Server App Updates

August 23, 2021

In this post I return to my server app to make some much-needed maintenance updates and prepare it for changes I’ll be making to the budget API.

Update My Environment

First I updated my environment, I downloaded the latest version of node and updated my npm version with npm install -g npm then updated all packages with npm update. I also ran npm audit and npm audit fix until I had 0 vulnerabilities showing. Because I updated to npm version 7 this updated my package.lock file too which needed to be committed.

Remove Deprecated Code

Next up the body-parser library has been deprecated so I removed it and replaced this:

const bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());

With the straight express equivalent:

app.use(express.urlencoded({ extended: true }));
app.use(express.json());

Fix error handling

In my current implementation I was catching errors and exiting the node process during the setup methods, but I was exiting without a code so Jenkins thought that creating or destroying tables in the database was successful even when they failed. To fix this was super easy to just pass in a non-zero value to the method, i.e. add exit code of 1 process.exit(1); instead of process.exit(); when catching errors.

db.destroySensorDatabase()
    // ... 
    .catch((error) => {
        console.log(error);
        process.exit(1);
    });

This means the Jenkins build will fail when the database fails to create or destroy properly even before the tests are run.

Release the Database Connection Back to Pool

Another problem I was having was Jenkins “hanging” after a few queries. I reailsed I wasn’t releasing the connection after querying so I just added the connection.release() method to release the connection. Otherwise it was causing some kind of memory leak and I had to keep restarting Jenkins periodically.

function runQuery(query) {
    return new Promise(function (resolve, reject) {
        pool.getConnection((error, connection) => {
            if (error) reject(error);
            connection.query(query, (error, result) => {
                connection.release();
                if (error) {
                    reject(error);
                } else {
                    resolve(result);
                }
            });
        });
    }); 
}