Make Flask Fast and Reliable – Simple Steps

Flask is a microframework for Python, which is mostly used in web-backend development.There are projects in FOSSASIA that are using flask for development purposes such as Open Event Server, Query Server, Badgeyay. Optimization is indeed one of the most important steps for a successful software product. So, in this post some few off- the-hook tricks will be shown which will make your flask-app more fast and reliable.


  1. Flask-Compress is a python package which basically provides de-facto lossless compression  to your Flask application.
  2. Enough with the theory, now let’s understand the coding part:
    1. First install the module

2. Then for a basic setup

3.That’s it! All it takes is just few lines of code to make your flask app optimized .To know more about the module check out flask-compress module.

Requirements Directory

  1. A common practice amongst different FOSSASIA  projects which involves dividing requirements.txt files for development,testing as well as production.
  2. Basically when projects either use TRAVIS CI for testing or are deployed to Cloud Services like Heroku, there are some modules which are not really required at some places.  For example: gunicorn is only required for deployment purposes and not for development.
  3. So how about we have a separate directory wherein different .txt files are created for different purposes.
  4. Below is the image of file directory structure followed for requirements in badgeyay project.

  1. As you can see different .txt files are created for different purposes
    1. dev.txt – for development
    2. prod.txt – for production(i.e. deployment)
    3. test.txt – for testing.


Status Badges for Repositories Registered to Yaydoc

Yaydoc, our automatic documentation generation and deployment project, generates and deploys documentation for each of its registered repository at every commit. It is possible that due to any misconfiguration in users’ project the build process may fail. Hence, it is vital for an improved user experience to store the build status for at least the most recent build process.

There are different ways with which a user can be notified about the build status after a commit. At Yaydoc, we chose to notify the user by emailing a status report. Since sending an email at each at every commit can be quite annoying, we chose to limit it to specific scenarios. We decided that we will send the mail

  • On the first build after the repository is registered to Yaydoc, irrespective of the status
  • On every failed build
  • On the change of build status (Success to Failed or vice versa)
  • To the user who registered the repository to Yaydoc
exports.updateBuildStatus = function (name, buildStatus) {
    function (callback) {
      Repository.setBuildStatusToRepository(name, buildStatus, 
      function (error, repository) {
        callback(error, repository);
    function (repository, callback) {
      if (repository.mailService === true && 
          (repository.buildStatus === false || buildStatus === false || 
           repository.buildStatus === undefined)) {
        function (error, user)) {
          callback(null, user, repository);
  ], function (error, user, repository) {
    mailer.sendMailOnBuild(buildStatus,, repository);

Considering the fact that the user may not wish to receive build emails and hence made them configurable by adding a mailService: Boolean  key in repository’s collection.

Taking this forward, we then decided to generate status badges similar to how Travis and other Continuous Integration platform do. Since we now store a `buildStatus` for each repository, we can use it to generate an svg image to be added to README files of repositories. We generated  the status badges using and added them to the route /<owner>/<reponame>.svg.  The dynamicity of image generated is achieved by retrieving the value of buildStatus and render the images with different constructs based on its value.

router.get(‘/:owner/:reponame.svg’, function (req, res, next) {
  var fullName = req.params.owner + ‘/’ + req.params.reponame;
  Repository.getBuildStatusByRepositoryName(fullName, function(error, result)) {
    var buildStatus = ‘invalid’; var width =94’; 
    var color = ‘#9f9f9f’; var x =70.5’;
    if (result.buildStatus) {
      buildStatus = ‘success’; width =102’; color = ‘#97CA00’; x =74.5’;
    } else {
      buildStatus = ‘failed’; width =88’; color = ‘#E05d44’; x =67.5’;

    res.set(‘Content-Type’, ‘image/svg+xml’);
    res.render(“badge”, {
      status: buildStatus,
      width: width,
      color: color,
      x: x,

The status tags generated can then be added as:

[![Yaydoc Status] (] (


  1. Quality metadata badges for open source projects –
  2. Async utilities for node and browser –