fix: Include hdfs principal names in discovery ConfigMap

CHANGELOG.md

@@ -12,7 +12,13 @@ All notable changes to this project will be documented in this file.
 
 - `operator-rs` `0.56.1` -> `0.57.0` ([#433]).
 
+### Fixed
+
+- Include hdfs principals `dfs.journalnode.kerberos.principal`, `dfs.namenode.kerberos.principal`
+  and `dfs.datanode.kerberos.principal` in the discovery ConfigMap in case Kerberos is enabled ([#451]).
+
 [#433]: https://github.com/stackabletech/hdfs-operator/pull/433
+[#451]: https://github.com/stackabletech/hdfs-operator/pull/451
 
 ## [23.11.0] - 2023-11-24
 

docs/modules/hdfs/pages/reference/discovery.adoc

@@ -37,4 +37,13 @@ The ConfigMap data values are formatted as Hadoop XML files which allows simple
 Contains the `fs.DefaultFS` which defaults to `hdfs://{clusterName}/`.
 
 `hdfs-site.xml`::
-Contains the `dfs.namenode.*` properties for `rpc` and `http` addresses for the `namenodes` as well as the `dfs.nameservices` property which defaults to `hdfs://{clusterName}/`.
+Contains the `dfs.namenode.*` properties for `rpc` and `http` addresses for the `namenodes` as well as the `dfs.nameservices` property which defaults to `hdfs://{clusterName}/`.
+
+=== Kerberos
+In case Kerberos is enabled according to the xref:usage-guide/security.adoc[security documentation], the discovery ConfigMap also includes the information that clients must authenticate themselves using Kerberos.
+
+Some Kerberos-related configuration settings require the environment variable `KERBEROS_REALM` to be set (e.g. using `export KERBEROS_REALM=$(grep -oP 'default_realm = \K.*' /stackable/kerberos/krb5.conf)`).
+If you want to use the discovery ConfigMap outside Stackable services, you need to provide this environment variable.
+As an alternative you can substitute `${env.KERBEROS_REALM}` with your actual realm (e.g. by using `sed -i -e 's/${{env.KERBEROS_REALM}}/'"$KERBEROS_REALM/g" core-site.xml`).
+
+One example would be the property `dfs.namenode.kerberos.principal` being set to `nn/hdfs.default.svc.cluster.local@${env.KERBEROS_REALM}`.

rust/crd/src/lib.rs

@@ -441,6 +441,11 @@ impl HdfsRole {
 }
 
 impl HdfsCluster {
+    /// Return the namespace of the cluster or an error in case it is not set.
+    pub fn namespace_or_error(&self) -> Result<String, Error> {
+        self.namespace().context(NoNamespaceSnafu)
+    }
+
     /// Kubernetes labels to attach to Pods within a role group.
     ///
     /// The same labels are also used as selectors for Services and StatefulSets.

rust/operator-binary/src/discovery.rs

@@ -1,6 +1,7 @@
 use crate::{
     build_recommended_labels,
     config::{CoreSiteConfigBuilder, HdfsSiteConfigBuilder},
+    hdfs_controller::Error,
 };
 use stackable_hdfs_crd::{
     constants::{CORE_SITE_XML, HDFS_SITE_XML},
@@ -9,9 +10,8 @@ use stackable_hdfs_crd::{
 use stackable_operator::{
     builder::{ConfigMapBuilder, ObjectMetaBuilder},
     commons::product_image_selection::ResolvedProductImage,
-    error::OperatorResult,
     k8s_openapi::api::core::v1::ConfigMap,
-    kube::ResourceExt,
+    kube::{runtime::reflector::ObjectRef, ResourceExt},
 };
 
 /// Creates a discovery config map containing the `hdfs-site.xml` and `core-site.xml`
@@ -21,12 +21,16 @@ pub fn build_discovery_configmap(
     controller: &str,
     namenode_podrefs: &[HdfsPodRef],
     resolved_product_image: &ResolvedProductImage,
-) -> OperatorResult<ConfigMap> {
+) -> Result<ConfigMap, crate::hdfs_controller::Error> {
     ConfigMapBuilder::new()
         .metadata(
             ObjectMetaBuilder::new()
                 .name_and_namespace(hdfs)
-                .ownerreference_from_resource(hdfs, None, Some(true))?
+                .ownerreference_from_resource(hdfs, None, Some(true))
+                .map_err(|err| Error::ObjectMissingMetadataForOwnerRef {
+                    source: err,
+                    obj_ref: ObjectRef::from_obj(hdfs),
+                })?
                 .with_recommended_labels(build_recommended_labels(
                     hdfs,
                     controller,
@@ -42,9 +46,10 @@ pub fn build_discovery_configmap(
         )
         .add_data(
             CORE_SITE_XML,
-            build_discovery_core_site_xml(hdfs, hdfs.name_any()),
+            build_discovery_core_site_xml(hdfs, hdfs.name_any())?,
         )
         .build()
+        .map_err(|err| Error::BuildDiscoveryConfigMap { source: err })
 }
 
 fn build_discovery_hdfs_site_xml(
@@ -62,9 +67,12 @@ fn build_discovery_hdfs_site_xml(
         .build_as_xml()
 }
 
