env.go

// Copyright 2016 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

package envutil

import (
	"bytes"
	"fmt"
	"os"
	"os/user"
	"runtime"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/cockroachdb/cockroach/pkg/util/humanizeutil"
	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
	"github.com/cockroachdb/redact"
)

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() (result []redact.RedactableString) {
	allVarsRaw := os.Environ()
	sort.Strings(allVarsRaw)
	allVarsValues := make(map[redact.SafeString]string, len(allVarsRaw))
	allVarNames := make([]redact.SafeString, 0, len(allVarsRaw))
	for _, v := range allVarsRaw {
		i := strings.IndexByte(v, '=')
		if i < 0 {
			continue
		}
		varName := redact.SafeString(v[:i])
		allVarNames = append(allVarNames, varName)
		var value string
		if i+1 < len(v) {
			value = v[i+1:]
		}
		allVarsValues[varName] = value
	}

	envVarRegistry.mu.Lock()
	defer envVarRegistry.mu.Unlock()

	for _, varName := range allVarNames {
		_, crdbVar := envVarRegistry.cache[string(varName)]
		_, safeVar := safeVarRegistry[varName]
		if crdbVar || safeVar {
			result = append(result, redact.Sprintf("%s=%s", varName, redact.Safe(allVarsValues[varName])))
		} else if _, reportable := valueReportableUnsafeVarRegistry[varName]; reportable {
			result = append(result, redact.Sprintf("%s=%s", varName, allVarsValues[varName]))
		} else if _, reportable := nameReportableUnsafeVarRegistry[varName]; reportable {
			result = append(result, redact.Sprintf("%s=...", varName))
		}
		// For any env var just the name could contain too many sensitive details and we
		// don't really want them to show up in logs.
	}

	return result
}

// safeVarRegistry is the list of variables where we can both report
// the name and the value safely: the value is known to never contain
// sensitive information.
var safeVarRegistry = map[redact.SafeString]struct{}{
	"GOGC":        {},
	"GODEBUG":     {},
	"GOMAXPROCS":  {},
	"GOTRACEBACK": {},
}

// valueReportableUnsafeVarRegistry is the list of variables where we can
// report the name safely, and the value as a redactable payload.
// The value may contain sensitive information, but not so sensitive
// that users would be unhappy to see them enclosed within redaction
// markers in log files.
var valueReportableUnsafeVarRegistry = map[redact.SafeString]struct{}{
	"DEBUG_HTTP2_GOROUTINES":      {},
	"GRPC_GO_LOG_SEVERITY_LEVEL":  {},
	"GRPC_GO_LOG_VERBOSITY_LEVEL": {},
	"LANG":                        {},
	"LC_ALL":                      {},
	"LC_COLLATE":                  {},
	"LC_CTYPE":                    {},
	"LC_TIME":                     {},
	"LC_NUMERIC":                  {},
	"LC_MESSAGES":                 {},
	"LS_METRICS_ENABLED":          {},
	"TERM":                        {},
	"TZ":                          {},
	"ZONEINFO":                    {},
	// From the Go runtime.
	"LOCALDOMAIN":    {},
	"RES_OPTIONS":    {},
	"HOSTALIASES":    {},
	"HTTP_PROXY":     {},
	"HTTPS_PROXY":    {},
	"NO_PROXY":       {},
	"REQUEST_METHOD": {},
}

// nameReportableUnsafeVarRegistry is the list of variables where we can
// report the name safely, but not the value in any form because it is
// too likely to contain an unsafe payload that users would be horrified
// to see in a log file, redaction markers or not.
var nameReportableUnsafeVarRegistry = map[redact.SafeString]struct{}{
	// GCP.
	"GOOGLE_API_USE_MTLS":  {},
	"GOOGLE_CLOUD_PROJECT": {},
	// AWS.
	"AWS_ACCESS_KEY":              {},
	"AWS_ACCESS_KEY_ID":           {},
	"AWS_PROFILE":                 {},
	"AWS_REGION":                  {},
	"AWS_SDK_LOAD_CONFIG":         {},
	"AWS_SECRET_ACCESS_KEY":       {},
	"AWS_SECRET_KEY":              {},
	"AWS_SESSION_TOKEN":           {},
	"AWS_SHARED_CREDENTIALS_FILE": {},
	// Azure.
	"AZURE_ACCESS_TOKEN_FILE": {},
	"AZURE_AUTH_LOCATION":     {},
	"AZURE_CONFIG_DIR":        {},
	"AZURE_GO_SDK_LOG_FILE":   {},
	"AZURE_GO_SDK_LOG_LEVEL":  {},
	// Google auth.
	"GAE_APPLICATION":     {},
	"GAE_DEPLOYMENT_ID":   {},
	"GAE_ENV":             {},
	"GAE_INSTANCE":        {},
	"GAE_LONG_APP_ID":     {},
	"GAE_MINOR_VERSION":   {},
	"GAE_MODULE_INSTANCE": {},
	"GAE_MODULE_NAME":     {},
	"GAE_PARTITION":       {},
	"GAE_SERVICE":         {},
	// gRPC.
	"GRPC_GO_LOG_SEVERITY_LEVEL":  {},
	"GRPC_GO_LOG_VERBOSITY_LEVEL": {},
	// Kerberos.
	"KRB5CCNAME": {},
	// Pprof.
	"PPROF_BINARY_PATH": {},
	"PPROF_TMPDIR":      {},
	"PPROF_TOOLS":       {},
	// Sentry-go.
	"SENTRY_RELEASE": {},
}

// 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
}

// EnvOrDefaultFloat64 returns the value set by the specified environment
// variable, if any, otherwise the specified default value.
func EnvOrDefaultFloat64(name string, value float64) float64 {
	if str, present := getEnv(name, 1); present {
		v, err := strconv.ParseFloat(str, 64)
		if err != nil {
			panic(fmt.Sprintf("error parsing %s: %s", name, err))
		}
		return v
	}
	return value
}

var _ = EnvOrDefaultFloat64 // silence unused warning

// 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
}

// TestSetEnv sets an environment variable and the cleanup function
// resets it to the original value.
func TestSetEnv(name string, value string) func() {
	ClearEnvCache()
	before, exists := os.LookupEnv(name)

	if err := os.Setenv(name, value); err != nil {
		panic(err)
	}
	return func() {
		if exists {
			if err := os.Setenv(name, before); err != nil {
				panic(err)
			}
		} else {
			if err := os.Unsetenv(name); err != nil {
				panic(err)
			}
		}
		ClearEnvCache()
	}
}