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95c67d8309
* allowed using dashes and dots in environment variables names for templating config files with envtemplate (#3999) Signed-off-by: Alexander Marshalov <_@marshalov.org> * Apply suggestions from code review --------- Signed-off-by: Alexander Marshalov <_@marshalov.org> Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
119 lines
2.9 KiB
Go
119 lines
2.9 KiB
Go
package envtemplate
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import (
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"fmt"
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"io"
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"log"
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"os"
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"regexp"
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"strings"
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"github.com/valyala/fasttemplate"
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)
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// ReplaceBytes replaces `%{ENV_VAR}` placeholders in b with the corresponding ENV_VAR values.
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//
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// Error is returned if ENV_VAR isn't set for some `%{ENV_VAR}` placeholder.
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func ReplaceBytes(b []byte) ([]byte, error) {
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result, err := expand(envVars, string(b))
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if err != nil {
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return nil, err
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}
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return []byte(result), nil
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}
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// ReplaceString replaces `%{ENV_VAR}` placeholders in b with the corresponding ENV_VAR values.
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//
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// Error is returned if ENV_VAR isn't set for some `%{ENV_VAR}` placeholder.
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func ReplaceString(s string) (string, error) {
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result, err := expand(envVars, s)
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if err != nil {
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return "", err
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}
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return result, nil
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}
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// LookupEnv returns the expanded environment variable value for the given name.
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//
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// The expanded means that `%{ENV_VAR}` placeholders in env var value are replaced
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// with the corresponding ENV_VAR values (recursively).
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//
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// false is returned if environment variable isn't found.
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func LookupEnv(name string) (string, bool) {
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value, ok := envVars[name]
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return value, ok
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}
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var envVars = func() map[string]string {
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envs := os.Environ()
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m := parseEnvVars(envs)
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return expandTemplates(m)
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}()
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func parseEnvVars(envs []string) map[string]string {
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m := make(map[string]string, len(envs))
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for _, env := range envs {
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n := strings.IndexByte(env, '=')
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if n < 0 {
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m[env] = ""
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continue
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}
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name := env[:n]
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value := env[n+1:]
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m[name] = value
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}
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return m
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}
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func expandTemplates(m map[string]string) map[string]string {
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for i := 0; i < len(m); i++ {
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mExpanded := make(map[string]string, len(m))
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expands := 0
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for name, value := range m {
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valueExpanded, err := expand(m, value)
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if err != nil {
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// Do not use lib/logger here, since it is uninitialized yet.
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log.Fatalf("cannot expand %q env var value %q: %s", name, value, err)
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}
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mExpanded[name] = valueExpanded
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if valueExpanded != value {
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expands++
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}
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}
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if expands == 0 {
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return mExpanded
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}
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m = mExpanded
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}
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return m
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}
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func expand(m map[string]string, s string) (string, error) {
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if !strings.Contains(s, "%{") {
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// Fast path - nothing to expand
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return s, nil
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}
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result, err := fasttemplate.ExecuteFuncStringWithErr(s, "%{", "}", func(w io.Writer, tag string) (int, error) {
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if !isValidEnvVarName(tag) {
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return fmt.Fprintf(w, "%%{%s}", tag)
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}
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v, ok := m[tag]
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if !ok {
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return 0, fmt.Errorf("missing %q env var", tag)
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}
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return fmt.Fprintf(w, "%s", v)
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})
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if err != nil {
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return "", err
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}
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return result, nil
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}
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func isValidEnvVarName(s string) bool {
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return envVarNameRegex.MatchString(s)
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}
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// envVarNameRegex is used for validating environment variable names.
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//
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// Allow dashes and dots in env var names - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3999
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var envVarNameRegex = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_\-.]*$`)
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