How do I install a specific version of python on alpine linux (python3.8)?

Currently I'm using a dind configuration in gitlab
This dind works for me to deploy a dockerized lambda function through SAM.

This is my before script

   - apk add --no-cache curl jq
   - apk add --no-cache python3 python3-dev py3-setuptools
   - apk add py3-pip
   - apk add --no-cache build-base g++ make cmake unzip curl-dev
   - apk add --no-cache autoconf automake libtool libexecinfo-dev
   - apk add --no-cache git
   - pip3 install --no-cache --upgrade wheel
   - pip3 install awscli --upgrade
   - pip3 install aws-sam-cli --upgrade

I'm having troubles because the lambda function python version is 3.8 an sam builds complains that the version the docker gitlab setup is different and doesn't find 3.8

Solution

Finally I solve it Probably I lacked context I'm doing a gitlab.yaml file to build, test and deploy my application in AWS thorugh SAM.

Since one of my lambda functions is a dockerized lambda function I nee sam to be able to access docker as a command so it can run docker pull and docker build
The other lambda functions that I have use python3.8 as runtime so the docker version I was using as a base image pointed to https://dl-cdn.alpinelinux.org/alpine/v3.15/main/x86_64/ so everyt time something was installed with apk the version was 3.15 which has python3.10. A solution to this is use: image: docker:19.03.15-alpine3.13 as a base image with the service dind like this:

image: docker:19.03.15-alpine3.13
## This will run a Docker daemon in a container (Docker-In-Docker), which will
## be available at thedockerhost:2375. If you make e.g. port 5000 public in Docker
## (`docker run -p 5000:5000 yourimage`) it will be exposed at thedockerhost:5000.
services:
  - name: docker:dind
    alias: thedockerhost

variables:
  # Tell docker CLI how to talk to Docker daemon; see
  # https://docs.gitlab.com/ee/ci/docker/using_docker_build.html#use-docker-in-docker-executor
  DOCKER_HOST: tcp://thedockerhost:2375/
  # DOCKER_HOST: tcp://docker:2375/
  # Use the overlays driver for improved performance:
  DOCKER_DRIVER: overlay2
  DOCKER_TLS_CERTDIR: ""
  REPOSITORY_URL: ######.dkr.ecr.region.amazonaws.com/
  REGION: us-east-2

deploy:
  stage: deploy
  before_script:
    - apk add --no-cache python3
    - apk add --no-cache curl jq
    - apk add --no-cache python3-dev py3-setuptools
    - apk add --no-cache py3-pip
    - apk add --no-cache py-pip
    - apk add --no-cache build-base g++ make cmake unzip curl-dev
    - apk add --no-cache autoconf automake libtool libexecinfo-dev
    - apk add --no-cache git
    - pip3 install --no-cache --upgrade wheel
    - pip3 install --no-cache awscli --upgrade
    - pip3 install --no-cache aws-sam-cli --upgrade
  script:
    - aws ecr get-login-password --region ${REGION} | docker login --username AWS --password-stdin ${REPOSITORY_URL}
    - sam build
    - sam deploy --no-confirm-changeset --no-fail-on-empty-changeset
  only:
    - master

This alphine version points to:
https://dl-cdn.alpinelinux.org/alpine/v3.13/main/x86_64/APKINDEX.tar.gz
which installs python3.8 and now sam is able to package/build the rest of the lambda functions.