build: Migrate to flat project structure

This change updates the project structure to become flattened.
Previously, the simulator, frontend and API each lived into their own
directory.

With this change, all modules of the project live in the top-level
directory of the repository. This should improve discoverability of
modules of the project.

9 files changed, 486 insertions, 0 deletions

diff --git a/opendc-compute/opendc-compute-api/build.gradle.kts b/opendc-compute/opendc-compute-api/build.gradle.kts
new file mode 100644
index 00000000..835dbbb8
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/build.gradle.kts
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+description = "API interface for the OpenDC Compute service"
+
+/* Build configuration */
+plugins {
+    `kotlin-library-conventions`
+}
+
+dependencies {
+    api(platform(project(":opendc-platform")))
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ComputeClient.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ComputeClient.kt
new file mode 100644
index 00000000..baa1ba2f
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ComputeClient.kt
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+import java.util.UUID
+
+/**
+ * A client interface for the OpenDC Compute service.
+ */
+public interface ComputeClient : AutoCloseable {
+    /**
+     * Obtain the list of [Flavor]s accessible by the requesting user.
+     */
+    public suspend fun queryFlavors(): List<Flavor>
+
+    /**
+     * Obtain a [Flavor] by its unique identifier.
+     *
+     * @param id The identifier of the flavor.
+     */
+    public suspend fun findFlavor(id: UUID): Flavor?
+
+    /**
+     * Create a new [Flavor] instance at this compute service.
+     *
+     * @param name The name of the flavor.
+     * @param cpuCount The amount of CPU cores for this flavor.
+     * @param memorySize The size of the memory.
+     * @param labels The identifying labels of the image.
+     * @param meta The non-identifying meta-data of the image.
+     */
+    public suspend fun newFlavor(
+        name: String,
+        cpuCount: Int,
+        memorySize: Long,
+        labels: Map<String, String> = emptyMap(),
+        meta: Map<String, Any> = emptyMap()
+    ): Flavor
+
+    /**
+     * Obtain the list of [Image]s accessible by the requesting user.
+     */
+    public suspend fun queryImages(): List<Image>
+
+    /**
+     * Obtain a [Image] by its unique identifier.
+     *
+     * @param id The identifier of the image.
+     */
+    public suspend fun findImage(id: UUID): Image?
+
+    /**
+     * Create a new [Image] instance at this compute service.
+     *
+     * @param name The name of the image.
+     * @param labels The identifying labels of the image.
+     * @param meta The non-identifying meta-data of the image.
+     */
+    public suspend fun newImage(
+        name: String,
+        labels: Map<String, String> = emptyMap(),
+        meta: Map<String, Any> = emptyMap()
+    ): Image
+
+    /**
+     * Obtain the list of [Server]s accessible by the requesting user.
+     */
+    public suspend fun queryServers(): List<Server>
+
+    /**
+     * Obtain a [Server] by its unique identifier.
+     *
+     * @param id The identifier of the server.
+     */
+    public suspend fun findServer(id: UUID): Server?
+
+    /**
+     * Create a new [Server] instance at this compute service.
+     *
+     * @param name The name of the server to deploy.
+     * @param image The image to be deployed.
+     * @param flavor The flavor of the machine instance to run this [image] on.
+     * @param labels The identifying labels of the server.
+     * @param meta The non-identifying meta-data of the server.
+     * @param start A flag to indicate that the server should be started immediately.
+     */
+    public suspend fun newServer(
+        name: String,
+        image: Image,
+        flavor: Flavor,
+        labels: Map<String, String> = emptyMap(),
+        meta: Map<String, Any> = emptyMap(),
+        start: Boolean = true
+    ): Server
+
+    /**
+     * Release the resources associated with this client, preventing any further API calls.
+     */
+    public override fun close()
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Flavor.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Flavor.kt
new file mode 100644
index 00000000..5f511f91
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Flavor.kt
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * Flavors define the compute and memory capacity of [Server] instance. To put it simply, a flavor is an available
+ * hardware configuration for a server. It defines the size of a virtual server that can be launched.
+ */
+public interface Flavor : Resource {
+    /**
+     * The number of (virtual) processing cores to use.
+     */
+    public val cpuCount: Int
+
+    /**
+     * The amount of RAM available to the server (in MB).
+     */
+    public val memorySize: Long
+
+    /**
+     * Delete the flavor instance.
+     */
+    public suspend fun delete()
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Image.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Image.kt
new file mode 100644
index 00000000..83e63b81
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Image.kt
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * An image containing a bootable operating system that can directly be executed by physical or virtual server.
