |
| Named snapshot* | β | 6.5s (Longhorn, disk-only) | β (VM snapshot trees via the k7d API) | β (same as k7d) |
| Fork β usable* | n/a (rejected) | 46.7s (disk clone + cold boot) | **~5 ms VM CoW fork**; **~2.4 s** end-to-end via k7/k8s (pod Ready + exec) | **~2.5 s** end-to-end (same CoW; child `--docker` stays overlay2) |
| Pause / resume* | scale to 0 / 1 | 1.3s / 4.1s (disk survives) | **0.2s / 0.3s (VM frozen in place, memory survives)** | **0.2s / ββ‘** |
| Docker in the VM | **`--docker`**: vehicle + overlay2 on ephemeral LVM block | **`--docker`**: vehicle + overlay2 on Longhorn block (fork/restore) | **`--docker`**: in-guest dockerd, overlay2 on virtio-blk, **forkable** | **same guest dockerd**, overlay2, **forkable** |
| Cross-pod persistence | β | β
snapshots/restore | β (fork carries state instead) | β |
\* medians of 3 on one Hetzner AX41 node β methodology, ranges, and docker-in-VM
numbers are in [PERFORMANCE.md](PERFORMANCE.md).
β kfd needs a spare raw disk the lifecycle-bench node didn't have; Show HN
measured kfd createβexec 3.74s and **fork n/a (rejected)**. Docker-workload
numbers for kfd are in the [PERFORMANCE.md](PERFORMANCE.md) Docker benchmark section.
β‘ k7-fc VMM pause/resume returns immediately; CRI exec after resume hung on this
run (`guest_cid=0` retained β CHALLENGES #17). k7d resumeβexec is **0.3s**.
Also available today
- π οΈ Docker build / run inside VM sandboxes: k7 create --docker --backend k7d --egress-open builder ubuntu:24.04 (name then image; or --backend k7d-fc). In-guest dockerd, overlay2, forkable. The same --docker flag on Kata (kfd/kql) injects a privileged docker-vehicle with overlay2 on a block disk β kql persists/forks the graph, kfd is ephemeral. --sidecar docker is a deprecated alias. See [PERFORMANCE.md](PERFORMANCE.md)
- β‘ Warm VM fork on the k7d backend: k7 fork CoW-clones a running sandbox's disk and memory in ~5 ms at the VMM; end-to-end through k7/Kubernetes is ~2 s to a Ready pod
- π Multi-node clusters (Ansible + Longhorn)
- π Cilium CNI with FQDN egress policies (optional Hubble flow observability via k7 install --hubble; off by default, observability only)
- πΈ Pause / resume / fork / restore and k7 snapshot lifecycle
- π Python SDK: pip install k7-sdk==0.4.0 (katakate package deprecated)
π **See [ROADMAP.md](ROADMAP.md) for upcoming work (GPU passthrough, β¦).**
Note: k7 is currently in beta and under security review. Use with caution for highly sensitive workloads.
# Usage
For usage you need:
- **Node(s)** that will host the VM sandboxes
- **Client** from where to send requests
We provide a:
- **CLI**: to use on the node(s) directly --> `apt install k7`
- **API**: deployed automatically by `k7 install` (toggle with `k7 api enable` / `k7 api disable`)
- **Python SDK**: HTTP client sync/async --> `pip install k7-sdk==0.4.0`
## Current requirements
### For the node(s)
- Ubuntu (amd64 or arm64) host.
- **`k7d` backend is amd64 / x86_64 only** (same ISA; Debian calls it `amd64`,
the release tarball is `*-x86_64-linux.tar.gz`). `kfd` and `kql` support
amd64 and arm64.
- Hardware virtualization (KVM) available and accessible
- Check: `ls /dev/kvm` should exist.
- This is typically available on your own Linux machine.
- On cloud providers, it varies.
- Hetzner (the only one I tested so far) yes for their `Robot` instances only, i.e. "dedicated": robot.hetzner.com.
- AWS: only `.metal` EC2 instances.
- GCP: virtualization friendly, most instances, with `--enable-nested-virtualization` flag.
