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dataclients/kubernetes: add metadata route
Adds a special route with a predefined id `kube__metadata` that contains `False` predicate, no filters and endpoints metadata. Endpoints metadata is encoded as JSON via [data URI scheme](https://en.wikipedia.org/wiki/Data_URI_scheme) into the route backend address field. Example eskip: ``` kube__metadata: False() -> "data:application/json;base64,eyJhZGRyZXNzZXMiO..."; ... ``` A special route pre-processor detects and removes this route, decodes metadata and stores it as EndpointRegistry metrics. The endpoint metrics then used to obtain endpoint node and pod names for tracing and logging. TODO: - [ ] add flag to enable metadata route - [ ] tests Fixes #1559 Signed-off-by: Alexander Yastrebov <[email protected]>
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Original file line number | Diff line number | Diff line change |
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package kubernetes | ||
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import ( | ||
"encoding/base64" | ||
"encoding/json" | ||
"fmt" | ||
"net" | ||
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log "github.com/sirupsen/logrus" | ||
"github.com/zalando/skipper/eskip" | ||
"github.com/zalando/skipper/predicates" | ||
"github.com/zalando/skipper/routing" | ||
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snet "github.com/zalando/skipper/net" | ||
) | ||
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type MetadataPreProcessorOptions struct { | ||
EndpointRegistry *routing.EndpointRegistry | ||
} | ||
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type metadataPreProcessor struct { | ||
options MetadataPreProcessorOptions | ||
} | ||
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type kubeRouteMetadata struct { | ||
Addresses map[string]*kubeRouteMetadataAddress `json:"addresses"` | ||
} | ||
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type kubeRouteMetadataAddress struct { | ||
Zone string `json:"zone,omitempty"` | ||
NodeName string `json:"nodeName,omitempty"` | ||
PodName string `json:"podName,omitempty"` | ||
} | ||
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// NewMetadataPreProcessor creates pre-processor for metadata route. | ||
func NewMetadataPreProcessor(options MetadataPreProcessorOptions) routing.PreProcessor { | ||
return &metadataPreProcessor{options: options} | ||
} | ||
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func (pp *metadataPreProcessor) Do(routes []*eskip.Route) []*eskip.Route { | ||
var metadataRoute *eskip.Route | ||
filtered := make([]*eskip.Route, 0, len(routes)) | ||
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for _, r := range routes { | ||
if r.Id == MetadataRouteID { | ||
if metadataRoute == nil { | ||
metadataRoute = r | ||
} else { | ||
log.Errorf("Found multiple metadata routes, using the first one") | ||
} | ||
} else { | ||
filtered = append(filtered, r) | ||
} | ||
} | ||
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if metadataRoute == nil { | ||
log.Errorf("Metadata route not found") | ||
return routes | ||
} | ||
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metadata, err := decodeMetadata(metadataRoute) | ||
if err != nil { | ||
log.Errorf("Failed to decode metadata route: %v", err) | ||
return filtered | ||
} | ||
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for _, r := range filtered { | ||
if r.BackendType == eskip.NetworkBackend { | ||
pp.addMetadata(metadata, r.Backend) | ||
} else if r.BackendType == eskip.LBBackend { | ||
for _, ep := range r.LBEndpoints { | ||
pp.addMetadata(metadata, ep) | ||
} | ||
} | ||
} | ||
return filtered | ||
} | ||
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// metadataRoute creates a route with [MetadataRouteID] id that matches no requests and | ||
// contains metadata for each endpoint address used by Ingresses and RouteGroups. | ||
func metadataRoute(s *clusterState) *eskip.Route { | ||
metadata := kubeRouteMetadata{ | ||
Addresses: make(map[string]*kubeRouteMetadataAddress), | ||
} | ||
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for id := range s.cachedEndpoints { | ||
if s.enableEndpointSlices { | ||
if eps, ok := s.endpointSlices[id.ResourceID]; ok { | ||
for _, ep := range eps.Endpoints { | ||
metadata.Addresses[ep.Address] = &kubeRouteMetadataAddress{ | ||
Zone: ep.Zone, | ||
NodeName: ep.NodeName, | ||
PodName: ep.TargetRef.getPodName(), | ||
} | ||
} | ||
} | ||
} else { | ||
if ep, ok := s.endpoints[id.ResourceID]; ok { | ||
for _, subset := range ep.Subsets { | ||
for _, addr := range subset.Addresses { | ||
metadata.Addresses[addr.IP] = &kubeRouteMetadataAddress{ | ||
// Endpoints do not provide zone | ||
NodeName: addr.NodeName, | ||
PodName: addr.TargetRef.getPodName(), | ||
} | ||
} | ||
} | ||
} | ||
} | ||
} | ||
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return &eskip.Route{ | ||
Id: MetadataRouteID, | ||
Predicates: []*eskip.Predicate{{Name: predicates.FalseName}}, | ||
BackendType: eskip.NetworkBackend, | ||
Backend: encodeDataURI(&metadata), | ||
} | ||
} | ||
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func decodeMetadata(r *eskip.Route) (map[string]*kubeRouteMetadataAddress, error) { | ||
metadata, err := decodeDataURI(r.Backend) | ||
if err != nil { | ||
return nil, err | ||
} | ||
return metadata.Addresses, nil | ||
} | ||
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const dataUriPrefix = "data:application/json;base64," | ||
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// encodeDataURI encodes metadata into data URI. | ||
// Note that map keys are sorted and used as JSON object keys | ||
// therefore encodeDataURI produces the same output for the same input. | ||
// See https://datatracker.ietf.org/doc/html/rfc2397 | ||
func encodeDataURI(metadata *kubeRouteMetadata) string { | ||
data, _ := json.Marshal(&metadata) | ||
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buf := make([]byte, len(dataUriPrefix)+base64.StdEncoding.EncodedLen(len(data))) | ||
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copy(buf, dataUriPrefix) | ||
base64.StdEncoding.Encode(buf[len(dataUriPrefix):], data) | ||
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return string(buf) | ||
} | ||
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// encodeDataURI encodes metadata into data URI. | ||
// See https://datatracker.ietf.org/doc/html/rfc2397 | ||
func decodeDataURI(uri string) (*kubeRouteMetadata, error) { | ||
var metadata kubeRouteMetadata | ||
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data, err := base64.StdEncoding.DecodeString(uri[len(dataUriPrefix):]) | ||
if err != nil { | ||
return nil, fmt.Errorf("failed to decode base64: %w", err) | ||
} | ||
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if err := json.Unmarshal(data, &metadata); err != nil { | ||
return nil, fmt.Errorf("failed to decode json: %w", err) | ||
} | ||
return &metadata, nil | ||
} | ||
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func (pp *metadataPreProcessor) addMetadata(metadata map[string]*kubeRouteMetadataAddress, endpoint string) { | ||
_, hostPort, err := snet.SchemeHost(endpoint) | ||
if err != nil { | ||
return | ||
} | ||
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host, _, _ := net.SplitHostPort(hostPort) | ||
if err != nil { | ||
host = hostPort | ||
} | ||
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addr, ok := metadata[host] | ||
if !ok { | ||
return | ||
} | ||
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metrics := pp.options.EndpointRegistry.GetMetrics(hostPort) | ||
setTag := func(name, value string) { | ||
if value != "" { | ||
metrics.SetTag(name, value) | ||
} | ||
} | ||
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setTag("zone", addr.Zone) | ||
setTag("nodeName", addr.NodeName) | ||
setTag("podName", addr.PodName) | ||
} |
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