feat: Implement resource:limit and resource:reserve

Also add the install and post-delete hooks
This commit is contained in:
Jose Diaz-Gonzalez
2019-03-13 17:52:09 -04:00
parent 2e895286cf
commit ab88dbb03d
23 changed files with 1471 additions and 0 deletions

6
plugins/resource/.gitignore vendored Normal file
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/commands
/subcommands/*
/triggers/*
/install
/post-delete
/report

37
plugins/resource/Makefile Normal file
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include ../../common.mk
GO_ARGS ?= -a
SUBCOMMANDS = subcommands/limit subcommands/reserve
TRIGGERS = triggers/install triggers/post-delete
build-in-docker: clean
docker run --rm \
-v $$PWD/../..:$(GO_REPO_ROOT) \
-w $(GO_REPO_ROOT)/plugins/resource \
$(BUILD_IMAGE) \
bash -c "GO_ARGS='$(GO_ARGS)' make -j4 build" || exit $$?
build: commands subcommands triggers
$(MAKE) triggers-copy
commands: **/**/commands.go
go build $(GO_ARGS) -o commands src/commands/commands.go
subcommands: $(SUBCOMMANDS)
subcommands/%: src/subcommands/*/%.go
go build $(GO_ARGS) -o $@ $<
clean:
rm -rf commands subcommands triggers install post-delete
src-clean:
rm -rf .gitignore src triggers vendor Makefile *.go
triggers: $(TRIGGERS)
triggers/%: src/triggers/*/%.go
go build $(GO_ARGS) -o $@ $<
triggers-copy:
cp triggers/* .

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package: .
import:
- package: github.com/ryanuber/columnize

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[plugin]
description = "dokku core resource plugin"
version = "0.14.6"
[plugin.config]

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package resource
type Resource struct {
Cpu string `json:"cpu"`
Memory string `json:"memory"`
MemorySwap string `json:"memory-swap"`
Network string `json:"network"`
NetworkIngress string `json:"network-ingress"`
NetworkEgress string `json:"network-egress"`
}
const PluginName = "resource"

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package main
import (
"flag"
"fmt"
"os"
"strconv"
"strings"
"github.com/dokku/dokku/plugins/common"
columnize "github.com/ryanuber/columnize"
)
const (
helpHeader = `Usage: dokku resource[:COMMAND]
Manages resource settings for an app
Additional commands:`
helpContent = `
resource:limit [--process-type process-type] [RESOURCE_OPTS...] <app>, Limit resources for a given app/process-type combination
resource:reserve [--process-type process-type] [RESOURCE_OPTS...] <app>, Reserve resources for a given app/process-type combination
`
)
func main() {
flag.Usage = usage
flag.Parse()
cmd := flag.Arg(0)
switch cmd {
case "resource", "resource:help":
usage()
case "help":
command := common.NewShellCmd(fmt.Sprintf("ps -o command= %d", os.Getppid()))
command.ShowOutput = false
output, err := command.Output()
if err == nil && strings.Contains(string(output), "--all") {
fmt.Println(helpContent)
} else {
fmt.Print("\n resource, Manages resource settings for an app\n")
}
default:
dokkuNotImplementExitCode, err := strconv.Atoi(os.Getenv("DOKKU_NOT_IMPLEMENTED_EXIT"))
if err != nil {
fmt.Println("failed to retrieve DOKKU_NOT_IMPLEMENTED_EXIT environment variable")
dokkuNotImplementExitCode = 10
}
os.Exit(dokkuNotImplementExitCode)
}
}
func usage() {
config := columnize.DefaultConfig()
config.Delim = ","
config.Prefix = " "
config.Empty = ""
content := strings.Split(helpContent, "\n")[1:]
fmt.Println(helpHeader)
fmt.Println(columnize.Format(content, config))
}

6
plugins/resource/src/glide.lock generated Normal file
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hash: 1ddab5de41d1514c2722bd7e24758ad4b60bf6956eb5b9b925fa071a1427f149
updated: 2017-01-03T17:16:50.97156327-08:00
imports:
- name: github.com/ryanuber/columnize
version: 0fbbb3f0e3fbdc5bae7c6cd5f6c1887ebfb76360
testImports: []

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package: .
import:
- package: github.com/ryanuber/columnize

