Documentation
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Overview ¶
Package flow implements the Flow component graph system. Flow configuration files are parsed from River, which contain a listing of components to run.
Components ¶
Each component has a set of arguments (River attributes and blocks) and optionally a set of exported fields. Components can reference the exports of other components using River expressions.
See the top-level component package for more information on components, and subpackages for defined components.
Component Health ¶
A component will have various health states during its lifetime:
- Unknown: The initial health state for new components.
- Healthy: A healthy component
- Unhealthy: An unhealthy component.
- Exited: A component which is no longer running.
Health states are paired with a time for when the health state was generated and a message providing more detail for the health state.
Components can report their own health states. The health state reported by a component is merged with the Flow-level health of that component: an error when evaluating the configuration for a component will always be reported as unhealthy until the next successful evaluation.
Component Evaluation ¶
The process of converting the River block associated with a component into the appropriate Go struct is called "component evaluation."
Components are only evaluated after all components they reference have been evaluated; cyclic dependencies are invalid.
If a component updates its Exports at runtime, other components which directly or indirectly reference the updated component will have their Arguments re-evaluated.
The arguments and exports for a component will be left in their last valid state if a component shuts down or is given an invalid config. This prevents a domino effect of a single failed component taking down other components which are otherwise healthy.
Index ¶
- type Argument
- type File
- type Flow
- func (f *Flow) GetComponent(id component.ID, opts component.InfoOptions) (*component.Info, error)
- func (f *Flow) GetServiceConsumers(serviceName string) []any
- func (f *Flow) ListComponents(moduleID string, opts component.InfoOptions) ([]*component.Info, error)
- func (f *Flow) LoadFile(file *File, args map[string]any) error
- func (f *Flow) Ready() bool
- func (f *Flow) Run(ctx context.Context)
- type Options
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Argument ¶ added in v0.33.0
type Argument struct { // Name of the argument. Name string `river:",label"` // Whether the Argument must be provided when evaluating the file. Optional bool `river:"optional,attr,optional"` // Description for the Argument. Comment string `river:"comment,attr,optional"` // Default value for the argument. Default any `river:"default,attr,optional"` }
An Argument is an input to a Flow module.
type File ¶
type File struct { Name string // File name given to ReadFile. Node *ast.File // Raw File node. // Components holds the list of raw River AST blocks describing components. // The Flow controller can interpret them. Components []*ast.BlockStmt ConfigBlocks []*ast.BlockStmt }
File holds the contents of a parsed Flow file.
type Flow ¶
type Flow struct {
// contains filtered or unexported fields
}
Flow is the Flow system.
func (*Flow) GetComponent ¶ added in v0.35.0
GetComponent implements component.Provider.
func (*Flow) GetServiceConsumers ¶ added in v0.35.0
GetServiceConsumers implements [service.Host]. It returns a slice of component.Component and [service.Service]s which declared a dependency on the named service.
func (*Flow) ListComponents ¶ added in v0.35.0
func (f *Flow) ListComponents(moduleID string, opts component.InfoOptions) ([]*component.Info, error)
ListComponents implements component.Provider.
func (*Flow) LoadFile ¶
LoadFile synchronizes the state of the controller with the current config file. Components in the graph will be marked as unhealthy if there was an error encountered during Load.
The controller will only start running components after Load is called once without any configuration errors.
type Options ¶
type Options struct { // ControllerID is an identifier used to represent the controller. // ControllerID is used to generate a globally unique display name for // components in a binary where multiple controllers are used. // // If running multiple Flow controllers, each controller must have a // different value for ControllerID to be able to differentiate between // components in telemetry data. ControllerID string // Logger to use for controller logs and components. A no-op logger will be // created if this is nil. Logger *logging.Logger // Tracer for components to use. A no-op tracer will be created if this is // nil. Tracer *tracing.Tracer // Clusterer for implementing distributed behavior among components running // on different nodes. Clusterer *cluster.Clusterer // Directory where components can write data. Constructed components will be // given a subdirectory of DataPath using the local ID of the component. // // If running multiple Flow controllers, each controller must have a // different value for DataPath to prevent components from colliding. DataPath string // Reg is the prometheus register to use Reg prometheus.Registerer // HTTPPathPrefix is the path prefix given to managed components. May be // empty. When provided, it should be an absolute path. // // Components will be given a path relative to HTTPPathPrefix using their // local ID. // // If running multiple Flow controllers, each controller must have a // different value for HTTPPathPrefix to prevent components from colliding. HTTPPathPrefix string // HTTPListenAddr is the base address (host:port) where component APIs are // exposed to other components. HTTPListenAddr string // OnExportsChange is called when the exports of the controller change. // Exports are controlled by "export" configuration blocks. If // OnExportsChange is nil, export configuration blocks are not allowed in the // loaded config file. OnExportsChange func(exports map[string]any) // DialFunc is a function to use for components to properly connect to // HTTPListenAddr. If nil, DialFunc defaults to (&net.Dialer{}).DialContext. DialFunc func(ctx context.Context, network, address string) (net.Conn, error) }
Options holds static options for a flow controller.
Source Files
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Directories
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Path | Synopsis |
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Package componenttest provides utilities for testing Flow components.
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Package componenttest provides utilities for testing Flow components. |
internal
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dag
Package dag defines a Directed Acyclic Graph.
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Package dag defines a Directed Acyclic Graph. |
testcomponents
Package testcomponents contains components useful for testing.
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Package testcomponents contains components useful for testing. |
Package tracing implements the tracing subsystem of Grafana Agent Flow.
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Package tracing implements the tracing subsystem of Grafana Agent Flow. |
internal/jaegerremote
Package jaegerremote implements the Jaeger Remote protocol.
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Package jaegerremote implements the Jaeger Remote protocol. |