Improve HTTP headers logic (#1584)

* Relax forbidden headers constraints
  - remove restriction on browser-related headers
- allow any glob pattern (no need to end with `/` or `*`, because glob
patterns already require users to explicitly declare prefix matches if
that's the intention)
* Replace `List<Pair<, ...>>`; use `Map<String, ...>` instead
* Use glob pattern strings as an API throughout, instead of `Pattern`
(e.g. in `HttpClientBuilder`)
* Add HTTP headers to message passing API
* Add HTTP headers to executor API (introduces `ExecutorSpiOptions4`)
* Add tests for Gradle, CLI, and pkl-executor invocations
* Improve documentation
* Add `isGlobPattern` API to class `String` for in-language validation
of http headers
* Behavior change: make sure explicitly configured `User-Agent` in
`HttpClientBuilder` can be shadowed by headers (allows users to set
`--http-header "**=User-Agent: My User Agent"` and for this to be the
only user agent).

CC @kyokuping

pkl-gradle/pkl-gradle.gradle.kts

@@ -47,6 +47,7 @@ dependencies {
   }
 
   testImplementation(projects.pklCommonsTest)
+  testImplementation(libs.wiremock)
 }
 
 sourceSets {

pkl-gradle/src/main/java/org/pkl/gradle/PklPlugin.java

@@ -487,6 +487,7 @@ public class PklPlugin implements Plugin<Project> {
     task.getTestPort().set(spec.getTestPort());
     task.getHttpProxy().set(spec.getHttpProxy());
     task.getHttpNoProxy().set(spec.getHttpNoProxy());
+    task.getHttpHeaders().set(spec.getHttpHeaders());
     task.getHttpRewrites().set(spec.getHttpRewrites());
     task.getExternalModuleReaders()
         .set(providers.provider(() -> spec.getExternalModuleReaders().getAsMap()));

pkl-gradle/src/main/java/org/pkl/gradle/spec/BasePklSpec.java

@@ -17,6 +17,8 @@ package org.pkl.gradle.spec;
 
 import java.net.URI;
 import java.time.Duration;
+import java.util.List;
+import java.util.Map;
 import org.gradle.api.NamedDomainObjectContainer;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.DirectoryProperty;
@@ -61,6 +63,8 @@ public interface BasePklSpec {
 
   MapProperty<URI, URI> getHttpRewrites();
 
+  MapProperty<String, Map<String, List<String>>> getHttpHeaders();
+
   NamedDomainObjectContainer<ExternalReaderSpec> getExternalModuleReaders();
 
   NamedDomainObjectContainer<ExternalReaderSpec> getExternalResourceReaders();

pkl-gradle/src/main/java/org/pkl/gradle/task/BasePklTask.java

@@ -25,6 +25,7 @@ import java.nio.file.Paths;
 import java.time.Duration;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import javax.inject.Inject;
@@ -50,7 +51,6 @@ import org.gradle.api.tasks.PathSensitivity;
 import org.gradle.api.tasks.TaskAction;
 import org.jspecify.annotations.Nullable;
 import org.pkl.commons.cli.CliBaseOptions;
-import org.pkl.core.Pair;
 import org.pkl.core.evaluatorSettings.Color;
 import org.pkl.gradle.spec.ExternalReaderSpec;
 import org.pkl.gradle.utils.PluginUtils;
@@ -167,7 +167,7 @@ public abstract class BasePklTask extends DefaultTask {
 
   @Input
   @Optional
-  public abstract ListProperty<Pair<Pattern, List<Pair<String, String>>>> getHttpHeaders();
+  public abstract MapProperty<String, Map<String, List<String>>> getHttpHeaders();
 
   @Input
   @Optional

pkl-gradle/src/test/kotlin/org/pkl/gradle/EvaluatorsTest.kt

@@ -15,6 +15,15 @@
  */
 package org.pkl.gradle
 
+import com.github.tomakehurst.wiremock.client.WireMock.equalTo
+import com.github.tomakehurst.wiremock.client.WireMock.get
+import com.github.tomakehurst.wiremock.client.WireMock.getRequestedFor
+import com.github.tomakehurst.wiremock.client.WireMock.ok
+import com.github.tomakehurst.wiremock.client.WireMock.stubFor
+import com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo
+import com.github.tomakehurst.wiremock.client.WireMock.verify
+import com.github.tomakehurst.wiremock.junit5.WireMockRuntimeInfo
+import com.github.tomakehurst.wiremock.junit5.WireMockTest
 import java.nio.file.Path
 import kotlin.io.path.readText
 import org.assertj.core.api.Assertions.assertThat
@@ -24,6 +33,7 @@ import org.junit.jupiter.api.io.TempDir
 import org.pkl.commons.readString
 import org.pkl.commons.test.PackageServer
 
+@WireMockTest
 class EvaluatorsTest : AbstractTest() {
   @Test
   fun `render Pcf`() {
@@ -907,6 +917,28 @@ class EvaluatorsTest : AbstractTest() {
     assertThat(secondRun.output).contains(CONFIG_CACHE_REUSED)
   }
 
+  @Test
+  fun `http headers`(wwRuntimeInfo: WireMockRuntimeInfo) {
+    stubFor(get(urlEqualTo("/foo.pkl")).willReturn(ok("foo = 1")))
+    writeBuildFile(
+      "pcf",
+      """
+      httpHeaders = [
+        "**": ["X-Foo": ["Foo"]]
+      ]
+      allowedModules = ["http:", "pkl:", "repl:", "file:"]
+      """
+        .trimIndent(),
+    )
+    writePklFile(
+      """
+      res = import("${wwRuntimeInfo.httpBaseUrl}/foo.pkl")
+      """
+    )
+    runTask("evalTest")
+    verify(getRequestedFor(urlEqualTo("/foo.pkl")).withHeader("X-Foo", equalTo("Foo")))
+  }
+
   private fun writeBuildFile(
     // don't use `org.pkl.core.OutputFormat`
     // because test compile class path doesn't contain pkl-core