[FIX] runbot: find docker gateway for build smtp host

When a build is running, the stmp is the localhost.
Since Docker builds, the localhost is the container which does not catch
port 25 smtp. Mails are lost in the limbo.

With this commit, the default gateway of the Docker network is used as
smtp host for the builds. It's the responsability of the runbot host to
catch smtp traffic from the container.

This bridge interface exists by default on a system where Docker is
running. However, Docker is affected by this issue:
https://github.com/moby/moby/issues/26799

The first time the Docker daemon is installed, the Gateway is not
defined on the bridge interface. When the Docker daemon is restarted,
the gateway is correctly defined. Pay attention that restarting the
Docker daemon will kill all the running/testing builds.

runbot/container.py

@@ -10,6 +10,7 @@ When testing this file:
 """
 import argparse
 import datetime
+import json
 import logging
 import os
 import shutil
@@ -97,6 +98,17 @@ def docker_is_running(container_name):
     dinspect = subprocess.run(['docker', 'container', 'inspect', container_name], stderr=subprocess.DEVNULL, stdout=subprocess.DEVNULL)
     return True if dinspect.returncode == 0 else False
 
+def docker_get_gateway_ip():
+    """Return the host ip of the docker default bridge gateway"""
+    docker_net_inspect = subprocess.run(['docker', 'network', 'inspect', 'bridge'], stdout=subprocess.PIPE)
+    if docker_net_inspect.returncode != 0:
+        return None
+    if docker_net_inspect.stdout:
+        try:
+            return json.loads(docker_net_inspect.stdout)[0]['IPAM']['Config'][0]['Gateway']
+        except KeyError:
+            return None
+
 def build(args):
     """Build container from CLI"""
     _logger.info('Building the base image container')
@@ -157,6 +169,9 @@ def tests(args):
             '-r %s' % os.getlogin(), '-i', 'web',  '--max-cron-threads=1',
             '--data-dir', '/data/build/datadir', '--workers', '2',
             '--longpolling-port', '8070']
+        smtp_host = docker_get_gateway_ip()
+        if smtp_host:
+            odoo_cmd.extend(['--smtp', smtp_host])
         container_name = 'odoo-container-test-%s' % datetime.datetime.now().microsecond
         docker_run(odoo_cmd, logfile, args.build_dir, container_name, exposed_ports=[args.odoo_port, args.odoo_port + 1], cpu_limit=300)
 

runbot/models/build.py

@@ -12,7 +12,7 @@ import subprocess
 import time
 from subprocess import CalledProcessError
 from ..common import dt2time, fqdn, now, grep, time2str, rfind, uniq_list, local_pgadmin_cursor, get_py_version
-from ..container import docker_build, docker_run, docker_stop, docker_is_running
+from ..container import docker_build, docker_run, docker_stop, docker_is_running, docker_get_gateway_ip
 from odoo import models, fields, api
 from odoo.exceptions import UserError
 from odoo.http import request
@@ -840,4 +840,7 @@ class runbot_build(models.Model):
                 cmd += ['--db-filter', '%d.*$']
             else:
                 cmd += ['--db-filter', '%s.*$' % build.dest]
+        smtp_host = docker_get_gateway_ip()
+        if smtp_host:
+            cmd += ['--smtp', smtp_host]
         return docker_run(cmd, log_path, build._path(), build._get_docker_name(), exposed_ports = [build.port, build.port + 1])