labels

Documentation

Overview

Package labels implements a simple label system, parsing and matching selectors with sets of labels.

Index

• func AreLabelsInWhiteList(labels, whitelist Set) bool
• func Conflicts(labels1, labels2 Set) bool
• func Equals(labels1, labels2 Set) bool
• func FormatLabels(labelMap map[string]string) string
• type ByKey
  • func (a ByKey) Len() int
  • func (a ByKey) Less(i, j int) bool
  • func (a ByKey) Swap(i, j int)
• type Labels
• type Lexer
  • func (l *Lexer) Lex() (tok Token, lit string)
• type Parser
• type ParserContext
• type Requirement
  • func NewRequirement(key string, op selection.Operator, vals []string) (*Requirement, error)
  • func ParseToRequirements(selector string) ([]Requirement, error)
  • func (r *Requirement) Key() string
  • func (r *Requirement) Matches(ls Labels) bool
  • func (r *Requirement) Operator() selection.Operator
  • func (r *Requirement) String() string
  • func (r *Requirement) Values() sets.String
• type Requirements
• type ScannedItem
• type Selector
  • func Everything() Selector
  • func NewSelector() Selector
  • func Nothing() Selector
  • func Parse(selector string) (Selector, error)
  • func SelectorFromSet(ls Set) Selector
  • func SelectorFromValidatedSet(ls Set) Selector
• type Set
  • func ConvertSelectorToLabelsMap(selector string) (Set, error)
  • func Merge(labels1, labels2 Set) Set
  • func (ls Set) AsSelector() Selector
  • func (ls Set) AsSelectorPreValidated() Selector
  • func (ls Set) Get(label string) string
  • func (ls Set) Has(label string) bool
  • func (ls Set) String() string
• type Token

Functions

func AreLabelsInWhiteList

func AreLabelsInWhiteList(labels, whitelist Set) bool

AreLabelsInWhiteList verifies if the provided label list is in the provided whitelist and returns true, otherwise false.

func Conflicts

func Conflicts(labels1, labels2 Set) bool

Conflicts takes 2 maps and returns true if there a key match between the maps but the value doesn't match, and returns false in other cases

func Equals

func Equals(labels1, labels2 Set) bool

Equals returns true if the given maps are equal

func FormatLabels

func FormatLabels(labelMap map[string]string) string

FormatLables convert label map into plain string

Types

type ByKey

type ByKey []Requirement

Sort by key to obtain determisitic parser

func (ByKey) Len

func (a ByKey) Len() int

func (ByKey) Less

func (a ByKey) Less(i, j int) bool

func (ByKey) Swap

func (a ByKey) Swap(i, j int)

type Labels

type Labels interface {
	// Has returns whether the provided label exists.
	Has(label string) (exists bool)

	// Get returns the value for the provided label.
	Get(label string) (value string)
}

Labels allows you to present labels independently from their storage.

type Lexer

type Lexer struct {
	// contains filtered or unexported fields
}

Lexer represents the Lexer struct for label selector. It contains necessary informationt to tokenize the input string

func (*Lexer) Lex

func (l *Lexer) Lex() (tok Token, lit string)

Lex returns a pair of Token and the literal literal is meaningfull only for IdentifierToken token

type Parser

type Parser struct {
	// contains filtered or unexported fields
}

Parser data structure contains the label selector parser data structure

type ParserContext

type ParserContext int

Parser context represents context during parsing: some literal for example 'in' and 'notin' can be recognized as operator for example 'x in (a)' but it can be recognized as value for example 'value in (in)'

const (
	KeyAndOperator ParserContext = iota
	Values
)

type Requirement

type Requirement struct {
	// contains filtered or unexported fields
}

Requirement contains values, a key, and an operator that relates the key and values. The zero value of Requirement is invalid. Requirement implements both set based match and exact match Requirement should be initialized via NewRequirement constructor for creating a valid Requirement.

func NewRequirement

func NewRequirement(key string, op selection.Operator, vals []string) (*Requirement, error)

NewRequirement is the constructor for a Requirement. If any of these rules is violated, an error is returned: (1) The operator can only be In, NotIn, Equals, DoubleEquals, NotEquals, Exists, or DoesNotExist. (2) If the operator is In or NotIn, the values set must be non-empty. (3) If the operator is Equals, DoubleEquals, or NotEquals, the values set must contain one value. (4) If the operator is Exists or DoesNotExist, the value set must be empty. (5) If the operator is Gt or Lt, the values set must contain only one value, which will be interpreted as an integer. (6) The key is invalid due to its length, or sequence

of characters. See validateLabelKey for more details.

The empty string is a valid value in the input values set.

func ParseToRequirements

func ParseToRequirements(selector string) ([]Requirement, error)

ParseToRequirements takes a string representing a selector and returns a list of requirements. This function is suitable for those callers that perform additional processing on selector requirements. See the documentation for Parse() function for more details. TODO: Consider exporting the internalSelector type instead.

func (*Requirement) Key

func (r *Requirement) Key() string

func (*Requirement) Matches

func (r *Requirement) Matches(ls Labels) bool

Matches returns true if the Requirement matches the input Labels. There is a match in the following cases: (1) The operator is Exists and Labels has the Requirement's key. (2) The operator is In, Labels has the Requirement's key and Labels'

value for that key is in Requirement's value set.