- Azure: Dv3, Ev3, Dv4, Ev4, Dv5, Ev5 (Intel/AMD x86) or Dpdsv5, Dpldsv5, Epsv5 (ARM64).
- DigitalOcean: Premium Intel and AMD droplets with nested virtualization enabled.
- Others: in general, hardware virtualization is not exposed on cloud VPS, so you'll likely want a dedicated / bare metal.
- **kfd only:** one raw disk (unformatted, unpartitioned) for the thin-pool. Other backends (`kql`, `k7d`) install without a spare drive. `k7 install` does not imply kfd.
- Use `./utils/wipe-disk.sh /your/disk` to wipe a disk clean before provisioning. DANGER: destructive - it will remove data/partitions/formatting/SWRAID.
- Ansible (for installer):
```bash
sudo add-apt-repository universe -y
sudo apt update
sudo apt install -y ansible
```
- Docker and Docker Compose (for the API):
```bash
curl -fsSL https://get.docker.com | sh
```
Already tested setups:
- Hetzner Robot dedicated with Ubuntu 24.04 and a **spare raw NVMe** for the `kfd` thin-pool. Dual-NVMe boxes (no third drive): install the OS on one disk only β see [tutorials/k7_hetzner_node_setup.md](tutorials/k7_hetzner_node_setup.md). (Older PDF that assumed an add-on third NVMe: [tutorials/k7_hetzner_node_setup.pdf](tutorials/k7_hetzner_node_setup.pdf).)
### For the client
Recent Python, or the **`k7`** CLI / **`k7-sdk`** from a Linux node or your laptop (API URL + key).
#### Development on macOS
The **`.deb` / PPA package is Linux-only** (amd64/arm64). On a MacBook:
- **CLI from source:** `./src/k7/cli/dev.sh` (same commands as `k7`; uses `uv` + `PYTHONPATH=src`)
- **API client from laptop:** set `K7_API_URL` and `K7_API_KEY`, then `dev.sh create` / `dev.sh list` (no `--core`)
- **`k7 install`** targets Linux servers with KVM β run on the node or via SSH, not on macOS locally
- **`pip install k7-sdk==0.4.0`** for Python scripts only
Do not install the Ubuntu `.deb` on macOS.
## Quick Start
### Get your node(s) ready
The Launchpad PPA publishes **0.4.0**. Install the CLI, then clone the matching
source β `k7 install` builds `k7-api:local` from the current working directory:
```shell
sudo add-apt-repository ppa:katakate.org/k7
sudo apt update
sudo apt install k7
k7 -V # 0.4.0
# GitHub .deb is the same package if you prefer not to add the PPA:
# curl -fsSL -O https://github.com/Katakate/k7/releases/download/v0.4.0/k7_0.4.0_amd64.deb
# sudo apt install ./k7_0.4.0_amd64.deb
git clone --branch v0.4.0 https://github.com/Katakate/k7.git
cd k7
sudo apt install -y ansible
curl -fsSL https://get.docker.com | sh
```
Then let `k7` get your node ready. **`--backend` is required** (no silent
default). kfd needs a spare raw disk; kql uses Longhorn on the OS disk; k7d
is the warm-fork daemon. `none` is control-plane only (no sandbox runtime):
```console
$ k7 install --backend kfd,kql,k7d
Current task: Reminder about logging out and back in for group changes
Installing K7 on 1 host(s)... ββββββββββββββββββββββββββββββββββββββββ 100% 0:01:41
β
Installation completed successfully!
```
Optionally pass `-v` for a verbose output.
> Dual-NVMe Hetzner boxes have no third empty disk for the `kfd` thin-pool.
> Put Ubuntu on **one** NVMe (`SWRAID 0` / `TWO_DISK=1`) and leave the other
> raw β the playbook auto-detects that spare. Do **not** pin
> `--disk /dev/nvme1n1`: NVMe names swap across reboots. Walkthrough:
> [tutorials/k7_hetzner_node_setup.md](tutorials/k7_hetzner_node_setup.md)
> (this file is also in public [Katakate/k7](https://github.com/Katakate/k7)).
