feat: support mounting custom volumes to servers (jeremylvln#281)

* feat(shulker-crds): add custom volume and volume mounts to MinecraftServer

* feat(shulker-operator): add custom volume and volume mounts to created MinecraftServer

* docs: add mounting volumes recipe

docs/src/next/guide/recipes/overriding-pod-properties.md

@@ -13,7 +13,7 @@ You can find all the properties overridable by looking at the
 - [ProxyFleet](https://github.com/jeremylvln/Shulker/blob/main/packages/shulker-crds/src/v1alpha1/proxy_fleet.rs)
 - [MinecraftServerFleet](https://github.com/jeremylvln/Shulker/blob/main/packages/shulker-crds/src/v1alpha1/minecraft_server_fleet.rs)
 
-## Add environment variables
+## Adding environment variables
 
 Shulker already injects some environment variables that could
 be useful. But adding your own is fully supported:
@@ -39,7 +39,7 @@ spec:
 
 ## Setting custom affinities
 
-By default, Agones adds a \*_preferred_ scheduling on nodes
+By default, Agones adds a _preferred_ scheduling on nodes
 labelled with `agones.dev/role=gameserver`. However you
 may want to customize more the scheduling behavior.
 
@@ -73,3 +73,35 @@ spec:
             value: "my-server" // [!code focus]
             effect: "NoSchedule" // [!code focus]
 ```
+
+## Mounting volumes <Badge type="tip" text="servers" />
+
+Additional volumes can be injected to the `MinecraftServer`'s
+created `Pod`:
+
+```yaml
+apiVersion: shulkermc.io/v1alpha1
+kind: MinecraftServer
+metadata:
+  name: my-server
+spec:
+  clusterRef:
+    name: my-cluster
+  podOverrides: // [!code focus]
+    volumeMounts: // [!code focus]
+      - name: my_extra_volume // [!code focus]
+        mountPath: /mnt/path // [!code focus]
+    volumes: // [!code focus]
+      - name: my_extra_volume // [!code focus]
+        emptyDir: {} // [!code focus]
+```
+
+:::warning
+
+Agones, and thus Shulker, are not meant for data persistence but
+rather ephemeral workload. While adding custom volumes to a `MinecraftServer`
+is expected to work perfectly, adding some to a `MinecraftServerFleet`
+will only work if your volume source support multiple mounts (it is
+essentially the same as mounting the same volume to a `Deployment`).
+
+:::

packages/shulker-crds/src/v1alpha1/minecraft_server.rs

@@ -147,7 +147,7 @@ pub struct MinecraftServerPodOverridesSpec {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub image: Option<ImageOverrideSpec>,
 
-    /// Extra environment variables to add to the crated `Pod`
+    /// Extra environment variables to add to the created `Pod`
     #[serde(skip_serializing_if = "Option::is_none")]
     pub env: Option<Vec<k8s_openapi::api::core::v1::EnvVar>>,
 
@@ -170,6 +170,12 @@ pub struct MinecraftServerPodOverridesSpec {
     /// Name of the ServiceAccount to use
     #[serde(skip_serializing_if = "Option::is_none")]
     pub service_account_name: Option<String>,
+
+    /// Extra volumesmounts to add to the created `Pod`
+    pub volume_mounts: Option<Vec<k8s_openapi::api::core::v1::VolumeMount>>,
+
+    /// Extra volumes to add to the created `Pod`
+    pub volumes: Option<Vec<k8s_openapi::api::core::v1::Volume>>,
 }
 
 /// The status object of `MinecraftServer`

packages/shulker-operator/src/reconcilers/minecraft_server/fixtures.rs

@@ -67,6 +67,8 @@ lazy_static! {
                 )])),
                 tolerations: None,
                 service_account_name: None,
+                volume_mounts: None,
+                volumes: None,
             })
         },
         status: None,

packages/shulker-operator/src/reconcilers/minecraft_server/gameserver.rs

@@ -271,6 +271,22 @@ impl<'a> GameServerBuilder {
             }
 
             pod_spec.tolerations = pod_overrides.tolerations.clone();
+
+            if let Some(volume_mounts_overrides) = &pod_overrides.volume_mounts {
+                pod_spec.containers[0]
+                    .volume_mounts
+                    .as_mut()
+                    .unwrap()
