Added fix for malformed warehouse file path

examples/localfileio/.ice-rest-catalog.yaml

@@ -1,6 +1,5 @@
 uri: jdbc:sqlite:file:data/ice-rest-catalog/catalog.sqlite?journal_mode=WAL&synchronous=OFF&journal_size_limit=500
-warehouse: file://warehouse
-localFileIOBaseDir: data/ice-rest-catalog
+warehouse: file:///tmp/ice-example/warehouse
 anonymousAccess:
   enabled: true
   accessConfig:

examples/localfileio/.ice.yaml

@@ -1,3 +1,4 @@
+warehouse: file:///tmp/ice-example/warehouse
+
 uri: http://localhost:5000
-localFileIOBaseDir: data/ice-rest-catalog
 httpCacheDir: data/ice/http/cache

examples/localfileio/README.md

@@ -1,13 +1,15 @@
 # examples/localfileio
 
-This example is primarily intended for learning and experimentation.  
-All data is stored in data/ directory as regular files.
+This is an example setup where Iceberg table data is stored on your local disk (under /tmp/ice-example/warehouse) instead of
+in cloud object storage (S3, GCS, etc.).
+This example is primarily intended for learning and experimentation, and development without cloud credentials.
+Table data is stored under `/tmp/ice-example/warehouse` as regular files (see `warehouse` in `.ice-rest-catalog.yaml`). The catalog metadata stays under `data/ice-rest-catalog/`.
 
 ```shell
 # optional: open shell containing `sqlite3` (sqlite command line client)
 devbox shell
 
-# start Iceberg REST Catalog server backed by sqlite with warehouse set to file://warehouse
+# start Iceberg REST Catalog server backed by sqlite with warehouse set to file:///tmp/ice-example/warehouse
 ice-rest-catalog
 
 # insert data into catalog
@@ -17,7 +19,7 @@ ice insert flowers.iris -p file://iris.parquet
 ice describe
 
 # list all warehouse files
-find data/ice-rest-catalog/warehouse
+find /tmp/ice-example/warehouse
 
 # inspect sqlite data
 sqlite3 data/ice-rest-catalog/catalog.sqlite
@@ -28,12 +30,18 @@ sqlite> select * from iceberg_tables;
 sqlite> select * from iceberg_namespace_properties;
 sqlite> .quit
 
-# open ClickHouse* shell, then try SQL below
-docker run -it --rm --network host -v $(pwd)/data/ice-rest-catalog/warehouse:/warehouse \
-  altinity/clickhouse-server:25.3.3.20186.altinityantalya clickhouse local
+# open ClickHouse* shell, then try SQL below 
+# IMPORTANT: make sure mount path is set to /tmp
+# For Linux:
+docker run -it --rm  --add-host=host.docker.internal:host-gateway --network host -v /tmp/ice-example/warehouse:/tmp/ice-example/warehouse \
+  altinity/clickhouse-server:25.8.16.20002.altinityantalya clickhouse local
+# For Mac:
+docker run -it --rm --network host -v /tmp/ice-example/warehouse:/tmp/ice-example/warehouse \
+  altinity/clickhouse-server:25.8.16.20002.altinityantalya clickhouse local
+
 ```
 
-> \* currently this only works with altinity/clickhouse-server:25.3+ builds.
+>  currently this only works with altinity/clickhouse-server:25.3+ builds.
 
 ```sql
 -- enable Iceberg support (required as of 25.4.1.1795)
@@ -43,18 +51,50 @@ SET allow_experimental_database_iceberg = 1;
 DROP DATABASE IF EXISTS ice;
 
 CREATE DATABASE ice
-  ENGINE = DataLakeCatalog('http://localhost:5000')
+  ENGINE = DataLakeCatalog('http://host.docker.internal:5000')
   SETTINGS catalog_type = 'rest',
     vended_credentials = false,
     warehouse = 'warehouse';
 
-SHOW TABLES FROM ice;
-
 -- inspect
 SHOW DATABASES;
 SHOW TABLES FROM ice;
+
+
+Query id: 8c671684-ec90-4e18-aacd-aee5fae2aeed
+
+   ┌─name──────────┐
+1. │ flowers.iris  │
+
+
+
 SHOW CREATE TABLE ice.`flowers.iris`;
 
 select count(*) from ice.`flowers.iris`;
 select * from ice.`flowers.iris` limit 10 FORMAT CSVWithNamesAndTypes;
+
+Query id: f3a1773d-ebeb-4d26-80fb-7d9e29b5c07e
+
+     ┌─sepal.length─┬─sepal.width─┬─petal.length─┬─petal.width─┬─variety────┐
+  1. │          5.1 │         3.5 │          1.4 │         0.2 │ Setosa     │
+  2. │          4.9 │           3 │          1.4 │         0.2 │ Setosa     │
+  3. │          4.7 │         3.2 │          1.3 │         0.2 │ Setosa     │
+  4. │          4.6 │         3.1 │          1.5 │         0.2 │ Setosa     │
+  5. │            5 │         3.6 │          1.4 │         0.2 │ Setosa     │
+  6. │          5.4 │         3.9 │          1.7 │         0.4 │ Setosa     │
+  7. │          4.6 │         3.4 │          1.4 │         0.3 │ Setosa     │
+  8. │            5 │         3.4 │          1.5 │         0.2 │ Setosa     │
+  9. │          4.4 │         2.9 │          1.4 │         0.2 │ Setosa     │
+ 10. │          4.9 │         3.1 │          1.5 │         0.1 │ Setosa     │
+ 11. │          5.4 │         3.7 │          1.5 │         0.2 │ Setosa     │
+ 12. │          4.8 │         3.4 │          1.6 │         0.2 │ Setosa     │
+ 13. │          4.8 │           3 │          1.4 │         0.1 │ Setosa     │
+ 14. │          4.3 │           3 │          1.1 │         0.1 │ Setosa     │
+ 15. │          5.8 │           4 │          1.2 │         0.2 │ Setosa     │
+ 16. │          5.7 │         4.4 │          1.5 │         0.4 │ Setosa     │
+ 17. │          5.4 │         3.9 │          1.3 │         0.4 │ Setosa     │
+ 18. │          5.1 │         3.5 │          1.4 │         0.3 │ Setosa     │
+ 19. │          5.7 │         3.8 │          1.7 │
 ```
+
+The REST catalog `warehouse` must be an absolute `file:///` URI (e.g. `file:///tmp/ice-example/warehouse`). A relative form like `file://warehouse` is rejected by the server.

