You'll need to setup a keystore + configure signing for installRelease. Follow the instructions here:
https://facebook.github.io/react-native/docs/signed-apk-android.html

from https://github.com/xinthink/rnmk-demo/issues/7#issuecomment-218613454

# gradlew clean & debug run
cls && cd android && gradlew clean && cd .. && react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res &&  react-native run-android --variant=release

# reset fbsdk modifications by yarn
cd node_modules && git checkout HEAD -- react-native-fbsdk && cd ..

git rm -r --cached .
git add .
git commit -m "Clean up ignored files"

# create assets folder
mkdir android/app/src/main/assets

# build that shit
react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

# run
react-native run-android

# clean shit:
cd android
gradlew clean

# build that shit
cd ..
react-native run-android

# ensure config is correct
Reactotron
  .configure({
    host: 'localhost', // can be any IP address
	port: '9090' // default
    })
  // ...
  .connect()
  
# list forwarded ports:
adb reverse --list

# forward default port for Reactotron:
adb reverse tcp:9090 tcp:9090

const axios = require('axios');
axios.defaults.baseURL = 'http://localhost/';
axios.defaults.url = '/graphql';
axios.defaults.method = 'POST';
axios.defaults.headers.post['Content-Type'] = 'application/json';

axios
  .request({
    data: {
      query: `{
        hello
      }`
    }
  })
  .then((response)=>{
    console.log(response.data);
  })
  .catch((error)=>{
    console.log(error.response.data);
  });

const EventEmitter = require('eventemitter3');

Class SampleClass{
  constructor () {
    const emitter = new EventEmitter();
    this.emit = emitter.emit.bind(emitter);
    this.on = emitter.on.bind(emitter);
  }
  Test () {
    this.emit('ready');
  }
}

const Instance = new SampleClass();
Instance.on('ready', ()=>{
  console.log('ready!');
});
Instance.Test();

const fs = require('fs');
const http = require('http');
const https = require('https');
const express = require('express');
const bodyParser = require('body-parser');

const SSL = {
  credentials: {
    key: fs.readFileSync('ssl/private.key', 'utf8'),
    cert: fs.readFileSync('ssl/api_realtycoast_io.crt', 'utf8'),
    ca: [
      fs.readFileSync('ssl/COMODORSADomainValidationSecureServerCA.crt', 'utf8')
    ]
  }
};

const app = express();
app.use(bodyParser.json());
app.get('/', (req, res) => res.send('Hello World!'));
http.createServer(app).listen(80);
https.createServer(SSL.credentials, app).listen(443);

import { WebView, View } from 'react-native';

// in your component render(), below

return (
<View style={{flex:1}}>
	<WebView
	source={{uri: 'https://api.realtycoast.io/auth'}}
	javaScriptEnabled={true}
	domStorageEnabled={true}
	startInLoadingState={true}
	style={{ flex:1, height: 500, width: 350 }}
	/>
	</View>
);

	// replace your baseURL and url, below
	
          <Button onPress={
            ()=>{
              const x = axios.create({
                baseURL: 'https://api.realtycoast.io/',
                timeout: 10000,
                headers: {
                  'Accept': 'application/json',
                  'Content-Type': 'application/json',
                }
              });
            x.request({
              url: '/user/123'
            })
              .then(function (response) {
                console.log(response);
              })
              .catch(function (error) {
                console.log(error);
              });
            }
          }>
            <Text>Axios Test</Text>
          </Button>

git add -A && git commit -m "update" && git push -u origin master