I need to install Discourse in Ubuntu by using Docker

I have installed Discourse in Ubuntu by using Docker . I am unable to get the activation email . Will you provide any guidance. And I’m getting logs like below:

run-parts: executing /etc/runit/1.d/00-ensure-links run-parts: executing /etc/runit/1.d/00-fix-var-logs run-parts: executing /etc/runit/1.d/anacron run-parts: executing /etc/runit/1.d/cleanup-pids Cleaning stale PID files run-parts: executing /etc/runit/1.d/copy-env Started runsvdir, PID is 38 ok: run: redis: (pid 51) 0s ok: run: postgres: (pid 47) 0s chgrp: invalid group: ‘syslog’ rsyslogd: imklog: cannot open kernel log (/proc/kmsg): Operation not permitted. rsyslogd: activation of module imklog failed [v8.1901.0 try https://www.rsyslog.com/e/2145 ] supervisor pid: 48 unicorn pid: 76   
```

And setting in app.yml:

```yaml
--DISCOURSE_SMTP_ADDRESS: smtp.google.com   
DISCOURSE_SMTP_PORT: 587   
DISCOURSE_SMTP_USER_NAME: sample@gmail.com   
DISCOURSE_SMTP_PASSWORD: password   
DISCOURSE_SMTP_ENABLE_START_TLS: false
```