How can I host a TCP Listener in Azure?
I am looking to build an application in Azure which will act as TCP listener, receive TCP message streams on a specified port, and then add the information to a database. The incoming TCP communication will be secured with a certificate.
I'm considering the following options:
Cloud Service Worker Role
This definitely looks like it will work. However that means I have to use a Cloud Service, and I miss out on the features and simplicity offered by the App Service. The Cloud Service documentation also specifically describes how to open the required TCP ports.
App Service
In a Logic App (preferred), however this doesn't seem to natively support a TCP listener, so I would look to build a custom API App. Alternatively I could create a Web Job.
However I'm not sure this approach will work, and I have the following questions:
- Can I expose arbitrary TCP ports on the App Service?
- Whilst the Cloud Service documentation specifically describes how to do this, I can't find anything similar for the App Service. So, either the configuration is not required or TCP communication is just not possible within the App Service.
- Can I build a TCP listener inside an Logic App, API App, or Web Job, e.g. does the architecture of Azure support the behaviour required for a TCP listener?
Can I host a TCP Listener in an Azure App Service?
Answer
Cloud Service Worker Role
This definitely looks like it will work. However that means I have to use a Cloud Service, and I miss out on the features and simplicity offered by the App Service. The Cloud Service documentation also specifically describes how to open the required TCP ports.
Definitely works.
https://msdn.microsoft.com/en-us/library/azure/gg557553.aspx
In ServiceDefinition.csdef:
<Endpoints>
<InputEndpoint name="RawTCP" protocol="tcp" port="54321" localPort="54321" />
</Endpoints>
App Service
In a Logic App (preferred), however this doesn't seem to natively support a TCP >listener, so I would look to build a custom API App. Alternatively I could create a Web Job. ...
Can I expose arbitrary TCP ports on the App Service? ...
Can I host a TCP Listener in an Azure App Service?
No and No. Only 80/TCP and 443/TCP are exposed publicly and the only protocol that works is HTTP. You can't do custom listeners with App Service.
See the sandbox limitations listed here: https://github.com/projectkudu/kudu/wiki/Azure-Web-App-sandbox#network-endpoint-listening
Feel free to make a pull request in the Azure documentation if this limitation is not mentioned on the App Service page.
Service Fabric would be a cool 3rd (or 1st?) option: https://azure.microsoft.com/en-us/services/service-fabric/