Static analysis with KubeAudit for Red Hat OpenShift
In this article, we introduce a new utility for developers who want to ensure that their code transitions cleanly from upstream Kubernetes to Red Hat OpenShift. OpenShiftKubeAudit (KubeAudit) is a static analyzer that semantically checks a user’s code for known incompatibilities so you can fix them before bringing the code into OpenShift. KubeAudit is also simple to use and easy to extend.
Running an audit
This being the first release, KubeAudit currently offers only a handful of audits, but they’re easy to write. We’re looking for feedback and additional use cases from the community to help make the tool more comprehensive.
To start, find KubeAudit on GitHub.
You’ll want to clone the git repo somewhere on the same machine where the manifests to audit reside, and set up a Python virtual environment:
$ git clone https://github.com/AICoE/OpenShiftKubeAudit.git $ cd OpenShiftKubeAudit $ python3 -m virtualenv venv $ source venv/bin/activate $ python3 -m pip install -r requirements.txt
Now, let’s run the auditing tool:
$ ./audit.py /path/to/yaml/directory
It should produce similar output to this:
$ ./audit.py ./testaudits Audit Results: Issue: Pod Security Policies in manifests Severity: 1 - High Resolution: In OpenShift PodSecurityPolicies are replaced by SecurityContextConstraints. See https://docs.openshift.com/container-platform/4.5/authentication/managing-security-context-constraints.html Affected Files: Matched regex: testaudits/yaml/PodSecurityPolicies.yaml Issue: NetworkPolicy has an IPBlock Severity: 2 - Medium Resolution: The Kubernetes v1 NetworkPolicy features are available in OpenShift Container Platform except for egress policy types and IPBlock. Affected Files: Matched regex: testaudits/yaml/NetworkPolicies.yaml Issue: Egress network policy set Severity: 2 - Medium Resolution: The Kubernetes v1 NetworkPolicy features are available in OpenShift Container Platform except for egress policy types and IPBlock. Affected Files: Matched regex: testaudits/yaml/NetworkPolicies.yaml
Now with these issues identified, a developer could fix them before they become issues in production. However, since the tool is new, there are many use cases that have not yet been identified, which is why the tool is easy to extend.
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Adding a custom audit
KubeAudit uses a simple initialization (INI) syntax to define an audit with a few fields:
- Name: A name or title to identify the audit.
- Query (optional): This is a jq-syntax query, which the auditing tool uses for semantic analysis of parts of a manifest. Note that the
queryis optional if you are using
regex. This type of query is useful when you need a more comprehensive analysis.
- Regex (optional): You can specify a
regexto search for in each file. Although
regexis a simpler check than
query, the utility can ignore
regexes found in the code comments.
- Regexes section (optional): Use this section when you need multiple
regexes. Once again, the utility ignores
regexmatches found in comments, and it matches the results in the order that they appear. If all of the
regexes are found in the corresponding order, it is considered a match.
- Severity: This message indicates the relative severity of the issue. It needs to start with a number, and can then be followed by a text description of the severity.
- Message: The diagnostic message to output to the user.
Below is an example audit:
[Default] # The name/title of the issue, e.g., "Pod Security Policies in manifests" name = RunAsUser is set outside range, has some known issues # A jq-syntax query to be applied to the yaml files. The query must return # either True or False, but can be otherwise any valid jq string query = ((.. | .runAsUser? | numbers) != 0) and ((.. | .runAsUser? | numbers) < 10000000 or (.. | .runAsUser? | numbers) > 20000000) # Python-compatible regex to search for. The script automatically ignores # commented lines regex = runAsUser: # Severity to help the user prioritize fixes severity = 4 - Warning # Message to output to the user, usually a resolution or more information message = Setting runAsUser ID explicitly is not recommended. Additionally setting runAsUser explicitly outside of the expected range in OpenShift (10000000 - 20000000) has known incompatibilities # This section can be used to construct a multiline regex for the files. # Each regex is searched for in the order that it appears and automatically # ignores comments. Any number of regexes can be added this way [regexes] regex1 = regex2 =
This auditing tool currently only supports Kubernetes manifests, but we plan to expand it to include Helm charts and Go code, as well. The tool is in very early stages, but is looking for community input to help add use cases.