>
> The playbook pins k7d **0.7.0**. `--docker` needs the guest docker
> service (payload on the node); an older k7d fails loudly with
> `this k7d has no docker service; upgrade`. Multi-node inventory shapes
> (2-node server+agent, 3-node `--ha`) are in
> `src/k7/deploy/inventory.ini.example`. Every inventory host must set
> `k7_backends` (or inherit group vars). Use `k7_backends=none` on
> `[k7_servers]` when agents run the sandboxes β empty/omitted is an error.
`k7 install` serves `k7-api` on NodePort `31007` over HTTPS. The default
is a playbook-minted cluster CA (Let's Encrypt cannot issue for a bare
IP). Copy `/etc/k7/tls/ca.crt` off the node and point the CLI at it:
```bash
scp root@:/etc/k7/tls/ca.crt ./k7-ca.crt
k7 config set api.url https://:31007
k7 config set api.ca ./k7-ca.crt
k7 config set api.key
```
`--api-hostname ` uses Let's Encrypt via a Caddy sidecar (the DNS
A record must point at the first master). `--api-tls-cert` +
`--api-tls-key` installs an operator-supplied pair. `--api-insecure-http`
is today's plain HTTP NodePort and must be called what it is: keys travel
in cleartext. None of this is rate limiting; do not write "the API is
now secure".
Pass `--api-allow-cidr ` (repeatable, Cilium only) to restrict who
can connect. Off by default. Defence in depth for operators who know
their client CIDRs β it stacks with TLS and does not replace it. See
[docs/BACKENDS.md](docs/BACKENDS.md) "TLS for `k7-api`" and
"Restricting who can reach `k7-api`".
Pass `--hubble` to turn on Cilium Hubble (relay + CLI, no UI) so policy
drops are a `hubble observe` question. Off by default; requires the
Cilium CNI (`--hubble --cni flannel` fails loudly). See
[docs/BACKENDS.md](docs/BACKENDS.md) "Debugging policy drops".
This will install and most importantly connect together the following components (depending on `--backend`):
- Kubernetes (K3s prod-ready distribution)
- Kata (for container virtualization)
- Firecracker + Jailer + devmapper thin-pool (`kfd`)
- QEMU via Kata + Longhorn PVC-backed roots (`kql`)
- k7d daemon + `containerd-shim-k7-v1` + RuntimeClass `k7` (`k7d`)
- Optional: Hubble relay + `hubble` CLI when `--hubble` is passed
Careful design: config updates will not touch your existing Docker or containerd setups. We chose to use K3s' own containerd for minimal disruption. Installation may however overwrite existing installations of K3s, Kata, Firecracker, Jailer, QEMU/Kata config, or Longhorn.
### CLI Usage
You can run workloads directly from the node(s) using the CLI. To create a sandbox, just create a yaml config for it.
#### k7.yaml example:
```yaml
name: my-sandbox-123
image: alpine:latest
namespace: default
# Optional: restrict egress (safe pattern: whitelist only your own egress proxy IP)
egress_whitelist:
- "10.0.0.5/32" # Your private egress proxy/gateway
# Optional: resource limits
limits:
cpu: "1"
memory: "1Gi"
ephemeral-storage: "2Gi"
# Optional: run before_script inside the container once at start. Network restrictions apply after the before-script, so you can install packages here, pull git repos, etc
before_script: |
apk add --no-cache git curl
# Optional: load environment variables from a file. These will be available both during the before-script, and in the sandbox
