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decoder.go
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decoder.go
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package decoder
import (
"errors"
"fmt"
"sync"
"github.com/ahas-sigs/kube-ebpf-exporter/config"
)
// ErrSkipLabelSet instructs exporter to skip label set
var ErrSkipLabelSet = errors.New("this label set should be skipped")
// Decoder transforms byte field value into a byte value representing string
// to either use as an input for another Decoder or to use as the final
// label value for Prometheus metrics
type Decoder interface {
Decode([]byte, config.Decoder) ([]byte, error)
}
// Set is a set of Decoders that may be applied to produce a label
type Set struct {
mu sync.Mutex
decoders map[string]Decoder
}
// NewSet creates a Set with all known decoders
func NewSet() *Set {
return &Set{
decoders: map[string]Decoder{
"ksym": &KSym{},
"majorminor": &MajorMinor{},
"regexp": &Regexp{},
"static_map": &StaticMap{},
"string": &String{},
"uint": &UInt{},
"inet_ip": &InetIP{},
"kube_podnamespace": &KubePodNamespace{},
"kube_podname": &KubePodName{},
"kube_containername": &KubeContainerName{},
},
}
}
// Decode transforms input byte field into a string according to configuration
func (s *Set) Decode(in []byte, label config.Label) ([]byte, error) {
result := in
for _, decoder := range label.Decoders {
if _, ok := s.decoders[decoder.Name]; !ok {
return result, fmt.Errorf("unknown decoder %q", decoder.Name)
}
s.mu.Lock()
decoded, err := s.decoders[decoder.Name].Decode(result, decoder)
s.mu.Unlock()
if err != nil {
if err == ErrSkipLabelSet {
return decoded, err
}
return decoded, fmt.Errorf("error decoding with decoder %q: %s", decoder.Name, err)
}
result = decoded
}
return result, nil
}
// DecodeLabels transforms eBPF map key bytes into a list of label values
// according to configuration
func (s *Set) DecodeLabels(in []byte, labels []config.Label) ([]string, error) {
values := make([]string, len(labels))
off := uint(0)
totalSize := uint(0)
for _, label := range labels {
size := label.Size
if size == 0 {
return nil, fmt.Errorf("error decoding label %q: size is zero or not set", label.Name)
}
if !label.Reuse {
totalSize += size
}
}
if totalSize != uint(len(in)) {
return nil, fmt.Errorf("error decoding labels: total size of key %#v is %d bytes, but wehave labels to decode %d", in, len(in), totalSize)
}
for i, label := range labels {
if len(label.Decoders) == 0 {
return nil, fmt.Errorf("error decoding label %q: no decoders set", label.Name)
}
size := label.Size
decoded, err := s.Decode(in[off:off+size], label)
if err != nil {
return nil, err
}
if !label.Reuse {
off += size
}
values[i] = string(decoded)
}
return values, nil
}