refactor(maven): Clarify HTTP resource check function (#12640)

lib/datasource/maven/index.ts

@@ -10,11 +10,11 @@ import type { GetReleasesConfig, Release, ReleaseResult } from '../types';
 import { MAVEN_REPO } from './common';
 import type { MavenDependency, ReleaseMap } from './types';
 import {
+  checkHttpResource,
   downloadMavenXml,
   getDependencyInfo,
   getDependencyParts,
   getMavenUrl,
-  isHttpResourceExists,
 } from './util';
 
 export { id } from './common';
@@ -198,19 +198,21 @@ async function addReleasesUsingHeadRequests(
             repoUrl
           );
           const artifactUrl = getMavenUrl(dependency, repoUrl, pomUrl);
-          const res = await isHttpResourceExists(artifactUrl);
           const release: Release = { version };
 
-          if (is.string(res)) {
-            release.releaseTimestamp = res;
-          }
+          const res = await checkHttpResource(artifactUrl);
 
-          // Retry earlier for error status other than 404
-          if (res === null) {
+          if (res === 'error') {
             retryEarlier = true;
           }
 
-          workingReleaseMap[version] = res ? release : null;
+          if (is.date(res)) {
+            release.releaseTimestamp = res.toISOString();
+          }
+
+          if (res !== 'not-found' && res !== 'error') {
+            workingReleaseMap[version] = release;
+          }
         }
       );
 

lib/datasource/maven/types.ts

@@ -14,3 +14,5 @@ export interface MavenXml {
 }
 
 export type ReleaseMap = Record<string, Release | null>;
+
+export type HttpResourceCheckResult = 'found' | 'not-found' | 'error' | Date;

lib/datasource/maven/util.ts

@@ -1,14 +1,20 @@
 import url from 'url';
+import { DateTime } from 'luxon';
 import { XmlDocument } from 'xmldoc';
 import { HOST_DISABLED } from '../../constants/error-messages';
 import { logger } from '../../logger';
 import { ExternalHostError } from '../../types/errors/external-host-error';
 import { Http, HttpResponse } from '../../util/http';
 import { regEx } from '../../util/regex';
+import { normalizeDate } from '../metadata';
 
 import type { ReleaseResult } from '../types';
 import { MAVEN_REPO, id } from './common';
-import type { MavenDependency, MavenXml } from './types';
+import type {
+  HttpResourceCheckResult,
+  MavenDependency,
+  MavenXml,
+} from './types';
 
 const http: Record<string, Http> = {};
 
@@ -100,18 +106,27 @@ export async function downloadHttpProtocol(
   }
 }
 
-export async function isHttpResourceExists(
+export async function checkHttpResource(
   pkgUrl: url.URL | string,
   hostType = id
-): Promise<boolean | string | null> {
+): Promise<HttpResourceCheckResult> {
   try {
     const httpClient = httpByHostType(hostType);
     const res = await httpClient.head(pkgUrl.toString());
     const timestamp = res?.headers?.['last-modified'] as string;
-    return timestamp || true;
+    if (timestamp) {
+      const isoTimestamp = normalizeDate(timestamp);
+      if (isoTimestamp) {
+        const releaseDate = DateTime.fromISO(isoTimestamp, {
+          zone: 'UTC',
+        }).toJSDate();
+        return releaseDate;
+      }
+    }
+    return 'found';
   } catch (err) {
     if (isNotFoundError(err)) {
-      return false;
+      return 'not-found';
     }
 
     const failedUrl = pkgUrl.toString();
@@ -119,7 +134,7 @@ export async function isHttpResourceExists(
       { failedUrl, statusCode: err.statusCode },
       `Can't check HTTP resource existence`
     );
-    return null;
+    return 'error';
   }
 }
 

lib/datasource/metadata.ts

@@ -126,7 +126,7 @@ function massageGitlabUrl(url: string): string {
     .replace('.git', '');
 }
 
-function normalizeDate(input: any): string | null {
+export function normalizeDate(input: any): string | null {
   if (
     typeof input === 'number' &&
     !Number.isNaN(input) &&