(3) The operator is NotIn, Labels has the Requirement's key and

Labels' value for that key is not in Requirement's value set.

(4) The operator is DoesNotExist or NotIn and Labels does not have the

Requirement's key.

(5) The operator is GreaterThanOperator or LessThanOperator, and Labels has

the Requirement's key and the corresponding value satisfies mathematical inequality.

func (*Requirement) Operator

func (r *Requirement) Operator() selection.Operator

func (*Requirement) String

func (r *Requirement) String() string

String returns a human-readable string that represents this Requirement. If called on an invalid Requirement, an error is returned. See NewRequirement for creating a valid Requirement.

func (*Requirement) Values

func (r *Requirement) Values() sets.String

type Requirements

type Requirements []Requirement

Requirements is AND of all requirements.

type ScannedItem

type ScannedItem struct {
	// contains filtered or unexported fields
}

The item produced by the lexer. It contains the Token and the literal.

type Selector

type Selector interface {
	// Matches returns true if this selector matches the given set of labels.
	Matches(Labels) bool

	// Empty returns true if this selector does not restrict the selection space.
	Empty() bool

	// String returns a human readable string that represents this selector.
	String() string

	// Add adds requirements to the Selector
	Add(r ...Requirement) Selector

	// Requirements converts this interface into Requirements to expose
	// more detailed selection information.
	// If there are querying parameters, it will return converted requirements and selectable=true.
	// If this selector doesn't want to select anything, it will return selectable=false.
	Requirements() (requirements Requirements, selectable bool)
}

Selector represents a label selector.

func Everything

func Everything() Selector

Everything returns a selector that matches all labels.

func NewSelector

func NewSelector() Selector

func Nothing

func Nothing() Selector

Nothing returns a selector that matches no labels

func Parse

func Parse(selector string) (Selector, error)

Parse takes a string representing a selector and returns a selector object, or an error. This parsing function differs from ParseSelector as they parse different selectors with different syntaxes. The input will cause an error if it does not follow this form:

<selector-syntax> ::= <requirement> | <requirement> "," <selector-syntax> ] <requirement> ::= [!] KEY [ <set-based-restriction> | <exact-match-restriction> ] <set-based-restriction> ::= "" | <inclusion-exclusion> <value-set> <inclusion-exclusion> ::= <inclusion> | <exclusion>

<exclusion> ::= "notin"
<inclusion> ::= "in"
<value-set> ::= "(" <values> ")"
   <values> ::= VALUE | VALUE "," <values>

<exact-match-restriction> ::= ["="|"=="|"!="] VALUE KEY is a sequence of one or more characters following [ DNS_SUBDOMAIN "/" ] DNS_LABEL. Max length is 63 characters. VALUE is a sequence of zero or more characters "([A-Za-z0-9_-\.])". Max length is 63 characters. Delimiter is white space: (' ', '\t') Example of valid syntax:

"x in (foo,,baz),y,z notin ()"

Note:

(1) Inclusion - " in " - denotes that the KEY exists and is equal to any of the
    VALUEs in its requirement
(2) Exclusion - " notin " - denotes that the KEY is not equal to any
    of the VALUEs in its requirement or does not exist
(3) The empty string is a valid VALUE
(4) A requirement with just a KEY - as in "y" above - denotes that
    the KEY exists and can be any VALUE.
(5) A requirement with just !KEY requires that the KEY not exist.

func SelectorFromSet

func SelectorFromSet(ls Set) Selector

SelectorFromSet returns a Selector which will match exactly the given Set. A nil and empty Sets are considered equivalent to Everything().

func SelectorFromValidatedSet

func SelectorFromValidatedSet(ls Set) Selector

SelectorFromValidatedSet returns a Selector which will match exactly the given Set. A nil and empty Sets are considered equivalent to Everything(). It assumes that Set is already validated and doesn't do any validation.

type Set

type Set map[string]string

Set is a map of label:value. It implements Labels.

func ConvertSelectorToLabelsMap

func ConvertSelectorToLabelsMap(selector string) (Set, error)

ConvertSelectorToLabelsMap converts selector string to labels map and validates keys and values

func Merge

func Merge(labels1, labels2 Set) Set

Merge combines given maps, and does not check for any conflicts between the maps. In case of conflicts, second map (labels2) wins

func (Set) AsSelector

func (ls Set) AsSelector() Selector

AsSelector converts labels into a selectors.

func (Set) AsSelectorPreValidated

func (ls Set) AsSelectorPreValidated() Selector

AsSelectorPreValidated converts labels into a selector, but assumes that labels are already validated and thus don't preform any validation. According to our measurements this is significantly faster in codepaths that matter at high sccale.

func (Set) Get

func (ls Set) Get(label string) string

Get returns the value in the map for the provided label.

func (Set) Has

func (ls Set) Has(label string) bool

Has returns whether the provided label exists in the map.

func (Set) String

func (ls Set) String() string

String returns all labels listed as a human readable string. Conveniently, exactly the format that ParseSelector takes.

type Token

type Token int

constants definition for lexer token

const (
	ErrorToken Token = iota
	EndOfStringToken
	ClosedParToken
	CommaToken
	DoesNotExistToken
	DoubleEqualsToken
	EqualsToken
	GreaterThanToken
	IdentifierToken // to represent keys and values
	InToken
	LessThanToken
	NotEqualsToken
	NotInToken
	OpenParToken
)