Opened port 25 in container to docker host (for SMTP)

[namangupta01]

Closes #2065

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[icarito]

I was researching this and I think this could be a part of the solution.
In order to work in production I'd need to alias smtp to localhost.
Then in order to work in staging, we'd need to figure out a way to bind smtp hostname to the docker host. Some documentation on it here https://stackoverflow.com/questions/17770902/forward-host-port-to-docker-container .

Summarizing @jywarren it's a good idea but requires:
[ ] - smtp alias in production
[ ] - smtp alias dockerhost in docker-compose.yml file
[ ] - configure host exim to listen on docker virtual network (currently only listens to localhost).

[namangupta01]

@icarito so the problem is that :
We have a docker container for staging and we have another docker container where we have smtp server setup so all we want to do here is to access one docker container port from another docker container?

[icarito]

@namangupta01 sorry, no. We do not have another container doing smtp.
In staging, the app is running in a container. The docker host is listening for SMTP on localhost.
In production, the app is running directly on the server (not yet in a container). The same server is listening for SMTP on localhost.

So we want to access the appropriate SMTP host in each instance.

This might become simpler once we have containers in production.

From the plan above, the one thing that needs to be done here is to somehow see if we can setup docker-compose.yml for the app to reach the docker host smtp service in staging, without breaking production.

[icarito]

Currently this would break production and doesn't by itself address the problem. Could we change smtp for localhost? This should work in production and is a step in the right direction because we will need to use SMTP in staging to fix the actual issue as well.
@jywarren this would change the default mail settings - perhaps it would be in order to leave a comment on how to setup sendmail instead?

[namangupta01]

@icarito I was researching over this issue, i want to know one thing where are you defining your smtp settings? In rails config files or in linux files?

[icarito]

Currently since plots2 runs locally in production, it relies on sendmail command, if I understood the configuration. But the host itself is listening to SMTP on localhost, so it should be safe to switch from sendmail to SMTP.

[namangupta01]

I think directly writing the smtp setting in config files should work everywhere:
Like this:
config.action_mailer.smtp_settings = { address: 'smtp.gmail.com', port: 587, domain: 'gmail.com', user_name: 'xyz@gmail.com', password: 'yourpassword', authentication: :plain, enable_starttls_auto: true } what do you say?

[icarito]

Yeah - a sensible default would be localhost:25 which is standard SMTP.

I think having the other options as comments would be great so they are easy to figure out.

[namangupta01]

I think using above configuration has nothing to do with whether it is running in container or directly.
And i think action_mailer.smtp_settings manages itself for standard SMTP but i'm not sure.

[namangupta01]

I have been using these settings in my projects and everything working fine for me https://github.com/namangupta01/MCQ/blob/master/config/environments/development.rb#L44

[icarito]

I don't know what you mean with manages itself :-)
The issue at hand is providing a mechanism for staging (docker-compose up -d) to send mail, without breaking production.
Thanks for trying to resolve it!

[jywarren]

What's the next step for this, do you think? Perhaps we should consider an approach that sets up a "fallback" mailing system that would be overridden by the production setup, but would silently accept mail (but not send it) from staging. What might that look like?

[jywarren]

Hi @icarito if you have some time to think about how this could work, we're hoping to test out #2257 based on fixing mail in staging; currently it doesn't let us test that out. What do you think? Thanks!

[icarito]

Hi Jeff, Previously I had thought this might need some kind of tunneling or proxying but was reluctant to add complexity. Since then we tested container in production and it had same problem, needed access to the a docker host service (production MySQL engine in this case). Just a note that we need to add something like this to `docker-compose-production.yml` ```     network_mode: "host" ``` ...in order to access Docker host smtp. In sum, we have a path forward. Regards, Sebastian

…

On 03/03/18 09:54, Jeffrey Warren wrote: Hi @icarito <https://github.com/icarito> if you have some time to think about how this could work, we're hoping to test out #2257 <#2257> based on fixing mail in staging; currently it doesn't let us test that out. What do you think? Thanks! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2095 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAMMSxQCbogkP0j2LK87fTFboyS-UDFQks5taq6ZgaJpZM4Rrl0R>.

[jywarren]

OK, so should we first create a separate docker-compose-production.yml in Git?

Thanks!

[jywarren]

@icarito - do we have to start version tracking docker-compose-production.yml then? Thanks!

[icarito]

No, we use docker-compose.yml in staging. We need to add a SMTP service to docker-compose.yml and set networking to `host`.

…

On 14/03/18 13:32, Jeffrey Warren wrote: @icarito <https://github.com/icarito> - do we have to start version tracking |docker-compose-production.yml| then? Thanks! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2095 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAMMS1ibOEN_brAW6EXioQEx-VmzKkxLks5teWIvgaJpZM4Rrl0R>.

[jywarren]

ah, perfect! On Wed, Mar 14, 2018 at 3:20 PM, Sebastian Silva <notifications@github.com> wrote:

…

No, we use docker-compose.yml in staging. We need to add a SMTP service to docker-compose.yml and set networking to `host`. On 14/03/18 13:32, Jeffrey Warren wrote: > > @icarito <https://github.com/icarito> - do we have to start version > tracking |docker-compose-production.yml| then? Thanks! > > — > You are receiving this because you were mentioned. > Reply to this email directly, view it on GitHub > <#2095 (comment)>, > or mute the thread > <https://github.com/notifications/unsubscribe- auth/AAMMS1ibOEN_brAW6EXioQEx-VmzKkxLks5teWIvgaJpZM4Rrl0R>. > — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2095 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AABfJ34YiIuNegRnnX9lhLC_yk6EnnASks5teW1qgaJpZM4Rrl0R> .

[jywarren]

Trying this in #2495 -- let's see if that passes! @icarito if it does, please go ahead and merge it so we can test in staging. Thanks!

[icarito]

Apologies I thought this would be simpler. The problem is that with containers SMTP won't be 127.0.0.1 unless we do some tricks that make everything more complex. See moby/moby#1143 for a discussion on this specific issue.
The simplest solution is to containerize the SMTP service.

[jywarren]

Great work! Thank you!!! 👍