title: Facing this error : container_linux.go:367: starting container process caused: exec: "python": executable file not found in $PATH: unknown
body: <p>So I'm a beginner in docker and containers and I've been getting this error for days now.
  I get this error when my lambda function runs a sagemaker processing job.
  My core python file resides in an s3 bucket.
  My docker image resides in ECR.
  But I dont understand why I dont get a similar error when I run the same processing job with a python docker image.
  PFB the python docker file that didnt throw any errors.</p>
  <pre class="lang-sh prettyprint-override"><code>FROM python:latest
  #installing dependencies
  RUN pip3 install argparse
  RUN pip3 install boto3
  RUN pip3 install numpy
  RUN pip3 install scipy
  RUN pip3 install pandas
  RUN pip3 install scikit-learn
  RUN pip3 install matplotlib
  </code></pre>
  <p>I only get this error when i run this with a an ubunutu docker image with python3 installed.
  PFB the dockerfile which throws the error mentioned.</p>
  <pre class="lang-sh prettyprint-override"><code>FROM ubuntu:20.04
  
  RUN apt-get update -y
  RUN apt-get install -y python3
  RUN apt-get install -y python3-pip
  
  RUN pip3 install argparse
  RUN pip3 install boto3
  RUN pip3 install numpy==1.19.1
  RUN pip3 install scipy
  RUN pip3 install pandas
  RUN pip3 install scikit-learn
  
  ENTRYPOINT [ &quot;python3&quot; ]
  </code></pre>
  <p>How do I fix this?</p>