From 7593d969e316cc0144bce378a5be58c76c2c37ee Mon Sep 17 00:00:00 2001 From: Slavi Pantaleev Date: Thu, 10 Dec 2020 23:51:11 +0200 Subject: [PATCH] Make matrix-mailer not occupy matrix_server_fqn_matrix Starting with Docker 20.10, `--hostname` seems to have the side-effect of making Docker's internal DNS server resolve said hostname to the IP address of the container. Because we were giving the mailer service a hostname of `matrix.DOMAIN`, all requests destined for `matrix.DOMAIN` originating from other services on the container network were resolving to `matrix-mailer`. This is obviously wrong. Initially reported here: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/748 We normally try to not use the public hostname (and IP address) on the container network and try to make services talk to one another locally, but it sometimes could happen. With this, we use a `matrix-mailer` hostname for the matrix-mailer container. My testing shows that it doesn't cause any trouble with email deliverability. --- roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 b/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 index cab031288..9345a1d6d 100644 --- a/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 +++ b/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 @@ -19,7 +19,7 @@ ExecStart={{ matrix_host_command_docker }} run --rm --name matrix-mailer \ --tmpfs=/var/spool/exim:rw,noexec,nosuid,size=100m \ --network={{ matrix_docker_network }} \ --env-file={{ matrix_mailer_base_path }}/env-mailer \ - --hostname={{ matrix_server_fqn_matrix }} \ + --hostname=matrix-mailer \ {% for arg in matrix_mailer_container_extra_arguments %} {{ arg }} \ {% endfor %}