Discovery

CHANGELOG.md

@@ -6,13 +6,18 @@ All notable changes to this project will be documented in this file.
 
 ### Changed
 
+- Fixed a port reference in the role services ([#102])
 - Shut down gracefully ([#101]).
 
+### Added
+
+- Added the discovery ConfigMap creation ([#102])
+
 [#101]: https://github.com/stackabletech/druid-operator/pull/101
+[#102]: https://github.com/stackabletech/druid-operator/pull/102
 
 ## [0.2.0] - 2021-12-23
 
-
 ### Changed
 
 - Migrated to StatefulSet rather than direct Pod management ([#59]).

docs/modules/ROOT/pages/usage.adoc

@@ -37,7 +37,7 @@ Then a cluster can be deployed using the example below. Make sure you have *exac
 apiVersion: druid.stackable.tech/v1alpha1
 kind: DruidCluster
 metadata:
-  name: simple
+  name: simple-druid
 spec:
   version: 0.22.0
   zookeeperReference: simple-zk
@@ -79,7 +79,7 @@ spec:
         config: {}
         replicas: 1
 
-The Router is hosting the web UI, a `NodePort` service is created by the operator to access the web UI. Connect to the `simple-router` `NodePort` service and follow the https://druid.apache.org/docs/latest/tutorials/index.html#step-4-load-data[druid documentation] on how to load and query sample data.
+The Router is hosting the web UI, a `NodePort` service is created by the operator to access the web UI. Connect to the `simple-druid-router` `NodePort` service and follow the https://druid.apache.org/docs/latest/tutorials/index.html#step-4-load-data[druid documentation] on how to load and query sample data.
 
 == Using S3
 
@@ -106,4 +106,12 @@ This allows to ingest data from accessible buckets already. To configure a bucke
   deepStorage:
     storageType: s3
     bucket: druid-deepstorage
-    baseKey: storage           # the base key is the prefix to be used; optional
+    baseKey: storage           # the base key is the prefix to be used; optional
+
+== Connecting to Druid from other Services
+
+The operator creates a `ConfigMap` with the name of the cluster which contains connection information. Following our example above (the name of the cluster is `simple-druid`) a `ConfigMap` with the name `simple-druid` will be created containing 3 keys:
+
+- `DRUID_ROUTER` with the format `<host>:<port>`, which points to the router processes HTTP endpoint. Here you can connect to the web UI, or use REST endpoints such as `/druid/v2/sql/` to query data. https://druid.apache.org/docs/latest/querying/sql.html#http-post[More information in the Druid Docs].
+- `DRUID_AVATICA_JDBC` contains a JDBC connect string which can be used together with the https://calcite.apache.org/avatica/downloads/[Avatica JDBC Driver] to connect to Druid and query data. https://druid.apache.org/docs/latest/querying/sql.html#jdbc[More information in the Druid Docs].
+- `DRUID_SQALCHEMY` contains a connection string used to connect to Druid with SQAlchemy, in - for example - Apache Superset.

examples/derby/druidcluster.yaml

@@ -1,7 +1,7 @@
 apiVersion: druid.stackable.tech/v1alpha1
 kind: DruidCluster
 metadata:
-  name: simple
+  name: derby-druid
 spec:
   version: 0.22.0
   zookeeperReference:

examples/psql-s3/druidcluster.yaml

@@ -1,7 +1,7 @@
 apiVersion: druid.stackable.tech/v1alpha1
 kind: DruidCluster
 metadata:
-  name: simple
+  name: psqls3-druid
 spec:
   version: 0.22.0
   zookeeperReference:

examples/psql/druidcluster.yaml

@@ -1,7 +1,7 @@
 apiVersion: druid.stackable.tech/v1alpha1
 kind: DruidCluster
 metadata:
-  name: simple
+  name: psql-druid
 spec:
   version: 0.22.0
   zookeeperReference:

rust/crd/src/lib.rs

@@ -1,8 +1,10 @@
 use serde::{Deserialize, Serialize};
-use stackable_operator::kube::CustomResource;
-use stackable_operator::product_config_utils::{ConfigError, Configuration};
-use stackable_operator::role_utils::Role;
-use stackable_operator::schemars::{self, JsonSchema};
+use stackable_operator::{
+    kube::CustomResource,
+    product_config_utils::{ConfigError, Configuration},
+    role_utils::Role,
+    schemars::{self, JsonSchema},
+};
 use std::collections::BTreeMap;
 use std::str::FromStr;
 use strum_macros::Display;
@@ -145,6 +147,7 @@ impl DruidRole {
 }
 
 impl DruidCluster {
+    /// The spec for the given Role
     pub fn get_role(&self, role: &DruidRole) -> &Role<DruidConfig> {
         match role {
             DruidRole::Coordinator => &self.spec.coordinators,
@@ -154,6 +157,20 @@ impl DruidCluster {
             DruidRole::Router => &self.spec.routers,
         }
     }
+
+    /// The name of the role-level load-balanced Kubernetes `Service`
+    pub fn role_service_name(&self, role: &DruidRole) -> Option<String> {
+        Some(format!("{}-{}", self.metadata.name.clone()?, role))
+    }
+
+    /// The fully-qualified domain name of the role-level load-balanced Kubernetes `Service`
+    pub fn role_service_fqdn(&self, role: &DruidRole) -> Option<String> {
+        Some(format!(
+            "{}.{}.svc.cluster.local",
+            self.role_service_name(role)?,
+            self.metadata.namespace.as_ref()?
+        ))
+    }
 }
 