+                    .append(&mut volume_mounts_overrides.clone());
+            }
+
+            if let Some(volumes_override) = &pod_overrides.volumes {
+                pod_spec
+                    .volumes
+                    .as_mut()
+                    .unwrap()
+                    .append(&mut volumes_override.clone());
+            }
         }
 
         let mut pod_labels = minecraft_server.labels().clone();
@@ -561,6 +577,7 @@ impl<'a> GameServerBuilder {
 
 #[cfg(test)]
 mod tests {
+    use k8s_openapi::api::core::v1::{EmptyDirVolumeSource, Volume, VolumeMount};
     use shulker_crds::resourceref::ResourceRefSpec;
     use shulker_kube_utils::reconcilers::builder::ResourceBuilder;
 
@@ -607,6 +624,85 @@ mod tests {
         insta::assert_yaml_snapshot!(game_server);
     }
 
+    #[tokio::test]
+    async fn get_pod_template_spec_contains_volume_mounts() {
+        // G
+        let client = create_client_mock();
+        let resourceref_resolver = ResourceRefResolver::new(client);
+        let mut server = TEST_SERVER.clone();
+        server.spec.pod_overrides.as_mut().unwrap().volume_mounts = Some(vec![VolumeMount {
+            name: "my_extra_volume".to_string(),
+            mount_path: "/mnt/path".to_string(),
+            ..VolumeMount::default()
+        }]);
+        let context = super::GameServerBuilderContext {
+            cluster: &TEST_CLUSTER,
+            agent_config: &AgentConfig {
+                maven_repository: constants::SHULKER_PLUGIN_REPOSITORY.to_string(),
+                version: constants::SHULKER_PLUGIN_VERSION.to_string(),
+            },
+        };
+
+        // W
+        let pod_template = super::GameServerBuilder::get_pod_template_spec(
+            &resourceref_resolver,
+            &context,
+            &server,
+        )
+        .await
+        .unwrap();
+
+        // T
+        let extra_volume_mount = pod_template.spec.as_ref().unwrap().containers[0]
+            .volume_mounts
+            .as_ref()
+            .unwrap()
+            .iter()
+            .find(|volume_mount| volume_mount.name == "my_extra_volume");
+        assert!(extra_volume_mount.is_some());
+    }
+
+    #[tokio::test]
+    async fn get_pod_template_spec_contains_volumes() {
+        // G
+        let client = create_client_mock();
+        let resourceref_resolver = ResourceRefResolver::new(client);
+        let mut server = TEST_SERVER.clone();
+        server.spec.pod_overrides.as_mut().unwrap().volumes = Some(vec![Volume {
+            name: "my_extra_volume".to_string(),
+            empty_dir: Some(EmptyDirVolumeSource::default()),
+            ..Volume::default()
+        }]);
+        let context = super::GameServerBuilderContext {
+            cluster: &TEST_CLUSTER,
+            agent_config: &AgentConfig {
+                maven_repository: constants::SHULKER_PLUGIN_REPOSITORY.to_string(),
+                version: constants::SHULKER_PLUGIN_VERSION.to_string(),
+            },
+        };
+
+        // W
+        let pod_template = super::GameServerBuilder::get_pod_template_spec(
+            &resourceref_resolver,
+            &context,
+            &server,
+        )
+        .await
+        .unwrap();
+
+        // T
+        let extra_volume = pod_template
+            .spec
+            .as_ref()
+            .unwrap()
+            .volumes
+            .as_ref()
+            .unwrap()
+            .iter()
+            .find(|volume| volume.name == "my_extra_volume");
+        assert!(extra_volume.is_some());
+    }
+
     #[tokio::test]
     async fn get_init_env_contains_world() {
         // G

packages/shulker-operator/src/reconcilers/minecraft_server_fleet/fixtures.rs

@@ -88,6 +88,8 @@ lazy_static! {
                         )])),
                         tolerations: None,
                         service_account_name: None,
+                        volume_mounts: None,
+                        volumes: None,
                     })
                 },
             },