isle/go/cmd/entrypoint/daemon.go

package main

import (
	"context"
	"fmt"
	"os"

	"isle/daemon"

	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

var subCmdDaemon = subCmd{
	name:  "daemon",
	descr: "Runs the isle daemon (Default if no sub-command given)",
	do: func(subCmdCtx subCmdCtx) error {

		flags := subCmdCtx.flagSet(false)

		daemonConfigPath := flags.StringP(
			"config-path", "c", "",
			"Optional path to a daemon.yml file to load configuration from.",
		)

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

		logLevelStr := flags.StringP(
			"log-level", "l", "info",
			`Maximum log level which should be output. Values can be "debug", "info", "warn", "error", "fatal". Does not apply to sub-processes`,
		)

		if err := flags.Parse(subCmdCtx.args); err != nil {
			return fmt.Errorf("parsing flags: %w", err)
		}

		ctx := subCmdCtx.ctx

		if *dumpConfig {
			return daemon.CopyDefaultConfig(os.Stdout, envAppDirPath)
		}

		logLevel := mlog.LevelFromString(*logLevelStr)
		if logLevel == nil {
			return fmt.Errorf("couldn't parse log level %q", *logLevelStr)
		}

		logger := subCmdCtx.logger.WithMaxLevel(logLevel.Int())

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

		daemonInst, err := daemon.NewDaemon(
			logger, daemonConfig, envBinDirPath, nil,
		)
		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, daemon.NewRPC(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
	},
}