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package main
import (
"flag"
"os"
"github.com/dokku/dokku/plugins/common"
"github.com/dokku/dokku/plugins/resource"
)
func main() {
args := flag.NewFlagSet("resource:limit", flag.ExitOnError)
processeType := args.String("process-type", "", "process-type: A process type to manage")
cpu := args.String("cpu", "", "cpu: The amount of cpu to limit processes by")
memory := args.String("memory", "", "memory: The amount of memory to limit processes by")
memorySwap := args.String("memory-swap", "", "memory-swap: The amount of swap memory to limit processes by")
network := args.String("network", "", "network: The amount of network bandwidth to limit processes by")
networkIngress := args.String("network-ingress", "", "network-ingress: The amount of ingress network bandwidth to limit processes by")
networkEgress := args.String("network-egress", "", "network-egress: The amount of egress network bandwidth to limit processes by")
args.Parse(os.Args[2:])
resources := resource.Resource{
Cpu: *cpu,
Memory: *memory,
MemorySwap: *memorySwap,
Network: *network,
NetworkIngress: *networkIngress,
NetworkEgress: *networkEgress,
}
err := resource.CommandLimit(args.Args(), *processeType, resources)
if err != nil {
common.LogFail(err.Error())
}
}

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package main
import (
"flag"
"os"
"github.com/dokku/dokku/plugins/common"
"github.com/dokku/dokku/plugins/resource"
)
func main() {
args := flag.NewFlagSet("resource:reserve", flag.ExitOnError)
processeType := args.String("process-type", "", "process-type: A process type to manage")
cpu := args.String("cpu", "", "cpu: The amount of cpu to reserve for processes")
memory := args.String("memory", "", "memory: The amount of memory to reserve for processes")
memorySwap := args.String("memory-swap", "", "memory-swap: The amount of swap memory to reserve for processes")
network := args.String("network", "", "network: The amount of network bandwidth to reserve for processes")
networkIngress := args.String("network-ingress", "", "network-ingress: The amount of ingress network bandwidth to reserve for processes")
networkEgress := args.String("network-egress", "", "network-egress: The amount of egress network bandwidth to reserve for processes")
args.Parse(os.Args[2:])
resources := resource.Resource{
Cpu: *cpu,
Memory: *memory,
MemorySwap: *memorySwap,
Network: *network,
NetworkIngress: *networkIngress,
NetworkEgress: *networkEgress,
}
err := resource.CommandReserve(args.Args(), *processeType, resources)
if err != nil {
common.LogFail(err.Error())
}
}

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package main
import (
"fmt"
"github.com/dokku/dokku/plugins/common"
)
// runs the install step for the resource plugin
func main() {
if err := common.PropertySetup("resource"); err != nil {
common.LogFail(fmt.Sprintf("Unable to install the resource plugin: %s", err.Error()))
}
}

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package main
import (
"flag"
"github.com/dokku/dokku/plugins/common"
)
// destroys the resource property for a given app container
func main() {
flag.Parse()
appName := flag.Arg(0)
err := common.PropertyDestroy("resource", appName)
if err != nil {
common.LogFail(err.Error())
}
}

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language: go
go:
- tip

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Copyright (c) 2016 Ryan Uber
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Columnize
=========
Easy column-formatted output for golang
[![Build Status](https://travis-ci.org/ryanuber/columnize.svg)](https://travis-ci.org/ryanuber/columnize)
[![GoDoc](https://godoc.org/github.com/ryanuber/columnize?status.svg)](https://godoc.org/github.com/ryanuber/columnize)
Columnize is a really small Go package that makes building CLI's a little bit
easier. In some CLI designs, you want to output a number similar items in a
human-readable way with nicely aligned columns. However, figuring out how wide
to make each column is a boring problem to solve and eats your valuable time.
Here is an example:
```go
package main
import (
"fmt"
"github.com/ryanuber/columnize"
)
func main() {
output := []string{
"Name | Gender | Age",
"Bob | Male | 38",
"Sally | Female | 26",
}
result := columnize.SimpleFormat(output)
fmt.Println(result)
}
```
As you can see, you just pass in a list of strings. And the result:
```
Name Gender Age
Bob Male 38
Sally Female 26
```
Columnize is tolerant of missing or empty fields, or even empty lines, so
passing in extra lines for spacing should show up as you would expect.
Configuration
=============
Columnize is configured using a `Config`, which can be obtained by calling the
`DefaultConfig()` method. You can then tweak the settings in the resulting
`Config`:
```
config := columnize.DefaultConfig()
config.Delim = "|"
config.Glue = " "
config.Prefix = ""
config.Empty = ""
```
* `Delim` is the string by which columns of **input** are delimited
* `Glue` is the string by which columns of **output** are delimited
* `Prefix` is a string by which each line of **output** is prefixed
* `Empty` is a string used to replace blank values found in output
You can then pass the `Config` in using the `Format` method (signature below) to
have text formatted to your liking.
See the [godoc](https://godoc.org/github.com/ryanuber/columnize) page for usage.

