state

Documentation

Overview

Package state describes a service's migration state: the modules a migration moves, the IO each performs, and how far each has got.

Index

• Constants
• func Validate(out io.Writer, config Config, palette terminal.Palette, ...) error
• func WriteTypes(out io.Writer, config TypesConfig, palette terminal.Palette, ...) error
• type Config
• type InvalidError
  • func (e *InvalidError) Error() string
• type Node
• type NodeType
  • func NodeTypes(catalog *boundary.Catalog) []NodeType
• type Problem
  • func (p Problem) String() string
• type State
  • func Load(path string, catalog *boundary.Catalog) (State, error)
  • func Parse(data []byte, catalog *boundary.Catalog) (State, error)
  • func (s State) Unreached() []Problem
• type Status
• type TypesConfig

Constants

const Library = "library"

Library is the node type of shared code that performs no IO.

Functions

func Validate

func Validate(out io.Writer, config Config, palette terminal.Palette, catalog *boundary.Catalog) error

Validate checks the state file and writes each error and warning to out. It fails when the state is invalid; warnings alone do not fail it.

func WriteTypes

func WriteTypes(out io.Writer, config TypesConfig, palette terminal.Palette, catalog *boundary.Catalog) error

WriteTypes writes every node type with its description and settings, for an agent that writes the migration state.

Types

type Config

type Config struct {
	// StateFile is the path to the migration state TOML file.
	StateFile string `default:"spectre/state.toml" type:"path" help:"Path to the migration state TOML file."`
}

Config locates the migration state file.

type InvalidError

type InvalidError struct {
	Problems []Problem
}

InvalidError lists every problem that makes a migration state invalid.

func (*InvalidError) Error

func (e *InvalidError) Error() string

Error returns the first problem and how many more there are.

type Node

type Node struct {
	ID        string
	DependsOn []string
	Status    Status
	// IO holds the settings of each IO kind the node has. A library has none.
	IO map[boundary.Kind]map[string]any
	// Line is where the node's table starts in the file, or 0 when unknown.
	Line int
}

Node is one module of the service.

type NodeType

type NodeType struct {
	// Name is how the type is referred to, e.g. "library" or "ingress[http]".
	Name string `json:"name"`
	// Description says what code has the type and how to recognise it.
	Description string `json:"description"`
	// Table is where a node of an IO kind holds its settings, or empty for library.
	Table string `json:"table,omitzero"`
	// Settings are the fields the table can hold.
	Settings []boundary.Setting `json:"settings,omitzero"`
}

NodeType is a type that a node in the migration state can have.

func NodeTypes

func NodeTypes(catalog *boundary.Catalog) []NodeType

NodeTypes returns library, then each kind of IO the catalog supports.

type Problem

type Problem struct {
	// Line is where the problem is in the file, or 0 when unknown.
	Line    int
	Message string
}

Problem is one thing wrong with a migration state.

func (Problem) String

func (p Problem) String() string

String returns the problem prefixed with its line, if known.

type State

type State struct {
	// Nodes are the service's modules, sorted by ID.
	Nodes []Node
}

State is a service's migration state.

func Load

func Load(path string, catalog *boundary.Catalog) (State, error)

Load reads and parses the migration state file at path.

func Parse

func Parse(data []byte, catalog *boundary.Catalog) (State, error)

Parse reads a migration state and checks it against the IO kinds the catalog supports. An invalid state returns an *InvalidError.

func (State) Unreached

func (s State) Unreached() []Problem

Unreached returns a warning for each node that no ingress node is or depends on, since ingress traffic never reaches its code.

type Status

type Status string

Status says where a node's code lives.

const (
	// Pending code is only in the reference.
	Pending Status = "pending"
	// Migrated code is in the candidate as well as the reference.
	Migrated Status = "migrated"
)

type TypesConfig

type TypesConfig struct {
	// JSON prints the node types as a JSON array instead of text.
	JSON bool `help:"Print JSON instead of text."`
}

TypesConfig selects how node types are printed.