 #[derive(Clone, Debug, Default, Deserialize, JsonSchema, Serialize)]
@@ -361,3 +378,98 @@ fn build_string_list(strings: &[String]) -> String {
     let comma_list = quoted_strings.join(", ");
     format!("[{}]", comma_list)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use stackable_operator::role_utils::CommonConfiguration;
+    use stackable_operator::role_utils::RoleGroup;
+    use std::array::IntoIter;
+    use std::collections::HashMap;
+
+    #[test]
+    fn test_service_name_generation() {
+        let mut cluster = DruidCluster::new(
+            "testcluster",
+            DruidClusterSpec {
+                stopped: None,
+                version: "".to_string(),
+                brokers: Role {
+                    config: CommonConfiguration {
+                        config: DruidConfig {},
+                        config_overrides: Default::default(),
+                        env_overrides: Default::default(),
+                        cli_overrides: Default::default(),
+                    },
+                    role_groups: Default::default(),
+                },
+                coordinators: Role {
+                    config: CommonConfiguration {
+                        config: DruidConfig {},
+                        config_overrides: Default::default(),
+                        env_overrides: Default::default(),
+                        cli_overrides: Default::default(),
+                    },
+                    role_groups: Default::default(),
+                },
+                historicals: Role {
+                    config: CommonConfiguration {
+                        config: DruidConfig {},
+                        config_overrides: Default::default(),
+                        env_overrides: Default::default(),
+                        cli_overrides: Default::default(),
+                    },
+                    role_groups: Default::default(),
+                },
+                middle_managers: Role {
+                    config: CommonConfiguration {
+                        config: DruidConfig {},
+                        config_overrides: Default::default(),
+                        env_overrides: Default::default(),
+                        cli_overrides: Default::default(),
+                    },
+                    role_groups: Default::default(),
+                },
+                routers: Role {
+                    config: CommonConfiguration {
+                        config: DruidConfig {},
+                        config_overrides: Default::default(),
+                        env_overrides: Default::default(),
+                        cli_overrides: Default::default(),
+                    },
+                    role_groups: HashMap::<_, _>::from_iter(IntoIter::new([(
+                        "default".to_string(),
+                        RoleGroup {
+                            config: CommonConfiguration {
+                                config: DruidConfig {},
+                                config_overrides: Default::default(),
+                                env_overrides: Default::default(),
+                                cli_overrides: Default::default(),
+                            },
+                            replicas: Some(1),
+                            selector: None,
+                        },
+                    )])),
+                },
+                metadata_storage_database: Default::default(),
+                deep_storage: Default::default(),
+                s3: None,
+                zookeeper_reference: Default::default(),
+            },
+        );
+
+        cluster.metadata.namespace = Some("default".to_string());
+
+        assert_eq!(cluster.metadata.name, Some("testcluster".to_string()));
+
+        assert_eq!(
+            cluster.role_service_name(&DruidRole::Router),
+            Some("testcluster-router".to_string())
+        );
+
+        assert_eq!(
+            cluster.role_service_fqdn(&DruidRole::Router),
+            Some("testcluster-router.default.svc.cluster.local".to_string())
+        )
+    }
+}

