rewrite requests for always on bot in linux Azure app service - node.js

Question

We are seeing some 404 logs coming from a bot in Azure always On. It trigged every 5min. Our health check is not in the root directory.
We are using Docker image for this, NodeJs 14.x. In documentation, they say to use web.config to redirect some urls but I'm not sure this will work.
<rule name="Redirect AlwaysOn requests from root to custom url" stopProcessing="true">
<match url="^$" />
<conditions>
<add input="{HTTP_USER_AGENT}" pattern="^AlwaysOn$" />
</conditions>
<action type="Redirect" url="https://{HTTP_HOST}/status" logRewrittenUrl="true" redirectType="Permanent"/>
</rule>
and not sure where to put this file in the container. Here's docker file
FROM node:15.0.1-alpine3.10
WORKDIR /usr/src/app
RUN mkdir node_modules
RUN mkdir dist
COPY node_modules node_modules
COPY dist dist
COPY apps/api/.docker/sshd_config /etc/ssh/
COPY apps/api/.docker/init.sh /usr/local/bin/
RUN chmod u+x /usr/local/bin/init.sh
ENTRYPOINT ["/usr/local/bin/init.sh"]

Answer 1

404 logs coming from a bot in Azure always On.
Issue can be fixed by rewriting the Always on path.
After a cold start of your application, AlwaysOn will send a request to the ROOT of your application “/”. Whatever file is delivered when a request is made to, / is the one which will be warmed up, it will fail because the root doesn’t exist.
Make AlwaysOn to warmup a specific page instead of the root, implement URL Rewrite rule.
<?xml version="1.0" encoding="UTF-8" standalone="no">
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Rewrite AlwaysOn" stopProcessing="true">
<match url="^$" />
<conditions>
<add input="{HTTP_USER_AGENT}" pattern="^AlwaysOn$" />
</conditions>
<action type="Redirect" url="https://{HTTP_HOST}/status" logRewrittenUrl="true" redirectType="Permanent"/>
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>
web.config file needs to be added to the node app at the root
If your app has a server.js or app.js file in your Node.js project, the web.config file should be in the same directory.
If you are using Visual Studio Code , then Put web.config file in /public folder, It will then be copied over to /dist folder during build.
I have created the config file in public folder, After running npm run build , web.config file is copied to dist folder.
To create web.config, Right click on the public folder
Add new file, name it as web.config and add the above mentioned code snippet and save.
Go to Azure portal, your Web App =>Advanced Tools=>KUDU - Debug Console =>CMD => site=>wwwroot , check if web.config file exists or not.
If you are using Visual Studio, then select Azure Node.js Express template to craete the Web App, then web.config will be generated automatically.You can edit the settings directly.