Clarify hostname and service name in external mongod search snippets (#483)

# Summary

This pull request updates the configuration and code snippets for
setting up an external MongoDB Search service to improve clarity and
consistency in variable naming. The main change is the introduction of
the `MDB_SEARCH_SERVICE_NAME` variable, replacing the previous use of
`MDB_SEARCH_HOSTNAME` for Kubernetes service references, while
`MDB_SEARCH_HOSTNAME` is now used specifically for the DNS hostname.

**Configuration variable updates:**

* Introduced `MDB_SEARCH_SERVICE_NAME` to represent the Kubernetes
service name and updated all related references in `env_variables.sh`
and `README.md`. The `MDB_SEARCH_HOSTNAME` variable is now used to
specify the DNS hostname (e.g., `mdbs-search.example.com`).
[[1]](diffhunk://#diff-e45215de7c861006344586b40839be9eff775ee82754ace9f0d83f208fcb127fL11-R12)
[[2]](diffhunk://#diff-78a9bbf913195ad01e7814be0a2937858af6c019f895fa45726b5730974bc78cL53-R54)

**Kubernetes service creation and referencing:**

* Updated service creation in
`04_0322_create_search_loadbalancer_service.sh` to use
`MDB_SEARCH_SERVICE_NAME` for the service name instead of
`MDB_SEARCH_HOSTNAME`.
* Changed all `kubectl` commands and log messages in scripts to
reference `MDB_SEARCH_SERVICE_NAME` instead of `MDB_SEARCH_HOSTNAME`,
ensuring consistency throughout the deployment process.
[[1]](diffhunk://#diff-3b631e2e08f0d1e1b57c8118a489bd479473d66343885e68b50f8614589a2954L16-R20)
[[2]](diffhunk://#diff-7f7d23e97cadad8c2d81c63dab8f285f921bfbd83f39940febd47989a60986e1L1-R7)

## Proof of Work

Snippet tests pass

Author: anandsyncs

docs/search/04-search-external-mongod/README.md

@@ -50,7 +50,8 @@ export MDB_USER_PASSWORD="mdb-user-password-CHANGE-ME"
 # user for MongoDB Search to connect to the replica set to synchronise data from
 export MDB_SEARCH_SYNC_USER_PASSWORD="search-sync-user-password-CHANGE-ME"
 
-export MDB_SEARCH_HOSTNAME="mdbs-search"
+export MDB_SEARCH_SERVICE_NAME="mdbs-search"
+export MDB_SEARCH_HOSTNAME="mdbs-search.example.com"
 
 # External MongoDB replica set members - REPLACE THESE VALUES with your actual external MongoDB hosts
 # For testing purposes, these point to the MongoDB Community resource created by test.sh

docs/search/04-search-external-mongod/code_snippets/04_0322_create_search_loadbalancer_service.sh

@@ -2,7 +2,7 @@ kubectl apply --context "${K8S_CTX}" -n "${MDB_NS}" -f - <<YAML
 apiVersion: v1
 kind: Service
 metadata:
-  name: ${MDB_SEARCH_HOSTNAME}
+  name: ${MDB_SEARCH_SERVICE_NAME}
 spec:
   type: LoadBalancer
   selector:
@@ -13,11 +13,11 @@ spec:
       targetPort: 27027
 YAML
 
-echo "Waiting for external IP to be assigned to service ${MDB_SEARCH_HOSTNAME}..."
+echo "Waiting for external IP to be assigned to service ${MDB_SEARCH_SERVICE_NAME}..."
 TIMEOUT=120  # 2 minutes timeout
 ELAPSED=0
 while [ ${ELAPSED} -lt ${TIMEOUT} ]; do
-  EXTERNAL_IP=$(kubectl get service "${MDB_SEARCH_HOSTNAME}" --context "${K8S_CTX}" -n "${MDB_NS}" -o jsonpath='{.status.loadBalancer.ingress[0].ip}' 2>/dev/null)
+  EXTERNAL_IP=$(kubectl get service "${MDB_SEARCH_SERVICE_NAME}" --context "${K8S_CTX}" -n "${MDB_NS}" -o jsonpath='{.status.loadBalancer.ingress[0].ip}' 2>/dev/null)
   if [ -n "${EXTERNAL_IP}" ] && [ "${EXTERNAL_IP}" != "null" ]; then
     echo "External IP assigned: ${EXTERNAL_IP}"
     break

docs/search/04-search-external-mongod/code_snippets/04_0323_update_coredns_configmap.sh

@@ -1,10 +1,10 @@
-SEARCH_IP=$(kubectl --context "${K8S_CTX}" -n "${MDB_NS}" get svc "${MDB_SEARCH_HOSTNAME}" -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+SEARCH_IP=$(kubectl --context "${K8S_CTX}" -n "${MDB_NS}" get svc "${MDB_SEARCH_SERVICE_NAME}" -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
 if [ -z "${SEARCH_IP}" ]; then
-  SEARCH_IP=$(kubectl --context "${K8S_CTX}" -n "${MDB_NS}" get svc "${MDB_SEARCH_HOSTNAME}" -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')
+  SEARCH_IP=$(kubectl --context "${K8S_CTX}" -n "${MDB_NS}" get svc "${MDB_SEARCH_SERVICE_NAME}" -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')
 fi
 
 if [ -z "${SEARCH_IP}" ]; then
-  echo "Error: Could not get LoadBalancer external IP/hostname for service ${MDB_SEARCH_HOSTNAME}"
+  echo "Error: Could not get LoadBalancer external IP/hostname for service ${MDB_SEARCH_SERVICE_NAME}"
   exit 1
 fi
 

docs/search/04-search-external-mongod/env_variables.sh

@@ -8,7 +8,8 @@ export MDB_ADMIN_USER_PASSWORD="admin-user-password-CHANGE-ME"
 export MDB_USER_PASSWORD="mdb-user-password-CHANGE-ME"
 export MDB_SEARCH_SYNC_USER_PASSWORD="search-sync-user-password-CHANGE-ME"
 
-export MDB_SEARCH_HOSTNAME="mdbs-search"
+export MDB_SEARCH_SERVICE_NAME="mdbs-search"
+export MDB_SEARCH_HOSTNAME="mdbs-search.example.com"
 
 # External MongoDB replica set members - REPLACE THESE VALUES with your actual external MongoDB hosts
 # In production, replace with your actual external MongoDB replica set members