mesh-sdk/go/catalogue/environment_into.go

package catalogue

// EnvironmentSeat and LoginShellSeat are the seats whose holders may place what the modules
// contributed: the account's environment, and the login shell's code.
const (
	EnvironmentSeat = "node-environment"
	LoginShellSeat  = "node-login-shell"
	// PowerSeat is the seat whose holder places code for the power moments (novox/hq ADR 0211).
	PowerSeat = "node-power"
)

// Where an environment entry on PATH goes: before the account's existing PATH, or after it.
const (
	PathAtStart = "start"
	PathAtEnd   = "end"
)

// Environment is what one module adds to the account's environment (novox/hq ADR 0203).
type Environment struct {
	// Variables are names and literal values. A value may name the machine's own facts with
	// ${machine:…}, resolved before anything is written, and nothing else that expands.
	Variables map[string]string `json:"variables,omitempty"`
	// Path is entries on the account's PATH, each at its start or its end, in the order declared.
	Path []PathEntry `json:"path,omitempty"`
}

// PathEntry is one directory a module puts on the account's PATH.
type PathEntry struct {
	Entry string `json:"entry"`
	At    string `json:"at"`
}

// ShellCode is one piece of code a module adds to a shell's startup (novox/hq ADR 0204).
type ShellCode struct {
	// For is the shell the code is written in.
	For string `json:"for"`
	// Slot is where it runs among the other modules' code: first, normal or last. Named rather
	// than numbered, because every contributor would guess a number and a collision says nothing.
	Slot string `json:"slot"`
	// Code is never interpreted — it is the shell's syntax, and only the shell reads it.
	Code string `json:"code"`
}

// The shells and slots a contribution may name (novox/hq ADR 0204). Closed, so a typo is a refusal
// at the check rather than code that silently lands in no placeholder.
var (

	// sessionFiles are the two files of the graphical session's start that read no directory, so a
	// contribution to them is a slot rather than a drop-in (novox/hq ADR 0208 §4): `xinitrc` is POSIX
	// code the session's start runs, `xresources` X resources merged at its start. Placed by the
	// display server's holder, as a shell's slots are placed by the login shell's.
	sessionFiles = []string{"xinitrc", "xresources"}
	// powerMoments are the moments of a machine's power a module may run code at (novox/hq ADR
	// 0211 §3): POSIX code run as root by node-power's holder, in module order, each piece bounded.
	powerMoments = []string{"after-boot", "before-sleep", "after-wake", "before-shutdown", "on-mains", "on-battery"}
)

// placerOf is the seat whose holder places a contribution for this target (novox/hq ADR 0204,
// ADR 0208 §4).
func placerOf(target string) string {
	if oneOf(sessionFiles, target) {
		return DisplayServerSeat
	}
	if oneOf(powerMoments, target) {
		return PowerSeat
	}
	return LoginShellSeat
}

// The two renderings of the environment a holder may place (novox/hq ADR 0203, decision 3).
const (
	EnvironmentPOSIX   = "posix"
	EnvironmentSystemd = "systemd"
)