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package columnize
import (
"bytes"
"fmt"
"strings"
)
// Config can be used to tune certain parameters which affect the way
// in which Columnize will format output text.
type Config struct {
// The string by which the lines of input will be split.
Delim string
// The string by which columns of output will be separated.
Glue string
// The string by which columns of output will be prefixed.
Prefix string
// A replacement string to replace empty fields
Empty string
}
// DefaultConfig returns a *Config with default values.
func DefaultConfig() *Config {
return &Config{
Delim: "|",
Glue: " ",
Prefix: "",
Empty: "",
}
}
// MergeConfig merges two config objects together and returns the resulting
// configuration. Values from the right take precedence over the left side.
func MergeConfig(a, b *Config) *Config {
var result Config = *a
// Return quickly if either side was nil
if a == nil || b == nil {
return &result
}
if b.Delim != "" {
result.Delim = b.Delim
}
if b.Glue != "" {
result.Glue = b.Glue
}
if b.Prefix != "" {
result.Prefix = b.Prefix
}
if b.Empty != "" {
result.Empty = b.Empty
}
return &result
}
// stringFormat, given a set of column widths and the number of columns in
// the current line, returns a sprintf-style format string which can be used
// to print output aligned properly with other lines using the same widths set.
func stringFormat(c *Config, widths []int, columns int) string {
// Create the buffer with an estimate of the length
buf := bytes.NewBuffer(make([]byte, 0, (6+len(c.Glue))*columns))
// Start with the prefix, if any was given. The buffer will not return an
// error so it does not need to be handled
buf.WriteString(c.Prefix)
// Create the format string from the discovered widths
for i := 0; i < columns && i < len(widths); i++ {
if i == columns-1 {
buf.WriteString("%s\n")
} else {
fmt.Fprintf(buf, "%%-%ds%s", widths[i], c.Glue)
}
}
return buf.String()
}
// elementsFromLine returns a list of elements, each representing a single
// item which will belong to a column of output.
func elementsFromLine(config *Config, line string) []interface{} {
seperated := strings.Split(line, config.Delim)
elements := make([]interface{}, len(seperated))
for i, field := range seperated {
value := strings.TrimSpace(field)
// Apply the empty value, if configured.
if value == "" && config.Empty != "" {
value = config.Empty
}
elements[i] = value
}
return elements
}
// runeLen calculates the number of visible "characters" in a string
func runeLen(s string) int {
l := 0
for _ = range s {
l++
}
return l
}
// widthsFromLines examines a list of strings and determines how wide each
// column should be considering all of the elements that need to be printed
// within it.
func widthsFromLines(config *Config, lines []string) []int {
widths := make([]int, 0, 8)
for _, line := range lines {
elems := elementsFromLine(config, line)
for i := 0; i < len(elems); i++ {
l := runeLen(elems[i].(string))
if len(widths) <= i {
widths = append(widths, l)
} else if widths[i] < l {
widths[i] = l
}
}
}
return widths
}
// Format is the public-facing interface that takes a list of strings and
// returns nicely aligned column-formatted text.
func Format(lines []string, config *Config) string {
conf := MergeConfig(DefaultConfig(), config)
widths := widthsFromLines(conf, lines)
// Estimate the buffer size
glueSize := len(conf.Glue)
var size int
for _, w := range widths {
size += w + glueSize
}
size *= len(lines)
// Create the buffer
buf := bytes.NewBuffer(make([]byte, 0, size))
// Create a cache for the string formats
fmtCache := make(map[int]string, 16)
// Create the formatted output using the format string
for _, line := range lines {
elems := elementsFromLine(conf, line)
// Get the string format using cache
numElems := len(elems)
stringfmt, ok := fmtCache[numElems]
if !ok {
stringfmt = stringFormat(conf, widths, numElems)
fmtCache[numElems] = stringfmt
}
fmt.Fprintf(buf, stringfmt, elems...)
}
// Get the string result
result := buf.String()
// Remove trailing newline without removing leading/trailing space
if n := len(result); n > 0 && result[n-1] == '\n' {
result = result[:n-1]
}
return result
}
// SimpleFormat is a convenience function to format text with the defaults.
func SimpleFormat(lines []string) string {
return Format(lines, nil)
}

