Tuesday, March 6, 2018

Azure @ Enterprise - Limits on AppServices

AppService mechanism allows free tier to host Azure WebApps. Though this has 2 min execution timeout, it is a good place to host web sites.If we ask is this enterprise friendly, we will end up in different answers. It has enterprise friendly mechanism called AppServiceEnvironment to host applications in isolated environment ie an environment which is not open to public. Enterprise can host its internal services in it.

Though it says technically we can host any .Net application, it has good number of limits. For example if we have legacy application which uses any COM component, it cannot be used in AppService. This post is a journey towards such a limit


It is a browser specifically Chrome automation framework in NodeJS. It helps to start headless browser instance and control it via JavaScript.  It needs a separate post to explain about Puppeteer. Ideally if we host the code in Azure NodeJS WebApp, it should work.

But fails due to unavailability of of some APIs in WebApp.

Details on WebAPI limits 

Below goes the error message
Error: spawn UNKNOWN
    at _errnoException (util.js:1022:11)
    at ChildProcess.spawn (internal/child_process.js:323:11)
    at Object.exports.spawn (child_process.js:502:9)
    at Function.launch (D:\home\site\wwwroot\node_modules\puppeteer\lib\Launcher.js:81:40)
    at Function.launch (D:\home\site\wwwroot\node_modules\puppeteer\lib\Puppeteer.js:25:21)
    at Server.<anonymous> (D:\home\site\wwwroot\server.js:14:39)
    at emitTwo (events.js:126:13)
    at Server.emit (events.js:214:7)
    at parserOnIncoming (_http_server.js:602:12)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:116:23) code: 'UNKNOWN', errno: 'UNKNOWN', syscall: 'spawn' }
started server.js

How to reach to a conclusion that Puppeteer not supported in Azure WebApp? Lets look at the below issue logged in their GitHub project

This will take us to the Azure Functions page which says Windows based Azure Functions don't support headless browsers? Really are there windows based functions and Linux based functions?

Unfortunately yes. The Below link explains the same.

This again takes us to the kudu page where the limit is documented.

Moral of the story. Read the docs and understand what it really means.

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