Added config-file flag to accept file based input params (#164)

* Added config-file flag to accept file based input params

* Added changelog

* Fix changelog

* Fix slice override

* Fix issues

* Fix comments

* Fix comments

* Fix bug

.changelog/164.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+Add the `-config-file` flag to support reading configuration options from a JSON file.
+```

cmd/consul-dataplane/config.go

@@ -0,0 +1,327 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"strings"
+
+	"dario.cat/mergo"
+	"github.com/hashicorp/consul-dataplane/pkg/consuldp"
+)
+
+type FlagOpts struct {
+	dataplaneConfig DataplaneConfigFlags
+
+	printVersion bool
+	configFile   string
+}
+
+type DataplaneConfigFlags struct {
+	Consul    ConsulFlags    `json:"consul,omitempty"`
+	Service   ServiceFlags   `json:"service,omitempty"`
+	Logging   LogFlags       `json:"logging,omitempty"`
+	XDSServer XDSServerFlags `json:"xdsServer,omitempty"`
+	DNSServer DNSServerFlags `json:"dnsServer,omitempty"`
+	Telemetry TelemetryFlags `json:"telemetry,omitempty"`
+	Envoy     EnvoyFlags     `json:"envoy,omitempty"`
+}
+
+type ConsulFlags struct {
+	Addresses           *string `json:"addresses,omitempty"`
+	GRPCPort            *int    `json:"grpcPort,omitempty"`
+	ServerWatchDisabled *bool   `json:"serverWatchDisabled,omitempty"`
+
+	TLS         TLSFlags         `json:"tls,omitempty"`
+	Credentials CredentialsFlags `json:"credentials,omitempty"`
+}
+
+type TLSFlags struct {
+	Disabled           *bool   `json:"disabled,omitempty"`
+	CACertsPath        *string `json:"caCertsPath,omitempty"`
+	ServerName         *string `json:"serverName,omitempty"`
+	CertFile           *string `json:"certFile,omitempty"`
+	KeyFile            *string `json:"keyFile,omitempty"`
+	InsecureSkipVerify *bool   `json:"insecureSkipVerify,omitempty"`
+}
+
+type CredentialsFlags struct {
+	Type   *string                `json:"type,omitempty"`
+	Static StaticCredentialsFlags `json:"static,omitempty"`
+	Login  LoginCredentialsFlags  `json:"login,omitempty"`
+}
+
+type StaticCredentialsFlags struct {
+	Token *string `json:"token,omitempty"`
+}
+
+type LoginCredentialsFlags struct {
+	AuthMethod      *string           `json:"authMethod,omitempty"`
+	Namespace       *string           `json:"namespace,omitempty"`
+	Partition       *string           `json:"partition,omitempty"`
+	Datacenter      *string           `json:"datacenter,omitempty"`
+	BearerToken     *string           `json:"bearerToken,omitempty"`
+	BearerTokenPath *string           `json:"bearerTokenPath,omitempty"`
+	Meta            map[string]string `json:"meta,omitempty"`
+}
+
+type ServiceFlags struct {
+	NodeName      *string `json:"nodeName,omitempty"`
+	NodeID        *string `json:"nodeID,omitempty"`
+	ServiceID     *string `json:"serviceID,omitempty"`
+	ServiceIDPath *string `json:"serviceIDPath,omitempty"`
+	Namespace     *string `json:"namespace,omitempty"`
+	Partition     *string `json:"partition,omitempty"`
+}
+
+type XDSServerFlags struct {
+	BindAddr *string `json:"bindAddress,omitempty"`
+	BindPort *int    `json:"bindPort,omitempty"`
+}
+
+type DNSServerFlags struct {
+	BindAddr *string `json:"bindAddress,omitempty"`
+	BindPort *int    `json:"bindPort,omitempty"`
+}
+
+type LogFlags struct {
+	Name     string
+	LogLevel *string `json:"logLevel,omitempty"`
+	LogJSON  *bool   `json:"logJSON,omitempty"`
+}
+
+type TelemetryFlags struct {
+	UseCentralConfig *bool                    `json:"useCentralConfig"`
+	Prometheus       PrometheusTelemetryFlags `json:"prometheus,omitempty"`
+}
+
+type PrometheusTelemetryFlags struct {
+	RetentionTime     *Duration `json:"retentionTime,omitempty"`
+	CACertsPath       *string   `json:"caCertsPath,omitempty"`
+	KeyFile           *string   `json:"keyFile,omitempty"`
+	CertFile          *string   `json:"certFile,omitempty"`
+	ServiceMetricsURL *string   `json:"serviceMetricsURL,omitempty"`
+	ScrapePath        *string   `json:"scrapePath,omitempty"`
+	MergePort         *int      `json:"mergePort,omitempty"`
+}
+
+type EnvoyFlags struct {
