Get Docker Hub repo tags

get_docker_hub_tags.sh

#!/bin/bash

# Call by running
#   ./get_docker_hub_tags.sh "library" "alpine"

[[ -z "${DOCKER_HUB_TOKEN}" ]] && echo "Error: DOCKER_HUB_TOKEN must be defined" && exit 100

export DOCKER_NAMESPACE="$1"
export DOCKER_REPOSITORY="$2"
[[ -z "${DOCKER_NAMESPACE}" ]] && echo "Error: a Docker namespace must be passed as first argument" && exit 10
[[ -z "${DOCKER_REPOSITORY}" ]] && echo "Error: a Docker repository must be passed as second argument" && exit 20

function get_repo_tags() {
  PAGE_SIZE="$1"
  PAGE_NUMBER="$2"
  DOCKER_TAGS_URL="https://hub.docker.com/v2/namespaces/${DOCKER_NAMESPACE}/repositories/${DOCKER_REPOSITORY}/tags"
  curl --silent \
    --header "Authorization: Bearer ${DOCKER_HUB_TOKEN}" \
    "${DOCKER_TAGS_URL}?page_size=${PAGE_SIZE}&page=${PAGE_NUMBER}"
}
export -f get_repo_tags

REPOSITORY_TAGS_COUNT=$(get_repo_tags 1 1 | jq --raw-output '.count')

export MAX_REPOSITORY_TAGS_PAGE_SIZE=100
export NUMBER_OF_PAGES=$(((REPOSITORY_TAGS_COUNT + MAX_REPOSITORY_TAGS_PAGE_SIZE - 1) / MAX_REPOSITORY_TAGS_PAGE_SIZE))

MAX_CONCURRENT_REQUESTS=32
seq "${NUMBER_OF_PAGES}" |\
  xargs \
    -P "${MAX_CONCURRENT_REQUESTS}" \
    -I ^ \
    bash -c "
      get_repo_tags ${MAX_REPOSITORY_TAGS_PAGE_SIZE} ^ |\
        jq --raw-output '.results[] | .name'
    "