From 2dae2ac3ca7b0167355980bc8eb05d188e1d669e Mon Sep 17 00:00:00 2001
From: notplants <@notplants>
Date: Tue, 23 Jun 2026 16:46:20 +0000
Subject: [PATCH] fix(app): use stack-prefixed hostnames for redis and db
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The app service was missing DISCOURSE_REDIS_HOST entirely, so the
bitnami image defaulted to the bare hostname 'redis', which does not
resolve when the service is attached to multiple overlay networks
(proxy + internal) — causing a restart loop.

sidekiq had the same problem worse: both DISCOURSE_DATABASE_HOST=db
and DISCOURSE_REDIS_HOST=redis used bare hostnames instead of the
stack-prefixed service names. On a swarm stack the reliable DNS name
is ${STACK_NAME}_db / ${STACK_NAME}_redis.
---
 compose.yml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/compose.yml b/compose.yml
index 3365c28..dfc775c 100644
--- a/compose.yml
+++ b/compose.yml
@@ -16,6 +16,8 @@ services:
       - DISCOURSE_DATABASE_USER=discourse
       - DISCOURSE_HOST=${DOMAIN}
       - DISCOURSE_NOTIFICATION_EMAIL
+      # bare "redis" doesn't resolve when app is on multiple networks; use stack-prefixed name
+      - DISCOURSE_REDIS_HOST=${STACK_NAME}_redis
       - DISCOURSE_SMTP_AUTH
       - DISCOURSE_SMTP_HOST
       - DISCOURSE_SMTP_PORT
@@ -100,13 +102,13 @@ services:
       - db_password
     environment:
       - ALLOW_EMPTY_PASSWORD=yes
-      - DISCOURSE_DATABASE_HOST=db
+      - DISCOURSE_DATABASE_HOST=${STACK_NAME}_db
       - DISCOURSE_DATABASE_NAME=discourse
       - DISCOURSE_DATABASE_PASSWORD_FILE=/run/secrets/db_password
       - DISCOURSE_DATABASE_PORT_NUMBER=5432
       - DISCOURSE_DATABASE_USER=discourse
       - DISCOURSE_HOST=${DOMAIN}
-      - DISCOURSE_REDIS_HOST=redis
+      - DISCOURSE_REDIS_HOST=${STACK_NAME}_redis
       - DISCOURSE_REDIS_PORT_NUMBER=6379
       - DISCOURSE_SMTP_HOST
       - DISCOURSE_SMTP_PORT