+	AdminBindAddr    *string `json:"adminBindAddress,omitempty"`
+	AdminBindPort    *int    `json:"adminBindPort,omitempty"`
+	ReadyBindAddr    *string `json:"readyBindAddress,omitempty"`
+	ReadyBindPort    *int    `json:"readyBindPort,omitempty"`
+	Concurrency      *int    `json:"concurrency,omitempty"`
+	DrainTimeSeconds *int    `json:"drainTimeSeconds,omitempty"`
+	DrainStrategy    *string `json:"drainStrategy,omitempty"`
+
+	ShutdownDrainListenersEnabled *bool   `json:"shutdownDrainListenersEnabled,omitempty"`
+	ShutdownGracePeriodSeconds    *int    `json:"shutdownGracePeriodSeconds,omitempty"`
+	GracefulShutdownPath          *string `json:"gracefulShutdownPath,omitempty"`
+	GracefulPort                  *int    `json:"gracefulPort,omitempty"`
+	DumpEnvoyConfigOnExitEnabled  *bool   `json:"dumpEnvoyConfigOnExitEnabled,omitempty"`
+}
+
+const (
+	DefaultLogName = "consul-dataplane"
+)
+
+// buildDataplaneConfig builds the necessary config needed for the
+// dataplane to start. We begin with the default version of the dataplane
+// config(with the default values) followed by merging the file based
+// config generated from the `-config-file` input into it.
+// Since values given via CLI flags take the most precedence, we finally
+// merge the config generated from the flags into the previously
+// generated/merged config
+func (f *FlagOpts) buildDataplaneConfig(extraArgs []string) (*consuldp.Config, error) {
+	consulDPDefaultFlags, err := buildDefaultConsulDPFlags()
+	if err != nil {
+		return nil, err
+	}
+
+	if f.configFile != "" {
+		consulDPFileBasedFlags, err := f.buildConfigFromFile()
+		if err != nil {
+			return nil, err
+		}
+
+		consulDPDefaultFlags, err = mergeConfigs(consulDPDefaultFlags, consulDPFileBasedFlags)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	consulDPDefaultFlags, err = mergeConfigs(consulDPDefaultFlags, f.dataplaneConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	consuldpRuntimeConfig, err := constructRuntimeConfig(consulDPDefaultFlags, extraArgs)
+	if err != nil {
+		return nil, err
+	}
+
+	return consuldpRuntimeConfig, nil
+}
+
+// Constructs a config based on the values present in the config json file
+func (f *FlagOpts) buildConfigFromFile() (DataplaneConfigFlags, error) {
+	var cfg DataplaneConfigFlags
+	data, err := os.ReadFile(f.configFile)
+	if err != nil {
+		return DataplaneConfigFlags{}, err
+	}
+
+	err = json.Unmarshal(data, &cfg)
+	if err != nil {
+		return DataplaneConfigFlags{}, err
+	}
+
+	return cfg, nil
+}
+
+// Constructs a config with the default values
+func buildDefaultConsulDPFlags() (DataplaneConfigFlags, error) {
+	data := `
+	{
+		"consul": {
+			"grpcPort": 8502,
+			"serverWatchDisabled": false,
+			"tls": {
+				"disabled": false,
+				"insecureSkipVerify": false
+			}
+		},
+		"logging": {
+			"name": "consul-dataplane",
+			"logJSON": false,
+			"logLevel": "info"
+		},
+		"telemetry": {
+			"useCentralConfig": true,
+			"prometheus": {
+				"retentionTime": "60s",
+				"scrapePath": "/metrics",
+				"mergePort": 20100
+			}
+		},
+		"envoy": {
+			"adminBindAddress": "127.0.0.1",
+			"adminBindPort": 19000,
+			"readyBindPort": 0,
+			"concurrency": 2,
+			"drainTimeSeconds": 30,
+			"drainStrategy": "immediate",
+			"shutdownDrainListenersEnabled": false,
+			"shutdownGracePeriodSeconds": 0,
+			"gracefulShutdownPath": "/graceful_shutdown",
+			"gracefulPort": 20300,
+			"dumpEnvoyConfigOnExitEnabled": false
+		},
+		"xdsServer": {
+			"bindAddress": "127.0.0.1",
+			"bindPort": 0
+		},
+		"dnsServer": {
+			"bindAddress": "127.0.0.1",
+			"bindPort": -1
+		}
+	}`
+
+	var defaultCfgFlags DataplaneConfigFlags
+	err := json.Unmarshal([]byte(data), &defaultCfgFlags)
+	if err != nil {
+		return DataplaneConfigFlags{}, err
+	}
+
+	return defaultCfgFlags, nil
+}
+
+// constructRuntimeConfig constructs the final config needed for dataplane to start
+// itself after substituting all the user provided inputs
+func constructRuntimeConfig(cfg DataplaneConfigFlags, extraArgs []string) (*consuldp.Config, error) {
+	return &consuldp.Config{
