Allow pom download failures

rewrite-maven/src/main/java/org/openrewrite/maven/internal/MavenPomDownloader.java

@@ -561,51 +561,75 @@ public Pom download(GroupArtifactVersion gav,
                     Path inputPath = Paths.get(gav.getGroupId(), gav.getArtifactId(), gav.getVersion());
 
                     try {
-                        File f = new File(uri);
+                        File pomFile = new File(uri);
+                        File jarFile = pomFile.toPath().resolveSibling(gav.getArtifactId() + '-' + versionMaybeDatedSnapshot + ".jar").toFile();
 
-                        //NOTE: The pom may exist without a .jar artifact if the pom packaging is "pom"
-                        if (!f.exists()) {
+                        //NOTE:
+                        // - The pom may exist without a .jar artifact if the pom packaging is "pom"
+                        // - The jar may exist without a pom, if manually installed
+                        if (!pomFile.exists() && !jarFile.exists()) {
                             continue;
                         }
 
-                        try (FileInputStream fis = new FileInputStream(f)) {
-                            RawPom rawPom = RawPom.parse(fis, Objects.equals(versionMaybeDatedSnapshot, gav.getVersion()) ? null : versionMaybeDatedSnapshot);
-                            Pom pom = rawPom.toPom(inputPath, repo).withGav(resolvedGav);
-
-                            if (pom.getPackaging() == null || pom.hasJarPackaging()) {
-                                File jar = f.toPath().resolveSibling(gav.getArtifactId() + '-' + versionMaybeDatedSnapshot + ".jar").toFile();
-                                if (!jar.exists() || jar.length() == 0) {
-                                    // The jar has not been downloaded, making this dependency unusable.
-                                    continue;
-                                }
+                        RawPom rawPom;
+                        if (pomFile.exists()) {
+                            try (FileInputStream fis = new FileInputStream(pomFile)) {
+                                rawPom = RawPom.parse(fis, Objects.equals(versionMaybeDatedSnapshot, gav.getVersion()) ? null : versionMaybeDatedSnapshot);
                             }
+                        } else {
+                            // Record the absense of the pom file
+                            ctx.getResolutionListener().downloadError(gav, uris, (containingPom == null) ? null : containingPom.getRequested());
+                            // infer rawPom from jar
+                            rawPom = rawPomFromGav(gav);
+                        }
 
-                            if (repo.getUri().equals(MavenRepository.MAVEN_LOCAL_DEFAULT.getUri())) {
-                                // so that the repository path is the same regardless of username
-                                pom = pom.withRepository(MavenRepository.MAVEN_LOCAL_USER_NEUTRAL);
-                            }
+                        Pom pom = rawPom.toPom(inputPath, repo).withGav(resolvedGav);
 
-                            if (!Objects.equals(versionMaybeDatedSnapshot, pom.getVersion())) {
-                                pom = pom.withGav(pom.getGav().withDatedSnapshotVersion(versionMaybeDatedSnapshot));
+                        if (pom.getPackaging() == null || pom.hasJarPackaging()) {
+                            if (!jarFile.exists() || jarFile.length() == 0) {
+                                // The jar has not been downloaded, making this dependency unusable.
+                                continue;
                             }
-                            mavenCache.putPom(resolvedGav, pom);
-                            ctx.getResolutionListener().downloadSuccess(resolvedGav, containingPom);
-                            sample.stop(timer.tags("outcome", "from maven local").register(Metrics.globalRegistry));
-                            return pom;
                         }
+
+                        if (repo.getUri().equals(MavenRepository.MAVEN_LOCAL_DEFAULT.getUri())) {
+                            // so that the repository path is the same regardless of username
+                            pom = pom.withRepository(MavenRepository.MAVEN_LOCAL_USER_NEUTRAL);
+                        }
+
+                        if (!Objects.equals(versionMaybeDatedSnapshot, pom.getVersion())) {
+                            pom = pom.withGav(pom.getGav().withDatedSnapshotVersion(versionMaybeDatedSnapshot));
+                        }
+                        mavenCache.putPom(resolvedGav, pom);
+                        ctx.getResolutionListener().downloadSuccess(resolvedGav, containingPom);
+                        sample.stop(timer.tags("outcome", "from maven local").register(Metrics.globalRegistry));
+                        return pom;
                     } catch (IOException e) {
                         // unable to read the pom from a file-based repository.
                         repositoryResponses.put(repo, e.getMessage());
                     }
                 } else {
                     try {
-                        byte[] responseBody = requestAsAuthenticatedOrAnonymous(repo, uri.toString());
+                        RawPom rawPom;
+                        try {
+                            byte[] responseBody = requestAsAuthenticatedOrAnonymous(repo, uri.toString());
+                            rawPom = RawPom.parse(
+                                    new ByteArrayInputStream(responseBody),
+                                    Objects.equals(versionMaybeDatedSnapshot, gav.getVersion()) ? null : versionMaybeDatedSnapshot
+                            );
+                        } catch (HttpSenderResponseException e) {
+                            repositoryResponses.put(repo, e.getMessage());
+                            // When `pom` is not found, try to see if `jar` exists for the same GAV
+                            if (!e.isClientSideException() || !jarExistsForPomUri(repo, uri.toString())) {
+                                throw e;
+                            }
+                            // Record the absense of the pom file
+                            ctx.getResolutionListener().downloadError(gav, uris, (containingPom == null) ? null : containingPom.getRequested());
 
