Makes static (pre-generated) configuration files possible

Experimental, based on the assumption that things like broker.rack
and listener addresses can be set using --overide flags with ev expansion.

If we had the statefulset por-ordinal label we could set those things too,
but now we need to rely on the pod name (+ for zookeeper ID_OFFSET).

Author: solsson

kafka/10broker-config.yml

@@ -41,6 +41,7 @@ data:
     }
     printf '%s\n' "${SEDS[@]}" | sed -f - /etc/kafka-configmap/server.properties > /etc/kafka/server.properties.tmp
     [ $? -eq 0 ] && mv /etc/kafka/server.properties.tmp /etc/kafka/server.properties
+    ln -s /etc/kafka/server.properties /etc/kafka/server.properties.$POD_NAME
 
   server.properties: |-
     ############################# Log Basics #############################

kafka/50kafka.yml

@@ -47,6 +47,10 @@ spec:
       - name: broker
         image: solsson/kafka:2.4.0@sha256:201a1c7fd378405b6b1bfd801127c8a530ed7a971282bfcee4ec731bc0c50ad2
         env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: CLASSPATH
           value: /opt/kafka/libs/extensions/*
         - name: KAFKA_LOG4J_OPTS
@@ -62,7 +66,7 @@ spec:
           containerPort: 5555
         command:
         - ./bin/kafka-server-start.sh
-        - /etc/kafka/server.properties
+        - /etc/kafka/server.properties.$(POD_NAME)
         lifecycle:
           preStop:
             exec:

zookeeper/10zookeeper-config.yml

@@ -20,6 +20,7 @@ data:
       for N in $(seq $ZOO_REPLICAS); do echo "server.$(( $PZOO_REPLICAS + $N ))=zoo-$(( $N - 1 )).zoo:2888:3888:participant" >> /etc/kafka/zookeeper.properties; done
     }
     sed -i "s/server\.$ZOOKEEPER_SERVER_ID\=[a-z0-9.-]*/server.$ZOOKEEPER_SERVER_ID=0.0.0.0/" /etc/kafka/zookeeper.properties
+    ln -s /etc/kafka/zookeeper.properties /etc/kafka/zookeeper.properties.$POD_NAME
 
   zookeeper.properties: |
     4lw.commands.whitelist=ruok

zookeeper/50pzoo.yml

@@ -25,6 +25,11 @@ spec:
       - name: init-config
         image: solsson/kafka-initutils@sha256:f6d9850c6c3ad5ecc35e717308fddb47daffbde18eb93e98e031128fe8b899ef
         command: ['/bin/bash', '/etc/kafka-configmap/init.sh']
+        env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         volumeMounts:
         - name: configmap
           mountPath: /etc/kafka-configmap
@@ -36,11 +41,15 @@ spec:
       - name: zookeeper
         image: solsson/kafka:2.4.0@sha256:201a1c7fd378405b6b1bfd801127c8a530ed7a971282bfcee4ec731bc0c50ad2
         env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KAFKA_LOG4J_OPTS
           value: -Dlog4j.configuration=file:/etc/kafka/log4j.properties
         command:
         - ./bin/zookeeper-server-start.sh
-        - /etc/kafka/zookeeper.properties
+        - /etc/kafka/zookeeper.properties.$(POD_NAME)
         lifecycle:
           preStop:
             exec:

zookeeper/51zoo.yml

@@ -26,6 +26,10 @@ spec:
         image: solsson/kafka-initutils@sha256:f6d9850c6c3ad5ecc35e717308fddb47daffbde18eb93e98e031128fe8b899ef
         command: ['/bin/bash', '/etc/kafka-configmap/init.sh']
         env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: ID_OFFSET
           value: "4"
         volumeMounts:
@@ -39,11 +43,15 @@ spec:
       - name: zookeeper
         image: solsson/kafka:2.4.0@sha256:201a1c7fd378405b6b1bfd801127c8a530ed7a971282bfcee4ec731bc0c50ad2
         env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KAFKA_LOG4J_OPTS
           value: -Dlog4j.configuration=file:/etc/kafka/log4j.properties
         command:
         - ./bin/zookeeper-server-start.sh
-        - /etc/kafka/zookeeper.properties
+        - /etc/kafka/zookeeper.properties.$(POD_NAME)
         lifecycle:
           preStop:
             exec: