The midterm is an an extension of the GitIgnoreTestDockerMicro and DockerCompose assignments. In some cases, students have used RestBasics rather than DockerComposer. As long as it works, then I’m fine with that decision.

The goal of the midterm is to create a program that will allow us to query our repositories to ensure they contain certain key elements. In particular, we are looking to see that all branches contain valid .gitignore files and that no inappropriate code, such as a node_modules directory, has been checked in.

Your code should compile cleanly with no errors or warnings from prettier or eslint.


These images are meant as rough guidelines or inspiration, there is no need to duplication them exactly. Indeed you can, within reason, do more or less what you want inside your React components, so long as you display data similar to that shown here. The data matters, not the format, but of course your data probably does not look exactly like mine.

NOTE: Additional detail on these images is available in GitIgnoreTestDockerMicro.

A single React component and displaying a bit of information gleaned from the System Environment container:

Git React Get Branches

Here we check all branches for things missing from .gitignore and find that .c9 is missing from .gitignore in the week01 branch:

Git React Missing C9

I’ll want you to add one more section, which should display any stray files or directories that should not have been checked in.

Assuming that we have accidentally checking in bundle.js and bundle.js.map into our week02 branch, then this is what we get when we run the Bad File Tests:

Bad file test

Special Repo

I have create a special repo that you can test against. Besides branches with bad .gitignore files and “bad files” such as bundle.js, it also provides three example starter projects that ensure that you have the basics of your program laid out correctly. The repository is called git-ignore-tests. At least a few details are outlined in the README.

NOTE: Because I provide code for system-environment/you-rang, I ask that you also provide a call to route-tester/you-rang in your GUI. See the Five Tasks.

Here is another way to think about the starter projects in git-ignore-tests:

  • If you follow the pattern in the standard or master branch you can get a 100 on the midterm. You must add the gitIgnoreTests section shown in various screenshots found in this assignment.
  • If you follow the pattern in standard and master and add the Bad File Tests you can get extra credit.
  • If you follow the pattern in the router-dom branch you get extra credit if you have menu items (anchors) for both you-rangs, getBranches, gitIgnoreTests and BadFileTests and each appears in its own “Page” of the SPA when the menuitem is selected.
  • If you follow the pattern in the hooks branch you get extra extra.

The trifecta, then, is to implement Bad Files Tests in the hooks branch. This branch also uses React Router Dom, thus this option uses all three extra-credit technologies. In my usual vague grading system, I’ll guess that each extra credit section is worth 2 points, so you could get a 106 on the midterm, which covers a multitude of sins.

When you use this repository, your output should look like this:

Special git-ignore-tests output

Five Tasks

In the image shown above the react component in main application calls into system-environment and performs four tasks:

  • You Rang: Call /you-rang from system-environment
  • You Rang: Call /you-rang from router-tester
  • Get Branches: Call /getBranches and display the branches in your repository.
  • The Git Ignore Tests: For each branch, test the .gitignore file to be sure it contains all the strings we want it to contain.
  • The fourth task is for extra-credit. It is very much like the third, but you are checking for files that never should have been checked in, such as bundle.js. (In a loop like the one for the gitIgnoreTest you should exec code like this: **find . -iname **)

The first two are, I believe, self explanatory. The third requires that you:

  • Call getBranches to get an array of branches.
  • Loop over the array and use the magic of async/await to allow you to call code that:
    • switches to a new branch
    • runs your gitIgnoreTest in the new branch to confirm that the .gitignore file is valid, that it meets our requirements.

Here is a hint about how to compose a loop on a an array called allBranches.

for (let branch of allBranches) {
    console.log('BRANCH', branch);
    someInfo += await SomeAsyncAwaitFunc();
    const someMoreInfo = await SomeOtherAsyncAwaitFunc();;
    // Store return values in a structure such as an Array.
// Send back a respose to main that contains at least an appropriate subset of the values returned from the functions in the loop.

Of course, this code is not valid, you need to call the appropriate functions and handle their return values.

A demo:

The demo screenshot:

Bad Files

The bad files must be in .gitignore and should not be in the repository file system.

const asArray = [

Get Started

Here are a few steps you should take as you start work on the midterm proper.

