Function withCustomHeadersFromEnv

cli/command/cli_options.go:171–226

withCustomHeadersFromEnv overriding custom HTTP headers to be sent by the client through the [envOverrideHTTPHeaders] environment-variable. This environment variable is the equivalent to the HttpHeaders field in the configuration file. WARNING: If both config and environment-variable are set, the e

()

//
// TODO(thaJeztah): this is a client Option, and should be moved to the client. It is non-exported for that reason.
func withCustomHeadersFromEnv() (client.Opt, error) {
	value := os.Getenv(envOverrideHTTPHeaders)
	if value == "" {
		return nil, nil
	}
	csvReader := csv.NewReader(strings.NewReader(value))
	fields, err := csvReader.Read()
	if err != nil {
		return nil, invalidParameter(fmt.Errorf(
			"failed to parse custom headers from %s environment variable: value must be formatted as comma-separated key=value pairs",
			envOverrideHTTPHeaders,
		))
	}
	if len(fields) == 0 {
		return nil, nil
	}

	env := map[string]string{}
	for _, kv := range fields {
		k, v, hasValue := strings.Cut(kv, "=")

		// Only strip whitespace in keys; preserve whitespace in values.
		k = strings.TrimSpace(k)

		if k == "" {
			return nil, invalidParameter(fmt.Errorf(
				`failed to set custom headers from %s environment variable: value contains a key=value pair with an empty key: '%s'`,
				envOverrideHTTPHeaders, kv,
			))
		}

		// We don't currently allow empty key=value pairs, and produce an error.
		// This is something we could allow in future (e.g. to read value
		// from an environment variable with the same name). In the meantime,
		// produce an error to prevent users from depending on this.
		if !hasValue {
			return nil, invalidParameter(fmt.Errorf(
				`failed to set custom headers from %s environment variable: missing "=" in key=value pair: '%s'`,
				envOverrideHTTPHeaders, kv,
			))
		}

		env[http.CanonicalHeaderKey(k)] = v
	}

	if len(env) == 0 {
		// We should probably not hit this case, as we don't skip values
		// (only return errors), but we don't want to discard existing
		// headers with an empty set.
		return nil, nil
	}

	// TODO(thaJeztah): add a client.WithExtraHTTPHeaders() function to allow these headers to be _added_ to existing ones, instead of _replacing_
	//  see https://github.com/docker/cli/pull/5098#issuecomment-2147403871  (when updating, also update the WARNING in the function and env-var GoDoc)
	return client.WithHTTPHeaders(env), nil
}

// WithUserAgent configures the User-Agent string for cli HTTP requests.