feat: Make OPENSEARCH_HOME and OPENSEARCH_PATH_CONF overridable (#18)

* Make OPENSEARCH_HOME configurable

* doc: Document the environment variables OPENSEARCH_HOME and OPENSEARCH_PATH_CONF

* chore: Update changelog

Author: siegfriedweber

CHANGELOG.md

@@ -17,6 +17,9 @@ All notable changes to this project will be documented in this file.
   - PodDisruptionBudgets
   - Replicas
 - Add Listener support ([#17]).
+- Make the environment variables `OPENSEARCH_HOME` and `OPENSEARCH_PATH_CONF` overridable, so that
+  images can be used which have a different directory structure than the Stackable image ([#18]).
 
 [#10]: https://github.com/stackabletech/opensearch-operator/pull/10
 [#17]: https://github.com/stackabletech/opensearch-operator/pull/17
+[#18]: https://github.com/stackabletech/opensearch-operator/pull/18

docs/modules/opensearch/pages/usage-guide/configuration-environment-overrides.adoc

@@ -131,7 +131,7 @@ nodes:
     default:
       config: {}
       envOverrides:
-        OPENSEARCH_PATH_CONF: /etc/opensearch
+        OPENSEARCH_HOME: /usr/share/opensearch
 ----
 
 or per role:
@@ -140,12 +140,21 @@ or per role:
 ----
 nodes:
   envOverrides:
-    OPENSEARCH_PATH_CONF: /etc/opensearch
+    OPENSEARCH_HOME: /usr/share/opensearch
   roleGroups:
     default:
       config: {}
 ----
 
+The environment variables `OPENSEARCH_HOME` and `OPENSEARCH_PATH_CONF` are worth mentioning.
+`OPENSEARCH_HOME` contains the path in the image where OpenSearch is installed.
+`OPENSEARCH_PATH_CONF` contains the path with the OpenSearch configuration files.
+They are usually set in the image.
+In the Stackable image, `OPENSEARCH_HOME` is set to `/stackable/opensearch` and `OPENSEARCH_PATH_CONF` to `$\{OPENSEARCH_HOME}/config`.
+The operator must also know the values of these environment variables to mount volumes to the correct paths.
+Since the operator cannot read the values from the image, it assumes the ones from the Stackable image.
+If you use a custom image with different paths, you can override one or both of these environment variables as shown in the example above.
+
 == CLI parameters
 
 CLI parameters can be set with `cliOverrides` per role group:

rust/operator-binary/src/controller/build/role_group_builder.rs

@@ -41,8 +41,7 @@ const DATA_VOLUME_NAME: &str = "data";
 const LISTENER_VOLUME_NAME: &str = "listener";
 const LISTENER_VOLUME_DIR: &str = "/stackable/listener";
 
-// Path in opensearchproject/opensearch:3.0.0
-const OPENSEARCH_BASE_PATH: &str = "/stackable/opensearch";
+const DEFAULT_OPENSEARCH_HOME: &str = "/stackable/opensearch";
 
 pub struct RoleGroupBuilder<'a> {
     service_account_name: String,
@@ -271,26 +270,40 @@ impl<'a> RoleGroupBuilder<'a> {
             ..Probe::default()
         };
 
+        let env_vars = self.node_config.environment_variables();
+
+        // Use `OPENSEARCH_HOME` from envOverrides or default to `DEFAULT_OPENSEARCH_HOME`.
+        let opensearch_home = env_vars
+            .get_env_var("OPENSEARCH_HOME")
+            .and_then(|env_var| env_var.value.clone())
+            .unwrap_or(DEFAULT_OPENSEARCH_HOME.to_owned());
+        // Use `OPENSEARCH_PATH_CONF` from envOverrides or default to `{OPENSEARCH_HOME}/config`,
+        // i.e. depend on `OPENSEARCH_HOME`.
+        let opensearch_path_conf = env_vars
+            .get_env_var("OPENSEARCH_PATH_CONF")
+            .and_then(|env_var| env_var.value.clone())
+            .unwrap_or(format!("{opensearch_home}/config"));
+
         ContainerBuilder::new("opensearch")
             .expect("should be a valid container name")
             .image_from_product_image(&product_image)
             .command(vec![format!(
-                "{OPENSEARCH_BASE_PATH}/opensearch-docker-entrypoint.sh"
+                "{opensearch_home}/opensearch-docker-entrypoint.sh"
             )])
             .args(role_group_config.cli_overrides_to_vec())
-            .add_env_vars(self.node_config.environment_variables().into())
+            .add_env_vars(env_vars.into())
             .add_volume_mounts([
                 VolumeMount {
                     mount_path: format!(
-                        "{OPENSEARCH_BASE_PATH}/config/{CONFIGURATION_FILE_OPENSEARCH_YML}"
+                        "{opensearch_path_conf}/{CONFIGURATION_FILE_OPENSEARCH_YML}"
                     ),
                     name: CONFIG_VOLUME_NAME.to_owned(),
                     read_only: Some(true),
                     sub_path: Some(CONFIGURATION_FILE_OPENSEARCH_YML.to_owned()),
                     ..VolumeMount::default()
                 },
                 VolumeMount {
-                    mount_path: format!("{OPENSEARCH_BASE_PATH}/data"),
+                    mount_path: format!("{opensearch_home}/data"),
                     name: DATA_VOLUME_NAME.to_owned(),
                     ..VolumeMount::default()
                 },