env_file: path/to/your/secrets/.env
```
#### Running commands
```bash
# Create a sandbox (uses k7.yaml in the current directory by default, but you can also pass: -f myfile.yaml)
k7 create
# Or pick a backend explicitly (kfd | kql | k7d β aliases for the full names)
k7 create -f k7.yaml --backend k7d
# List sandboxes
k7 list
# Delete a sandbox
k7 delete my-sandbox-123
# Delete all sandboxes. You can also pass a namespace
k7 delete-all
```
#### Fork / pause / snapshot
```bash
# Warm CoW fork (disk + memory) β source must be a k7d sandbox
k7 create -f k7.yaml --backend k7d # name from yaml, e.g. my-sandbox-123
# exec wraps the argument in `sh -c`, so pass the whole guest command
# as one string (redirects and quotes survive). Do not add an extra `sh -c`.
k7 exec my-sandbox-123 -- 'echo hi > /tmp/state.txt'
k7 fork my-sandbox-123 branch-a
k7 exec branch-a -- 'cat /tmp/state.txt' # inherited memory + disk
# Disk-only fork (cold boot from cloned PVC) β kql / kata-qemu-longhorn
k7 create -f k7.yaml --backend kql
k7 fork my-sandbox-123 branch-b
# optional: pin the Longhorn VolumeSnapshot name used for the clone
k7 fork my-sandbox-123 branch-c --snapshot my-snap
# Parallel branches from one base
for i in $(seq 0 7); do k7 fork my-sandbox-123 exp-$i & done; wait
# Pause / resume (kql keeps the PVC; k7d freezes the live VM)
k7 pause my-sandbox-123
k7 resume my-sandbox-123
# Named disk snapshot without pausing (kql)
k7 snapshot create my-sandbox-123 my-named-snap
```
On **k7d**, the VMM fork itself is ~5 ms; end-to-end through Kubernetes
to a Ready pod is ~2 s. On **kql**, fork is a Longhorn snapshot + PVC
clone + cold boot (~45 s). See [PERFORMANCE.md](PERFORMANCE.md) and
[docs/BACKENDS.md](docs/BACKENDS.md).
### API usage
The K7 API is deployed automatically by `k7 install` as the `k7-api`
Deployment in `kube-system`. K3s keeps it running on its own; there's no
separate "start" step.
```shell
# Check status + endpoint
k7 api status
k7 api endpoint
# Generate API key (optionally pin to a namespace and/or node)
k7 generate-api-key my-key1
k7 nodes list # NAME is the Linux hostname K3s registered; not an inventory label
k7 generate-api-key tenant-a -n tenant-a --node k7-node-01
k7 nodes dedicate k7-node-01 --tenant acme
# Temporarily disable / re-enable
k7 api disable
k7 api enable
```
Generating / listing / revoking keys talks to `/etc/k7/api_keys.json`, so
those subcommands need to run on the node (typically `sudo` or `root`).
### Python SDK Usage
After your k7 API is up, usage is very simple.
Install the Python SDK via:
```shell
pip install k7-sdk==0.4.0
```
Or if you want async support:
```shell
pip install "k7-sdk[async]==0.4.0"
```
The legacy `katakate` PyPI name remains as a one-release shim that re-exports `k7_sdk` with a deprecation warning.
Then use with:
```python
from k7_sdk import Client
k7 = Client(
endpoint='https://',
api_key='your-key',
verify_ssl='./k7-ca.crt') # cluster CA from /etc/k7/tls/ca.crt on the node
# Create sandbox (pick backend: kata-firecracker-devmapper | kata-qemu-longhorn | k7d)
sb = k7.create({
"name": "base",
"image": "alpine:latest",
"backend": "k7d",
})
# Execute code
result = sb.exec('echo "Hello World" > /tmp/hi.txt && cat /tmp/hi.txt')
print(result['stdout'])
# Fork: k7d = warm CoW (disk + memory); kql = disk clone + cold boot
branch = sb.fork("branch-a")
print(branch.exec("cat /tmp/hi.txt")["stdout"]) # still there on k7d
# Parallel exploration
forks = [sb.fork(f"exp-{i}") for i in range(4)]
# List / delete
sandboxes = k7.list()
sb.delete()
```
#### Async variant
```python
import asyncio
from k7_sdk import AsyncClient
async def main():
k7 = AsyncClient(
endpoint='https://',
api_key='your-key'
)
print(await k7.list())
await k7.aclose()
asyncio.run(main())
```
### Tutorials
- LangChain ReAct agent with a K7 sandbox tool
- Path: tutorials/langchain-react-agent
- Setup: copy .env.example to .env and fill K7_ENDPOINT/K7_API_KEY/OPENAI_API_KEY
- Run: python agent.py
- Try asking it anything! e.g. "List files from '/'"
## Build from source
First install make if not already available:
```bash
sudo add-apt-repository universe -y
sudo apt update
sudo apt install make
```
To build the `k7` CLI and API into `.deb` package:
```shell
make build
```
You can then install it with:
```shell
sudo make install
```
To uninstall later:
```shell
sudo make uninstall
```
Note: we recommend running `make uninstall` before reinstalling if it is not your first install, to avoid stale copies of cached files in the .deb package.
