feat(cli): add mock s3 server

packages/cli/build.gradle.kts

@@ -657,6 +657,9 @@ dependencies {
   implementation(libs.jib.core)
   implementation(libs.jib.extension.commons)
 
+  // Mock S3
+  implementation(libs.locals3)
+
   // Tests
   testImplementation(libs.kotlin.test.junit5)
   testImplementation(projects.packages.test)

packages/cli/src/main/kotlin/elide/tool/cli/Elide.kt

@@ -56,6 +56,7 @@ import elide.tool.cli.cmd.pkl.ToolPklCommand
 import elide.tool.cli.cmd.project.ToolProjectCommand
 import elide.tool.cli.cmd.tool.ToolInvokeCommand
 import elide.tool.cli.cmd.repl.ToolShellCommand
+import elide.tool.cli.cmd.s3.ToolS3Command
 import elide.tool.cli.cmd.secrets.ToolSecretsCommand
 import elide.tool.cli.cmd.tool.jar.JarToolAdapter
 import elide.tool.cli.cmd.tool.javac.JavaCompilerAdapter
@@ -132,6 +133,7 @@ internal const val ELIDE_HEADER = ("@|bold,fg(magenta)%n" +
     McpCommand::class,
     Elide.Completions::class,
     ToolSecretsCommand::class,
+    ToolS3Command::class,
   ],
   customSynopsis = [
     "",

packages/cli/src/main/kotlin/elide/tool/cli/cmd/s3/ToolS3Command.kt

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2024-2025 Elide Technologies, Inc.
+ *
+ * Licensed under the MIT license (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ *   https://opensource.org/license/mit/
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under the License.
+ */
+package elide.tool.cli.cmd.s3
+
+import com.robothy.s3.rest.LocalS3
+import com.robothy.s3.rest.bootstrap.LocalS3Mode
+import elide.tool.cli.CommandContext
+import elide.tool.cli.CommandResult
+import elide.tool.cli.ProjectAwareSubcommand
+import elide.tool.cli.ToolState
+import io.micronaut.core.annotation.Introspected
+import io.micronaut.core.annotation.ReflectiveAccess
+import kotlin.coroutines.cancellation.CancellationException
+import kotlin.time.Duration.Companion.seconds
+import kotlinx.coroutines.awaitCancellation
+import kotlinx.coroutines.delay
+import picocli.CommandLine
+import picocli.CommandLine.Command
+
+/** TBD. */
+@Command(
+  name = "s3",
+  description = ["Run a local S3 server"],
+  mixinStandardHelpOptions = true,
+)
+@Introspected
+@ReflectiveAccess
+internal class ToolS3Command : ProjectAwareSubcommand<ToolState, CommandContext>() {
+  /** Specifies the directory where files should be served. */
+  @CommandLine.Option(
+    names = ["--directory", "--dir", "-d"],
+    description = ["Root directory of the server. Current directory will be used if omitted."],
+  )
+  internal var directory: String? = null
+
+  /** Specifies the port of the server. */
+  @CommandLine.Option(
+    names = ["--port", "-P"],
+    description = ["Port of the server."],
+    defaultValue = "8080",
+  )
+  internal var port: Int = 8080
+
+  @CommandLine.Option(
+    names = ["--in-memory", "--memory", "-m"],
+    description = ["Run the server in memory. Files will be read from the directory, but will not be modified."],
+    defaultValue = "false",
+  )
+  internal var memory: Boolean = false
+
+  @CommandLine.Option(
+    names = ["--shutdown-after"],
+    description = ["Automatically shut down the server after this many seconds."],
+    defaultValue = "-1",
+  )
+  internal var timeout: Int = -1
+
+  /** @inheritDoc */
+  override suspend fun CommandContext.invoke(state: ToolContext<ToolState>): CommandResult {
+    val mode = if (memory) LocalS3Mode.IN_MEMORY else LocalS3Mode.PERSISTENCE
+    val userDir = System.getProperty("user.dir")
+    val dataPath = directory?.let { if (it.isCharAt(0, '/') || it.isCharAt(1, ':')) it else "$userDir/$it" } ?: userDir
+    val server = LocalS3.builder().port(port).mode(mode).dataPath(dataPath).build()
+    server.start()
+    if (timeout > 0) {
+      delay(timeout.seconds)
+      server.shutdown()
+      return CommandResult.success()
+    }
+    try {
+      awaitCancellation()
+    } catch (t: Throwable) {
+      return if (t is CancellationException) CommandResult.success() else CommandResult.err(1, exc = t)
+    } finally {
+      server.shutdown()
+    }
+  }
+
+  private fun String.isCharAt(index: Int, char: Char): Boolean = length > index && this[index] == char
+}