  • Update Pristine Lubuntu (update-all) and update the npm global packages (ncu -g).
  • Update JsObjects
  • Navigate back to your repository
  • Create a branch called midterm based on your most recent work.
  • Submit your work in a folder called: midterm
    • This will probably mean renaming your working folder to midterm:
    • For instance: git mv week04-docker-compose midterm
  • Tag your repo with this string: “Starting midterm in week06”

HINT: To tag a repo, do something like this:

git tag -a v0.0.1 -m "Tagging in week06 just before the midterm"

Increment the tags as appropriate:

git tag -a v0.0.2 -m "React component can display you-rang in a table"

So part of the midterm is having a commit and tag made with elf-tagger.

To push a tag: git push origin v0.0.2

The Private Key

I have come up with a two step solution that I hope will mitigate somewhat the chances of us pushing a private key to DockerHub.

1) When creating the container, we delete the key immediately after using it to clone the repo. 2) When we pull the container onto our private server, we copy the key into our system-environment container.

NOTE: One might object that once we have cloned the Git repo and deleted the private key we are done, since we will have no further use for it. But we might, in some future assignment, want to pull our Git repo to update it and then confirm that all is still well after any recent updates to our repo. In that case, we will need the private key to pull from GitHub.

For the first step, we modify the Dockerfile for system-environment by adding one more line to our custom code:

RUN mkdir /root/.ssh
RUN chmod 700 /root/.ssh
RUN ssh-keyscan github.com >> ~/.ssh/known_hosts
RUN ssh-agent bash -c 'ssh-add YOUR_SSH_KEY; git clone git@github.com:charliecalvert/isit320-calvert-2019.git'

The key line is the last one, where we remove the the key.

For the second step, here is how to copy a file called temp01 into our container:

docker cp temp01 week04-docker-composer_system-environment_1:/usr/src/system-environment

Another solution would be to put our system-environment image in a private DockerHub repository, but before we go to that route, let’s see if the above solution works. (I believe DockerHub has a student plan that gives you five private repos for free.)

Eslint and Prettier

Install eslint and prettier into all projects:

  • Run get-gist and choose Run ESLintRc and Prettier
  • Run prettier, and it should clean both client and server.

I had few troubles with eslint except in one case where we call sed in getBranges. It is best, I think, not to use double quotes in a sed statement, as a result, I escape the single quotes in getBranches to satisfy ESLint:

const { stdout, stderr } = await exec('git branch -a | sed -n -e \'s/remotes.origin*.//p\' | grep -v \'HEAD\'', {
    cwd: workingDir

NOTES: This is a plain letter: n. Here is an escaped letter: \n. We put a backslash in front of a character to escape it. Here are some common escaped characters:

Escape Sequence Meaning
\\ Backslash (\)
\’ Single quote (‘)
\” Double quote (“)
\a ASCII Bell
\b Backspace
\f Formfeed
\n Linefeed (LF)
\r Carriage Return (CR)
\t Tab
\v Vertical Tab
\ooo The octal value ooo
\xhh… The hex value hh…

In our case, we are interested in the second escaped character, the single quote.

Prettier Ignore

Sometimes prettier does one thing, then eslint does another. In these cases, only one can be happy at a time. The solution I’m using now is to ask prettier to ignore a statement in exec-git.js. I’m mentioning that one file because I expect you hit this issue in system-environment/routes/exec-git.js. However, I don’t want you to use this trick except under the direst necessity, such as the one we encounter with quotes in sed statement for getBranches.

Suppose you had code like this:

const x = "3";

Suppose prettier would normally convert it to use single quotes:

const x = '3';

If we put a special prettier comment in front of the statement we want to ignore, then it will be ignored:

// prettier-ignore  
const x = "3";

Now running prettier will leave the double-quotes in this one statement. Some statements, like if statements, have multiple lines. If you put the special comment in front of the if statement, then all of it would be ignored.

Reference: https://prettier.io/docs/en/ignore.html

Push and Tag

At various points, you might want to push and tag:

git tag -a vX.Y.Z -m "Completed Midterm setup phase"

Loading CSS in Express Apps

In Main, install both style-loader and css-loader with npm

npm i -D style-loader css-loader

Inside webpack.config.js (this is the whole file on my system at this time):

module.exports = {
    mode: 'development',
    entry: './source/control.js',
    output: {
        path: __dirname + '/public/',
        filename: 'bundle.js'
    devtool: 'source-map',
    module: {
        rules: [
                test: /.js?$/,
                exclude: /(node_modules|bower_components)/,
                use: [
                        loader: 'babel-loader',
                        options: {
                            presets: [
                test: /\.css$/i,
                use: ['style-loader', 'css-loader']

Working with JSX Tables

You don’t have to use tables to display your data in your main application, but you have seen that is the choice I made.