-fn build_discovery_core_site_xml(hdfs: &HdfsCluster, logical_name: String) -> String {
-    CoreSiteConfigBuilder::new(logical_name)
+fn build_discovery_core_site_xml(
+    hdfs: &HdfsCluster,
+    logical_name: String,
+) -> Result<String, Error> {
+    Ok(CoreSiteConfigBuilder::new(logical_name)
         .fs_default_fs()
-        .security_discovery_config(hdfs)
-        .build_as_xml()
+        .security_discovery_config(hdfs)?
+        .build_as_xml())
 }

rust/operator-binary/src/hdfs_controller.rs

@@ -277,8 +277,7 @@ pub async fn reconcile_hdfs(hdfs: Arc<HdfsCluster>, ctx: Arc<Ctx>) -> HdfsOperat
         HDFS_CONTROLLER,
         &namenode_podrefs,
         &resolved_product_image,
-    )
-    .context(BuildDiscoveryConfigMapSnafu)?;
+    )?;
 
     // The discovery CM is linked to the cluster lifecycle via ownerreference.
     // Therefore, must not be added to the "orphaned" cluster resources
@@ -482,11 +481,6 @@ fn rolegroup_config_map(
         .with_context(|| ObjectHasNoNameSnafu {
             obj_ref: ObjectRef::from_obj(hdfs),
         })?;
-    let hdfs_namespace = hdfs
-        .namespace()
-        .with_context(|| ObjectHasNoNamespaceSnafu {
-            obj_ref: ObjectRef::from_obj(hdfs),
-        })?;
 
     let mut hdfs_site_xml = String::new();
     let mut core_site_xml = String::new();
@@ -525,7 +519,7 @@ fn rolegroup_config_map(
                 core_site_xml = CoreSiteConfigBuilder::new(hdfs_name.to_string())
                     .fs_default_fs()
                     .ha_zookeeper_quorum()
-                    .security_config(hdfs, hdfs_name, &hdfs_namespace)
+                    .security_config(hdfs)?
                     // the extend with config must come last in order to have overrides working!!!
                     .extend(config)
                     .build_as_xml();

rust/operator-binary/src/kerberos.rs

@@ -2,7 +2,10 @@ use stackable_hdfs_crd::{
     constants::{SSL_CLIENT_XML, SSL_SERVER_XML},
     HdfsCluster,
 };
-use stackable_operator::commons::product_image_selection::ResolvedProductImage;
+use stackable_operator::{
+    commons::product_image_selection::ResolvedProductImage,
+    kube::{runtime::reflector::ObjectRef, ResourceExt},
+};
 
 use crate::{
     config::{CoreSiteConfigBuilder, HdfsSiteConfigBuilder},
@@ -52,29 +55,14 @@ impl HdfsSiteConfigBuilder {
 }
 
 impl CoreSiteConfigBuilder {
-    pub fn security_config(
-        &mut self,
-        hdfs: &HdfsCluster,
-        hdfs_name: &str,
-        hdfs_namespace: &str,
-    ) -> &mut Self {
+    pub fn security_config(&mut self, hdfs: &HdfsCluster) -> Result<&mut Self, Error> {
         if hdfs.authentication_config().is_some() {
-            // For a long time we tried using `_HOST` in principals, e.g. `jn/_HOST@REALM.COM`.
-            // Turns out there are a lot of code paths that check the principal of the requester using a reverse lookup of the incoming IP address
-            // and getting a different hostname than the principal has.
-            // What ultimately killed this approach was
-            //
-            // 2023-05-30 09:23:01,745 ERROR namenode.EditLogInputStream (EditLogFileInputStream.java:nextOpImpl(220)) - caught exception initializing https://hdfs-journalnode-default-1.hdfs-journalnode-default.kuttl-test-fine-rat.svc.cluster.local:8481/getJournal?jid=hdfs&segmentTxId=1&storageInfo=-65%3A595659877%3A1685437352616%3ACID-90c52400-5b07-49bf-bdbe-3469bbdc5ebb&inProgressOk=true
-            // org.apache.hadoop.hdfs.server.common.HttpGetFailedException: Fetch of https://hdfs-journalnode-default-1.hdfs-journalnode-default.kuttl-test-fine-rat.svc.cluster.local:8481/getJournal?jid=hdfs&segmentTxId=1&storageInfo=-65%3A595659877%3A1685437352616%3ACID-90c52400-5b07-49bf-bdbe-3469bbdc5ebb&inProgressOk=true failed with status code 403
-            // Response message:
-            // Only Namenode and another JournalNode may access this servlet
-            //
-            // After we have switched to using the following principals everything worked without problems
+            let principal_host_part = principal_host_part(hdfs)?;
 
