commit 9a6d76b529ebc6bcfc98b2c9098485dbcc326f8e Author: Knut Ahlers Date: Thu Oct 18 23:19:20 2018 +0200 Initial version diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..1193305 --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +waitfor diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..e31d023 --- /dev/null +++ b/LICENSE @@ -0,0 +1,202 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. 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We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + + Copyright 2018- Knut Ahlers + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + diff --git a/README.md b/README.md new file mode 100644 index 0000000..3199082 --- /dev/null +++ b/README.md @@ -0,0 +1,43 @@ +[![Go Report Card](https://goreportcard.com/badge/github.com/Luzifer/waitfor)](https://goreportcard.com/report/github.com/Luzifer/waitfor) +![](https://badges.fyi/github/license/Luzifer/waitfor) +![](https://badges.fyi/github/downloads/Luzifer/waitfor) +![](https://badges.fyi/github/latest-release/Luzifer/waitfor) + +# Luzifer / waitfor + +`waitfor` is a small utility to check the exit code of an command to be used within a shell command. + +## Usage + +```console +$ waitfor --help +Usage of waitfor: + -i, --check-interval duration How long to wait after an unsuccessful check (default 1s) + -c, --command-timeout duration Stop the command execution after this time + --log-level string Log level (debug, info, warn, error, fatal) (default "info") + -s, --shell string Shell to execute with the given command (must accept -c flag) (default "/bin/bash") + --version Prints current version and exits + -w, --wait-timeout duration Stop waiting for the command after this time +``` + +When a `wait-timeout` is specified and the check command did not exit with status code 0 before the timeout is reached `waitfor` will exit with status 1. This ensures a shell command connected with `&&` is not executed afterwards. + +## Examples + +- Wait for the VPN connection to be available before executing a command using it + + ```console + $ waitfor 'ip a | grep 10.123.0' && echo "VPN connected" + ``` + +- Ensure you are online before executing a curl command + + ```console + $ waitfor -- ping -c 1 8.8.8.8 && curl ... + ``` + +- Wait at most 5m for a file to appear before accessing it + + ```console + $ waitfor -w 5m -- ls myfile && cat myfile + ``` diff --git a/main.go b/main.go new file mode 100644 index 0000000..b9b9b96 --- /dev/null +++ b/main.go @@ -0,0 +1,93 @@ +package main + +import ( + "context" + "fmt" + "os" + "os/exec" + "strings" + "time" + + "github.com/pkg/errors" + log "github.com/sirupsen/logrus" + + "github.com/Luzifer/rconfig" +) + +var ( + cfg = struct { + CheckInterval time.Duration `flag:"check-interval,i" default:"1s" description:"How long to wait after an unsuccessful check"` + CommandTimeout time.Duration `flag:"command-timeout,c" default:"0" description:"Stop the command execution after this time"` + LogLevel string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"` + Shell string `flag:"shell,s" default:"/bin/bash" description:"Shell to execute with the given command (must accept -c flag)"` + WaitTimeout time.Duration `flag:"wait-timeout,w" default:"0" description:"Stop waiting for the command after this time"` + VersionAndExit bool `flag:"version" default:"false" description:"Prints current version and exits"` + }{} + + version = "dev" +) + +func init() { + if err := rconfig.ParseAndValidate(&cfg); err != nil { + log.Fatalf("Unable to parse commandline options: %s", err) + } + + if cfg.VersionAndExit { + fmt.Printf("waitfor %s\n", version) + os.Exit(0) + } + + if l, err := log.ParseLevel(cfg.LogLevel); err != nil { + log.WithError(err).Fatal("Unable to parse log level") + } else { + log.SetLevel(l) + } +} + +func main() { + started := time.Now() + + for { + if err := executeCommand(rconfig.Args()[1:]); err == nil { + break + } else { + log.WithField("error", err.Error()).Debug("Command was not successful") + } + + if cfg.WaitTimeout > 0 && started.Add(cfg.WaitTimeout).Before(time.Now()) { + log.WithField("timeout", cfg.WaitTimeout).Fatal("Wait timed out") + } + + time.Sleep(cfg.CheckInterval) + } + + log.Info("Command exited successful") +} + +func executeCommand(cmdStr []string) error { + cmd := exec.Command(cfg.Shell, "-c", strings.Join(cmdStr, " ")) + + var ( + c = make(chan error, 1) + ctx = context.Background() + cancel context.CancelFunc = func() {} + ) + if cfg.CommandTimeout > 0 { + ctx, cancel = context.WithTimeout(context.Background(), cfg.CommandTimeout) + } + + go func() { + c <- cmd.Run() + }() + + for { + select { + case <-ctx.Done(): + cmd.Process.Kill() + return errors.New("Command execution timed out") + case err := <-c: + cancel() + return err + } + } +}