Validation

2 min read

Check that free text is the kind of value it claims to be: an email address, a URL, JSON, a port number. A form field is free text until something checks it; catching a malformed value early, with a clear message, beats finding out downstream.

Check references to artifacts the tools around Kubernetes consume: a git repository (Argo CD, Flux) and a container image reference (registries). Catching a malformed one early beats finding out when the tool fails to reconcile it.

Reference

FunctionDescription
isValidEmailReports whether s is a single, bare email address — “[email protected]”, not a display-name form like “User <[email protected]>”.
isValidGitRepositoryReports whether s looks like a git repository URL — https://, git://, ssh://, or the SCP-like “git@host:org/repo.git” shorthand.
isValidImageRefReports whether s looks like a valid container image reference: optional registry, lowercase repo path, optional :tag or @digest.
isValidJSONReports whether s is syntactically valid JSON.
isValidPortReports whether s parses as an integer in the valid TCP/UDP port range, 1–65535.
isValidURLReports whether s is an absolute http or https URL with a non-empty host.

Functions

isValidEmail

isValidEmail reports whether s is a single, bare email address — “[email protected]”, not a display-name form like “User <[email protected]>”.

{{ isValidEmail "[email protected]" }}  → true
{{ isValidEmail "not-an-email"  }}  → false

isValidGitRepository

isValidGitRepository reports whether s looks like a git repository URL — https://, git://, ssh://, or the SCP-like “git@host:org/repo.git” shorthand. This is a shape check, not a reachability check — it doesn’t dial the host.

{{ isValidGitRepository "https://github.com/myorg/payments"    }}  → true
{{ isValidGitRepository "[email protected]:myorg/payments.git"    }}  → true
{{ isValidGitRepository "not a repo"                            }}  → false

isValidImageRef

isValidImageRef reports whether s looks like a valid container image reference: optional registry, lowercase repo path, optional :tag or @digest.

{{ isValidImageRef "myorg/app:v1.2.3"                    }}  → true
{{ isValidImageRef "registry.myorg.io:5000/team/app:latest" }}  → true
{{ isValidImageRef "MyOrg/App"                            }}  → false

isValidJSON

isValidJSON reports whether s is syntactically valid JSON.

{{ isValidJSON "{\"app\": \"payments-api\"}" }}  → true
{{ isValidJSON "{not json"                    }}  → false

isValidPort

isValidPort reports whether s parses as an integer in the valid TCP/UDP port range, 1–65535.

{{ isValidPort "8080"  }}  → true
{{ isValidPort "0"     }}  → false
{{ isValidPort "70000" }}  → false

isValidURL

isValidURL reports whether s is an absolute http or https URL with a non-empty host.

{{ isValidURL "https://example.com/webhook" }}  → true
{{ isValidURL "ftp://example.com"            }}  → false
{{ isValidURL "not a url"                     }}  → false