NOTE: Truly, you don’t need to use tables if you have some other technique you think looks better. But if you want a suggestion, I found that tables give a clean and easy to understand format to our data.

For the most part, you can write ordinary HTML table syntax in your JSX:

<h2>You Rang</h2>
            <td className="left"> {this.state.result}</td>
            <td className="left"> {this.state.file}</td>



Create Table Dynamically

There are times when you will want to create the body of the table in a loop. You need to do this because you won’t know, for instance, how many branches a call to getBranches is going to return. As a result, you can’t hard code the table as we do above with you-rang.

Instead, you do something like this:

        {this.state.branches.map((branch, index) => {
            return (
                <tr key={index}>
                    // YOU WRITE THE TWO TD ELEMENTS

fetch and async/await

The code above assumes that your call to getBranches initialized a field of your state object called branches to the array of branches you got from the system-environment server. To do this, you declare state in your constructor:

constructor(props) {
    this.state = {
        branches: ['unknown'],
        gitIgnoreTests: [{ branch: 'unknown', missing: ['none'] }]
    this.queryGetBranches = this.queryGetBranches.bind(this);
// npm install --save-dev  @babel/plugin-transform-runtime

Note that we are using bind to set up the this keyword in our call to queryGetBranches.

When you use fetch to call getBranches you should set the this.state.branches to the array of branches returned by your function. I’ll give you the whole button response method as example of how to use fetch with async/await.

async queryGetBranches() {
    try {
        let response = await fetch('/system-environment/getBranches');
        let result = await response.json();
        this.setState({branches: result.gitBranchesAsArray});
    } catch (ex) {

These calls to await just work, they tell me, if you use create-react-app. To make this work in our elf-express apps, you need to do some configuration.

Remember to bind these methods at the end of your constructor:

this.queryGetBranches = this.queryGetBranches.bind(this);

In Main, make sure you install @babel/plugin-transform-runtime and @babel/runtime:

npm i -D @babel/plugin-transform-runtime @babel/runtime

At least one commentator, who I have followed successfully, thinks we should also perform some inexplicable magic with @babel/preset-env in our .babelrc:

    "presets": [
                "targets": {
                    "browsers": [
                        "not ie 11",
                        "not op_mini all"
    "plugins": [
        ["@babel/transform-runtime", {
            "regenerator": true

Note that we also created or updated our plugins section of .babelrc. (Is @babel/plugin-proposal-class-properties needed in .babel.rc?)

NOTE: One advantage of using async/await when calling fetch is that you can write this.setState rather than that.setState On the other hand, fetch is not a method that usually benefits much from async/await since it is rarely part of a set of nested callbacks. fetch without async/await takes some getting used to, but once you understand it, it rarely is a source of confusion.

Push Container

Try something like this:

docker tag week04-docker-composer_main:latest charliecalvert/dcmain:first
docker push charliecalvert/dcmain

Turn it in

Tag and push with script:

  • Tag your repo “Submitting midterm”
  • Make sure you use our git-ignore-tests repo.

If you need to resubmit, then you could write something like: “Submitting midterm for the second time”

Probably a good idea to include a screenshot as well. Make sure prettier and eslint can be run without generating errors or warnings.

Remember that the Find Bad Files is extra credit.

Using React Router DOM in the midterm is extra-credit.


I ended up with two reset files. This one I call reset and it is the one I use most often:

#! /usr/bin/env bash

docker-compose down

Here is one I call reset-hard, and I think you should use it and then build before you turn in your assignment. I can’t justify that logically, it just seems wise to me to be sure you know your containers can be built entirely from scratch:

#! /usr/bin/env bash

docker container stop week04-docker-composer_main_1
docker container rm week04-docker-composer_main_1
docker image rm week04-docker-composer_main


Where I write “etc…” you need to write code to completely delete system-environment and route-tester. It is very similar to the code shown in the first three active lines of the script.