isle/go/cmd/entrypoint/daemon.go

package main

import (
	"context"
	"fmt"
	"os"

	"isle/daemon"
	"isle/daemon/daecommon"
	"isle/daemon/network"
)

// TODO it would be good to have an `isle daemon config-check` kind of command,
// which could be run prior to a systemd service restart to make sure we don't
// restart the service into a configuration that will definitely fail.

var subCmdDaemon = subCmd{
	name:      "daemon",
	descr:     "Runs the isle daemon (Default if no sub-command given)",
	noNetwork: true,
	do: func(ctx subCmdCtx) error {
		daemonConfigPath := ctx.flags.StringP(
			"config-path", "c", "",
			"Optional path to a daemon.yml file to load configuration from.",
		)

		dumpConfig := ctx.flags.Bool(
			"dump-config", false,
			"Write the default configuration file to stdout and exit.",
		)

		ctx, err := ctx.withParsedFlags()
		if err != nil {
			return fmt.Errorf("parsing flags: %w", err)
		}

		if *dumpConfig {
			return daecommon.CopyDefaultConfig(os.Stdout)
		}

		logger := ctx.logger()
		defer logger.Close()

		// TODO check that daemon is either running as root, or that the
		// required linux capabilities are set.
		// TODO check that the tun module is loaded (for nebula).

		daemonConfig, err := daecommon.LoadConfig(*daemonConfigPath)
		if err != nil {
			return fmt.Errorf("loading daemon config: %w", err)
		}

		networkLoader, err := network.NewLoader(
			ctx,
			logger.WithNamespace("loader"),
			envBinDirPath,
			nil,
		)
		if err != nil {
			return fmt.Errorf("instantiating network loader: %w", err)
		}

		daemonInst, err := daemon.New(ctx, logger, networkLoader, daemonConfig)
		if err != nil {
			return fmt.Errorf("starting daemon: %w", err)
		}
		defer func() {
			logger.Info(ctx, "Stopping child processes")
			if err := daemonInst.Shutdown(); err != nil {
				logger.Error(ctx, "Shutting down daemon cleanly failed, there may be orphaned child processes", err)
			}
			logger.Info(ctx, "Child processes successfully stopped")
		}()

		{
			logger := logger.WithNamespace("http")
			httpSrv, err := newHTTPServer(
				ctx, logger, daemonInst,
			)
			if err != nil {
				return fmt.Errorf("starting HTTP server: %w", err)
			}
			defer func() {
				// see comment in daemonInst shutdown logic regarding background
				// context.
				logger.Info(ctx, "Shutting down HTTP socket")
				if err := httpSrv.Shutdown(context.Background()); err != nil {
					logger.Error(ctx, "Failed to cleanly shutdown http server", err)
				}
			}()
		}

		<-ctx.Done()
		return nil
	},
}