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env.go
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env.go
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// Copyright 2016 The Cockroach Authors.
//
// 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.
package envutil
import (
"bytes"
"fmt"
"os"
"os/user"
"runtime"
"strconv"
"strings"
"time"
"github.com/cockroachdb/cockroach/pkg/util/humanizeutil"
"github.com/cockroachdb/cockroach/pkg/util/syncutil"
)
type envVarInfo struct {
consumer string
present bool
value string
}
var envVarRegistry struct {
mu syncutil.Mutex
cache map[string]envVarInfo
}
func init() {
ClearEnvCache()
}
func checkVarName(name string) {
// Env vars must:
// - start with COCKROACH_
// - be uppercase
// - only contain letters, digits, and _
valid := strings.HasPrefix(name, "COCKROACH_")
for i := 0; valid && i < len(name); i++ {
c := name[i]
valid = ((c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_')
}
if !valid {
panic("invalid env var name " + name)
}
}
// getEnv retrieves an environment variable, keeps track of where
// it was accessed, and checks that each environment variable is accessed
// from at most one place.
// The bookkeeping enables a report of all influential environment
// variables with "cockroach debug env". To keep this report useful,
// all relevant environment variables should be read during start up.
func getEnv(varName string, depth int) (string, bool) {
_, consumer, _, _ := runtime.Caller(depth + 1)
checkVarName(varName)
envVarRegistry.mu.Lock()
defer envVarRegistry.mu.Unlock()
if f, ok := envVarRegistry.cache[varName]; ok {
if f.consumer != consumer {
panic("environment variable " + varName + " already used from " + f.consumer)
}
return f.value, f.present
}
v, found := os.LookupEnv(varName)
envVarRegistry.cache[varName] = envVarInfo{consumer: consumer, present: found, value: v}
return v, found
}
// ClearEnvCache clears saved environment values so that
// a new read access the environment again. (Used for testing)
func ClearEnvCache() {
envVarRegistry.mu.Lock()
defer envVarRegistry.mu.Unlock()
envVarRegistry.cache = make(map[string]envVarInfo)
}
// GetEnvReport dumps all configuration variables that may have been
// used and their value.
func GetEnvReport() string {
envVarRegistry.mu.Lock()
defer envVarRegistry.mu.Unlock()
var b bytes.Buffer
for k, v := range envVarRegistry.cache {
if v.present {
fmt.Fprintf(&b, "%s = %s # %s\n", k, v.value, v.consumer)
} else {
fmt.Fprintf(&b, "# %s is not set (read from %s)\n", k, v.consumer)
}
}
return b.String()
}
// GetEnvVarsUsed returns the names of all environment variables that
// may have been used.
func GetEnvVarsUsed() []string {
envVarRegistry.mu.Lock()
defer envVarRegistry.mu.Unlock()
var vars []string
for k, v := range envVarRegistry.cache {
if v.present {
vars = append(vars, k+"="+os.Getenv(k))
}
}
for _, name := range []string{"GOGC", "GODEBUG", "GOMAXPROCS", "GOTRACEBACK"} {
if val, ok := os.LookupEnv(name); ok {
vars = append(vars, name+"="+val)
}
}
return vars
}
// GetShellCommand returns a complete command to run with a prefix of the command line.
func GetShellCommand(cmd string) []string {
if runtime.GOOS == "windows" {
if shell := os.Getenv("COMSPEC"); len(shell) > 0 {
return []string{shell, "/C", cmd}
}
return []string{`C:\Windows\system32\cmd.exe`, "/C", cmd}
}
if shell := os.Getenv("SHELL"); len(shell) > 0 {
return []string{shell, "-c", cmd}
}
return []string{"/bin/sh", "-c", cmd}
}
// HomeDir returns the user's home directory, as determined by the env
// var HOME, if it exists, and otherwise the system's idea of the user
// configuration (e.g. on non-UNIX systems).
func HomeDir() (string, error) {
if homeDir := os.Getenv("HOME"); len(homeDir) > 0 {
return homeDir, nil
}
userAcct, err := user.Current()
if err != nil {
return "", err
}
return userAcct.HomeDir, nil
}
// EnvString returns the value set by the specified environment variable. The
// depth argument indicates the stack depth of the caller that should be
// associated with the variable.
// The returned boolean flag indicates if the variable is set.
func EnvString(name string, depth int) (string, bool) {
return getEnv(name, depth+1)
}
// EnvOrDefaultString returns the value set by the specified
// environment variable, if any, otherwise the specified default
// value.
func EnvOrDefaultString(name string, value string) string {
if v, present := getEnv(name, 1); present {
return v
}
return value
}
// EnvOrDefaultBool returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultBool(name string, value bool) bool {
if str, present := getEnv(name, 1); present {
v, err := strconv.ParseBool(str)
if err != nil {
panic(fmt.Sprintf("error parsing %s: %s", name, err))
}
return v
}
return value
}
// EnvOrDefaultInt returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultInt(name string, value int) int {
if str, present := getEnv(name, 1); present {
v, err := strconv.ParseInt(str, 0, 0)
if err != nil {
panic(fmt.Sprintf("error parsing %s: %s", name, err))
}
return int(v)
}
return value
}
// EnvOrDefaultInt64 returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultInt64(name string, value int64) int64 {
if str, present := getEnv(name, 1); present {
v, err := strconv.ParseInt(str, 0, 64)
if err != nil {
panic(fmt.Sprintf("error parsing %s: %s", name, err))
}
return v
}
return value
}
// EnvOrDefaultBytes returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultBytes(name string, value int64) int64 {
if str, present := getEnv(name, 1); present {
v, err := humanizeutil.ParseBytes(str)
if err != nil {
panic(fmt.Sprintf("error parsing %s: %s", name, err))
}
return v
}
return value
}
// EnvOrDefaultDuration returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultDuration(name string, value time.Duration) time.Duration {
if str, present := getEnv(name, 1); present {
v, err := time.ParseDuration(str)
if err != nil {
panic(fmt.Sprintf("error parsing %s: %s", name, err))
}
return v
}
return value
}