set unique PGDATA for each standby server

Author: taoxuau

db/Dockerfile

@@ -11,3 +11,7 @@ ARG mode
 #          with a data directory that is empty
 # See https://docs.docker.com/samples/library/postgres/#initialization-scripts
 COPY ./pg.$mode.setup.sh /docker-entrypoint-initdb.d/pg.$mode.setup.sh
+
+# Set PGDATA immediate after shebang
+RUN set -ex \
+  && sed -i "2s/^/PGDATA=\/var\/lib\/postgresql\/data\/$mode\/"'$HOSTNAME'"\n\n/" /usr/local/bin/docker-entrypoint.sh

db/pg.master.env

@@ -1,5 +1,4 @@
 # database
-PGDATA=/var/lib/postgresql/data/pgdata_master
 POSTGRES_USER=devops
 POSTGRES_PASSWORD=devops
 POSTGRES_DB=postgres

db/pg.standby.env

@@ -1,5 +1,4 @@
 # database
-PGDATA=/var/lib/postgresql/data/pgdata_standby
 PG_MASTER_HOST=db.master
 PG_MASTER_PORT=5432
 PG_MASTER_REP_USER=devops_rep