How to Fix Mongoose Connection Issues in Docker-Compose

Struggling with `Mongoose` failing to connect to `MongoDB` while using `Docker-Compose`? Explore this guide to uncover common pitfalls and find the solution. --- This video is based on the question https://stackoverflow.com/q/63920137/ asked by the user 'redsoxfantom' ( https://stackoverflow.com/u/1935089/ ) and on the answer https://stackoverflow.com/a/63920820/ provided by the user 'redsoxfantom' ( https://stackoverflow.com/u/1935089/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: mongoose failing to connect in docker-compose Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Fix Mongoose Connection Issues in Docker-Compose When working with Docker containers, it's common to run into various issues, and one particularly pesky problem is connecting your Mongoose app to a MongoDB instance when using Docker-Compose. If you've encountered a scenario where your app tries to connect to MongoDB, times out, and ends up failing, you're not alone. The Problem In a setup where your Node.js application relies on Mongoose to connect to a MongoDB database within Docker, you might see the following error: [[See Video to Reveal this Text or Code Snippet]] This error indicates that your app is trying to connect to MongoDB, but it's encountering a timeout issue, often because the connection is being attempted on 127.0.0.1 instead of the designated service name (mongodb-service in your case). Example docker-compose.yml Here's what a typical docker-compose.yml might look like: [[See Video to Reveal this Text or Code Snippet]] In this config, mongodb-seeder can connect to the mongodb-service without issues, but myapp struggles to make the same connection. The Solution: Check Your Environment Variables After examining the situation closer, it turns out the issue usually stems from how environment variables are passed into your application. In this particular case, the underlying problem was that the DockerFile for the app defined an entrypoint that overloaded and skipped the environment variables set in docker-compose.yml. Steps to Fix the Issue: Check Your Dockerfile: Ensure that the ENTRYPOINT script is not exporting the DATABASEURL variable before executing your application. This can prevent your defined environment variables from taking effect. Remove any export commands: [[See Video to Reveal this Text or Code Snippet]] Use process.env Correctly: Ensure your application correctly retrieves the environment variable containing the MongoDB connection URL. Rebuild Your Docker Images: When you make changes to your Dockerfile, don’t forget to rebuild your images. You can do this with: [[See Video to Reveal this Text or Code Snippet]] Verify Connectivity: You can test the connection manually by entering the running container of myapp using: [[See Video to Reveal this Text or Code Snippet]] Inside the container, you can run a simple command to ensure that mongodb-service is reachable, for example: [[See Video to Reveal this Text or Code Snippet]] Conclusion Connecting Mongoose to MongoDB in a Dockerized environment doesn’t have to be daunting. By ensuring your environment variables are correctly configured in both your Dockerfile and docker-compose.yml, you can avoid frustrating connection issues like the ones you may have encountered. If you find yourself still struggling, revisit these settings, rebuild your containers, and you should be up and running in no time. Remember, the key takeaway here is to always check how your environment variables are set and utilized within your Docker containers!