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package columnize
import (
"fmt"
"testing"
crand "crypto/rand"
)
func TestListOfStringsInput(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyLinesOutput(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestLeadingSpacePreserved(t *testing.T) {
input := []string{
"| Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := " Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestColumnWidthCalculator(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"Longer than A | Longer than B | Longer than C",
"short | short | short",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "Longer than A Longer than B Longer than C\n"
expected += "short short short"
if output != expected {
printableProof := fmt.Sprintf("\nGot: %+q", output)
printableProof += fmt.Sprintf("\nExpected: %+q", expected)
t.Fatalf("\n%s", printableProof)
}
}
func TestColumnWidthCalculatorNonASCII(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"⌘⌘⌘⌘⌘⌘⌘⌘ | Longer than B | Longer than C",
"short | short | short",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "⌘⌘⌘⌘⌘⌘⌘⌘ Longer than B Longer than C\n"
expected += "short short short"
if output != expected {
printableProof := fmt.Sprintf("\nGot: %+q", output)
printableProof += fmt.Sprintf("\nExpected: %+q", expected)
t.Fatalf("\n%s", printableProof)
}
}
func BenchmarkColumnWidthCalculator(b *testing.B) {
// Generate the input
input := []string{
"UUID A | UUID B | UUID C | Column D | Column E",
}
format := "%s|%s|%s|%s"
short := "short"
uuid := func() string {
buf := make([]byte, 16)
if _, err := crand.Read(buf); err != nil {
panic(fmt.Errorf("failed to read random bytes: %v", err))
}
return fmt.Sprintf("%08x-%04x-%04x-%04x-%12x",
buf[0:4],
buf[4:6],
buf[6:8],
buf[8:10],
buf[10:16])
}
for i := 0; i < 1000; i++ {
l := fmt.Sprintf(format, uuid()[:8], uuid()[:12], uuid(), short, short)
input = append(input, l)
}
config := DefaultConfig()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Format(input, config)
}
}
func TestVariedInputSpacing(t *testing.T) {
input := []string{
"Column A |Column B| Column C",
"x|y| z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestUnmatchedColumnCounts(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"Value A | Value B",
"Value A | Value B | Value C | Value D",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "Value A Value B\n"
expected += "Value A Value B Value C Value D"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternateDelimiter(t *testing.T) {
input := []string{
"Column | A % Column | B % Column | C",
"Value A % Value B % Value C",
}
config := DefaultConfig()
config.Delim = "%"
output := Format(input, config)
expected := "Column | A Column | B Column | C\n"
expected += "Value A Value B Value C"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternateSpacingString(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
config.Glue = " "
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestSimpleFormat(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
output := SimpleFormat(input)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternatePrefixString(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
config.Prefix = " "
output := Format(input, config)
expected := " Column A Column B Column C\n"
expected += " x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyFieldReplacement(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | | z",
}
config := DefaultConfig()
config.Empty = "<none>"
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x <none> z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyConfigValues(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := Config{}
output := Format(input, &config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestMergeConfig(t *testing.T) {
conf1 := &Config{Delim: "a", Glue: "a", Prefix: "a", Empty: "a"}
conf2 := &Config{Delim: "b", Glue: "b", Prefix: "b", Empty: "b"}
conf3 := &Config{Delim: "c", Prefix: "c"}
m := MergeConfig(conf1, conf2)
if m.Delim != "b" || m.Glue != "b" || m.Prefix != "b" || m.Empty != "b" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, conf3)
if m.Delim != "c" || m.Glue != "a" || m.Prefix != "c" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, nil)
if m.Delim != "a" || m.Glue != "a" || m.Prefix != "a" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, &Config{})
if m.Delim != "a" || m.Glue != "a" || m.Prefix != "a" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
}

