fix/conduktor-pgsql: Fix Postgres mount point and healthcheck in compose files

Change volume mount from /var/lib/postgresql/data to /var/lib/postgresql
and use $$POSTGRES_USER env var in pg_isready healthcheck instead of
hardcoded username across all compose files.

Fix for postgres:18-alpine and later versions since
docker-library/postgres#1394

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: iobruno

module6-stream-processing/compose.kraft-multi-broker.yaml

@@ -223,9 +223,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-metastore:/var/lib/postgresql/data
+      - vol-conduktor-metastore:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5
@@ -243,9 +243,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-sql:/var/lib/postgresql/data
+      - vol-conduktor-sql:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5

module6-stream-processing/compose.kraft-single-broker.yaml

@@ -187,9 +187,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-metastore:/var/lib/postgresql/data
+      - vol-conduktor-metastore:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5
@@ -207,9 +207,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-sql:/var/lib/postgresql/data
+      - vol-conduktor-sql:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5

module6-stream-processing/compose.redpanda.yaml

@@ -69,9 +69,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-metastore:/var/lib/postgresql/data
+      - vol-conduktor-metastore:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5
@@ -89,9 +89,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-sql:/var/lib/postgresql/data
+      - vol-conduktor-sql:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5

module6-stream-processing/compose.zookeeper-multi-broker.yaml

@@ -244,9 +244,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-metastore:/var/lib/postgresql/data
+      - vol-conduktor-metastore:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5
@@ -264,9 +264,9 @@ services:
     ports:
       - '5432'
     volumes:
-      - vol-conduktor-sql:/var/lib/postgresql/data
+      - vol-conduktor-sql:/var/lib/postgresql
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
       interval: 5s
       timeout: 5s
       retries: 5