sandcastle 0.1.0
Run untrusted commands in a sandbox.
License: MIT
Requires Python: >=3.6
Keywords: openshift,sandbox

# Sandcastle [![Build Status](https://ci.centos.org/job/sandcastle-master/badge/icon)](https://ci.centos.org/job/sandcastle-master/)

Run untrusted code in a castle (OpenShift pod), which stands in a sandbox.


## Usage

The prerequisite is that you're logged in an OpenShift cluster:
```
$ oc status
 In project Local Project (myproject) on server https://localhost:8443
```

The simplest use case is to invoke a command in a new openshift pod:

```python
from sandcastle import Sandcastle

s = Sandcastle(
    image_reference="docker.io/this-is-my/image:latest",
    k8s_namespace_name="myproject"
)
output = s.run(command=["ls", "-lha"])
```

These things will happen:

* A new pod is created, using the image set in `image_reference`.
* The library actively waits for the pod to finish.
* If the pod terminates with a return code greater than 0, an exception is raised.
* Output of the command is return from the `.run()` method.


### Sharing data between sandbox and current pod

This library allows you to share volumes between the pod it is running in and between sandbox.

There is a dedicated class and an interface to access this functionality:
* `VolumeSpec` class
* `volume_mounts` kwarg of Sandcastle constructor

An example is worth of thousand words:
```python
from pathlib import Path
from sandcastle import Sandcastle, VolumeSpec

# the expectation is that volume assigned to PVC set
# via env var SANDCASTLE_PVC is mounted in current pod at /path
vs = VolumeSpec(path="/path", pvc_from_env="SANDCASTLE_PVC")

s = Sandcastle(
    image_reference="docker.io/this-is-my/image:latest",
    k8s_namespace_name="myproject",
    volume_mounts=[vs]
)
s.run()
s.exec(command=["bash", "-c", "ls -lha /path"])    # will be empty
s.exec(command=["bash", "-c", "mkdir /path/dir"])  # will create a dir
assert Path("/path/dir").is_dir()                  # should pass
```

#### Sharing data by copying them

Sandcastle is able to run the sandbox pod in a different namespace. This
improves security since it's trivial to lock networking of this project down -
the pod won't be able to access OpenShift API server nor any of your services
deployed in the cluster. For more info, check out [egress
rules](https://blog.openshift.com/accessing-external-services-using-egress-router/)
and [network
policy](https://docs.openshift.com/container-platform/3.6/admin_guide/managing_networking.html#admin-guide-networking-networkpolicy).

When you set up this sandbox namespace, please make sure that service account
of namespace your app is deployed in can manage pods in the sandbox namespace.
This command should help:
```bash
$ oc adm -n ${SANDBOX_NAMESPACE} policy add-role-to-user edit system:serviceaccount:${APP_NAMESPACE}:default
```

Real code:

```python
m_dir = MappedDir(
    local_dir,             # share this dir
    sandbox_mountpoint,    # make it available here
    with_interim_pvc=True  # the data will be placed in a volume
)

o = Sandcastle(
    image_reference=container_image,
    k8s_namespace_name=namespace,      # can be a different namespace
    mapped_dir=m_dir,
    working_dir=sandbox_mountpoint,
)
o.run()
# happy execing
o.exec(command=["ls", "-lha", f"{sandbox_mountpoint}/"])
```

## Developing sandcastle

In order to develop this project (and run tests), there are several requirements which need to be met.

1. Build container images using makefile target `make test-image-build`.

2. An openshift cluster and be logged into it

   Which means that running `oc status` should yield the cluster where you want
   to run the tests.

   The e2e test `test_from_pod` builds current codebase and runs the other e2e
   tests in a pod: to verify the E2E functionality. This expects that the
   openshift cluster is deployed in your current environment, meaning that
   openshift can access your local container images in your dockerd. Otherwise the
   image needs to be pushed somewhere so openshift can access it.

3. In the default `oc cluster up` environment, the tests create sandbox pod
   using the default service account which is assigned to every pod. This SA
   doesn't have permissions to create nor delete pods (so the sandboxing would
   not work). With this command, the SA is allowed to change any objects in the
   namespace:
   ```
   oc adm policy add-role-to-user edit system:serviceaccount:myproject:default
   ```

4. Docker binary and docker daemon running. This is implied from the first point.