Make sure port is actually free and show what port was used.

This commit is contained in:
trading_peter 2024-09-11 11:14:27 +02:00
parent e276649fc5
commit e7ed0407a3
6 changed files with 255 additions and 102 deletions

View File

@ -0,0 +1,64 @@
package commands
import (
"context"
"fmt"
"hoster/internals/conf"
"io/fs"
"path/filepath"
"strings"
dc "github.com/compose-spec/compose-go/v2/cli"
"github.com/urfave/cli/v2"
)
func CmdCheckUpdated(c *cli.Context) error {
projectRoot := conf.App.MustString("projects.root")
composeFiles := []string{}
// Find compose files recursively
err := filepath.WalkDir(projectRoot, func(path string, d fs.DirEntry, err error) error {
if err != nil {
// Ignore errors on purpose.
return nil
}
if d.IsDir() {
return nil
}
fileName := d.Name()
if strings.HasPrefix(fileName, "docker-compose") && (strings.HasSuffix(fileName, ".yml") || strings.HasSuffix(fileName, ".yaml")) {
composeFiles = append(composeFiles, path)
}
return nil
})
if err != nil {
return err
}
composeFilePath := composeFiles[0]
options, err := dc.NewProjectOptions(
[]string{composeFilePath},
)
if err != nil {
return err
}
project, err := dc.ProjectFromOptions(context.Background(), options)
if err != nil {
return err
}
for srvName, srv := range project.AllServices() {
fmt.Printf("%s => %s\n", srvName, srv.Image)
}
return nil
}

View File

@ -0,0 +1,117 @@
package commands
import (
"fmt"
"hoster/internals/conf"
"hoster/internals/helpers"
"hoster/internals/templates"
"hoster/internals/types"
"os"
"path/filepath"
"slices"
"github.com/gookit/goutil/fsutil"
"github.com/gookit/goutil/sysutil/cmdr"
"github.com/kataras/golog"
"github.com/urfave/cli/v2"
)
func CmdNew(c *cli.Context) error {
name := c.String("name")
domain := c.String("domain")
projectRoot := conf.App.MustString("projects.root")
sitesAvail := conf.App.MustString("nginx.sitesAvailable")
sitesEnabled := conf.App.MustString("nginx.sitesEnabled")
nginxFile := filepath.Join(sitesAvail, name)
projectFolder := filepath.Join(projectRoot, name)
existingProjects, err := helpers.FindHostConfigs(sitesAvail)
if err != nil {
return err
}
usedPorts := []int{}
for _, project := range existingProjects {
usedPorts = append(usedPorts, project.InternalPort)
}
port := conf.App.Int("nginx.portRangeStart")
freePort := 0
for port <= conf.App.Int("nginx.portRangeEnd") {
if !slices.Contains(usedPorts, port) && helpers.IsFreePort(port) {
freePort = port
break
}
port++
}
if freePort == 0 {
return fmt.Errorf("no free port available")
}
if !fsutil.IsDir(projectFolder) {
golog.Infof("Creating project folder '%s'", projectFolder)
err := os.MkdirAll(projectFolder, 0755)
if err != nil {
return err
}
}
if fsutil.IsFile(nginxFile) {
return fmt.Errorf("the nginx config file '%s' already exists", nginxFile)
}
// Set owner and group of project folder
err = os.Chown(projectFolder, conf.App.Int("projects.owner"), conf.App.Int("projects.group"))
if err != nil {
return err
}
project := types.Project{
Name: name,
Domain: domain,
InternalPort: freePort,
}
// Create nginx config file
err = templates.Execute("nginx", nginxFile, project)
if err != nil {
return err
}
// Symlink nginx config file
err = os.Symlink(nginxFile, filepath.Join(sitesEnabled, name))
if err != nil {
return err
}
// Execute certbot command: "systemctl stop nginx && sudo certbot certonly --standalone --preferred-challenges http -d {domain} && sudo systemctl start nginx"
com := cmdr.NewCmd("systemctl").
WithArgs([]string{"stop", "nginx"})
_, err = com.Output()
if err != nil {
return err
}
com = cmdr.NewCmd("certbot").
WithArgs([]string{"certonly", "--standalone", "--preferred-challenges", "http", "-d", domain})
_, err = com.Output()
if err != nil {
return err
}
com = cmdr.NewCmd("systemctl").
WithArgs([]string{"start", "nginx"})
_, err = com.Output()
if err != nil {
return err
}
golog.Infof("Project successfully '%s' created. Uses port %d.", name, freePort)
return nil
}

