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Published: Nov 7, 2023 License: Apache-2.0 Imports: 74 Imported by: 2,101



The server package is responsible for providing the mechanisms necessary to start an ABCI CometBFT application and provides the CLI framework (based on cobra) necessary to fully bootstrap an application. The package exposes two core functions: StartCmd and ExportCmd which creates commands to start the application and export state respectively.


The root command of an application typically is constructed with:

  • command to start an application binary
  • three meta commands: query, tx, and a few auxiliary commands such as genesis. utilities.

It is vital that the root command of an application uses PersistentPreRun() cobra command property for executing the command, so all child commands have access to the server and client contexts. These contexts are set as their default values initially and maybe modified, scoped to the command, in their respective PersistentPreRun() functions. Note that the client.Context is typically pre-populated with "default" values that may be useful for all commands to inherit and override if necessary.


var (
	initClientCtx  = client.Context{...}

	rootCmd = &cobra.Command{
		Use:   "simd",
		Short: "simulation app",
		PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
			if err := client.SetCmdClientContextHandler(initClientCtx, cmd); err != nil {
				return err

			return server.InterceptConfigsPreRunHandler(cmd)
    // add root sub-commands ...

The SetCmdClientContextHandler call reads persistent flags via ReadPersistentCommandFlags which creates a client.Context and sets that on the root command's Context.

The InterceptConfigsPreRunHandler call creates a viper literal, default server.Context, and a logger and sets that on the root command's Context. The server.Context will be modified and saved to disk via the internal interceptConfigs call, which either reads or creates a CometBFT configuration based on the home path provided. In addition, interceptConfigs also reads and loads the application configuration, app.toml, and binds that to the server.Context viper literal. This is vital so the application can get access to not only the CLI flags, but also to the application configuration values provided by this file.


The StartCmd accepts an AppCreator function which returns an Application. The AppCreator is responsible for constructing the application based on the options provided to it via AppOptions. The AppOptions interface type defines a single method, Get() interface{}, and is implemented as a viper literal that exists in the server.Context. All the possible options an application may use and provide to the construction process are defined by the StartCmd and by the application's config file, app.toml.

The application can either be started in-process or as an external process. The former creates a CometBFT service and the latter creates a CometBFT Node.

Under the hood, StartCmd will call GetServerContextFromCmd, which provides the command access to a server.Context. This context provides access to the viper literal, the CometBFT config and logger. This allows flags to be bound the viper literal and passed to the application construction.


func newApp(logger log.Logger, db dbm.DB, traceStore io.Writer, appOpts server.AppOptions) server.Application {
	var cache sdk.MultiStorePersistentCache

	if cast.ToBool(appOpts.Get(server.FlagInterBlockCache)) {
		cache = store.NewCommitKVStoreCacheManager()

	pruningOpts, err := server.GetPruningOptionsFromFlags(appOpts)
	if err != nil {

	return simapp.NewSimApp(
		logger, db, traceStore, true,

Note, some of the options provided are exposed via CLI flags in the start command and some are also allowed to be set in the application's app.toml. It is recommend to use the cast package for type safety guarantees and due to the limitations of CLI flag types.



The commands from the SDK are defined with `cobra` and configured with the `viper` package.

This takes place in the `InterceptConfigsPreRunHandler` function. Since the `viper` package is used for configuration the precedence is dictated by that package. That is

1. Command line switches 2. Environment variables 3. Files from configuration values 4. Default values

The global configuration instance exposed by the `viper` package is not used by Cosmos SDK in this function. A new instance of `viper.Viper` is created and the following is performed. The environmental variable prefix is set to the current program name. Environmental variables consider the underscore to be equivalent to the `.` or `-` character. This means that an configuration value called `rpc.laddr` would be read from an environmental variable called `MYTOOL_RPC_LADDR` if the current program name is `mytool`.

Running the `InterceptConfigsPreRunHandler` also reads `app.toml` and `config.toml` from the home directory under the `config` directory. If `config.toml` or `app.toml` do not exist then those files are created and populated with default values. `InterceptConfigsPreRunHandler` takes two parameters to set/update a custom template to create custom `app.toml`. If these parameters are empty, the server then creates a default template provided by the SDK.



