Ganeti.Confd.Server

ganeti-htools

Ganeti.Confd.Server

Contents

Types and constants definitions

Confd base functionality

Configuration handling

Helper functions
Configuration loading
Watcher threads
Client input/output handlers

Description

Implementation of the Ganeti confd server functionality.

Synopsis

type CRef = IORef (Result (ConfigData, LinkIpMap))

type FStat = (EpochTime, FileID, FileOffset)

nullFStat :: FStat

type StatusAnswer = (ConfdReplyStatus, JSValue)

data ReloadModel

| ReloadPoll Int

data ServerState = ServerState {

reloadModel :: ReloadModel

reloadTime :: Integer

reloadFStat :: FStat

}

maxIdlePollRounds :: Int

configReloadTimeout :: Int

configReloadRatelimit :: Int

initialPoll :: ReloadModel

initialState :: ServerState

data ConfigReload

| ConfigReloaded

| ConfigIOError

queryUnknownEntry :: StatusAnswer

queryArgumentError :: StatusAnswer

getCurrentTime :: IO Integer

getClusterHmac :: IO HashKey

nodeRole :: ConfigData -> String -> Result ConfdNodeRole

getNodePipByInstanceIp :: ConfigData -> LinkIpMap -> String -> String -> StatusAnswer

buildResponse :: (ConfigData, LinkIpMap) -> ConfdRequest -> Result StatusAnswer

parseRequest :: HashKey -> String -> Result (String, String, ConfdRequest)

serializeResponse :: Result StatusAnswer -> ConfdReply

signMessage :: HashKey -> String -> String -> SignedMessage

moveToPolling :: String -> INotify -> FilePath -> CRef -> MVar ServerState -> IO ReloadModel

moveToNotify :: IO ReloadModel

updateConfig :: FilePath -> CRef -> IO ()

safeUpdateConfig :: FilePath -> FStat -> CRef -> IO (FStat, ConfigReload)

buildFileStatus :: FileStatus -> FStat

getFStat :: FilePath -> IO FStat

needsReload :: FStat -> FilePath -> IO (Maybe FStat)

onTimeoutTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()

onTimeoutInner :: FilePath -> CRef -> ServerState -> IO ServerState

onReloadTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()

onReloadInner :: IO Bool -> FilePath -> CRef -> ServerState -> IO (ServerState, Bool)

addNotifier :: INotify -> FilePath -> CRef -> MVar ServerState -> IO Bool

onInotify :: INotify -> String -> CRef -> MVar ServerState -> Event -> IO ()

responder :: CRef -> Socket -> HashKey -> String -> SockAddr -> IO ()

parseMessage :: HashKey -> String -> Integer -> Result (String, ConfdRequest)

respondInner :: Result (ConfigData, LinkIpMap) -> HashKey -> ConfdRequest -> String

listener :: Socket -> HashKey -> (Socket -> HashKey -> String -> SockAddr -> IO ()) -> IO ()

main :: DaemonOptions -> IO ()

Types and constants definitions

type CRef = IORef (Result (ConfigData, LinkIpMap))

What we store as configuration.

type FStat = (EpochTime, FileID, FileOffset)

File stat identifier.

nullFStat :: FStat

Null FStat value.

type StatusAnswer = (ConfdReplyStatus, JSValue)

A small type alias for readability.

data ReloadModel

Reload model data type.

Constructors

ReloadNotify	We are using notifications
ReloadPoll Int	We are using polling

data ServerState

Server state data type.

Constructors

ServerState

reloadModel :: ReloadModel
reloadTime :: Integer
reloadFStat :: FStat

maxIdlePollRounds :: Int

Maximum no-reload poll rounds before reverting to inotify.

configReloadTimeout :: Int

Reload timeout in microseconds.

configReloadRatelimit :: Int

Ratelimit timeout in microseconds.

initialPoll :: ReloadModel

Initial poll round.

initialState :: ServerState

Initial server state.

data ConfigReload

Reload status data type.

