metahook

Documentation

Index

• type MetaHook
  • func CreateMetaHook(socketpath string, socketperm fs.FileMode, updatehooks UpdateHooks, ...) (*MetaHook, error)
  • func (m *MetaHook) Serve() error
• type UpdateHooks

Types

type MetaHook

type MetaHook struct {
	// contains filtered or unexported fields
}

*

• MetaHook is a component to update the MetaConfiguration
• over a controlled HTTP API *
• It uses a updateHookMap to specify callback functions
• for specific MetaConfig keys, those callbacks can be used
• to live-update the configuration in the components. *
• MetaHook launches a HTTP API over a UNIX socket on the specified location *
• Main purpose for this API is that infrastructure controllers like juju
• can manage the MetaConfig at runtime.

func CreateMetaHook

func CreateMetaHook(
	socketpath string,
	socketperm fs.FileMode,
	updatehooks UpdateHooks,
	config *metaconfig.MetaConfig) (*MetaHook, error)

*

• Initialize MetaHook API

func (*MetaHook) Serve

func (m *MetaHook) Serve() error

*

• Create unix socket / listener and start HTTP server *
• Serve() will block execution, you can safely push it to a goroutine

type UpdateHooks

type UpdateHooks struct {
	// Hooks for string fields
	StringFieldHooks map[string]func(string, string) error
	// Hooks for bool fields
	BoolFieldHooks map[string]func(string, bool) error
	// Hooks for double fields
	DoubleFieldHooks map[string]func(string, float64) error
	// Hooks for list fields
	ListFieldHooks map[string]func(string, []string) error
}

*

• Structure which holds function definitions for specific MetaConfig fields *
• The hook function callback is called when the API is called to change the specified MetaConfig field. *
• Every hook is executed synchroniously, make sure they do not use cost-intensive IO operations. *
• Hooks are expected to bring the system into a state where it operates like
• the field was set at application start!