core/cmd/init/main.go

// Copyright 2020 The Monogon Project Authors.
//
// SPDX-License-Identifier: Apache-2.0
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"runtime/debug"

	"git.monogon.dev/source/nexantic.git/core/internal/common/supervisor"
	"git.monogon.dev/source/nexantic.git/core/internal/network"
	"git.monogon.dev/source/nexantic.git/core/internal/node"
	"git.monogon.dev/source/nexantic.git/core/internal/storage"
	"git.monogon.dev/source/nexantic.git/core/pkg/tpm"

	"go.uber.org/zap"
	"golang.org/x/sys/unix"
)

const (
	apiPort       = 7833
	consensusPort = 7834
)

func main() {
	defer func() {
		if r := recover(); r != nil {
			fmt.Println("Init panicked:", r)
			debug.PrintStack()
		}
		unix.Sync()
		// TODO(lorenz): Switch this to Reboot when init panics are less likely
		// Best effort, nothing we can do if this fails except printing the error to the console.
		if err := unix.Reboot(unix.LINUX_REBOOT_CMD_POWER_OFF); err != nil {
			panic(fmt.Sprintf("failed to halt node: %v\n", err))
		}
	}()
	logger, err := zap.NewDevelopment()
	if err != nil {
		panic(err)
	}

	// Remount onto a tmpfs and re-exec if needed. Otherwise, keep running.
	err = switchRoot(logger)
	if err != nil {
		panic(fmt.Errorf("could not remount root: %w", err))
	}

	// Linux kernel default is 4096 which is far too low. Raise it to 1M which is what gVisor suggests.
	if err := unix.Setrlimit(unix.RLIMIT_NOFILE, &unix.Rlimit{Cur: 1048576, Max: 1048576}); err != nil {
		logger.Panic("Failed to raise rlimits", zap.Error(err))
	}

	logger.Info("Starting Smalltown Init")

	signalChannel := make(chan os.Signal, 2)
	signal.Notify(signalChannel)

	if err := tpm.Initialize(logger.With(zap.String("component", "tpm"))); err != nil {
		logger.Panic("Failed to initialize TPM 2.0", zap.Error(err))
	}

	storageManager, err := storage.Initialize(logger.With(zap.String("component", "storage")))
	if err != nil {
		panic(fmt.Errorf("could not initialize storage: %w", err))
	}

	networkSvc := network.New(network.Config{})
	if err != nil {
		panic(err)
	}

	// This function initializes a headless Delve if this is a debug build or does nothing if it's not
	initializeDebugger(networkSvc)

	supervisor.New(context.Background(), logger, func(ctx context.Context) error {
		if err := supervisor.Run(ctx, "network", networkSvc.Run); err != nil {
			return err
		}

		// TODO(q3k): convert node code to supervisor
		nodeInstance, err := node.NewSmalltownNode(logger, networkSvc, storageManager)
		if err != nil {
			panic(err)
		}

		err = nodeInstance.Start(ctx)
		if err != nil {
			panic(err)
		}

		supervisor.Signal(ctx, supervisor.SignalHealthy)

		// We're PID1, so orphaned processes get reparented to us to clean up
		for {
			select {
			case <-ctx.Done():
				return ctx.Err()
			case sig := <-signalChannel:
				switch sig {
				case unix.SIGCHLD:
					var status unix.WaitStatus
					var rusage unix.Rusage
					for {
						res, err := unix.Wait4(-1, &status, unix.WNOHANG, &rusage)
						if err != nil && err != unix.ECHILD {
							logger.Error("Failed to wait on orphaned child", zap.Error(err))
							break
						}
						if res <= 0 {
							break
						}
					}
				case unix.SIGURG:
					// Go 1.14 introduced asynchronous preemption, which uses SIGURG.
					// In order not to break backwards compatibility in the unlikely case
					// of an application actually using SIGURG on its own, they're not filtering them.
					// (https://github.com/golang/go/issues/37942)
					logger.Debug("Ignoring SIGURG")
				// TODO(lorenz): We can probably get more than just SIGCHLD as init, but I can't think
				// of any others right now, just log them in case we hit any of them.
				default:
					logger.Warn("Got unexpected signal", zap.String("signal", sig.String()))
				}
			}
		}
	})
	select {}
}