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package resource
import (
"errors"
"fmt"
"github.com/dokku/dokku/plugins/common"
)
// CommandLimit implements resource:limit
func CommandLimit(args []string, processType string, r Resource) (err error) {
return setRequestType(args, processType, r, "limit")
}
// CommandReserve implements resource:reserve
func CommandReserve(args []string, processType string, r Resource) (err error) {
return setRequestType(args, processType, r, "reserve")
}
func setRequestType(args []string, processType string, r Resource, requestType string) (err error) {
var appName string
appName, err = getAppName(args)
if err != nil {
return
}
if err = common.VerifyAppName(appName); err != nil {
common.LogFail(err.Error())
}
if len(processType) == 0 {
processType = "_all_"
}
resources := map[string]string{
"cpu": r.Cpu,
"memory": r.Memory,
"memory-swap": r.MemorySwap,
"network": r.Network,
"network-ingress": r.NetworkIngress,
"network-egress": r.NetworkEgress,
}
hasValues := false
for _, value := range resources {
if value != "" {
hasValues = true
}
}
if !hasValues {
return errors.New("Please specify a resource to modify")
}
if requestType == "limit" {
common.LogInfo2Quiet(fmt.Sprintf("Setting resource limits for %v", appName))
} else if requestType == "reserve" {
common.LogInfo2Quiet(fmt.Sprintf("Setting resource reservation for %v", appName))
}
for key, value := range resources {
if value != "" {
common.LogVerbose(fmt.Sprintf("%v: %v", key, value))
}
property := fmt.Sprintf("%v.%v.%v", processType, requestType, key)
err = common.PropertyWrite(PluginName, appName, property, value)
if err != nil {
return
}
}
return
}
func getAppName(args []string) (appName string, err error) {
if len(args) >= 1 {
appName = args[0]
} else {
err = errors.New("Please specify an app to run the command on")
}
return
}

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language: go
go:
- tip

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Copyright (c) 2016 Ryan Uber
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Columnize
=========
Easy column-formatted output for golang
[![Build Status](https://travis-ci.org/ryanuber/columnize.svg)](https://travis-ci.org/ryanuber/columnize)
[![GoDoc](https://godoc.org/github.com/ryanuber/columnize?status.svg)](https://godoc.org/github.com/ryanuber/columnize)
Columnize is a really small Go package that makes building CLI's a little bit
easier. In some CLI designs, you want to output a number similar items in a
human-readable way with nicely aligned columns. However, figuring out how wide
to make each column is a boring problem to solve and eats your valuable time.
Here is an example:
```go
package main
import (
"fmt"
"github.com/ryanuber/columnize"
)
func main() {
output := []string{
"Name | Gender | Age",
"Bob | Male | 38",
"Sally | Female | 26",
}
result := columnize.SimpleFormat(output)
fmt.Println(result)
}
```
As you can see, you just pass in a list of strings. And the result:
```
Name Gender Age
Bob Male 38
Sally Female 26
```
Columnize is tolerant of missing or empty fields, or even empty lines, so
passing in extra lines for spacing should show up as you would expect.
Configuration
=============
Columnize is configured using a `Config`, which can be obtained by calling the
`DefaultConfig()` method. You can then tweak the settings in the resulting
`Config`:
```
config := columnize.DefaultConfig()
config.Delim = "|"
config.Glue = " "
config.Prefix = ""
config.Empty = ""
```
* `Delim` is the string by which columns of **input** are delimited
* `Glue` is the string by which columns of **output** are delimited
* `Prefix` is a string by which each line of **output** is prefixed
* `Empty` is a string used to replace blank values found in output
You can then pass the `Config` in using the `Format` method (signature below) to
have text formatted to your liking.
See the [godoc](https://godoc.org/github.com/ryanuber/columnize) page for usage.

