ContainerImage.Pinniped/internal/downward/downward.go

81 lines
2.4 KiB
Go

// Copyright 2020-2022 the Pinniped contributors. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
// Package downward implements a client interface for interacting with Kubernetes "downwardAPI" volumes.
// See https://kubernetes.io/docs/tasks/inject-data-application/downward-api-volume-expose-pod-information/.
package downward
import (
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"strings"
"go.pinniped.dev/internal/plog"
)
// PodInfo contains pod metadata about the current pod.
type PodInfo struct {
// Namespace where the current pod is running.
Namespace string
// Name of the current pod.
Name string
// Labels of the current pod.
Labels map[string]string
}
// Load pod metadata from a downwardAPI volume directory.
func Load(directory string) (*PodInfo, error) {
var result PodInfo
ns, err := os.ReadFile(filepath.Join(directory, "namespace"))
if err != nil {
return nil, fmt.Errorf("could not load namespace: %w", err)
}
result.Namespace = strings.TrimSpace(string(ns))
name, err := os.ReadFile(filepath.Join(directory, "name"))
if err != nil {
plog.Warning("could not read 'name' downward API file")
} else {
result.Name = strings.TrimSpace(string(name))
}
labels, err := os.ReadFile(filepath.Join(directory, "labels"))
if err != nil {
return nil, fmt.Errorf("could not load labels: %w", err)
}
result.Labels, err = parseMap(labels)
if err != nil {
return nil, fmt.Errorf("could not parse labels: %w", err)
}
return &result, nil
}
// parseMap parses the key/value format emitted by the Kubernetes Downward API for pod labels and annotations.
// See https://kubernetes.io/docs/tasks/inject-data-application/downward-api-volume-expose-pod-information/.
// See https://github.com/kubernetes/kubernetes/blob/4b2cb072dba10227083b16731f019f096c581787/pkg/fieldpath/fieldpath.go#L28.
func parseMap(input []byte) (map[string]string, error) {
result := map[string]string{}
for _, line := range bytes.Split(input, []byte("\n")) {
line = bytes.TrimSpace(line)
if len(line) == 0 {
continue
}
parts := bytes.SplitN(line, []byte("="), 2)
if len(parts) != 2 {
return nil, fmt.Errorf("expected 2 parts, found %d: %w", len(parts), io.ErrShortBuffer)
}
value, err := strconv.Unquote(string(parts[1]))
if err != nil {
return nil, fmt.Errorf("invalid quoted value: %w", err)
}
result[string(parts[0])] = value
}
return result, nil
}