Run untrusted commands in a sandbox.
Project description
Sandcastle
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:
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
classvolume_mounts
kwarg of Sandcastle constructor
An example is worth of thousand words:
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 and network policy.
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:
$ oc adm -n ${SANDBOX_NAMESPACE} policy add-role-to-user edit system:serviceaccount:${APP_NAMESPACE}:default
Real code:
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.
-
Build container images using makefile target
make test-image-build
. -
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. -
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
-
Docker binary and docker daemon running. This is implied from the first point.
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