Constructors

ConfigToDate	No need to reload
ConfigReloaded	Configuration reloaded
ConfigIOError	Error during configuration reload

queryUnknownEntry :: StatusAnswer

Unknown entry standard response.

queryArgumentError :: StatusAnswer

Argument error standard response.

getCurrentTime :: IO Integer

Returns the current time.

Confd base functionality

getClusterHmac :: IO HashKey

Returns the HMAC key.

nodeRole :: ConfigData -> String -> Result ConfdNodeRole

Computes the node role.

getNodePipByInstanceIp :: ConfigData -> LinkIpMap -> String -> String -> StatusAnswer

Does an instance ip -> instance -> primary node -> primary ip transformation.

buildResponse :: (ConfigData, LinkIpMap) -> ConfdRequest -> Result StatusAnswer

Builds the response to a given query.

parseRequest :: HashKey -> String -> Result (String, String, ConfdRequest)

Parses a signed request.

serializeResponse :: Result StatusAnswer -> ConfdReply

Creates a ConfdReply from a given answer.

signMessage :: HashKey -> String -> String -> SignedMessage

Signs a message with a given key and salt.

Configuration handling

Helper functions

moveToPolling :: String -> INotify -> FilePath -> CRef -> MVar ServerState -> IO ReloadModel

Helper function for logging transition into polling mode.

moveToNotify :: IO ReloadModel

Helper function for logging transition into inotify mode.

Configuration loading

updateConfig :: FilePath -> CRef -> IO ()

(Re)loads the configuration.

safeUpdateConfig :: FilePath -> FStat -> CRef -> IO (FStat, ConfigReload)

Wrapper over updateConfig that handles IO errors.

buildFileStatus :: FileStatus -> FStat

Computes the file cache data from a FileStatus structure.

getFStat :: FilePath -> IO FStat

Wrapper over buildFileStatus. This reads the data from the filesystem and then builds our cache structure.

needsReload :: FStat -> FilePath -> IO (Maybe FStat)

Check if the file needs reloading

Watcher threads

We have three threads/functions that can mutate the server state:

1. the long-interval watcher (onTimeoutTimer)

2. the polling watcher (onReloadTimer)

3. the inotify event handler (onInotify)

All of these will mutate the server state under modifyMVar or modifyMVar_, so that server transitions are more or less atomic. The inotify handler remains active during polling mode, but checks for polling mode and doesn't do anything in this case (this check is needed even if we would unregister the event handler due to how events are serialised).

onTimeoutTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()

Long-interval reload watcher.

This is on top of the inotify-based triggered reload.

onTimeoutInner :: FilePath -> CRef -> ServerState -> IO ServerState

Inner onTimeout handler.

This mutates the server state under a modifyMVar_ call. It never changes the reload model, just does a safety reload and tried to re-establish the inotify watcher.

onReloadTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()

Short-interval (polling) reload watcher.

This is only active when we're in polling mode; it will automatically exit when it detects that the state has changed to notification.

onReloadInner :: IO Bool -> FilePath -> CRef -> ServerState -> IO (ServerState, Bool)

Inner onReload handler.

This again mutates the state under a modifyMVar call, and also returns whether the thread should continue or not.

addNotifier :: INotify -> FilePath -> CRef -> MVar ServerState -> IO Bool

Setup inotify watcher.

This tries to setup the watch descriptor; in case of any IO errors, it will return False.

onInotify :: INotify -> String -> CRef -> MVar ServerState -> Event -> IO ()

Inotify event handler.

Client input/output handlers

responder :: CRef -> Socket -> HashKey -> String -> SockAddr -> IO ()

Main loop for a given client.

parseMessage :: HashKey -> String -> Integer -> Result (String, ConfdRequest)

Mesage parsing. This can either result in a good, valid message, or fail in the Result monad.

respondInner :: Result (ConfigData, LinkIpMap) -> HashKey -> ConfdRequest -> String

Inner helper function for a given client. This generates the final encoded message (as a string), ready to be sent out to the client.

listener :: Socket -> HashKey -> (Socket -> HashKey -> String -> SockAddr -> IO ()) -> IO ()

Main listener loop.

main :: DaemonOptions -> IO ()

Main function.

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