bs

---

---

---

BS IS DEPRECATED

This project has been renamed to bsh and moved to danbrakeley/bsh. This depot will get no further updates.

bsh removes all global state, and replaces it with the Bsh struct, which allows for mulitple concurrent Bsh instances, where each one can override error handling or Stdin/out/err routing as needed.

Otherwise, the API and functionality of bsh is pretty much identical to bs.

---

---

---

Overview

bs is a package to streamline building bash-like scripts.

The original intended use was inside a Magefile, but there's nothing stopping you from using this in a regular Go app.

Features include:

• Echo/Warn/Verbose for outputting lines
  • Verbose defaults to only printing if MAGEFILE_VERBOSE is set to true (mirroring how Mage's mg.Verbose() works), but the specific env var that is checked can be changed by calling SetVerboseEnvVarName.
• ANSI color support (which respects NO_COLOR env var)
• Protect secrets from being visible on-screen or in logs via PushEchoFilter/PopEchoFilter
• Read files to strings (or []byte)
• Write or Append strings (or []byte) to files
• Run commands via bash-like parsing of arguments, with support for redirecting stdin/out/err
• Command variants that can return stdout as string, exit code as int, or Go error
• Common File/Folder helpers, like Exists, IsFile, IsDir, Getwd, Chdir, Mkdir, MkdirAll, Remove, RemoveAll, etc
• Global error handler that allows most bs commands to not require exlicit error handling
  • This mimics bash's set -e, where any error results in a panic
  • The default "panic" behavior is overridable via a call to SetErrorHandler.

Example

I've got an example magefile below, but first, here's what the output looks like:

And then here's that same output, but with mage's "verbose" flag set:

And here's the corresponding magefile.go:

// +build mage

package main

import (
  "fmt"
  "regexp"
  "strings"

  "github.com/danbrakeley/bs"
  "github.com/magefile/mage/mg"
)

// BUILD COMMANDS

// Builds ardentd into the "local" folder.
func Build() {
  target := bs.ExeName("ardentd")

  bs.Echo("Running tests...")
  bs.Cmd("go test ./...").Run()

  bs.Echof("Building %s...", target)
  bs.MkdirAll("local/")
  bs.Cmdf("go build -o local/%s ./cmd/ardentd", target).Run()
}

// Removes all artifacts from previous builds.
// At the moment, this is accomplished by deleting the "local" folder.
func Clean() {
  bs.Echo("Deleting local...")
  bs.RemoveAll("local")
}

// Runs ardentd.
func Run() {
  mg.Deps(Build)

  target := bs.ExeName("ardentd")
  password := pgGetPass()
  bs.PushEchoFilter(password)
  defer bs.PopEchoFilter()
  pgURL := fmt.Sprintf("postgres://%s:%s@localhost:%s/%s?sslmode=disable", PG_USERNAME, password, PG_PORT, PG_DBNAME)

  bs.Chdir("local")
  bs.Echo("Running...")
  bs.Cmdf("%s", target).Env(
    "ARDENT_HOST=127.0.0.1:8080",
    "ARDENT_PGURL="+pgURL,
    "ARDENT_VERBOSE=true",
  ).Run()
}

// POSTGRES COMMANDS

// Passes command to Postgres: help, start, stop, destroy
func PG(cmd string) {
  cmd = strings.ToLower(cmd)
  switch cmd {
  case "start":
    pgStart()
  case "stop":
    pgStop()
  case "destroy":
    pgDestroy()
  case "psql":
    pgPsql()
  default:
    if cmd != "help" {
      bs.Warnf(`Unrecognized command "%s"`, cmd)
    }
    bs.Echo("pg start   - Starts the postgres docker container. If the container didn't previously exist, it is created.")
    bs.Echo("pg stop    - Stops the postgres docker container.")
    bs.Echo("pg destroy - Destroys the postgres docker container (including data).")
    bs.Echo("pg psql    - Starts psql interactive shell against running postgres db.")
  }
}

const (
  PG_DOCKER_IMAGE   = "postgres:13-alpine"
  PG_CONTAINER_NAME = "psql-ardent"
  PG_DBNAME         = "ardent"
  PG_USERNAME       = "super"
  PG_PASS_FILE      = "pg.pass.local"
  PG_PORT           = "5444"
)

func pgStart() {
  existingContainer := bs.Cmd(`docker ps --filter "name=` + PG_CONTAINER_NAME + `" -q -a`).RunStr()
  if len(existingContainer) > 0 {
    bs.Cmd("docker start " + PG_CONTAINER_NAME).OutErr(nil).Run()
  } else {
    if !bs.Exists(PG_PASS_FILE) {
      bs.Warnf(`Please create a file named "%s" that contains the database password.`, PG_PASS_FILE)
      return
    }
    pgpass := pgGetPass()
    bs.PushEchoFilter(pgpass)
    defer bs.PopEchoFilter()
    bs.Cmd(
      "docker run --name " + PG_CONTAINER_NAME +
        " -e POSTGRES_PASSWORD=" + pgpass +
        " -e POSTGRES_USER=" + PG_USERNAME +
        " -e POSTGRES_DB=" + PG_DBNAME +
        " --publish " + PG_PORT + ":5432" +
        " --detach " + PG_DOCKER_IMAGE,
    ).Run()
  }

  bs.Cmd(`docker ps --filter "name=` + PG_CONTAINER_NAME + `" -a`).Run()
}

func pgStop() {
  bs.Cmd("docker stop " + PG_CONTAINER_NAME).OutErr(nil).Run()
  bs.Cmd(`docker ps --filter "name=` + PG_CONTAINER_NAME + `" -a`).Run()
}

func pgDestroy() {
  deletePhrase := bs.Ask(`This will delete all data. To continue, type "i've been warned" (without quotes): `)
  if deletePhrase == "i've been warned" {
    bs.Cmd("docker stop " + PG_CONTAINER_NAME).OutErr(nil).Run()
    bs.Cmd("docker rm " + PG_CONTAINER_NAME).OutErr(nil).Run()
  } else {
    bs.Warnf(`You typed "%s", which was not what was asked for, so nothing was deleted.`, deletePhrase)
  }
}

func pgPsql() {
  pgpass := pgGetPass()
  bs.PushEchoFilter(pgpass)
  defer bs.PopEchoFilter()
  bs.Cmdf(
    `docker exec -it --env PGPASSWORD=%s %s psql -h localhost -d %s -U %s`,
    pgpass, PG_CONTAINER_NAME, PG_DBNAME, PG_USERNAME,
  ).Run()
}

// GOOSE COMMANDS

// Calls "goose {cmd}", where {cmd} is one of: status, up, up-by-one, down, redo, reset, or version
func Goose(cmd string) {
  password := pgGetPass()
  bs.PushEchoFilter(password)
  defer bs.PopEchoFilter()
  bs.Cmdf("goose -dir sql %s", cmd).Env("GOOSE_DRIVER=postgres", "GOOSE_DBSTRING="+pgDSN(password)).Run()
}

// helpers

var regexpPassword = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)

func pgGetPass() string {
  str := strings.TrimSpace(strings.Split(bs.Read(PG_PASS_FILE), "\n")[0])
  if !regexpPassword.MatchString(str) {
    panic(fmt.Errorf(`Password is only allowed alphanumerics and underscores. Please change "%s" by hand to fix.`, PG_PASS_FILE))
  }
  return str
}

func pgDSN(password string) string {
  return fmt.Sprintf(
    "host=localhost port=%s user=%s password=%s dbname=%s sslmode=disable",
    PG_PORT, PG_USERNAME, password, PG_DBNAME,
  )
}