-            let principal_host_part =
-                format!("{hdfs_name}.{hdfs_namespace}.svc.cluster.local@${{env.KERBEROS_REALM}}");
             self.add("hadoop.security.authentication", "kerberos")
-                .add("hadoop.registry.kerberos.realm", "${env.KERBEROS_REALM}")
+                // Not adding hadoop.registry.kerberos.realm, as it seems to not be used by our customers
+                // and would need text-replacement of the env var anyway.
+                // .add("hadoop.registry.kerberos.realm", "${env.KERBEROS_REALM}")
                 .add(
                     "dfs.journalnode.kerberos.principal",
                     format!("jn/{principal_host_part}"),
@@ -115,19 +103,58 @@ impl CoreSiteConfigBuilder {
 
             self.add_wire_encryption_settings();
         }
-        self
+        Ok(self)
     }
 
-    pub fn security_discovery_config(&mut self, hdfs: &HdfsCluster) -> &mut Self {
+    pub fn security_discovery_config(&mut self, hdfs: &HdfsCluster) -> Result<&mut Self, Error> {
         if hdfs.has_kerberos_enabled() {
-            self.add("hadoop.security.authentication", "kerberos");
+            let principal_host_part = principal_host_part(hdfs)?;
+
+            self.add("hadoop.security.authentication", "kerberos")
+                .add(
+                    "dfs.journalnode.kerberos.principal",
+                    format!("jn/{principal_host_part}"),
+                )
+                .add(
+                    "dfs.namenode.kerberos.principal",
+                    format!("nn/{principal_host_part}"),
+                )
+                .add(
+                    "dfs.datanode.kerberos.principal",
+                    format!("dn/{principal_host_part}"),
+                );
             self.add_wire_encryption_settings();
         }
-        self
+        Ok(self)
     }
 
     fn add_wire_encryption_settings(&mut self) -> &mut Self {
         self.add("hadoop.rpc.protection", "privacy");
         self
     }
 }
+
+/// For a long time we tried using `_HOST` in principals, e.g. `jn/_HOST@REALM.COM`.
+/// Turns out there are a lot of code paths that check the principal of the requester using a reverse lookup of the incoming IP address
+/// and getting a different hostname than the principal has.
+/// What ultimately killed this approach was
+///
+/// ```text
+/// 2023-05-30 09:23:01,745 ERROR namenode.EditLogInputStream (EditLogFileInputStream.java:nextOpImpl(220)) - caught exception initializing https://hdfs-journalnode-default-1.hdfs-journalnode-default.kuttl-test-fine-rat.svc.cluster.local:8481/getJournal?jid=hdfs&segmentTxId=1&storageInfo=-65%3A595659877%3A1685437352616%3ACID-90c52400-5b07-49bf-bdbe-3469bbdc5ebb&inProgressOk=true
+/// org.apache.hadoop.hdfs.server.common.HttpGetFailedException: Fetch of https://hdfs-journalnode-default-1.hdfs-journalnode-default.kuttl-test-fine-rat.svc.cluster.local:8481/getJournal?jid=hdfs&segmentTxId=1&storageInfo=-65%3A595659877%3A1685437352616%3ACID-90c52400-5b07-49bf-bdbe-3469bbdc5ebb&inProgressOk=true failed with status code 403
+/// Response message:
+/// Only Namenode and another JournalNode may access this servlet
+/// ```
+///
+/// After we have switched to using the following principals everything worked without problems
+fn principal_host_part(hdfs: &HdfsCluster) -> Result<String, Error> {
+    let hdfs_name = hdfs.name_any();
+    let hdfs_namespace = hdfs
+        .namespace_or_error()
+        .map_err(|_| Error::ObjectHasNoNamespace {
+            obj_ref: ObjectRef::from_obj(hdfs),
+        })?;
+    Ok(format!(
+        "{hdfs_name}.{hdfs_namespace}.svc.cluster.local@${{env.KERBEROS_REALM}}"
+    ))
+}