Use explicit variables for postgres/rabbitmq passwords.

This replaces the old default constants of `zulip`, which could be
confused with the usernames (etc.), and adds some more explanatory
comments.

docker-compose.yml

@@ -3,12 +3,12 @@ services:
   database:
     image: 'zulip/zulip-postgresql'
     environment:
-      POSTGRES_DB: zulip
-      POSTGRES_USER: zulip
+      POSTGRES_DB: 'zulip'
+      POSTGRES_USER: 'zulip'
       # Note that you need to do a manual `ALTER ROLE` query if you
       # change this on a system after booting the postgres container
       # the first time on a host.  Instructions are available in README.md.
-      POSTGRES_PASSWORD: zulip
+      POSTGRES_PASSWORD: 'REPLACE_WITH_SECURE_POSTGRES_PASSWORD'
     volumes:
       - '/opt/docker/zulip/postgresql/data:/var/lib/postgresql/data:rw'
   memcached:
@@ -20,7 +20,7 @@ services:
     restart: always
     environment:
         RABBITMQ_DEFAULT_USER: 'zulip'
-        RABBITMQ_DEFAULT_PASS: 'zulip'
+        RABBITMQ_DEFAULT_PASS: 'REPLACE_WITH_SECURE_RABBITMQ_PASSWORD'
     volumes:
       - '/opt/docker/zulip/rabbitmq:/var/lib/rabbitmq:rw'
   redis:
@@ -50,8 +50,8 @@ services:
       SETTING_REDIS_HOST: 'redis'
       SECRETS_email_password: '123456789'
       # These should match POSTGRES_PASSWORD and RABBITMQ_DEFAULT_PASS.
-      SECRETS_rabbitmq_password: 'zulip'
-      SECRETS_postgres_password: 'zulip'
+      SECRETS_rabbitmq_password: 'REPLACE_WITH_SECURE_RABBITMQ_PASSWORD'
+      SECRETS_postgres_password: 'REPLACE_WITH_SECURE_POSTGRES_PASSWORD'
       SECRETS_secret_key: 'REPLACE_WITH_SECURE_SECRET_KEY'
       SETTING_EXTERNAL_HOST: 'localhost.localdomain'
       SETTING_ZULIP_ADMINISTRATOR: 'admin@example.com'

kubernetes/zulip-rc.yml

@@ -41,7 +41,7 @@ spec:
         - name: RABBITMQ_DEFAULT_USER
           value: "zulip"
         - name: RABBITMQ_DEFAULT_PASS
-          value: "zulip"
+          value: "REPLACE_WITH_SECURE_RABBITMQ_PASSWORD"
         volumeMounts:
           - name: rabbitmq-persistent-storage
             mountPath: /var/lib/rabbitmq
@@ -57,7 +57,7 @@ spec:
         - name: POSTGRES_USER
           value: zulip
         - name: POSTGRES_PASSWORD
-          value: zulip
+          value: REPLACE_WITH_SECURE_POSTGRES_PASSWORD
         volumeMounts:
           - name: postgresql-persistent-storage
             mountPath: /var/lib/postgresql
@@ -97,8 +97,11 @@ spec:
           value: '123456789'
         - name: SECRETS_secret_key
           value: 'REPLCAE_WITH_SECURE_SECRET_KEY'
+        # These should match the passwords configured above
         - name: SECRETS_postgres_password
-          value: 'zulip'
+          value: 'REPLACE_WITH_SECURE_POSTGRES_PASSWORD'
+        - name: SECRETS_rabbitmq_password
+          value: 'REPLACE_WITH_SECURE_RABBITMQ_PASSWORD'
         - name: SSL_CERTIFICATE_GENERATION
           value: 'self-signed'
         # Uncomment this when configuring the mobile push notifications service