聊聊cortex的tenant

本文主要研究一下cortex的tenant

tenant

cortex/pkg/tenant/tenant.go

var (
	errTenantIDTooLong = errors.New("tenant ID is too long: max 150 characters")
)

type errTenantIDUnsupportedCharacter struct {
	pos      int
	tenantID string
}

func (e *errTenantIDUnsupportedCharacter) Error() string {
	return fmt.Sprintf(
		"tenant ID '%s' contains unsupported character '%c'",
		e.tenantID,
		e.tenantID[e.pos],
	)
}

const tenantIDsLabelSeparator = "|"

// NormalizeTenantIDs is creating a normalized form by sortiing and de-duplicating the list of tenantIDs
func NormalizeTenantIDs(tenantIDs []string) []string {
	sort.Strings(tenantIDs)

	count := len(tenantIDs)
	if count <= 1 {
		return tenantIDs
	}

	posOut := 1
	for posIn := 1; posIn < count; posIn++ {
		if tenantIDs[posIn] != tenantIDs[posIn-1] {
			tenantIDs[posOut] = tenantIDs[posIn]
			posOut++
		}
	}

	return tenantIDs[0:posOut]
}

// ValidTenantID
func ValidTenantID(s string) error {
	// check if it contains invalid runes
	for pos, r := range s {
		if !isSupported(r) {
			return &errTenantIDUnsupportedCharacter{
				tenantID: s,
				pos:      pos,
			}
		}
	}

	if len(s) > 150 {
		return errTenantIDTooLong
	}

	return nil
}

func JoinTenantIDs(tenantIDs []string) string {
	return strings.Join(tenantIDs, tenantIDsLabelSeparator)
}

// this checks if a rune is supported in tenant IDs (according to
// https://cortexmetrics.io/docs/guides/limitations/#tenant-id-naming)
func isSupported(c rune) bool {
	// characters
	if ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') {
		return true
	}

	// digits
	if '0' <= c && c <= '9' {
		return true
	}

	// special
	return c == '!' ||
		c == '-' ||
		c == '_' ||
		c == '.' ||
		c == '*' ||
		c == '\'' ||
		c == '(' ||
		c == ')'
}

// TenantIDsFromOrgID extracts different tenants from an orgID string value
//
// ignore stutter warning
//nolint:golint
func TenantIDsFromOrgID(orgID string) ([]string, error) {
	return TenantIDs(user.InjectOrgID(context.TODO(), orgID))
}
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tenant提供了NormalizeTenantIDs、ValidTenantID、JoinTenantIDs方法；NormalizeTenantIDs用于去重和排序tenantIDs；ValidTenantID会通过isSupported进行校验，并校验长度；JoinTenantIDs使用|来连接TenantID

Resolver

cortex/pkg/tenant/resolver.go

type Resolver interface {
	// TenantID returns exactly a single tenant ID from the context. It should be
	// used when a certain endpoint should only support exactly a single
	// tenant ID. It returns an error user.ErrNoOrgID if there is no tenant ID
	// supplied or user.ErrTooManyOrgIDs if there are multiple tenant IDs present.
	TenantID(context.Context) (string, error)

	// TenantIDs returns all tenant IDs from the context. It should return
	// normalized list of ordered and distinct tenant IDs (as produced by
	// NormalizeTenantIDs).
	TenantIDs(context.Context) ([]string, error)
}
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Resolver接口定义了TenantID、TenantIDs方法

SingleResolver

cortex/pkg/tenant/resolver.go

type SingleResolver struct {
}

func (t *SingleResolver) TenantID(ctx context.Context) (string, error) {
	//lint:ignore faillint wrapper around upstream method
	return user.ExtractOrgID(ctx)
}

func (t *SingleResolver) TenantIDs(ctx context.Context) ([]string, error) {
	//lint:ignore faillint wrapper around upstream method
	orgID, err := user.ExtractOrgID(ctx)
	if err != nil {
		return nil, err
	}
	return []string{orgID}, err
}
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SingleResolver实现了Resolver接口，其TenantID使用user.ExtractOrgID(ctx)提取TenantID；TenantIDs方法则返回的是orgID数组

MultiResolver

cortex/pkg/tenant/resolver.go

type MultiResolver struct {
}

// NewMultiResolver creates a tenant resolver, which allows request to have
// multiple tenant ids submitted separated by a '|' character. This enforces
// further limits on the character set allowed within tenants as detailed here:
// https://cortexmetrics.io/docs/guides/limitations/#tenant-id-naming)
func NewMultiResolver() *MultiResolver {
	return &MultiResolver{}
}

func (t *MultiResolver) TenantID(ctx context.Context) (string, error) {
	orgIDs, err := t.TenantIDs(ctx)
	if err != nil {
		return "", err
	}

	if len(orgIDs) > 1 {
		return "", user.ErrTooManyOrgIDs
	}

	return orgIDs[0], nil
}

func (t *MultiResolver) TenantIDs(ctx context.Context) ([]string, error) {
	//lint:ignore faillint wrapper around upstream method
	orgID, err := user.ExtractOrgID(ctx)
	if err != nil {
		return nil, err
	}

	orgIDs := strings.Split(orgID, tenantIDsLabelSeparator)
	for _, orgID := range orgIDs {
		if err := ValidTenantID(orgID); err != nil {
			return nil, err
		}
	}

	return NormalizeTenantIDs(orgIDs), nil
}
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MultiResolver实现了Resolver接口，其TenantID方法使用TenantIDs提取orgIDs，并校验其长度；TenantIDs方法使用user.ExtractOrgID(ctx)提取orgID，然后使用tenantIDsLabelSeparator分割提取为orgIDs，后通过NormalizeTenantIDs返回

小结

cortex的tenant提供了NormalizeTenantIDs、ValidTenantID、JoinTenantIDs方法；Resolver接口定义了TenantID、TenantIDs方法；SingleResolver及MultiResolver都实现了Resolver接口，基本都是通过user.ExtractOrgID(ctx)提取tenantID。

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