How to Modify Android Emulator Hosts File
Accessing the host machine from the Android emulator is easier than you think...
Have you tried to access the host machine from an Android emulator before?
You probably discovered that the default possibility is by utilizing 10.0.2.2.
So what if you need to utilize a fully qualified domain name in your development environment?
Did you already know that Android OS is a flavor of linux and that there exists a /etc/hosts file?
I'm going to teach you how to modify this hosts file so that you can access resources on your host machine.
First, you need to navigate to the folder in which your Android emulator is located.
For me, on an Apple M1, the SDK emulator is located at /Users/confessore/Library/Android/sdk/emulator.
I'll list out which Android Virtual Devices (AVD) are ready by issuing this command.
In this example, I received a response of pixel5-_api_33 which will be used in the next step.
To modify the hosts file on the Android emulator, a writable instance must be initialized.
This command starts an AVD with an editable filesystem in my environment. You may need to change the AVD input to reflect the name of your AVD.
./emulator -avd pixel_5_-_api_33 -writable-system
The emulator will start and while you're waiting for it to fully initialize, go ahead and open another terminal window.
In this new terminal window, I'll issue a few ADB commands which will allow me to modify the hosts file.
These commands are simply granting root access to and remounting the emulator's filesystem.
adb root adb remount
This command pulls the existing hosts file from the emulator's filesystem and saves it to the desktop.
adb pull /etc/hosts ~/Desktop/hosts
For my current purposes, I am editing the hosts file that was just now saved to my desktop so that it looks like this.
Of course, modify it as necessary for your own particular requirements.
Note: The blank line at the end may be required for full functionality.
127.0.0.1 localhost ::1 ip6-localhost 10.0.2.2 host.localhost 10.0.2.2 api.localhost
After modifying the pulled hosts file, it can be pushed back to the emulator.
adb push ~/Desktop/hosts /etc/hosts
Possibly Optional: It should be immediately picked up by the Android operating system with no further required commands however you may need to issue this final command.
And that's it! The host machine should now be accessible from the Android emulator via domain name resolution.
Please keep in mind that this process will need to be repeated every time you close and reopen the Android emulator. This modification is not persisted.