View File

@ -1,19 +1,12 @@
package main
import (
"fmt"
"hoster/cmd/hoster_cli/commands"
"hoster/internals/conf"
"hoster/internals/helpers"
"hoster/internals/templates"
"hoster/internals/types"
"os"
"path/filepath"
"github.com/gookit/goutil/fsutil"
"github.com/gookit/goutil/sysutil/cmdr"
"github.com/kataras/golog"
"github.com/urfave/cli/v2"
"golang.org/x/exp/slices"
)
func main() {
@ -22,7 +15,7 @@ func main() {
app := &cli.App{
Name: "hoster",
Usage: "Hoster",
Version: "1.0.0",
Version: "1.0.1",
Commands: []*cli.Command{
{
Name: "new",
@ -41,96 +34,12 @@ func main() {
Required: true,
},
},
Action: func(c *cli.Context) error {
name := c.String("name")
domain := c.String("domain")
projectRoot := conf.App.MustString("projects.root")
sitesAvail := conf.App.MustString("nginx.sitesAvailable")
sitesEnabled := conf.App.MustString("nginx.sitesEnabled")
nginxFile := filepath.Join(sitesAvail, name)
projectFolder := filepath.Join(projectRoot, name)
existingProjects, err := helpers.FindHostConfigs(sitesAvail)
if err != nil {
return err
}
usedPorts := []int{}
for _, project := range existingProjects {
usedPorts = append(usedPorts, project.InternalPort)
}
port := conf.App.Int("nginx.portRangeStart")
freePort := 0
for port <= conf.App.Int("nginx.portRangeEnd") {
if !slices.Contains(usedPorts, port) {
freePort = port
break
}
port++
}
if freePort == 0 {
return fmt.Errorf("no free port available")
}
if !fsutil.IsDir(projectFolder) {
golog.Infof("Creating project folder '%s'", projectFolder)
err := os.MkdirAll(projectFolder, 0755)
if err != nil {
return err
}
}
if fsutil.IsFile(nginxFile) {
return fmt.Errorf("the nginx config file '%s' already exists", nginxFile)
}
// Set owner and group of project folder
err = os.Chown(projectFolder, conf.App.Int("projects.owner"), conf.App.Int("projects.group"))
if err != nil {
return err
}
project := types.Project{
Name: name,
Domain: domain,
InternalPort: freePort,
}
// Create nginx config file
err = templates.Execute("nginx", nginxFile, project)
if err != nil {
return err
}
// Symlink nginx config file
err = os.Symlink(nginxFile, filepath.Join(sitesEnabled, name))
if err != nil {
return err
}
// Execute certbot command: "systemctl stop nginx && sudo certbot certonly --standalone --preferred-challenges http -d {domain} && sudo systemctl start nginx"
com := cmdr.NewCmd("systemctl").
WithArgs([]string{"stop", "nginx"})
out := com.SafeOutput()
fmt.Println(out)
com = cmdr.NewCmd("certbot").
WithArgs([]string{"certonly", "--standalone", "--preferred-challenges", "http", "-d", domain})
out = com.SafeOutput()
fmt.Println(out)
com = cmdr.NewCmd("systemctl").
WithArgs([]string{"start", "nginx"})
out = com.SafeOutput()
fmt.Println(out)
return nil
},
Action: commands.CmdNew,
},
{
Name: "check",
Usage: "Check if newer versions of docker images are available",
Action: commands.CmdCheckUpdated,
},
},
}

