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cb16774bcb
A few users reported unexpected errors when environment variables referred other environment variables
at VictoriaMetrics startup. This resulted in the following fatal error on startup:
cannot expand "..." env var value "...%{SOME_NON_EXISTING_ENV_VAR}..."
Fix this by leaving placeholders with non-existing env vars as is.
This improves the general usability of environment variables by VictoriaMetrics components
inside command-line flags and inside config files. User can easily notice placeholders with non-existing
environment variables by looking at the corresponding command-line flag or at the corresponding config option value.
While at it, replace duplicate docs about environment variables at the https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/#environment-variables
with the link to the same docs at https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/#environment-variables .
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3999
84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
package envtemplate
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import (
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"fmt"
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"io"
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"os"
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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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func ReplaceBytes(b []byte) []byte {
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result := expand(envVars, string(b))
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return []byte(result)
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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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func ReplaceString(s string) string {
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return expand(envVars, s)
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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 := expand(m, value)
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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 {
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return fasttemplate.ExecuteFuncString(s, "%{", "}", func(w io.Writer, tag string) (int, error) {
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v, ok := m[tag]
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if !ok {
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// Cannot find the tag in m. Leave it as is.
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return fmt.Fprintf(w, "%%{%s}", tag)
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}
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return fmt.Fprintf(w, "%s", v)
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})
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}
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