+		Consul: &consuldp.ConsulConfig{
+			Addresses:           stringVal(cfg.Consul.Addresses),
+			GRPCPort:            intVal(cfg.Consul.GRPCPort),
+			ServerWatchDisabled: boolVal(cfg.Consul.ServerWatchDisabled),
+			Credentials: &consuldp.CredentialsConfig{
+				Type: consuldp.CredentialsType(stringVal(cfg.Consul.Credentials.Type)),
+				Static: consuldp.StaticCredentialsConfig{
+					Token: stringVal(cfg.Consul.Credentials.Static.Token),
+				},
+				Login: consuldp.LoginCredentialsConfig{
+					AuthMethod:      stringVal(cfg.Consul.Credentials.Login.AuthMethod),
+					Namespace:       stringVal(cfg.Consul.Credentials.Login.Namespace),
+					Partition:       stringVal(cfg.Consul.Credentials.Login.Partition),
+					Datacenter:      stringVal(cfg.Consul.Credentials.Login.Datacenter),
+					BearerToken:     stringVal(cfg.Consul.Credentials.Login.BearerToken),
+					BearerTokenPath: stringVal(cfg.Consul.Credentials.Login.BearerTokenPath),
+					Meta:            cfg.Consul.Credentials.Login.Meta,
+				},
+			},
+			TLS: &consuldp.TLSConfig{
+				Disabled:           boolVal(cfg.Consul.TLS.Disabled),
+				CACertsPath:        stringVal(cfg.Consul.TLS.CACertsPath),
+				CertFile:           stringVal(cfg.Consul.TLS.CertFile),
+				KeyFile:            stringVal(cfg.Consul.TLS.KeyFile),
+				ServerName:         stringVal(cfg.Consul.TLS.ServerName),
+				InsecureSkipVerify: boolVal(cfg.Consul.TLS.InsecureSkipVerify),
+			},
+		},
+		Service: &consuldp.ServiceConfig{
+			NodeName:  stringVal(cfg.Service.NodeName),
+			NodeID:    stringVal(cfg.Service.NodeID),
+			ServiceID: stringVal(cfg.Service.ServiceID),
+			Namespace: stringVal(cfg.Service.Namespace),
+			Partition: stringVal(cfg.Service.Partition),
+		},
+		Logging: &consuldp.LoggingConfig{
+			Name:     DefaultLogName,
+			LogJSON:  boolVal(cfg.Logging.LogJSON),
+			LogLevel: strings.ToUpper(stringVal(cfg.Logging.LogLevel)),
+		},
+		Envoy: &consuldp.EnvoyConfig{
+			AdminBindAddress:              stringVal(cfg.Envoy.AdminBindAddr),
+			AdminBindPort:                 intVal(cfg.Envoy.AdminBindPort),
+			ReadyBindAddress:              stringVal(cfg.Envoy.ReadyBindAddr),
+			ReadyBindPort:                 intVal(cfg.Envoy.ReadyBindPort),
+			EnvoyConcurrency:              intVal(cfg.Envoy.Concurrency),
+			EnvoyDrainTimeSeconds:         intVal(cfg.Envoy.DrainTimeSeconds),
+			EnvoyDrainStrategy:            stringVal(cfg.Envoy.DrainStrategy),
+			ShutdownDrainListenersEnabled: boolVal(cfg.Envoy.ShutdownDrainListenersEnabled),
+			ShutdownGracePeriodSeconds:    intVal(cfg.Envoy.ShutdownGracePeriodSeconds),
+			DumpEnvoyConfigOnExitEnabled:  boolVal(cfg.Envoy.DumpEnvoyConfigOnExitEnabled),
+			GracefulShutdownPath:          stringVal(cfg.Envoy.GracefulShutdownPath),
+			GracefulPort:                  intVal(cfg.Envoy.GracefulPort),
+			ExtraArgs:                     extraArgs,
+		},
+		Telemetry: &consuldp.TelemetryConfig{
+			UseCentralConfig: boolVal(cfg.Telemetry.UseCentralConfig),
+			Prometheus: consuldp.PrometheusTelemetryConfig{
+				RetentionTime:     durationVal(cfg.Telemetry.Prometheus.RetentionTime),
+				CACertsPath:       stringVal(cfg.Telemetry.Prometheus.CACertsPath),
+				CertFile:          stringVal(cfg.Telemetry.Prometheus.CertFile),
+				KeyFile:           stringVal(cfg.Telemetry.Prometheus.KeyFile),
+				ServiceMetricsURL: stringVal(cfg.Telemetry.Prometheus.ServiceMetricsURL),
+				ScrapePath:        stringVal(cfg.Telemetry.Prometheus.ScrapePath),
+				MergePort:         intVal(cfg.Telemetry.Prometheus.MergePort),
+			},
+		},
+		XDSServer: &consuldp.XDSServer{
+			BindAddress: stringVal(cfg.XDSServer.BindAddr),
+			BindPort:    intVal(cfg.XDSServer.BindPort),
+		},
+		DNSServer: &consuldp.DNSServerConfig{
+			BindAddr: stringVal(cfg.DNSServer.BindAddr),
+			Port:     intVal(cfg.DNSServer.BindPort),
+		},
+	}, nil
+}
+
+func mergeConfigs(c1, c2 DataplaneConfigFlags) (DataplaneConfigFlags, error) {
+	err := mergo.Merge(&c1, c2, mergo.WithOverride, mergo.WithoutDereference)
+	if err != nil {
+		return DataplaneConfigFlags{}, err
+	}
+
+	return c1, nil
+}