terraform-inventory/cli.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"sort"
)

type allGroup struct {
	Hosts []string               `json:"hosts"`
	Vars  map[string]interface{} `json:"vars"`
}

func appendUniq(strs []string, item string) []string {
	if len(strs) == 0 {
		strs = append(strs, item)
		return strs
	}
	sort.Strings(strs)
	i := sort.SearchStrings(strs, item)
	if i == len(strs) || (i < len(strs) && strs[i] != item) {
		strs = append(strs, item)
	}
	return strs
}

func gatherResources(s *state) map[string]interface{} {
	groups := make(map[string]interface{}, 0)
	all_group := allGroup{Vars: make(map[string]interface{}), Hosts: make([]string, 0)}
	groups["all"] = &all_group

	for _, res := range s.resources() {
		for _, grp := range res.Groups() {

			_, ok := groups[grp]
			if !ok {
				groups[grp] = []string{}
			}

			groups[grp] = appendUniq(groups[grp].([]string), res.Address())
			all_group.Hosts = appendUniq(all_group.Hosts, res.Address())
		}
	}

	if len(s.outputs()) > 0 {
		for _, out := range s.outputs() {
			all_group.Vars[out.keyName] = out.value
		}
	}
	return groups
}

func cmdList(stdout io.Writer, stderr io.Writer, s *state) int {
	return output(stdout, stderr, gatherResources(s))
}

func cmdInventory(stdout io.Writer, stderr io.Writer, s *state) int {
	groups := gatherResources(s)
	for group, res := range groups {

		switch grp := res.(type) {
		case []string:
			writeLn("["+group+"]", stdout, stderr)
			for _, item := range grp {
				writeLn(item, stdout, stderr)
			}

		case *allGroup:
			writeLn("["+group+"]", stdout, stderr)
			for _, item := range grp.Hosts {
				writeLn(item, stdout, stderr)
			}
			writeLn("", stdout, stderr)
			writeLn("["+group+":vars]", stdout, stderr)
			for key, item := range grp.Vars {
				writeLn(key+"="+item.(string), stdout, stderr)
			}
		}

		writeLn("", stdout, stderr)
	}

	return 0
}

func writeLn(str string, stdout io.Writer, stderr io.Writer) {
	_, err := io.WriteString(stdout, str+"\n")
	checkErr(err, stderr)
}

func checkErr(err error, stderr io.Writer) int {
	if err != nil {
		fmt.Fprintf(stderr, "Error writing inventory: %s\n", err)
		return 1
	}
	return 0
}

func cmdHost(stdout io.Writer, stderr io.Writer, s *state, hostname string) int {
	for _, res := range s.resources() {
		if hostname == res.Address() {
			return output(stdout, stderr, res.Attributes())
		}
	}

	fmt.Fprintf(stderr, "No such host: %s\n", hostname)
	return 1
}

// output marshals an arbitrary JSON object and writes it to stdout, or writes
// an error to stderr, then returns the appropriate exit code.
func output(stdout io.Writer, stderr io.Writer, whatever interface{}) int {
	b, err := json.Marshal(whatever)
	if err != nil {
		fmt.Fprintf(stderr, "Error encoding JSON: %s\n", err)
		return 1
	}

	_, err = stdout.Write(b)
	if err != nil {
		fmt.Fprintf(stderr, "Error writing JSON: %s\n", err)
		return 1
	}

	return 0
}