### Build and run the API container
Local dev image:
```bash
# Build the API image locally
make api-build-local
# Run API using local image (no pull)
make api-run-local
```
### Build the k7-sdk Python SDK from source
Preferred (uv):
```bash
# create env
uv venv .venv-build
. .venv-build/bin/activate
# install directly from source in editable mode
uv pip install -e .
```
## Security
K7 sandboxes are hardened by default with multiple layers of security:
- **VM isolation**: Kata Containers (Firecracker or QEMU) or the k7d RuntimeClass provide hardware-level isolation via lightweight VMs
- On `kfd`, Firecracker processes are further restricted into a chroot using the Jailer
- Kata's Seccomp restrictions are enabled on the Kata backends
- `kql` uses QEMU + Longhorn for durable, cross-node-mobile disks; `k7d` has its own CoW-fork isolation trade-offs (see k7d `SECURITY.md`)
- **Linux capabilities**: All capabilities are dropped by default (`drop: ALL`) for defense-in-depth
- Only explicitly add back capabilities you need via `cap_add` parameter
- `allow_privilege_escalation` is always set to `false`
- Seccomp profile: `RuntimeDefault` is applied on the sandbox container
and enforced inside the guest: on k7d, and on Kata (`kfd` / `kql`)
with `disable_guest_seccomp = false` in the playbook's Kata config
(the sandbox container's OCI seccomp reaches guest runc).
- **Non-root execution**: Optionally run containers and pods as non-root user (UID 65532):
- `container_non_root`: Run the main container as non-root and disable privilege escalation
- `pod_non_root`: Run the entire pod as non-root with consistent filesystem ownership (UID/GID/FSGroup 65532)
- **API security**:
- API keys stored as SHA256 hashes with timing-attack-resistant comparison
- Expiry enforced; last-used timestamp recorded
- File-based storage with 600 permissions (`/etc/k7/api_keys.json` by default)
- **Network policies**: Complete network isolation for VM sandboxes
- **Ingress isolation**: All inter-VM communication is blocked by default to prevent sandbox-to-sandbox access; opt in per sandbox with `--ingress-port` / `--ingress-from` (`sandbox:`, `namespace:`, `cidr:`)
- **Egress lockdown**: per-sandbox allowlists β CIDRs via Kubernetes NetworkPolicy, or **FQDN / domain** allowlists via Cilium (`CiliumNetworkPolicy`; default CNI)
- **DNS is blocked** when egress is locked down; only entries in `egress_whitelist` (CIDR or domain) are reachable
- **Platform isolation** (Cilium only): a cluster-wide deny policy stops sandboxes in every egress mode β including `--egress-open` β from reaching the node, other nodes, the Kubernetes API, cloud metadata and the `kube-system`/`longhorn-system` pods (CoreDNS excepted). Not applied on `--cni flannel` clusters.
- Administrative access via `kubectl exec` and `k7 shell` is preserved (uses Kubernetes API, not pod networking)
More security features are on the roadmap (e.g. AppArmor).
## Packaging & Releases
- Layout uses `src/`:
- CLI, API, core live under `src/k7/`
- SDK under `src/k7_sdk/` (PyPI package `k7-sdk`; `src/katakate/` is a deprecation shim)
- Root `setup.py` publishes the SDK; assets under `src/k7/` belong to the Debian CLI / API image, not the PyPI wheel.
- User docs: `~/docs/k7/` (Mintlify). See `docs/README.md` in this repo.
- The CLI Debian package is built via `src/k7/cli/build.sh` and produces `dist/k7__amd64.deb` and `dist/k7__arm64.deb`.
- CI (tags `v*`) can publish the PyPI SDK and upload the `.deb` artifact.
