HODA/internal/apps/app.go

// Package apps turns labeled containers into dashboard apps and keeps the
// merged list from this host and any agents.
package apps

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"net/url"
	"strconv"
	"strings"

	"git.mariosem.es/msemes/hoda/internal/docker"
)

// State is what a tile's dot shows.
type State string

const (
	StateRunning   State = "running"
	StateUnhealthy State = "unhealthy"
	StateStopped   State = "stopped"
)

// DefaultGroup holds apps that have no group label.
const DefaultGroup = "Apps"

// App is one tile on the dashboard. Only the fields with JSON names leave the
// process; the rest feed icon resolution.
type App struct {
	ID          string `json:"id"`
	Name        string `json:"name"`
	URL         string `json:"url"`
	Description string `json:"description,omitempty"`
	Group       string `json:"group"`
	Order       int    `json:"order"`
	Icon        string `json:"icon,omitempty"`
	State       State  `json:"state"`
	Host        string `json:"host"`

	IconHint    string `json:"-"`
	InternalURL string `json:"-"`
	Image       string `json:"-"`
}

// FromContainer reads an app from a container's labels. ok is false when the
// container has not opted in; err says why an opted-in container can't be shown.
func FromContainer(c docker.Container, prefix, host string) (app App, ok bool, err error) {
	label := func(key string) string { return strings.TrimSpace(c.Labels[prefix+"."+key]) }
	if enabled, _ := strconv.ParseBool(label("enable")); !enabled {
		return App{}, false, nil
	}
	app = App{
		ID:          ID(host, c.Name()),
		Name:        firstNonEmpty(label("name"), c.Labels["com.docker.compose.service"], c.Name()),
		Description: label("description"),
		Group:       firstNonEmpty(label("group"), DefaultGroup),
		State:       stateOf(c),
		Host:        host,
		IconHint:    label("icon"),
		Image:       c.Image,
	}
	if app.URL = label("url"); app.URL == "" {
		return App{}, true, fmt.Errorf("missing %s.url label", prefix)
	}
	if !IsWebURL(app.URL) {
		return App{}, true, fmt.Errorf("%s.url %q is not an http or https URL", prefix, app.URL)
	}
	if app.InternalURL = label("internal_url"); app.InternalURL != "" && !IsWebURL(app.InternalURL) {
		return App{}, true, fmt.Errorf("%s.internal_url %q is not an http or https URL", prefix, app.InternalURL)
	}
	if raw := label("order"); raw != "" {
		if app.Order, err = strconv.Atoi(raw); err != nil {
			return App{}, true, fmt.Errorf("%s.order %q is not a whole number", prefix, raw)
		}
	}
	return app, true, nil
}

// ID is a short identifier for a container on a host. It survives the
// container being re-created, because compose keeps the name.
func ID(host, container string) string {
	sum := sha256.Sum256([]byte(host + "/" + container))
	return hex.EncodeToString(sum[:6])
}

// ValidID reports whether id has the shape ID produces.
func ValidID(id string) bool {
	if len(id) != 12 {
		return false
	}
	for _, r := range id {
		if !strings.ContainsRune("0123456789abcdef", r) {
			return false
		}
	}
	return true
}

// IsWebURL reports whether raw is an absolute http or https URL.
func IsWebURL(raw string) bool {
	u, err := url.Parse(raw)
	return err == nil && (u.Scheme == "http" || u.Scheme == "https") && u.Host != ""
}

func stateOf(c docker.Container) State {
	switch c.State {
	case "running":
		if strings.Contains(c.Status, "(unhealthy)") {
			return StateUnhealthy
		}
		return StateRunning
	case "restarting":
		return StateUnhealthy
	default:
		return StateStopped
	}
}

func firstNonEmpty(values ...string) string {
	for _, v := range values {
		if v != "" {
			return v
		}
	}
	return ""
}