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package columnize
import (
"bytes"
"fmt"
"strings"
)
// Config can be used to tune certain parameters which affect the way
// in which Columnize will format output text.
type Config struct {
// The string by which the lines of input will be split.
Delim string
// The string by which columns of output will be separated.
Glue string
// The string by which columns of output will be prefixed.
Prefix string
// A replacement string to replace empty fields
Empty string
}
// DefaultConfig returns a *Config with default values.
func DefaultConfig() *Config {
return &Config{
Delim: "|",
Glue: " ",
Prefix: "",
Empty: "",
}
}
// MergeConfig merges two config objects together and returns the resulting
// configuration. Values from the right take precedence over the left side.
func MergeConfig(a, b *Config) *Config {
var result Config = *a
// Return quickly if either side was nil
if a == nil || b == nil {
return &result
}
if b.Delim != "" {
result.Delim = b.Delim
}
if b.Glue != "" {
result.Glue = b.Glue
}
if b.Prefix != "" {
result.Prefix = b.Prefix
}
if b.Empty != "" {
result.Empty = b.Empty
}
return &result
}
// stringFormat, given a set of column widths and the number of columns in
// the current line, returns a sprintf-style format string which can be used
// to print output aligned properly with other lines using the same widths set.
func stringFormat(c *Config, widths []int, columns int) string {
// Create the buffer with an estimate of the length
buf := bytes.NewBuffer(make([]byte, 0, (6+len(c.Glue))*columns))
// Start with the prefix, if any was given. The buffer will not return an
// error so it does not need to be handled
buf.WriteString(c.Prefix)
// Create the format string from the discovered widths
for i := 0; i < columns && i < len(widths); i++ {
if i == columns-1 {
buf.WriteString("%s\n")
} else {
fmt.Fprintf(buf, "%%-%ds%s", widths[i], c.Glue)
}
}
return buf.String()
}
// elementsFromLine returns a list of elements, each representing a single
// item which will belong to a column of output.
func elementsFromLine(config *Config, line string) []interface{} {
seperated := strings.Split(line, config.Delim)
elements := make([]interface{}, len(seperated))
for i, field := range seperated {
value := strings.TrimSpace(field)
// Apply the empty value, if configured.
if value == "" && config.Empty != "" {
value = config.Empty
}
elements[i] = value
}
return elements
}
// runeLen calculates the number of visible "characters" in a string
func runeLen(s string) int {
l := 0
for _ = range s {
l++
}
return l
}
// widthsFromLines examines a list of strings and determines how wide each
// column should be considering all of the elements that need to be printed
// within it.
func widthsFromLines(config *Config, lines []string) []int {
widths := make([]int, 0, 8)
for _, line := range lines {
elems := elementsFromLine(config, line)
for i := 0; i < len(elems); i++ {
l := runeLen(elems[i].(string))
if len(widths) <= i {
widths = append(widths, l)
} else if widths[i] < l {
widths[i] = l
}
}
}
return widths
}
// Format is the public-facing interface that takes a list of strings and
// returns nicely aligned column-formatted text.
func Format(lines []string, config *Config) string {
conf := MergeConfig(DefaultConfig(), config)
widths := widthsFromLines(conf, lines)
// Estimate the buffer size
glueSize := len(conf.Glue)
var size int
for _, w := range widths {
size += w + glueSize
}
size *= len(lines)
// Create the buffer
buf := bytes.NewBuffer(make([]byte, 0, size))
// Create a cache for the string formats
fmtCache := make(map[int]string, 16)
// Create the formatted output using the format string
for _, line := range lines {
elems := elementsFromLine(conf, line)
// Get the string format using cache
numElems := len(elems)
stringfmt, ok := fmtCache[numElems]
if !ok {
stringfmt = stringFormat(conf, widths, numElems)
fmtCache[numElems] = stringfmt
}
fmt.Fprintf(buf, stringfmt, elems...)
}
// Get the string result
result := buf.String()
// Remove trailing newline without removing leading/trailing space
if n := len(result); n > 0 && result[n-1] == '\n' {
result = result[:n-1]
}
return result
}
// SimpleFormat is a convenience function to format text with the defaults.
func SimpleFormat(lines []string) string {
return Format(lines, nil)
}

