feat: agent metadata with custom collectors

internal/agent/metadata/collector.go

@@ -0,0 +1,12 @@
+package metadata
+
+import (
+	"context"
+	"errors"
+)
+
+var ErrMetadataNotAvailable = errors.New("metadata not available")
+
+type Collector interface {
+	Collect(context.Context) (string, string, error)
+}

internal/agent/metadata/collector/buildinfo/collector.go

@@ -0,0 +1,31 @@
+package buildinfo
+
+import (
+	"context"
+	"runtime/debug"
+
+	"forge.cadoles.com/Cadoles/emissary/internal/agent/metadata"
+	"github.com/pkg/errors"
+)
+
+const (
+	MetadataBuildInfo = "buildinfo"
+)
+
+type Collector struct{}
+
+// Collect implements agent.MetadataCollector
+func (c *Collector) Collect(ctx context.Context) (string, string, error) {
+	buildInfo, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", "", errors.WithStack(metadata.ErrMetadataNotAvailable)
+	}
+
+	return MetadataBuildInfo, buildInfo.String(), nil
+}
+
+func NewCollector() *Collector {
+	return &Collector{}
+}
+
+var _ metadata.Collector = &Collector{}

internal/agent/metadata/collector/shell/collector.go

@@ -0,0 +1,46 @@
+package shell
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"os/exec"
+	"strings"
+
+	"forge.cadoles.com/Cadoles/emissary/internal/agent/metadata"
+	"github.com/pkg/errors"
+)
+
+type Collector struct {
+	name    string
+	command string
+	args    []string
+}
+
+// Collect implements agent.MetadataCollector
+func (c *Collector) Collect(ctx context.Context) (string, string, error) {
+	cmd := exec.CommandContext(ctx, c.command, c.args...)
+
+	var buf bytes.Buffer
+
+	cmd.Stdout = &buf
+	cmd.Stderr = os.Stderr
+
+	if err := cmd.Run(); err != nil {
+		return "", "", errors.WithStack(err)
+	}
+
+	value := strings.TrimSpace(buf.String())
+
+	return c.name, value, nil
+}
+
+func NewCollector(name string, command string, args ...string) *Collector {
+	return &Collector{
+		name:    name,
+		command: command,
+		args:    args,
+	}
+}
+
+var _ metadata.Collector = &Collector{}

internal/agent/metadata/metadata.go

@@ -0,0 +1,3 @@
+package metadata
+
+type Metadata map[string]any

internal/agent/metadata/sort.go

@@ -0,0 +1,37 @@
+package metadata
+
+import (
+	"sort"
+)
+
+type Tuple struct {
+	Key   string `json:"key"`
+	Value any    `json:"value"`
+}
+
+func Sort(metadata map[string]any) []Tuple {
+	keys := make([]string, 0, len(metadata))
+	for k := range metadata {
+		keys = append(keys, k)
+	}
+
+	sort.Strings(keys)
+
+	tuples := make([]Tuple, len(keys))
+
+	for i, k := range keys {
+		tuples[i] = Tuple{k, metadata[k]}
+	}
+
+	return tuples
+}
+
+func FromSorted(tuples []Tuple) map[string]any {
+	metadata := make(map[string]any)
+
+	for _, t := range tuples {
+		metadata[t.Key] = t.Value
+	}
+
+	return metadata
+}