View Source
const (
	FlagHeight           = "height"
	FlagForZeroHeight    = "for-zero-height"
	FlagJailAllowedAddrs = "jail-allowed-addrs"
	FlagModulesToExport  = "modules-to-export"
View Source
const (
	FlagMinGasPrices       = "minimum-gas-prices"
	FlagQueryGasLimit      = "query-gas-limit"
	FlagHaltHeight         = "halt-height"
	FlagHaltTime           = "halt-time"
	FlagInterBlockCache    = "inter-block-cache"
	FlagUnsafeSkipUpgrades = "unsafe-skip-upgrades"
	FlagTrace              = "trace"
	FlagInvCheckPeriod     = "inv-check-period"

	FlagPruning             = "pruning"
	FlagPruningKeepRecent   = "pruning-keep-recent"
	FlagPruningInterval     = "pruning-interval"
	FlagIndexEvents         = "index-events"
	FlagMinRetainBlocks     = "min-retain-blocks"
	FlagIAVLCacheSize       = "iavl-cache-size"
	FlagDisableIAVLFastNode = "iavl-disable-fastnode"

	// state sync-related flags
	FlagStateSyncSnapshotInterval   = "state-sync.snapshot-interval"
	FlagStateSyncSnapshotKeepRecent = "state-sync.snapshot-keep-recent"

	// api-related flags
	FlagAPIEnable             = "api.enable"
	FlagAPISwagger            = "api.swagger"
	FlagAPIAddress            = "api.address"
	FlagAPIMaxOpenConnections = "api.max-open-connections"
	FlagRPCReadTimeout        = "api.rpc-read-timeout"
	FlagRPCWriteTimeout       = "api.rpc-write-timeout"
	FlagRPCMaxBodyBytes       = "api.rpc-max-body-bytes"
	FlagAPIEnableUnsafeCORS   = "api.enabled-unsafe-cors"

	// mempool flags
	FlagMempoolMaxTxs = "mempool.max-txs"
View Source
const ServerContextKey = sdk.ContextKey("server.context")

ServerContextKey defines the context key used to retrieve a server.Context from a command's Context.


This section is empty.


func AddCommands

func AddCommands(rootCmd *cobra.Command, defaultNodeHome string, appCreator types.AppCreator, appExport types.AppExporter, addStartFlags types.ModuleInitFlags)

add server commands

func BootstrapStateCmd added in v0.46.13

func BootstrapStateCmd(appCreator types.AppCreator) *cobra.Command

func CreateSDKLogger added in v0.50.0

func CreateSDKLogger(ctx *Context, out io.Writer) (log.Logger, error)

CreateSDKLogger creates a the default SDK logger. It reads the log level and format from the server context.

func DefaultBaseappOptions added in v0.46.7

func DefaultBaseappOptions(appOpts types.AppOptions) []func(*baseapp.BaseApp)

DefaultBaseappOptions returns the default baseapp options provided by the Cosmos SDK

func ExportCmd

func ExportCmd(appExporter types.AppExporter, defaultNodeHome string) *cobra.Command

ExportCmd dumps app state to JSON.

func ExternalIP

func ExternalIP() (string, error) TODO there must be a better way to get external IP

func GetAppDBBackend added in v0.46.0

func GetAppDBBackend(opts types.AppOptions) dbm.BackendType

GetAppDBBackend gets the backend type to use for the application DBs.

func GetPruningOptionsFromFlags

func GetPruningOptionsFromFlags(appOpts types.AppOptions) (pruningtypes.PruningOptions, error)

GetPruningOptionsFromFlags parses command flags and returns the correct PruningOptions. If a pruning strategy is provided, that will be parsed and returned, otherwise, it is assumed custom pruning options are provided.

func GetSnapshotStore added in v0.46.13

func GetSnapshotStore(appOpts types.AppOptions) (*snapshots.Store, error)

func InterceptConfigsPreRunHandler added in v0.40.0

func InterceptConfigsPreRunHandler(cmd *cobra.Command, customAppConfigTemplate string, customAppConfig interface{}, cmtConfig *cmtcfg.Config) error

InterceptConfigsPreRunHandler is identical to InterceptConfigsAndCreateContext except it also sets the server context on the command and the server logger.

func ListenForQuitSignals added in v0.50.0

func ListenForQuitSignals(g *errgroup.Group, block bool, cancelFn context.CancelFunc, logger log.Logger)

ListenForQuitSignals listens for SIGINT and SIGTERM. When a signal is received, the cleanup function is called, indicating the caller can gracefully exit or return.

