AWS Lambda Docker container runtime error: Runtime exited with error: exit status 127

While testing my Lambda using a Docker container, when the Lambda is invoked, I’m getting this runtime error:

Process 17(bootstrap) exited: Runtime exited with error: exit status 127

Process exit status code 127 errors are usually a file not found error. Going back through the Lambda logs, luckily there’s an error telling me I have an error in my shell script:

/var/task/ line 5: output: command not found

Quick and easy fix.

Debugging Docker container builds

When running a ‘docker build . -t imagename’ to build a new image, each of the steps in your Dockerfile outputs a one-line status, but if you need to see the actual output of each step, you need pass the –progress-plain option. If your build is stopping at a particular step and you need to see the output of previous steps that are now cached, you can use the –no-cache option:

docker build --progress=plain --no-cache . -tĀ imagename