Скачать или смотреть How to Fix MongoDB Connection Issues with Docker in GitLab CI/CD

Discover how to resolve MongoDB connection problems when using Docker with GitLab CI/CD. This guide explains the solution step-by-step for seamless integration.
---
This video is based on the question https://stackoverflow.com/q/65219754/ asked by the user 'RVA' ( https://stackoverflow.com/u/3584279/ ) and on the answer https://stackoverflow.com/a/70262036/ provided by the user 'Viettel Solutions' ( https://stackoverflow.com/u/7740166/ ) 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: can't connect to mongo docker within gitlab

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.
---
Troubleshooting MongoDB Connection Issues in Docker for GitLab CI/CD

Connecting to a MongoDB instance running within a Docker container can sometimes be challenging, especially when integrating it with GitLab's Continuous Integration (CI) tools. One common issue developers encounter is the inability to connect to the MongoDB server, resulting in frustrating error messages. In this guide, we will discuss a specific occurrence of this issue and provide a clear solution to get your MongoDB connection up and running within your GitLab CI workflow.

The Problem

You have a Docker service defined in your docker-compose.yml for MongoDB, but when you attempt to connect through your GitLab CI pipeline, you receive an error stating that the connection to the server failed. Here’s a summary of your current setup:

Docker Compose Configuration: You have defined a MongoDB service as follows:

[[See Video to Reveal this Text or Code Snippet]]

GitLab CI/CD Job: Your CI/CD configuration includes a step where you try to connect to MongoDB using the following command:

[[See Video to Reveal this Text or Code Snippet]]

Error Message: The pipeline fails with an error about not being able to connect to localhost:27017, indicating that the connection is being refused.

Understanding the Issue

The primary issue here lies in how Docker and GitLab CI handle networking for containers. In GitLab CI, localhost refers to the runner's environment rather than the containerized MongoDB instance you have deployed via Docker. Therefore, trying to connect to localhost:27017 does not route requests to the intended service.

Instead, GitLab CI provides a way to access service containers using their service names. By default, containers can communicate with each other using their defined service names as hostnames.

The Solution

To resolve the MongoDB connection problem in your GitLab CI/CD pipeline, make use of the service alias defined in your docker-compose.yml. Here’s how to adjust your connection string:

Step-by-Step Fix

Modify the Connection String: Instead of using localhost, update your MongoDB connection string to reference the service name defined in your Docker Compose file. Use the following connection string in your before_script:

[[See Video to Reveal this Text or Code Snippet]]

Test the Pipeline Again: Run your GitLab CI/CD pipeline with the updated connection string. You should now be able to connect to the MongoDB instance without encountering the "Connection refused" error.

Important Notes

Ensure the service name give_sync_test matches exactly what you provided in your Docker Compose file to avoid any typographical errors that can lead to further connection issues.

Ensure that the MongoDB service is up and running before your tests attempt to connect. You may need to add additional checks or waits in your CI script if your MongoDB service takes time to initialize.

Conclusion

By utilizing the service names as hostnames within GitLab CI/CD, you can seamlessly connect to your Dockerized MongoDB instance without issues. Remember, always check your networking configurations when dealing with containerized applications, as the scoping of localhost can easily lead to confusion. With these steps, your CI/CD pipeline should function smoothly, allowing you to focus on development and testing rather than troubleshooting connection issues.

If you have any more questions or need further assistance, feel free to reach out in the comments below!