== Why is this an issue?

Ephemeral storage is a type of storage that is temporary and non-persistent,
meaning it does not retain data once the process is terminated. In the context
of Kubernetes, ephemeral storage is used for storing temporary files that a
running container can write and read.

The issue at hand pertains to the creation of a container without any defined
limits for this ephemeral storage. This means that the container can potentially
consume as much ephemeral storage as is available on the node where it is
running.

=== What is the potential impact?

==== Resource exhaustion

Without a defined limit, a container can consume all available ephemeral storage
on a node. This can lead to resource exhaustion, where no more storage is
available for other containers or processes running on the same node. This could
cause these other containers or processes to fail or perform poorly.

==== Unpredictable application behavior

If a container exhausts the available ephemeral storage, it can lead to
unpredictable application behavior. For instance, if an application attempts to
write to the ephemeral storage and there is no space left, it may crash or
exhibit other unexpected behaviors.

== How to fix it

=== Code examples

==== Noncompliant code example

[source,yaml,diff-id=1,diff-type=noncompliant]
----
apiVersion: v1
kind: Pod
metadata:
  name: example
spec:
  containers:
    - name: web # Noncompliant
      image: nginx
      volumeMounts:
        - name: ephemeral
          mountPath: "/tmp"
----

==== Compliant solution

[source,yaml,diff-id=1,diff-type=compliant]
----
apiVersion: v1
kind: Pod
metadata:
  name: example
spec:
  containers:
    - name: web
      image: nginx
      resources:
        limits:
          ephemeral-storage: "2Gi"
      volumeMounts:
        - name: ephemeral
          mountPath: "/tmp"
----

=== How does this work?

A limit can be set through the property `resources.limits.ephemeral-storage` of
a container. Alternatively, a default limit for a namespace can be set with
`LimitRange`.

== Resources

=== Documentation

* Kubernetes Documentation - https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/[Resource Management for Pods and Containers]

=== Standards

* CWE - https://cwe.mitre.org/data/definitions/770[CWE-770 - Allocation of Resources Without Limits or Throttling]
ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Specify a storage limit for this container.


=== Highlighting

* Highlight the `containers` property.
endif::env-github,rspecator-view[]
