Kfl
KFL2 (Kubeshark Filter Language) reference.
Install
npx skills add kubeshark/kubeshark --skill kfl -g -a claude-code -y- Repository
- kubeshark/kubeshark12.1k
- Category
- DevOps
- Updated
- 3d ago
- License
- Apache-2.0
- Context cost
- Mediumabout 3,000 tokens
- Runs scripts
- No, instructions only
What it does
KFL2 (Kubeshark Filter Language) reference. This skill MUST be loaded before writing, constructing, or suggesting any KFL filter expression. KFL is statically typed, incorrect field names or syntax will fail silently or error. Do not guess at KFL syntax without this skill loaded. Trigger on any mention of KFL, CEL filters, traffic filtering, display filters, query syntax, filter expressions, write a filter, construct a query, build a KFL, create a filter expression, "how do I filter", "show me only", "find traffic where", protocol-specific queries (HTTP status codes, DNS lookups, Redis commands, Kafka topics), Kubernetes-aware filtering (by namespace, pod, service, label, annotation), L4 connection/flow filters, time-based queries, or any request to slice/search/narrow network traffic in Kubeshark. Also trigger when other skills need to construct filters, KFL is the query language for all Kubeshark traffic analysis.
KFL2, Kubeshark Filter Language
You are a KFL2 expert. KFL2 is built on Google's CEL (Common Expression Language) and is the query language for all Kubeshark traffic analysis. It operates as a display filter, it doesn't affect what's captured, only what you see.
Think of KFL the way you think of SQL for databases or Google search syntax for the web. Kubeshark captures and indexes all cluster traffic; KFL is how you search it.
For the complete variable and field reference, see references/kfl2-reference.md.
Core Syntax
KFL expressions are boolean CEL expressions. An empty filter matches everything.
Operators
| Category | Operators |
|---|---|
| Comparison | ==, !=, <, <=, >, >= |
| Logical | &&, ||, ! |
| Arithmetic | +, -, *, /, % |
| Membership | in |
| Ternary | condition ? true_val : false_val |
String Functions
str.contains(substring) // Substring search
str.startsWith(prefix) // Prefix match
str.endsWith(suffix) // Suffix match
str.matches(regex) // Regex match
size(str) // String length
Collection Functions
size(collection) // List/map/string length
key in map // Key existence
map[key] // Value access
map_get(map, key, default) // Safe access with default
value in list // List membership
Time Functions
timestamp("2026-03-14T22:00:00Z") // Parse ISO timestamp
duration("5m") // Parse duration
now() // Current time (snapshot at filter creation)
Negation
!http // Everything that is NOT HTTP
http && status_code != 200 // HTTP responses that aren't 200
http && !path.contains("/health") // Exclude health checks
!(src.pod.namespace == "kube-system") // Exclude system namespace
