Recently, I’ve developed Android app that during the development requires access to the backend service that is run in the docker behind reverse-proxy with custom myservice.traefik.me domain name.
For sure, from emulator you can get access to your local service when connect to it by IP address with specified port. But this approach leads to some issues and ugly workarounds in a code.
There are several solutions to this problem like edit hosts file, run own DNS server etc. But the simplest one is just simply editing hosts file on emulator.

Solution

By default the file system is read-only. So to be able to edit hosts file we need to start emulator from command line with -writable-system argument.

Open terminal and navigate to the tools folder \android-sdk\tools or \android-sdk\emulator, by default on windows Android SDK installed to c:\Program Files (x86)\Android\.

Run the following command to get list of the installed virtual devices

emulator -list-avds

# pixel_5_-_api_30

Next, let’s start emulator with writable file system

emulator -avd pixel_5_-_api_30 -partition-size 512 -writable-system

Now, when emulator has been started, we need to reconnect and remount ADB tool. Open new terminal window and navigate to the \android-sdk\platform-tools folder. On windows Android SDK installed to c:\Program Files (x86)\Android folder.

Restart ADB. This step is optional, but maybe required if following commands are failing.

adb reboot

Wait until emulator has been restarted, then

adb root

Next, get list of the available devices

adb devices
#emulator-5554

And finally let’s remount selected device

adb -s emulator-5554 remount

Now we are ready to edit hosts file. Download it to a local folder. In this example to the current folder.

adb -s emulator-5554 pull /system/etc/hosts hosts

Get the host machine IP address

ipconfig # on Windows
ifconfig # on Mac OS
ip addr  # on Linux

Edit hosts file like this.

Note: enter your IP and service name.

192.168.0.13 myservice1.traefik.me
192.168.0.13 myservice2.traefik.me

Upload hosts file back to the emulator

adb -s emulator-5554 push hosts /system/etc/hosts

Done. Now you can access your local resources from you app using custom domain names.

NOTE: If you have more than one service and you do not use reverse proxy, you will most likely need to specify a port number e.g. https://myservice1.traefik.me:8080.