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| 1 | +package com.linkedin.gms.factory.system_telemetry; |
| 2 | + |
| 3 | +import jakarta.annotation.PostConstruct; |
| 4 | +import jakarta.servlet.FilterChain; |
| 5 | +import jakarta.servlet.ServletException; |
| 6 | +import jakarta.servlet.http.HttpServletRequest; |
| 7 | +import jakarta.servlet.http.HttpServletResponse; |
| 8 | +import java.io.IOException; |
| 9 | +import java.nio.charset.StandardCharsets; |
| 10 | +import java.security.MessageDigest; |
| 11 | +import java.util.Base64; |
| 12 | +import lombok.extern.slf4j.Slf4j; |
| 13 | +import org.springframework.util.StringUtils; |
| 14 | +import org.springframework.web.filter.OncePerRequestFilter; |
| 15 | + |
| 16 | +/** |
| 17 | + * Optional HTTP Basic authentication for {@code /actuator/prometheus}. |
| 18 | + * |
| 19 | + * <p>Independent of DataHub token auth. When disabled, requests pass through unchanged. |
| 20 | + */ |
| 21 | +@Slf4j |
| 22 | +public class PrometheusScrapeAuthFilter extends OncePerRequestFilter { |
| 23 | + |
| 24 | + public static final String PROMETHEUS_ACTUATOR_PATH = "/actuator/prometheus"; |
| 25 | + private static final String BASIC_PREFIX = "Basic "; |
| 26 | + |
| 27 | + private final PrometheusScrapeAuthSettings settings; |
| 28 | + |
| 29 | + public PrometheusScrapeAuthFilter(PrometheusScrapeAuthSettings settings) { |
| 30 | + this.settings = settings; |
| 31 | + } |
| 32 | + |
| 33 | + @PostConstruct |
| 34 | + public void validateConfiguration() { |
| 35 | + if (!settings.isEnabled()) { |
| 36 | + return; |
| 37 | + } |
| 38 | + log.info("Prometheus scrape HTTP Basic auth enabled for {}", PROMETHEUS_ACTUATOR_PATH); |
| 39 | + if (settings.isUsingDefaultPassword()) { |
| 40 | + log.warn( |
| 41 | + "Prometheus scrape auth is using the default password ({}). Set " |
| 42 | + + "MANAGEMENT_METRICS_EXPORT_PROMETHEUS_AUTH_PASSWORD to a strong secret.", |
| 43 | + PrometheusScrapeAuthSettings.DEFAULT_PASSWORD); |
| 44 | + } |
| 45 | + } |
| 46 | + |
| 47 | + @Override |
| 48 | + protected boolean shouldNotFilter(HttpServletRequest request) { |
| 49 | + if (!settings.isEnabled()) { |
| 50 | + return true; |
| 51 | + } |
| 52 | + String path = request.getServletPath(); |
| 53 | + return path == null || !PROMETHEUS_ACTUATOR_PATH.equals(path); |
| 54 | + } |
| 55 | + |
| 56 | + @Override |
| 57 | + protected void doFilterInternal( |
| 58 | + HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) |
| 59 | + throws ServletException, IOException { |
| 60 | + |
| 61 | + if (isAuthorized(request)) { |
| 62 | + filterChain.doFilter(request, response); |
| 63 | + return; |
| 64 | + } |
| 65 | + |
| 66 | + response.setHeader("WWW-Authenticate", "Basic realm=\"Prometheus\""); |
| 67 | + response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized"); |
| 68 | + } |
| 69 | + |
| 70 | + private boolean isAuthorized(HttpServletRequest request) { |
| 71 | + String authorization = request.getHeader("Authorization"); |
| 72 | + if (!StringUtils.hasText(authorization) || !authorization.startsWith(BASIC_PREFIX)) { |
| 73 | + return false; |
| 74 | + } |
| 75 | + |
| 76 | + try { |
| 77 | + byte[] decoded = |
| 78 | + Base64.getDecoder().decode(authorization.substring(BASIC_PREFIX.length()).trim()); |
| 79 | + String credentials = new String(decoded, StandardCharsets.UTF_8); |
| 80 | + int separator = credentials.indexOf(':'); |
| 81 | + if (separator < 0) { |
| 82 | + return false; |
| 83 | + } |
| 84 | + String username = credentials.substring(0, separator); |
| 85 | + String password = credentials.substring(separator + 1); |
| 86 | + return constantTimeEquals(username, settings.getUsername()) |
| 87 | + && constantTimeEquals(password, settings.getPassword()); |
| 88 | + } catch (IllegalArgumentException e) { |
| 89 | + log.debug("Invalid Basic authorization header on {}", PROMETHEUS_ACTUATOR_PATH); |
| 90 | + return false; |
| 91 | + } |
| 92 | + } |
| 93 | + |
| 94 | + private static boolean constantTimeEquals(String actual, String expected) { |
| 95 | + if (actual == null || expected == null) { |
| 96 | + return false; |
| 97 | + } |
| 98 | + return MessageDigest.isEqual( |
| 99 | + actual.getBytes(StandardCharsets.UTF_8), expected.getBytes(StandardCharsets.UTF_8)); |
| 100 | + } |
| 101 | +} |
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