14
go.mod
View File

@ -3,29 +3,41 @@ module hoster
go 1.23.0
require (
github.com/compose-spec/compose-go/v2 v2.1.6
github.com/gookit/config/v2 v2.2.5
github.com/gookit/goutil v0.6.16
github.com/kataras/golog v0.1.12
github.com/urfave/cli/v2 v2.27.4
golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561
)
require (
dario.cat/mergo v1.0.0 // indirect
github.com/cpuguy83/go-md2man/v2 v2.0.4 // indirect
github.com/distribution/reference v0.5.0 // indirect
github.com/docker/go-connections v0.4.0 // indirect
github.com/docker/go-units v0.5.0 // indirect
github.com/fatih/color v1.14.1 // indirect
github.com/go-viper/mapstructure/v2 v2.0.0 // indirect
github.com/goccy/go-yaml v1.11.2 // indirect
github.com/gookit/color v1.5.4 // indirect
github.com/kataras/pio v0.0.13 // indirect
github.com/mattn/go-colorable v0.1.13 // indirect
github.com/mattn/go-isatty v0.0.17 // indirect
github.com/mattn/go-shellwords v1.0.12 // indirect
github.com/mitchellh/mapstructure v1.5.0 // indirect
github.com/opencontainers/go-digest v1.0.0 // indirect
github.com/russross/blackfriday/v2 v2.1.0 // indirect
github.com/sirupsen/logrus v1.9.0 // indirect
github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f // indirect
github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
github.com/xeipuuv/gojsonschema v1.2.0 // indirect
github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
golang.org/x/exp v0.0.0-20240112132812-db7319d0e0e3 // indirect
golang.org/x/sync v0.7.0 // indirect
golang.org/x/sys v0.22.0 // indirect
golang.org/x/term v0.22.0 // indirect
golang.org/x/text v0.16.0 // indirect
golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
gopkg.in/yaml.v3 v3.0.1 // indirect
)