+ */
+public interface Image : Resource {
+    /**
+     * Delete the image instance.
+     */
+    public suspend fun delete()
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/InsufficientServerCapacityException.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/InsufficientServerCapacityException.kt
new file mode 100644
index 00000000..8fbb7308
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/InsufficientServerCapacityException.kt
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * This exception is thrown to indicate that the compute service does not have enough capacity at the moment to
+ * fulfill a launch request.
+ */
+public class InsufficientServerCapacityException(override val cause: Throwable? = null) : Exception("There was insufficient capacity available to satisfy the launch request")
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Resource.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Resource.kt
new file mode 100644
index 00000000..08120848
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Resource.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+import java.util.UUID
+
+/**
+ * A generic resource provided by the OpenDC Compute service.
+ */
+public interface Resource {
+    /**
+     * The unique identifier of the resource.
+     */
+    public val uid: UUID
+
+    /**
+     * The name of the resource.
+     */
+    public val name: String
+
+    /**
+     * The identifying labels attached to the resource.
+     */
+    public val labels: Map<String, String>
+
+    /**
+     * The non-identifying metadata attached to the resource.
+     */
+    public val meta: Map<String, Any>
+
+    /**
+     * Refresh the local state of the resource.
+     */
+    public suspend fun refresh()
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Server.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Server.kt
new file mode 100644
index 00000000..b508a9f8
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/Server.kt
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * A stateful object representing a server instance that is running on some physical or virtual machine.
+ */
+public interface Server : Resource {
+    /**
+     * The flavor of the server.
+     */
+    public val flavor: Flavor
+
+    /**
+     * The image of the server.
+     */
+    public val image: Image
+
+    /**
+     * The last known state of the server.
+     */
+    public val state: ServerState
+
+    /**
+     * Request the server to be started.
+     *
+     * This method is guaranteed to return after the request was acknowledged, but might return before the server was
+     * started.
+     */
+    public suspend fun start()
+
+    /**
+     * Request the server to be stopped.
+     *
+     * This method is guaranteed to return after the request was acknowledged, but might return before the server was
+     * stopped.
+     */
+    public suspend fun stop()
+
+    /**
+     * Request the server to be deleted.
+     *
+     * This method is guaranteed to return after the request was acknowledged, but might return before the server was
+     * deleted.
+     */
+    public suspend fun delete()
+
+    /**
+     * Register the specified [ServerWatcher] to watch the state of the server.
+     *
+     * @param watcher The watcher to register for the server.
+     */
+    public fun watch(watcher: ServerWatcher)
+
+    /**
+     * De-register the specified [ServerWatcher] from the server to stop it from receiving events.
+     *
+     * @param watcher The watcher to de-register from the server.
+     */
+    public fun unwatch(watcher: ServerWatcher)
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerState.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerState.kt
new file mode 100644
index 00000000..a4d7d7d7
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerState.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * An enumeration describing the possible states of a server.
+ */
+public enum class ServerState {
+    /**
+     * Resources are being allocated for the instance. The instance is not running yet.
+     */
+    PROVISIONING,
+
+    /**
+     * A user shut down the instance.
+     */
+    TERMINATED,
+
+    /**
+     * The server instance is booting up or running.
+     */
+    RUNNING,
+
+    /**
+     * The server is in an error state.
+     */
+    ERROR,
+
+    /**
+     * The server has been deleted and cannot be started later on.
+     */
+    DELETED,
+}
diff --git a/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerWatcher.kt b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerWatcher.kt
new file mode 100644
index 00000000..48a17b30
--- /dev/null
+++ b/opendc-compute/opendc-compute-api/src/main/kotlin/org/opendc/compute/api/ServerWatcher.kt
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.compute.api
+
+/**
+ * An interface used to watch the state of [Server] instances.
+ */
+public interface ServerWatcher {
+    /**
+     * This method is invoked when the state of a [Server] changes.
+     *
+     * Note that the state of [server] might not reflect the state as reported by the invocation, as a call to
+     * [Server.refresh] is required to update its state.
+     *
+     * @param server The server whose state has changed.
+     * @param newState The new state of the server.
+     */
+    public fun onStateChanged(server: Server, newState: ServerState) {}
+}