rust/operator-binary/src/framework/builder/pod/container.rs

@@ -16,6 +16,22 @@ impl EnvVarSet {
         Self::default()
     }
 
+    pub fn get_env_var(&self, env_var_name: impl Into<EnvVarName>) -> Option<&EnvVar> {
+        self.0.get(&env_var_name.into())
+    }
+
+    pub fn add_env_var(mut self, env_var: EnvVar) -> Self {
+        self.0.insert(env_var.name.clone(), env_var);
+
+        self
+    }
+
+    pub fn merge(mut self, mut env_var_set: EnvVarSet) -> Self {
+        self.0.append(&mut env_var_set.0);
+
+        self
+    }
+
     pub fn with_values<I, K, V>(self, env_vars: I) -> Self
     where
         I: IntoIterator<Item = (K, V)>,

tests/templates/kuttl/external-access/opensearch.yaml.j2

@@ -5,7 +5,12 @@ metadata:
   name: opensearch
 spec:
   image:
-    productVersion: 3.1.0
+{% if test_scenario['values']['opensearch'].find(",") > 0 %}
+    custom: "{{ test_scenario['values']['opensearch'].split(',')[1] }}"
+    productVersion: "{{ test_scenario['values']['opensearch'].split(',')[0] }}"
+{% else %}
+    productVersion: "{{ test_scenario['values']['opensearch'] }}"
+{% endif %}
     pullPolicy: IfNotPresent
   nodes:
     roleGroups:
@@ -57,6 +62,7 @@ spec:
     envOverrides:
       # TODO Make these the defaults in the image
       DISABLE_INSTALL_DEMO_CONFIG: "true"
+      OPENSEARCH_HOME: {{ test_scenario['values']['opensearch_home'] }}
     configOverrides:
       # TODO Add the required options to the operator
       opensearch.yml:
@@ -66,24 +72,25 @@ spec:
         # TODO Check that this is safe despite the warning in the documentation
         plugins.security.allow_default_init_securityindex: "true"
         plugins.security.ssl.transport.enabled: "true"
-        plugins.security.ssl.transport.pemcert_filepath: /stackable/opensearch/config/tls/tls.crt
-        plugins.security.ssl.transport.pemkey_filepath: /stackable/opensearch/config/tls/tls.key
-        plugins.security.ssl.transport.pemtrustedcas_filepath: /stackable/opensearch/config/tls/ca.crt
+        plugins.security.ssl.transport.pemcert_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/tls.crt
+        plugins.security.ssl.transport.pemkey_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/tls.key
+        plugins.security.ssl.transport.pemtrustedcas_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/ca.crt
         plugins.security.ssl.http.enabled: "true"
-        plugins.security.ssl.http.pemcert_filepath: /stackable/opensearch/config/tls/tls.crt
-        plugins.security.ssl.http.pemkey_filepath: /stackable/opensearch/config/tls/tls.key
-        plugins.security.ssl.http.pemtrustedcas_filepath: /stackable/opensearch/config/tls/ca.crt
+        plugins.security.ssl.http.pemcert_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/tls.crt
+        plugins.security.ssl.http.pemkey_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/tls.key
+        plugins.security.ssl.http.pemtrustedcas_filepath: {{ test_scenario['values']['opensearch_home'] }}/config/tls/ca.crt
         plugins.security.authcz.admin_dn: "CN=generated certificate for pod"
     podOverrides:
       spec:
         containers:
           - name: opensearch
             volumeMounts:
               - name: security-config
-                mountPath: /stackable/opensearch/config/opensearch-security
+                mountPath: {{ test_scenario['values']['opensearch_home'] }}/config/opensearch-security
                 readOnly: true
               - name: tls
-                mountPath: /stackable/opensearch/config/tls
+                # The Java policy allows reading from ${OPENSEARCH_HOME}/config.
+                mountPath: {{ test_scenario['values']['opensearch_home'] }}/config/tls
                 readOnly: true
         securityContext:
           fsGroup: 1000