35
go.sum
View File

@ -1,9 +1,18 @@
dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
github.com/compose-spec/compose-go/v2 v2.1.6 h1:d0Cs0DffmOwmSzs0YPHwKCskknGq2jfGg4uGowlEpps=
github.com/compose-spec/compose-go/v2 v2.1.6/go.mod h1:lFN0DrMxIncJGYAXTfWuajfwj5haBJqrBkarHcnjJKc=
github.com/cpuguy83/go-md2man/v2 v2.0.4 h1:wfIWP927BUkWJb2NmU/kNDYIBTh/ziUX91+lVfRxZq4=
github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/distribution/reference v0.5.0 h1:/FUIFXtfc/x2gpa5/VGfiGLuOIdYa1t65IKK2OFGvA0=
github.com/distribution/reference v0.5.0/go.mod h1:BbU0aIcezP1/5jX/8MP0YiH4SdvB5Y4f/wlDRiLyi3E=
github.com/docker/go-connections v0.4.0 h1:El9xVISelRB7BuFusrZozjnkIM5YnzCViNKohAFqRJQ=
github.com/docker/go-connections v0.4.0/go.mod h1:Gbd7IOopHjR8Iph03tsViu4nIes5XhDvyHbTtUxmeec=
github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
github.com/fatih/color v1.14.1 h1:qfhVLaG5s+nCROl1zJsZRxFeYrHLqWroPOQ8BWiNb4w=
github.com/fatih/color v1.14.1/go.mod h1:2oHN61fhTpgcxD3TSWCgKDiH1+x4OiDVVGH8WlgGZGg=
github.com/go-playground/locales v0.13.0 h1:HyWk6mgj5qFqCT5fjGBuRArbVDfE4hi8+e8ceBS/t7Q=
@ -12,6 +21,8 @@ github.com/go-playground/universal-translator v0.17.0 h1:icxd5fm+REJzpZx7ZfpaD87
github.com/go-playground/universal-translator v0.17.0/go.mod h1:UkSxE5sNxxRwHyU+Scu5vgOQjsIJAF8j9muTVoKLVtA=
github.com/go-playground/validator/v10 v10.4.1 h1:pH2c5ADXtd66mxoE0Zm9SUhxE20r7aM3F26W0hOn+GE=
github.com/go-playground/validator/v10 v10.4.1/go.mod h1:nlOn6nFhuKACm19sB/8EGNn9GlaMV7XkbRSipzJ0Ii4=
github.com/go-viper/mapstructure/v2 v2.0.0 h1:dhn8MZ1gZ0mzeodTG3jt5Vj/o87xZKuNAprG2mQfMfc=
github.com/go-viper/mapstructure/v2 v2.0.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
github.com/goccy/go-yaml v1.11.2 h1:joq77SxuyIs9zzxEjgyLBugMQ9NEgTWxXfz2wVqwAaQ=
github.com/goccy/go-yaml v1.11.2/go.mod h1:wKnAMd44+9JAAnGQpWVEgBzGt3YuTaQ4uXoHvE4m7WU=
github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
@ -35,26 +46,42 @@ github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovk
github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
github.com/mattn/go-isatty v0.0.17 h1:BTarxUcIeDqL27Mc+vyvdWYSL28zpIhv3RoTdsLMPng=
github.com/mattn/go-isatty v0.0.17/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
github.com/mattn/go-shellwords v1.0.12 h1:M2zGm7EW6UQJvDeQxo4T51eKPurbeFbe8WtebGE2xrk=
github.com/mattn/go-shellwords v1.0.12/go.mod h1:EZzvwXDESEeg03EKmM+RmDnNOPKG4lLtQsUlTZDWQ8Y=
github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8Oi/yOhh5U=
github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
github.com/sirupsen/logrus v1.9.0 h1:trlNQbNUG3OdDrDil03MCb1H2o9nJ1x4/5LYw7byDE0=
github.com/sirupsen/logrus v1.9.0/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
github.com/urfave/cli/v2 v2.27.4 h1:o1owoI+02Eb+K107p27wEX9Bb8eqIoZCfLXloLUSWJ8=
github.com/urfave/cli/v2 v2.27.4/go.mod h1:m4QzxcD2qpra4z7WhzEGn74WZLViBnMpb1ToCAKdGRQ=
github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f h1:J9EGpcZtP0E/raorCMxlFGSTBrsSlaDGf3jU/qvAE2c=
github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=
github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 h1:EzJWgHovont7NscjpAxXsDA8S8BMYve8Y5+7cuRE7R0=
github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415/go.mod h1:GwrjFmJcFw6At/Gs6z4yjiIwzuJ1/+UwLxMQDVQXShQ=
github.com/xeipuuv/gojsonschema v1.2.0 h1:LhYJRs+L4fBtjZUfuSZIKGeVu0QRy8e5Xi7D17UxZ74=
github.com/xeipuuv/gojsonschema v1.2.0/go.mod h1:anYRn/JVcOK2ZgGU+IjEV4nwlhoK5sQluxsYJ78Id3Y=
github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavMF/ppJZNG9ZpyihvCd0w101no=
github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=
github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=
golang.org/x/crypto v0.7.0 h1:AvwMYaRytfdeVt3u6mLaxYtErKYjxA2OXjJ1HHq6t3A=
golang.org/x/crypto v0.7.0/go.mod h1:pYwdfH91IfpZVANVyUOhSIPZaFoJGxTFbZhFTx+dXZU=
golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561 h1:MDc5xs78ZrZr3HMQugiXOAkSZtfTpbJLDr/lwfgO53E=
golang.org/x/exp v0.0.0-20220909182711-5c715a9e8561/go.mod h1:cyybsKvd6eL0RnXn6p/Grxp8F5bW7iYuBgsNCOHpMYE=
golang.org/x/exp v0.0.0-20240112132812-db7319d0e0e3 h1:hNQpMuAJe5CtcUqCXaWga3FHu+kQvCqcsoVaQgSV60o=
golang.org/x/exp v0.0.0-20240112132812-db7319d0e0e3/go.mod h1:idGWGoKP1toJGkd5/ig9ZLuPcZBC3ewk7SzmH0uou08=
golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
@ -64,6 +91,10 @@ golang.org/x/text v0.16.0 h1:a94ExnEXNtEwYLGJSIUxnWoxoRz/ZcCsV63ROupILh4=
golang.org/x/text v0.16.0/go.mod h1:GhwF1Be+LQoKShO3cGOHzqOgRrGaYc9AvblQOmPVHnI=
golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 h1:H2TDz8ibqkAF6YGhCdN3jS9O0/s90v0rJh3X/OLHEUk=
golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2/go.mod h1:K8+ghG5WaK9qNqU5K3HdILfMLy1f3aNYFI/wnl100a8=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
gotest.tools/v3 v3.4.0 h1:ZazjZUfuVeZGLAmlKKuyv3IKP5orXcwtOwDQH6YVr6o=
gotest.tools/v3 v3.4.0/go.mod h1:CtbdzLSsqVhDgMtKsx03ird5YTGB3ar27v0u/yKBW5g=

20
internals/helpers/port.go Normal file
View File

@ -0,0 +1,20 @@
package helpers
import (
"fmt"
"net"
)
func IsFreePort(port int) bool {
addr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("localhost:%d", port))
if err != nil {
return false
}
l, err := net.ListenTCP("tcp", addr)
if err != nil {
return false
}
defer l.Close()
return true
}