+                            // Continue with a recreated pom
+                            rawPom = rawPomFromGav(gav);
+                        }
                         Path inputPath = Paths.get(gav.getGroupId(), gav.getArtifactId(), gav.getVersion());
-                        RawPom rawPom = RawPom.parse(
-                                new ByteArrayInputStream(responseBody),
-                                Objects.equals(versionMaybeDatedSnapshot, gav.getVersion()) ? null : versionMaybeDatedSnapshot
-                        );
                         Pom pom = rawPom.toPom(inputPath, repo).withGav(resolvedGav);
                         if (!Objects.equals(versionMaybeDatedSnapshot, pom.getVersion())) {
                             pom = pom.withGav(pom.getGav().withDatedSnapshotVersion(versionMaybeDatedSnapshot));
@@ -637,6 +661,12 @@ public Pom download(GroupArtifactVersion gav,
                 .setRepositoryResponses(repositoryResponses);
     }
 
+    private RawPom rawPomFromGav(GroupArtifactVersion gav) {
+        return new RawPom(null, null, gav.getGroupId(), gav.getArtifactId(), gav.getVersion(), null,
+                null, null, null, "jar", null, null, null,
+                null, null, null, null, null, null);
+    }
+
     /**
      * Gets the base version from snapshot timestamp version.
      */
@@ -850,6 +880,34 @@ private ReachabilityResult reachable(HttpSender.Request.Builder request) {
         }
     }
 
+    private boolean jarExistsForPomUri(MavenRepository repo, String pomUrl) {
+        String jarUrl = pomUrl.replaceAll("\\.pom$", ".jar");
+        try {
+            try {
+                return Failsafe.with(retryPolicy).get(() -> {
+                    HttpSender.Request authenticated = applyAuthenticationAndTimeoutToRequest(repo, httpSender.get(jarUrl)).build();
+                    try (HttpSender.Response response = httpSender.send(authenticated)) {
+                        return response.isSuccessful();
+                    }
+                });
+            } catch (FailsafeException failsafeException) {
+                Throwable cause = failsafeException.getCause();
+                if (cause instanceof HttpSenderResponseException && hasCredentials(repo) &&
+                        ((HttpSenderResponseException) cause).isClientSideException()) {
+                    return Failsafe.with(retryPolicy).get(() -> {
+                        HttpSender.Request unauthenticated = httpSender.get(jarUrl).build();
+                        try (HttpSender.Response response = httpSender.send(unauthenticated)) {
+                            return response.isSuccessful();
+                        }
+                    });
+                }
+            }
+        } catch (Throwable e) {
+            // Not interested in exceptions downloading the jar; we'll throw the original exception for the pom
+        }
+        return false;
+    }
+
 
     /**
      * Replicates Apache Maven's behavior to attempt anonymous download if repository credentials prove invalid

rewrite-maven/src/test/java/org/openrewrite/maven/internal/MavenPomDownloaderTest.java

@@ -573,6 +573,42 @@ void skipsLocalInvalidArtifactsEmptyJar(@TempDir Path localRepository) throws IO
                 .download(new GroupArtifactVersion("com.bad", "bad-artifact", "1"), null, null, List.of(mavenLocal)));
         }
 