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package columnize
import (
"fmt"
"testing"
crand "crypto/rand"
)
func TestListOfStringsInput(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyLinesOutput(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestLeadingSpacePreserved(t *testing.T) {
input := []string{
"| Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
output := Format(input, config)
expected := " Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestColumnWidthCalculator(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"Longer than A | Longer than B | Longer than C",
"short | short | short",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "Longer than A Longer than B Longer than C\n"
expected += "short short short"
if output != expected {
printableProof := fmt.Sprintf("\nGot: %+q", output)
printableProof += fmt.Sprintf("\nExpected: %+q", expected)
t.Fatalf("\n%s", printableProof)
}
}
func TestColumnWidthCalculatorNonASCII(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"⌘⌘⌘⌘⌘⌘⌘⌘ | Longer than B | Longer than C",
"short | short | short",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "⌘⌘⌘⌘⌘⌘⌘⌘ Longer than B Longer than C\n"
expected += "short short short"
if output != expected {
printableProof := fmt.Sprintf("\nGot: %+q", output)
printableProof += fmt.Sprintf("\nExpected: %+q", expected)
t.Fatalf("\n%s", printableProof)
}
}
func BenchmarkColumnWidthCalculator(b *testing.B) {
// Generate the input
input := []string{
"UUID A | UUID B | UUID C | Column D | Column E",
}
format := "%s|%s|%s|%s"
short := "short"
uuid := func() string {
buf := make([]byte, 16)
if _, err := crand.Read(buf); err != nil {
panic(fmt.Errorf("failed to read random bytes: %v", err))
}
return fmt.Sprintf("%08x-%04x-%04x-%04x-%12x",
buf[0:4],
buf[4:6],
buf[6:8],
buf[8:10],
buf[10:16])
}
for i := 0; i < 1000; i++ {
l := fmt.Sprintf(format, uuid()[:8], uuid()[:12], uuid(), short, short)
input = append(input, l)
}
config := DefaultConfig()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Format(input, config)
}
}
func TestVariedInputSpacing(t *testing.T) {
input := []string{
"Column A |Column B| Column C",
"x|y| z",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestUnmatchedColumnCounts(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"Value A | Value B",
"Value A | Value B | Value C | Value D",
}
config := DefaultConfig()
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "Value A Value B\n"
expected += "Value A Value B Value C Value D"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternateDelimiter(t *testing.T) {
input := []string{
"Column | A % Column | B % Column | C",
"Value A % Value B % Value C",
}
config := DefaultConfig()
config.Delim = "%"
output := Format(input, config)
expected := "Column | A Column | B Column | C\n"
expected += "Value A Value B Value C"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternateSpacingString(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
config.Glue = " "
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestSimpleFormat(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
output := SimpleFormat(input)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestAlternatePrefixString(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := DefaultConfig()
config.Prefix = " "
output := Format(input, config)
expected := " Column A Column B Column C\n"
expected += " x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyFieldReplacement(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | | z",
}
config := DefaultConfig()
config.Empty = "<none>"
output := Format(input, config)
expected := "Column A Column B Column C\n"
expected += "x <none> z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestEmptyConfigValues(t *testing.T) {
input := []string{
"Column A | Column B | Column C",
"x | y | z",
}
config := Config{}
output := Format(input, &config)
expected := "Column A Column B Column C\n"
expected += "x y z"
if output != expected {
t.Fatalf("\nexpected:\n%s\n\ngot:\n%s", expected, output)
}
}
func TestMergeConfig(t *testing.T) {
conf1 := &Config{Delim: "a", Glue: "a", Prefix: "a", Empty: "a"}
conf2 := &Config{Delim: "b", Glue: "b", Prefix: "b", Empty: "b"}
conf3 := &Config{Delim: "c", Prefix: "c"}
m := MergeConfig(conf1, conf2)
if m.Delim != "b" || m.Glue != "b" || m.Prefix != "b" || m.Empty != "b" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, conf3)
if m.Delim != "c" || m.Glue != "a" || m.Prefix != "c" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, nil)
if m.Delim != "a" || m.Glue != "a" || m.Prefix != "a" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
m = MergeConfig(conf1, &Config{})
if m.Delim != "a" || m.Glue != "a" || m.Prefix != "a" || m.Empty != "a" {
t.Fatalf("bad: %#v", m)
}
}