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fix(postfix-pgsql): disable chroot to fix pgsql lookup DNS resolution

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Damien
2026-06-26 11:17:36 +02:00
parent 0592bb2244
commit cc01910eb1
2 changed files with 13 additions and 0 deletions
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7
images/postfix-pgsql/README.md
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@@ -27,6 +27,13 @@ On startup, the entrypoint renders three files from templates under
- `/etc/postfix/pgsql-transport-maps.cf` — PostgreSQL lookup that tells - `/etc/postfix/pgsql-transport-maps.cf` — PostgreSQL lookup that tells
Postfix where to forward accepted mail (the internal SMTP relay target). Postfix where to forward accepted mail (the internal SMTP relay target).
Chroot is disabled for all Postfix services via `postconf -F '*/*/chroot = n'`
on every startup. Postfix's chrooted child processes (smtpd, trivial-rewrite,
etc.) lack access to `/etc/resolv.conf` inside the chroot jail, so they cannot
resolve Docker-internal hostnames — causing every PostgreSQL lookup to fail with
`451 4.3.0 Temporary lookup failure`. Disabling chroot is the standard remedy
in containerised deployments.
## Environment variables ## Environment variables
### Required ### Required

6
images/postfix-pgsql/docker-entrypoint.sh
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@@ -59,4 +59,10 @@ chmod 640 /etc/postfix/pgsql-relay-domains.cf /etc/postfix/pgsql-transport-maps.
postfix check postfix check
# Disable chroot for all master.cf services so child processes (smtpd,
# trivial-rewrite, etc.) can resolve Docker-internal hostnames via the host's
# /etc/resolv.conf. Without this, chrooted processes have no DNS and every
# pgsql lookup returns "451 4.3.0 Temporary lookup failure".
postconf -F '*/*/chroot = n'
exec /usr/sbin/postfix start-fg exec /usr/sbin/postfix start-fg