ice/src/main/java/com/altinity/ice/internal/iceberg/io/LocalFileIO.java

@@ -57,6 +57,11 @@ public void initialize(Map<String, String> properties) {
         warehouse.startsWith("file://"),
         "\"%s\" must start with file://",
         LOCALFILEIO_PROP_WAREHOUSE);
+    Preconditions.checkArgument(
+        warehouse.startsWith("file:///") || warehouse.equals("file://"),
+        "\"%s\" must use an absolute path (file:///abs/path), got: %s",
+        LOCALFILEIO_PROP_WAREHOUSE,
+        warehouse);
     this.workDir = resolveWorkdir(warehouse, properties.get(LOCALFILEIO_PROP_BASEDIR));
     Path warehousePath = resolveWarehousePath(warehouse, workDir);
     if (!Files.isDirectory(warehousePath)) {

ice/src/test/java/com/altinity/ice/internal/iceberg/io/LocalFileIOIT.java

@@ -13,11 +13,12 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import com.altinity.ice.internal.strings.Strings;
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
@@ -58,14 +59,23 @@ public void tearDown() throws IOException {
 
   @Test
   public void testBasicFlow() throws IOException {
-    for (var warehouse : new String[] {"file://.", "file://", "file://x/y/z"}) {
-      tempDir.toFile().mkdirs();
-      new File(tempDir.toString(), Strings.removePrefix(warehouse, "file://")).mkdirs();
-      Path fooFile = tempDir.resolve(Strings.removePrefix(warehouse, "file://")).resolve("foo");
-      Files.writeString(fooFile, "foo_content");
-      Files.writeString(
-          tempDir.resolve(Strings.removePrefix(warehouse, "file://")).resolve("bar"),
-          "bar_content");
+    Path absTemp = tempDir.toAbsolutePath().normalize();
+    String[] warehouses =
+        new String[] {
+          absTemp.toUri().toString(), "file://", absTemp.resolve("x/y/z").toUri().toString()
+        };
+
+    for (String warehouse : warehouses) {
+      Path warehousePhysical =
+          "file://".equals(warehouse)
+              ? absTemp
+              : Paths.get(Strings.removePrefix(warehouse, "file://"));
+      Files.createDirectories(warehousePhysical);
+      Files.writeString(warehousePhysical.resolve("foo"), "foo_content");
+      Files.writeString(warehousePhysical.resolve("bar"), "bar_content");
+
+      Path fooFile = warehousePhysical.resolve("foo");
+
       try (LocalFileIO io = new LocalFileIO()) {
         assertThatThrownBy(
                 () ->
@@ -81,12 +91,12 @@ public void testBasicFlow() throws IOException {
         Function<String, String> warehouseLocation =
             (String s) -> (warehouse.endsWith("/") ? warehouse : warehouse + "/") + s;
 
-        io.initialize(
-            Map.of(
-                LocalFileIO.LOCALFILEIO_PROP_BASEDIR,
-                tempDir.toString(),
-                LocalFileIO.LOCALFILEIO_PROP_WAREHOUSE,
-                warehouse));
+        Map<String, String> props = new HashMap<>();
+        props.put(LocalFileIO.LOCALFILEIO_PROP_WAREHOUSE, warehouse);
+        if ("file://".equals(warehouse)) {
+          props.put(LocalFileIO.LOCALFILEIO_PROP_BASEDIR, absTemp.toString());
+        }
+        io.initialize(props);
 
         InputFile inputFile = io.newInputFile("foo");
         OutputFile outputFile = io.newOutputFile("foo.out");
@@ -146,4 +156,15 @@ public void testBasicFlow() throws IOException {
       }
     }
   }
+
+  @Test
+  public void testRelativeFileUriRejected() {
+    try (LocalFileIO io = new LocalFileIO()) {
+      assertThatThrownBy(
+              () ->
+                  io.initialize(Map.of(LocalFileIO.LOCALFILEIO_PROP_WAREHOUSE, "file://warehouse")))
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessageContaining("absolute path");
+    }
+  }
 }