Is it possible to whitelist Heroku apps?

Question

I have a Heroku application that binds with a telco sms gateway via SMPP The telco guys need to whitelist IPs for my app to connect. I am aware of the new addon proximo, but it's just insanely priced. So that option is out. Is there a subnet or a list of IPs that I can get whitelisted and is there a guarantee that all requests from my app will originate from tose IPs? I found this https://api.heroku.com/vendor/logplex/allowlist. Is that only for syslog or all apps make a request from one of those IPs?

Thanks

Answer 1

You can host a proxy yourself using Dockhero Heroku add-on - https://dockhero.io/ - which has a static IP (AWS elastic IP).

1. Install the add-on and the CLI plugin:

   $ heroku addons:create dockhero
   $ heroku plugins:install dockhero
   

2. Wait until the provisioning is done and get DOCKHERO_HOST environment variable

   $ heroku dh:wait
   $ heroku config:get DOCKHERO_HOST
   --> e.g. dockhero-spherical-42047.dockhero.io
   

3. Create dockhero-compose.yml file with the following contents:

   version: "2"
   services:
     proxy:
       image: tecnativa/tcp-proxy
       environment:
         LISTEN: ":80"
         TALK: "www.wikipedia.org:80"
       ports: 
         - "80:80"
   

Here www.wikipedia.org:80 is the server which you build a proxy for. Find more about the syntax in https://docs.docker.com/compose/compose-file/compose-file-v2/

4. Run this stack in the cloud using Dockhero CLI:

   $ heroku dh:compose up -d
   

5. Any requests to the host from DOCKHERO_HOST Heroku config var will now be proxied according to your dockhero-compose.yml

   $ curl http://dockhero-spherical-42047.dockhero.io/
   --> <response from www.wikipedia.org> 
   

IMPORTANT: as of writing this, dockhero.io is in Beta and available for free. When switching to production, the assigned IP may be changed after a prior notification.

Answer 2

Fixie is another alternative add-on not mentioned here. Free plan with 500 requests per month. Requires some adjustments in code and heroku app to be in us region (or you can migrate it: Migrating an Application to Another Region). Worked for me.