Note, the blocking behavior of this depends on the block argument. The caller must ensure the corresponding context derived from the cancelFn is used correctly.

func NewCometABCIWrapper added in v0.50.0

func NewCometABCIWrapper(app servertypes.ABCI) abci.Application

func NewRollbackCmd added in v0.45.2

func NewRollbackCmd(appCreator types.AppCreator, defaultNodeHome string) *cobra.Command

NewRollbackCmd creates a command to rollback CometBFT and multistore state by one height.

func QueryBlockCmd added in v0.50.0

func QueryBlockCmd() *cobra.Command

QueryBlockCmd implements the default command for a Block query.

func QueryBlockResultsCmd added in v0.50.0

func QueryBlockResultsCmd() *cobra.Command

QueryBlockResultsCmd implements the default command for a BlockResults query.

func QueryBlocksCmd added in v0.50.0

func QueryBlocksCmd() *cobra.Command

QueryBlocksCmd returns a command to search through blocks by events.

func RegisterSwaggerAPI added in v0.47.0

func RegisterSwaggerAPI(_ client.Context, rtr *mux.Router, swaggerEnabled bool) error

RegisterSwaggerAPI provides a common function which registers swagger route with API Server

func SetCmdServerContext added in v0.40.0

func SetCmdServerContext(cmd *cobra.Command, serverCtx *Context) error

SetCmdServerContext sets a command's Context value to the provided argument. If the context has not been set, set the given context as the default.

func ShowAddressCmd

func ShowAddressCmd() *cobra.Command

ShowAddressCmd - show this node's validator address

func ShowNodeIDCmd

func ShowNodeIDCmd() *cobra.Command

ShowNodeIDCmd - ported from CometBFT, dump node ID to stdout

func ShowValidatorCmd

func ShowValidatorCmd() *cobra.Command

ShowValidatorCmd - ported from CometBFT, show this node's validator info

func StartCmd

func StartCmd(appCreator types.AppCreator, defaultNodeHome string) *cobra.Command

StartCmd runs the service passed in, either stand-alone or in-process with CometBFT.

func StartCmdWithOptions added in v0.50.0

func StartCmdWithOptions(appCreator types.AppCreator, defaultNodeHome string, opts StartCmdOptions) *cobra.Command

StartCmdWithOptions runs the service passed in, either stand-alone or in-process with CometBFT.

func StatusCommand added in v0.50.0

func StatusCommand() *cobra.Command

StatusCommand returns the command to return the status of the network.

func VersionCmd

func VersionCmd() *cobra.Command

VersionCmd prints CometBFT and ABCI version numbers.


type Context

type Context struct {
	Viper  *viper.Viper
	Config *cmtcfg.Config
	Logger log.Logger

server context

func GetServerContextFromCmd added in v0.40.0

func GetServerContextFromCmd(cmd *cobra.Command) *Context

GetServerContextFromCmd returns a Context from a command or an empty Context if it has not been set.

func InterceptConfigsAndCreateContext added in v0.50.0

func InterceptConfigsAndCreateContext(cmd *cobra.Command, customAppConfigTemplate string, customAppConfig interface{}, cmtConfig *cmtcfg.Config) (*Context, error)

InterceptConfigsAndCreateContext performs a pre-run function for the root daemon application command. It will create a Viper literal and a default server Context. The server CometBFT configuration will either be read and parsed or created and saved to disk, where the server Context is updated to reflect the CometBFT configuration. It takes custom app config template and config settings to create a custom CometBFT configuration. If the custom template is empty, it uses default-template provided by the server. The Viper literal is used to read and parse the application configuration. Command handlers can fetch the server Context to get the CometBFT configuration or to get access to Viper.

func NewContext

func NewContext(v *viper.Viper, config *cmtcfg.Config, logger log.Logger) *Context

func NewDefaultContext

func NewDefaultContext() *Context

type StartCmdOptions added in v0.50.0

type StartCmdOptions struct {
	// DBOpener can be used to customize db opening, for example customize db options or support different db backends,
	// default to the builtin db opener.
	DBOpener func(rootDir string, backendType dbm.BackendType) (dbm.DB, error)
	// PostSetup can be used to setup extra services under the same cancellable context,
	// it's not called in stand-alone mode, only for in-process mode.
	PostSetup func(svrCtx *Context, clientCtx client.Context, ctx context.Context, g *errgroup.Group) error
	// AddFlags add custom flags to start cmd
	AddFlags func(cmd *cobra.Command)

StartCmdOptions defines options that can be customized in `StartCmdWithOptions`,


Path Synopsis
Package gogoreflection implements gRPC reflection for gogoproto consumers the normal reflection library does not work as it points to a different singleton registry.
Package gogoreflection implements gRPC reflection for gogoproto consumers the normal reflection library does not work as it points to a different singleton registry.
Package v2alpha1 is a reverse proxy.
Package v2alpha1 is a reverse proxy.

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