rust/operator-binary/src/discovery.rs

@@ -0,0 +1,81 @@
+//! Discovery for Druid.  We make Druid discoverable by putting a connection string to the router service
+//! inside a config map.  We only provide a connection string to the router service, since it serves as
+//! a gateway to the cluster for client queries.
+
+use snafu::{OptionExt, ResultExt, Snafu};
+use stackable_druid_crd::{DruidCluster, DruidRole, APP_NAME};
+use stackable_operator::{
+    builder::{ConfigMapBuilder, ObjectMetaBuilder},
+    k8s_openapi::api::core::v1::ConfigMap,
+    kube::{runtime::reflector::ObjectRef, Resource, ResourceExt},
+};
+
+use crate::druid_controller::druid_version;
+
+#[derive(Snafu, Debug)]
+pub enum Error {
+    #[snafu(display("object {} is missing metadata to build owner reference", druid))]
+    ObjectMissingMetadataForOwnerRef {
+        source: stackable_operator::error::Error,
+        druid: ObjectRef<DruidCluster>,
+    },
+    #[snafu(display("failed to get service FQDN"))]
+    NoServiceFqdn,
+    #[snafu(display("failed to build ConfigMap"))]
+    BuildConfigMap {
+        source: stackable_operator::error::Error,
+    },
+}
+
+/// Builds discovery [`ConfigMap`]s for connecting to a [`DruidCluster`]
+pub async fn build_discovery_configmaps(
+    owner: &impl Resource<DynamicType = ()>,
+    druid: &DruidCluster,
+) -> Result<Vec<ConfigMap>, Error> {
+    let name = owner.name();
+    Ok(vec![build_discovery_configmap(&name, owner, druid)?])
+}
+
+/// Build a discovery [`ConfigMap`] containing information about how to connect to a certain [`DruidCluster`]
+fn build_discovery_configmap(
+    name: &str,
+    owner: &impl Resource<DynamicType = ()>,
+    druid: &DruidCluster,
+) -> Result<ConfigMap, Error> {
+    let router_host = format!(
+        "{}:{}",
+        druid
+            .role_service_fqdn(&DruidRole::Router)
+            .with_context(|| NoServiceFqdn)?,
+        DruidRole::Router.get_http_port()
+    );
+    let sqlalchemy_conn_str = format!("druid://{}/druid/v2/sql", router_host);
+    let avatica_conn_str = format!(
+        "jdbc:avatica:remote:url=http://{}/druid/v2/sql/avatica/",
+        router_host
+    );
+
+    ConfigMapBuilder::new()
+        .metadata(
+            ObjectMetaBuilder::new()
+                .name_and_namespace(druid)
+                .name(name)
+                .ownerreference_from_resource(owner, None, Some(true))
+                .with_context(|| ObjectMissingMetadataForOwnerRef {
+                    druid: ObjectRef::from_obj(druid),
+                })?
+                .with_recommended_labels(
+                    druid,
+                    APP_NAME,
+                    druid_version(druid).unwrap_or("unknown"),
+                    &DruidRole::Router.to_string(),
+                    "discovery",
+                )
+                .build(),
+        )
+        .add_data("DRUID_ROUTER", router_host)
+        .add_data("DRUID_SQLALCHEMY", sqlalchemy_conn_str)
+        .add_data("DRUID_AVATICA_JDBC", avatica_conn_str)
+        .build()
+        .context(BuildConfigMap)
+}

rust/operator-binary/src/druid_controller.rs

@@ -6,7 +6,10 @@ use std::{
     time::Duration,
 };
 
-use crate::config::{get_jvm_config, get_log4j_config, get_runtime_properties};
+use crate::{
+    config::{get_jvm_config, get_log4j_config, get_runtime_properties},
+    discovery::{self, build_discovery_configmaps},
+};
 use snafu::{OptionExt, ResultExt, Snafu};
 use stackable_druid_crd::{
     DeepStorageType, DruidCluster, DruidRole, APP_NAME, CONTAINER_HTTP_PORT,
@@ -114,6 +117,12 @@ pub enum Error {
     PropertiesWriteError {
         source: stackable_operator::product_config::writer::PropertiesWriterError,
     },
+    #[snafu(display("failed to build discovery ConfigMap"))]
+    BuildDiscoveryConfig { source: discovery::Error },
+    #[snafu(display("failed to apply discovery ConfigMap"))]
+    ApplyDiscoveryConfig {
+        source: stackable_operator::error::Error,
+    },
 }
 type Result<T, E = Error> = std::result::Result<T, E>;
 
@@ -210,6 +219,17 @@ pub async fn reconcile_druid(druid: DruidCluster, ctx: Context<Ctx>) -> Result<R
         }
     }
 
+    // discovery
+    for discovery_cm in build_discovery_configmaps(&druid, &druid)
+        .await
+        .context(BuildDiscoveryConfig)?
+    {
+        client
+            .apply_patch(FIELD_MANAGER_SCOPE, &discovery_cm, &discovery_cm)
+            .await
+            .context(ApplyDiscoveryConfig)?;
+    }
+
     Ok(ReconcilerAction {
         requeue_after: None,
     })
@@ -235,12 +255,12 @@ pub fn build_role_service(role_name: &str, druid: &DruidCluster) -> Result<Servi
             .build(),
         spec: Some(ServiceSpec {
             ports: Some(vec![ServicePort {
-                name: Some("plaintext".to_string()),
+                name: Some(CONTAINER_HTTP_PORT.to_string()),
                 port: DruidRole::from_str(role_name)
                     .unwrap()
                     .get_http_port()
                     .into(),
-                target_port: Some(IntOrString::String("plaintext".to_string())),
+                target_port: Some(IntOrString::String(CONTAINER_HTTP_PORT.to_string())),
                 protocol: Some("TCP".to_string()),
                 ..ServicePort::default()
             }]),

rust/operator-binary/src/main.rs

@@ -1,4 +1,5 @@
 mod config;
+mod discovery;
 mod druid_controller;
 
 use futures::StreamExt;