关于golang:聊聊cortex的tenant

序

本文次要钻研一下 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))
}

tenant 提供了 NormalizeTenantIDs、ValidTenantID、JoinTenantIDs 办法；NormalizeTenantIDs 用于去重和排序 tenantIDs；ValidTenantID 会通过 isSupported 进行校验，并校验长度；JoinTenantIDs 应用 | 来连贯 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)
}

Resolver 接口定义了 TenantID、TenantIDs 办法

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
}

SingleResolver 实现了 Resolver 接口，其 TenantID 应用 user.ExtractOrgID(ctx)提取 TenantID；TenantIDs 办法则返回的是 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
}

MultiResolver 实现了 Resolver 接口，其 TenantID 办法应用 TenantIDs 提取 orgIDs，并校验其长度；TenantIDs 办法应用 user.ExtractOrgID(ctx)提取 orgID，而后应用 tenantIDsLabelSeparator 宰割提取为 orgIDs，最初通过 NormalizeTenantIDs 返回

小结

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

doc

• cortex