config.go

// Copyright 2018 fydrah
//
// 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 (
	"fmt"
	"io/ioutil"
	"os"
	"strings"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/common/version"
	"github.com/sirupsen/logrus"
	"gopkg.in/yaml.v2"
)

type AppConfig struct {
	Name   string `yaml:"name"`
	Listen string `yaml:"listen"`
	OIDC   struct {
		Client struct {
			ID          string `yaml:"id"`
			Secret      string `yaml:"secret"`
			RedirectURL string `yaml:"redirect_url"`
		} `yaml:"client"`
		Issuer struct {
			URL    string `yaml:"url"`
			RootCA string `yaml:"root_ca"`
		} `yaml:"issuer"`
		ExtraScopes    []string `yaml:"extra_scopes"`
		OfflineAsScope *bool    `yaml:"offline_as_scope"`
		CrossClients   []string `yaml:"cross_clients"`
	} `yaml:"oidc"`
	TLS struct {
		Enabled bool   `yaml:"enabled"`
		Cert    string `yaml:"cert"`
		Key     string `yaml:"key"`
	} `yaml:"tls"`
	Log struct {
		Level  string `yaml:"level"`
		Format string `yaml:"format"`
	} `yaml:"log"`
	WebOutput struct {
		MainUsernameClaim string `yaml:"main_username_claim"`
		MainClientID      string `yaml:"main_client_id"`
		AssetsDir         string `yaml:"assets_dir"`
		SkipMainPage      bool   `yaml:"skip_main_page"`
	} `yaml:"web_output"`
	Template struct {
		ClusterServer string `yaml:"cluster_server"`
		ClusterCA     string `yaml:"cluster_ca"`
		ClusterName   string `yaml:"cluster_name"`
		ContextName   string `yaml:"context_name"`
	} `yaml:"template"`
}

// appCheck struct
// used by check function
type appCheck struct {
	Condition     bool
	Message       string
	DefaultAction func()
}

// check checks each appCheck, if one
// check fails, return true
func check(checks []appCheck) bool {
	checkFailed := false
	for _, c := range checks {
		if c.Condition {
			logger.Error(c.Message)
			checkFailed = true
			if c.DefaultAction != nil {
				c.DefaultAction()
			}
		}
	}
	return checkFailed
}

// configLogger setup application logger
// Default loglevel is info
func configLogger(format string, logLevel string) {
	switch f := format; f {
	case "json":
		logger.Formatter = &logrus.JSONFormatter{}
	case "text":
		logger.Formatter = &logrus.TextFormatter{}
	default:
		logger.Formatter = &logrus.JSONFormatter{}
		logger.Warningf("Format %q not available, use json|text. Using json format", f)
		format = "json"
	}
	logger.Debugf("Using %s log format", format)
	switch l := logLevel; l {
	case "debug":
		logger.Level = logrus.DebugLevel
	case "info":
		logger.Level = logrus.InfoLevel
	case "warning":
		logger.Level = logrus.WarnLevel
	case "error":
		logger.Level = logrus.ErrorLevel
	default:
		logger.Level = logrus.InfoLevel
		logger.Warningf("Log level %q not available, use debug|info|warning|error. Using Info log level", l)
		logLevel = "info"
	}
	logger.Debugf("Using %s log level", logLevel)
}

// Init load configuration,
// setup logger and run
// error/warning checks
func (a *AppConfig) Init(config string) error {
	prometheus.MustRegister(version.NewCollector("loginapp"))
	/*
		Extract data from yaml configuration file
	*/
	logger.Debugf("Loading configuration file: %v", config)
	configData, err := ioutil.ReadFile(config)
	if err != nil {
		return fmt.Errorf("failed to read config file %s: %v", config, err)
	}
	logger.Debugf("Unmarshal data: %v", configData)
	if err := yaml.Unmarshal(configData, &a); err != nil {
		return fmt.Errorf("error parse config file %s: %v", config, err)
	}

	/*
		Configure log level
	*/
	configLogger(strings.ToLower(a.Log.Format), strings.ToLower(a.Log.Level))

	/*
		Configuration checks
		(inspired from https://github.com/coreos/dex/blob/master/cmd/dex/serve.go)
	*/
	currentDir, err := os.Getwd()
	if err != nil {
		return fmt.Errorf("error getting current directory: %v", err)
	}
	defaultAssetsDir := fmt.Sprintf("%v/assets", currentDir)
	/*
		Error checks: list of checks which make loginapp failed
	*/
	errorChecks := []appCheck{
		{a.Name == "", "no name specified", nil},
		{a.Listen == "", "no bind 'ip:port' specified", nil},
		{a.OIDC.Client.ID == "", "no client id specified", nil},
		{a.OIDC.Client.Secret == "", "no client secret specified", nil},
		{a.OIDC.Client.RedirectURL == "", "no redirect url specified", nil},
		{a.OIDC.Issuer.URL == "", "no issuer url specified", nil},
		{a.OIDC.Issuer.RootCA == "", "no issuer root_ca specified", nil},
		{a.TLS.Enabled && a.TLS.Cert == "", "no tls cert specified", nil},
		{a.TLS.Enabled && a.TLS.Key == "", "no tls key specified", nil},
	}
	if check(errorChecks) {
		return fmt.Errorf("Error while loading configuration")
	}
	/*
		Default checks: list of check which make loginapp setup a default value

		Even if logger report this as an error log, this is not handle as an error.
		Hope the following issue will be merged to use loglevel as a parameter:
		https://github.com/sirupsen/logrus/issues/646
	*/
	defaultChecks := []appCheck{
		{a.WebOutput.MainClientID == "", fmt.Sprintf("no output main_client_id specified, using default: %v", a.OIDC.Client.ID), func() {
			a.WebOutput.MainClientID = a.OIDC.Client.ID
		}},
		{a.WebOutput.AssetsDir == "", fmt.Sprintf("no assets_dir specified, using default: %v", defaultAssetsDir), func() {
			a.WebOutput.AssetsDir = defaultAssetsDir
		}},
		{a.WebOutput.MainUsernameClaim == "", "no output main_username_claim specified, using default: 'name'", func() {
			a.WebOutput.MainUsernameClaim = "name"
		}},
	}
	_ = check(defaultChecks)

	logger.Debugf("Configuration loaded: %+v", a)
	return nil
}