+        @Test
+        void dontAllowPomDowloadFailureWithoutJar(@TempDir Path localRepository) throws IOException, MavenDownloadingException {
+            MavenRepository mavenLocal = MavenRepository.builder()
+              .id("local")
+              .uri(localRepository.toUri().toString())
+              .snapshots(false)
+              .knownToExist(true)
+              .build();
+
+            // Do not return invalid dependency
+            assertThrows(MavenDownloadingException.class, () -> new MavenPomDownloader(emptyMap(), ctx)
+              .download(new GroupArtifactVersion("com.bad", "bad-artifact", "1"), null, null, List.of(mavenLocal)));
+        }
+
+        @Test
+        void allowPomDowloadFailureWithJar(@TempDir Path localRepository) throws IOException, MavenDownloadingException {
+            MavenRepository mavenLocal = MavenRepository.builder()
+              .id("local")
+              .uri(localRepository.toUri().toString())
+              .snapshots(false)
+              .knownToExist(true)
+              .build();
+
+            // Create a valid jar
+            Path localJar = localRepository.resolve("com/some/some-artifact/1/some-artifact-1.jar");
+            assertThat(localJar.getParent().toFile().mkdirs()).isTrue();
+            Files.writeString(localJar, "some content not to be empty");
+
+            // Do not throw exception since we have a jar
+            var result = new MavenPomDownloader(emptyMap(), ctx)
+              .download(new GroupArtifactVersion("com.some", "some-artifact", "1"), null, null, List.of(mavenLocal));
+            assertThat(result.getGav().getGroupId()).isEqualTo("com.some");
+            assertThat(result.getGav().getArtifactId()).isEqualTo("some-artifact");
+            assertThat(result.getGav().getVersion()).isEqualTo("1");
+        }
+
         @Test
         void doNotRenameRepoForCustomMavenLocal(@TempDir Path tempDir) throws MavenDownloadingException, IOException {
             GroupArtifactVersion gav = createArtifact(tempDir);
@@ -1023,5 +1059,62 @@ public MockResponse dispatch(RecordedRequest recordedRequest) {
                 throw new RuntimeException(e);
             }
         }
+
+        @Test
+        @DisplayName("Throw exception if there is no pom and no jar for the artifact")
+        @Issue("https://github.com/openrewrite/rewrite/issues/4687")
+        void pomNotFoundWithNoJarShouldThrow() throws Exception {
+            try (MockWebServer mockRepo = getMockServer()) {
+                mockRepo.setDispatcher(new Dispatcher() {
+                    @Override
+                    public MockResponse dispatch(RecordedRequest recordedRequest) {
+                        assert recordedRequest.getPath() != null;
+                        return new MockResponse().setResponseCode(404).setBody("");
+                    }
+                });
+                mockRepo.start();
+                var repositories = List.of(MavenRepository.builder()
+                  .id("id")
+                  .uri("http://%s:%d/maven".formatted(mockRepo.getHostName(), mockRepo.getPort()))
+                  .username("user")
+                  .password("pass")
+                  .build());
+
+                var downloader = new MavenPomDownloader(emptyMap(), ctx);
+                var gav = new GroupArtifactVersion("fred", "fred", "1");
+                assertThrows(MavenDownloadingException.class, () -> downloader.download(gav, null, null, repositories));
+            }
+        }
+
+        @Test
+        @DisplayName("Don't throw exception if there is no pom and but there is a jar for the artifact")
+        @Issue("https://github.com/openrewrite/rewrite/issues/4687")
+        void pomNotFoundWithJarFoundShouldntThrow() throws Exception {
+            try (MockWebServer mockRepo = getMockServer()) {
+                mockRepo.setDispatcher(new Dispatcher() {
+                    @Override
+                    public MockResponse dispatch(RecordedRequest recordedRequest) {
+                        assert recordedRequest.getPath() != null;
+                        if (recordedRequest.getPath().endsWith("fred/fred/1/fred-1.pom"))
+                            return new MockResponse().setResponseCode(404).setBody("");
+                        return new MockResponse().setResponseCode(200).setBody("some bytes so the jar isn't empty");
+                    }
+                });
+                mockRepo.start();
+                var repositories = List.of(MavenRepository.builder()
+                  .id("id")
+                  .uri("http://%s:%d/maven".formatted(mockRepo.getHostName(), mockRepo.getPort()))
+                  .username("user")
+                  .password("pass")
+                  .build());
+
+                var gav = new GroupArtifactVersion("fred", "fred", "1");
+                var downloader = new MavenPomDownloader(emptyMap(), ctx);
+                Pom downloaded = downloader.download(gav, null, null, repositories);
+                assertThat(downloaded.getGav().getGroupId()).isEqualTo("fred");
+                assertThat(downloaded.getGav().getArtifactId()).isEqualTo("fred");
+                assertThat(downloaded.getGav().getVersion()).isEqualTo("1");
+            }
+        }
     }
 }

