open-nomad/command/var_list.go

package command

import (
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/hashicorp/nomad/api"
	"github.com/posener/complete"
)

const (
	msgVariableNotFound      = "No matching variables found"
	msgWarnFilterPerformance = "Filter queries require a full scan of the data; use prefix searching where possible"
)

type VarListCommand struct {
	Prefix string
	Meta
}

func (c *VarListCommand) Help() string {
	helpText := `
Usage: nomad var list [options] <prefix>

  List is used to list available variables. Supplying an optional prefix,
  filters the list to variables having a path starting with the prefix.

  If ACLs are enabled, this command will return only variables stored at
  namespaced paths where the token has the ` + "`read`" + ` capability.

General Options:

  ` + generalOptionsUsage(usageOptsDefault) + `

List Options:

  -per-page
    How many results to show per page.

  -page-token
    Where to start pagination.

  -filter
    Specifies an expression used to filter query results. Queries using this
    option are less efficient than using the prefix parameter; therefore,
    the prefix parameter should be used whenever possible.

  -json
    Output the variables in JSON format.

  -t
    Format and display the variables using a Go template.

  -q
    Output matching variable paths with no additional information.
    This option overrides the ` + "`-t`" + ` option.
`
	return strings.TrimSpace(helpText)
}

func (c *VarListCommand) AutocompleteFlags() complete.Flags {
	return mergeAutocompleteFlags(c.Meta.AutocompleteFlags(FlagSetClient),
		complete.Flags{
			"-json": complete.PredictNothing,
			"-t":    complete.PredictAnything,
		},
	)
}

func (c *VarListCommand) AutocompleteArgs() complete.Predictor {
	return complete.PredictNothing
}

func (c *VarListCommand) Synopsis() string {
	return "List variable metadata"
}

func (c *VarListCommand) Name() string { return "var list" }
func (c *VarListCommand) Run(args []string) int {
	var json, quiet bool
	var perPage int
	var tmpl, pageToken, filter, prefix string

	flags := c.Meta.FlagSet(c.Name(), FlagSetClient)
	flags.Usage = func() { c.Ui.Output(c.Help()) }
	flags.BoolVar(&quiet, "q", false, "")
	flags.BoolVar(&json, "json", false, "")
	flags.StringVar(&tmpl, "t", "", "")
	flags.IntVar(&perPage, "per-page", 0, "")
	flags.StringVar(&pageToken, "page-token", "", "")
	flags.StringVar(&filter, "filter", "", "")

	if err := flags.Parse(args); err != nil {
		return 1
	}

	// Check that we got no arguments
	args = flags.Args()
	if l := len(args); l > 1 {
		c.Ui.Error("This command takes flags and either no arguments or one: <prefix>")
		c.Ui.Error(commandErrorText(c))
		return 1
	}

	if len(args) == 1 {
		prefix = args[0]
	}

	// Get the HTTP client
	client, err := c.Meta.Client()
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error initializing client: %s", err))
		return 1
	}

	if filter != "" {
		c.Ui.Warn(msgWarnFilterPerformance)
	}

	qo := &api.QueryOptions{
		Filter:    filter,
		PerPage:   int32(perPage),
		NextToken: pageToken,
		Params:    map[string]string{},
	}

	vars, qm, err := client.Variables().PrefixList(prefix, qo)
	if err != nil {
		c.Ui.Error(fmt.Sprintf("Error retrieving vars: %s", err))
		return 1
	}

	switch {
	case json:

		// obj and items enable us to rework the output before sending it
		// to the Format method for transformation into JSON.
		var obj, items interface{}
		obj = vars
		items = vars

		if quiet {
			items = dataToQuietJSONReadySlice(vars, c.Meta.namespace)
			obj = items
		}

		// If the response is paginated, we need to provide a means for the
		// caller to get to the pagination information. Wrapping the list
		// in a struct for the special case allows this extra data without
		// adding unnecessary structure in the non-paginated case.
		if perPage > 0 {

			obj = struct {
				Data      interface{}
				QueryMeta *api.QueryMeta
			}{
				items,
				qm,
			}
		}

		// By this point, the output is ready to be transformed to JSON via
		// the Format func.
		out, err := Format(json, tmpl, obj)
		if err != nil {
			c.Ui.Error(err.Error())
			return 1
		}

		c.Ui.Output(out)

		// Since the JSON formatting deals with the pagination information
		// itself, exit the command here so that it doesn't double print.
		return 0

	case quiet:
		c.Ui.Output(
			formatList(
				dataToQuietStringSlice(vars, c.Meta.namespace)))

	case len(tmpl) > 0:
		out, err := Format(json, tmpl, vars)
		if err != nil {
			c.Ui.Error(err.Error())
			return 1
		}

		c.Ui.Output(out)

	default:
		c.Ui.Output(formatVarStubs(vars))
	}

	if qm.NextToken != "" {
		// This uses Ui.Warn to output the next page token to stderr
		// so that scripts consuming paths from stdout will not have
		// to special case the output.
		c.Ui.Warn(fmt.Sprintf("Next page token: %s", qm.NextToken))
	}

	return 0
}

func formatVarStubs(vars []*api.VariableMetadata) string {
	if len(vars) == 0 {
		return msgVariableNotFound
	}

	// Sort the output by variable namespace, path
	sort.Slice(vars, func(i, j int) bool {
		if vars[i].Namespace == vars[j].Namespace {
			return vars[i].Path < vars[j].Path
		}
		return vars[i].Namespace < vars[j].Namespace
	})

	rows := make([]string, len(vars)+1)
	rows[0] = "Namespace|Path|Last Updated"
	for i, sv := range vars {
		rows[i+1] = fmt.Sprintf("%s|%s|%s",
			sv.Namespace,
			sv.Path,
			time.Unix(0, sv.ModifyTime),
		)
	}
	return formatList(rows)
}

func dataToQuietStringSlice(vars []*api.VariableMetadata, ns string) []string {
	// If ns is the wildcard namespace, we have to provide namespace
	// as part of the quiet output, otherwise it can be a simple list
	// of paths.
	toPathStr := func(v *api.VariableMetadata) string {
		if ns == "*" {
			return fmt.Sprintf("%s|%s", v.Namespace, v.Path)
		}
		return v.Path
	}

	// Reduce the items slice to a string slice containing only the
	// variable paths.
	pList := make([]string, len(vars))
	for i, sv := range vars {
		pList[i] = toPathStr(sv)
	}

	return pList
}

func dataToQuietJSONReadySlice(vars []*api.VariableMetadata, ns string) interface{} {
	// If ns is the wildcard namespace, we have to provide namespace
	// as part of the quiet output, otherwise it can be a simple list
	// of paths.
	if ns == "*" {
		type pTuple struct {
			Namespace string
			Path      string
		}
		pList := make([]*pTuple, len(vars))
		for i, sv := range vars {
			pList[i] = &pTuple{sv.Namespace, sv.Path}
		}
		return pList
	}

	// Reduce the items slice to a string slice containing only the
	// variable paths.
	pList := make([]string, len(vars))
	for i, sv := range vars {
		pList[i] = sv.Path
	}

	return pList
}