Скачать или смотреть Resolving the no such file or directory Error in Docker for Golang Applications

Learn how to successfully build and run your Golang microservices in Docker using BusyBox without encountering the dreaded `no such file or directory` error.
---
This video is based on the question https://stackoverflow.com/q/64860989/ asked by the user 'Alessandro Argentieri' ( https://stackoverflow.com/u/5882375/ ) and on the answer https://stackoverflow.com/a/64861255/ provided by the user 'colm.anseo' ( https://stackoverflow.com/u/1218512/ ) 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: Docker golang busybox "no such file or directory" error

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 the no such file or directory Error in Docker for Golang Applications

Building and running microservices using Docker can often lead to unexpected errors, particularly when working with minimal base images like BusyBox. One such error that many developers encounter is the infamous no such file or directory message. In this guide, we’ll dive into the reasons behind this issue and provide an effective solution to ensure smooth operation of your Golang microservices deployed via Docker.

Understanding the Problem

The no such file or directory error typically surfaces when an executable is run inside a Docker container but cannot be found or fails to execute due to missing dependencies. This issue can be especially common when using lightweight base images such as BusyBox since they lack many of the libraries that are present in more comprehensive images.

In our scenario, the developer was attempting to build a multi-stage Docker image for a Golang microservice. Although the image built successfully, running it produced the following error message:

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

This problem was encountered while operating on an Ubuntu machine, contradicting some misconceptions that this issue primarily arises in Windows environments.

Breakdown of the Solution

The root cause of this issue lies in the default settings for Golang builds, specifically related to CGO (C Go). When CGO is enabled (which is the default behavior), the resulting executable may incorporate dynamically linked dependencies. These dependencies are not available in a minimal container like BusyBox, leading to the error.

Disabling CGO

To create a statically linked executable that can run independently of external libraries, you need to disable CGO during your build process. This is a crucial step when using lightweight base images for Docker images. Here's how you can adjust the Dockerfile:

Updated Dockerfile

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

Step-by-Step Explanation

Build Stage: The first part of the Dockerfile defines the build stage using the golang base image. It creates a directory for the build, adds the application files, and sets the working directory.

Dependencies: The Dockerfile downloads the Go modules and runs tests to ensure the application is functioning correctly before building.

Disabling CGO: The line RUN CGO_ENABLED=0 go build -o goapp . is the key to resolving the issue. Setting CGO_ENABLED=0 instructs the Go compiler to build the executable statically, avoiding the inclusion of any system-specific libraries.

Final Stage: The second part of the Dockerfile employs BusyBox as the base image to minimize the image size. It copies the statically linked executable into the BusyBox environment, ensuring that no dynamic dependencies exist.

Executing the Application: Finally, the application is set to run with the command CMD ["./goapp"], ensuring that Docker executes the built binary upon container startup.

Conclusion

By following the steps outlined above, you can effectively resolve the no such file or directory error when working with Golang applications in Docker, especially when using the lightweight BusyBox image. Remember, the crucial fix is to disable CGO during the build process to produce a statically linked binary. This approach not only alleviates the error but also results in a leaner Docker image, making your deployment more efficient.

Now you are equipped with the knowledge to tackle this common Docker issue in your Golang projects. Happy coding!