rewrite-maven/src/test/java/org/openrewrite/maven/tree/ResolvedPomTest.java

@@ -16,9 +16,20 @@
 package org.openrewrite.maven.tree;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.intellij.lang.annotations.Language;
+import org.jspecify.annotations.Nullable;
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.Issue;
+import org.openrewrite.maven.MavenExecutionContextView;
 import org.openrewrite.test.RewriteTest;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -278,4 +289,97 @@ void resolveExecutionsFromDifferentParents() {
           )
         );
     }
+
+    @Nested
+    @Issue("https://github.com/openrewrite/rewrite/issues/4687")
+    class TolerateMissingPom {
+
+        @Language("xml")
+        private static final String POM_WITH_DEPENDENCY = """
+          <project>
+              <modelVersion>4.0.0</modelVersion>
+              <groupId>foo</groupId>
+              <artifactId>bar</artifactId>
+              <version>1.0-SNAPSHOT</version>
+              <dependencies>
+                  <dependency>
+                      <groupId>com.some</groupId>
+                      <artifactId>some-artifact</artifactId>
+                      <version>1</version>
+                  </dependency>
+              </dependencies>
+          </project>
+          """;
+
+        @TempDir
+        Path localRepository;
+        @TempDir
+        Path localRepository2;
+
+        @Test
+        void singleRepositoryContainingJar() throws IOException {
+            MavenRepository mavenLocal = createMavenRepository(localRepository, "local");
+            createJarFile(localRepository);
+
+            List<List<@Nullable Object>> downloadErrorArgs = new ArrayList<>();
+            MavenExecutionContextView ctx = MavenExecutionContextView.view(new InMemoryExecutionContext(Throwable::printStackTrace));
+            ctx.setRepositories(List.of(mavenLocal));
+            ctx.setResolutionListener(new ResolutionEventListener() {
+                @Override
+                public void downloadError(GroupArtifactVersion gav, List<String> attemptedUris, @Nullable Pom containing) {
+                    List<Object> list = new ArrayList<>();
+                    list.add(gav);
+                    list.add(attemptedUris);
+                    list.add(containing);
+                    downloadErrorArgs.add(list);
+                }
+            });
+            rewriteRun(
+              spec -> spec.executionContext(ctx),
+              pomXml(POM_WITH_DEPENDENCY)
+            );
+            assertThat(downloadErrorArgs).hasSize(1);
+        }
+
+        @Test
+        void twoRepositoriesSecondContainingJar() throws IOException {
+            MavenRepository mavenLocal = createMavenRepository(localRepository, "local");
+            MavenRepository mavenLocal2 = createMavenRepository(localRepository2, "local2");
+            createJarFile(localRepository2);
+
+            List<List<@Nullable Object>> downloadErrorArgs = new ArrayList<>();
+            MavenExecutionContextView ctx = MavenExecutionContextView.view(new InMemoryExecutionContext(Throwable::printStackTrace));
+            ctx.setRepositories(List.of(mavenLocal, mavenLocal2));
+            ctx.setResolutionListener(new ResolutionEventListener() {
+                @Override
+                public void downloadError(GroupArtifactVersion gav, List<String> attemptedUris, @Nullable Pom containing) {
+                    List<Object> list = new ArrayList<>();
+                    list.add(gav);
+                    list.add(attemptedUris);
+                    list.add(containing);
+                    downloadErrorArgs.add(list);
+                }
+            });
+            rewriteRun(
+              spec -> spec.executionContext(ctx),
+              pomXml(POM_WITH_DEPENDENCY)
+            );
+            assertThat(downloadErrorArgs).hasSize(1);
+        }
+
+        private static void createJarFile(Path localRepository1) throws IOException {
+            Path localJar = localRepository1.resolve("com/some/some-artifact/1/some-artifact-1.jar");
+            assertThat(localJar.getParent().toFile().mkdirs()).isTrue();
+            Files.writeString(localJar, "some content not to be empty");
+        }
+
+        private static MavenRepository createMavenRepository(Path localRepository, String name) {
+            return MavenRepository.builder()
+              .id(name)
+              .uri(localRepository.toUri().toString())
+              .snapshots(false)
+              .knownToExist(true)
+              .build();
+        }
+    }
 }