emissary/internal/agent/agent.go

package agent

import (
	"context"
	"time"

	"forge.cadoles.com/Cadoles/emissary/internal/agent/metadata"
	"forge.cadoles.com/Cadoles/emissary/internal/auth/agent"
	"forge.cadoles.com/Cadoles/emissary/internal/client"
	"forge.cadoles.com/Cadoles/emissary/internal/jwk"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/api"
	"gitlab.com/wpetit/goweb/logger"
)

type Agent struct {
	thumbprint  string
	privateKey  jwk.Key
	serverURL   string
	controllers []Controller
	interval    time.Duration
	collectors  []metadata.Collector
}

func (a *Agent) Run(ctx context.Context) error {
	state := NewState()

	logger.Info(ctx, "starting reconciliation ticker", logger.F("interval", a.interval))

	ticker := time.NewTicker(a.interval)
	defer ticker.Stop()

	token, err := agent.GenerateToken(a.privateKey, a.thumbprint)
	if err != nil {
		return errors.WithStack(err)
	}

	client := client.New(a.serverURL, client.WithToken(token))

	ctx = withClient(ctx, client)

	tick := func() {
		logger.Debug(ctx, "registering agent")

		if err := a.registerAgent(ctx, client, state); err != nil {
			logger.Error(ctx, "could not register agent", logger.E(errors.WithStack(err)))
		}

		logger.Debug(ctx, "state before reconciliation", logger.F("state", state))

		if err := a.Reconcile(ctx, state); err != nil {
			logger.Error(ctx, "could not reconcile node with state", logger.E(errors.WithStack(err)))

			return
		}

		logger.Debug(ctx, "state after reconciliation", logger.F("state", state))
	}

	tick()

	for {
		select {
		case <-ticker.C:
			tick()
		case <-ctx.Done():
			return errors.WithStack(ctx.Err())
		}
	}
}

func (a *Agent) Reconcile(ctx context.Context, state *State) error {
	for _, ctrl := range a.controllers {
		ctrlCtx := logger.With(ctx, logger.F("controller", ctrl.Name()))

		logger.Debug(
			ctrlCtx, "executing controller",
			logger.F("state", state),
		)

		if err := ctrl.Reconcile(ctrlCtx, state); err != nil {
			logger.Error(ctx, "could not reconcile", logger.E(errors.WithStack(err)))
		}
	}

	return nil
}

func (a *Agent) registerAgent(ctx context.Context, client *client.Client, state *State) error {
	meta, err := a.collectMetadata(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	sorted := metadata.Sort(meta)

	agent, err := client.RegisterAgent(ctx, a.privateKey, a.thumbprint, sorted)
	if err != nil {
		return errors.WithStack(err)
	}

	state.agentID = agent.ID

	return nil
}

func (a *Agent) collectMetadata(ctx context.Context) (map[string]any, error) {
	metadata := make(map[string]any)

	for _, collector := range a.collectors {
		name, value, err := collector.Collect(ctx)
		if err != nil {
			logger.Error(
				ctx, "could not collect metadata",
				logger.E(errors.WithStack(err)), logger.F("name", name),
			)

			continue
		}

		metadata[name] = value
	}

	return metadata, nil
}

func isAPIError(err error, code api.ErrorCode) (bool, any) {
	apiError := &api.Error{}
	if errors.As(err, &apiError) && apiError.Code == code {
		return true, apiError.Data
	}

	return false, nil
}

func New(serverURL string, privateKey jwk.Key, thumbprint string, funcs ...OptionFunc) *Agent {
	opt := defaultOption()
	for _, fn := range funcs {
		fn(opt)
	}

	return &Agent{
		serverURL:   serverURL,
		privateKey:  privateKey,
		thumbprint:  thumbprint,
		controllers: opt.Controllers,
		interval:    opt.Interval,
		collectors:  opt.Collectors,
	}
}