Group all docker tags by image

docker-tag-groups.sh

#!/usr/bin/env bash

set -euo pipefail
#set -o xtrace

image=${1};
wanted_tag=${2:-""};

max_pages=10;
grouped_tags_tmp=$(mktemp);

function finish {
  rm -rf "{$grouped_tags_tmp}";
}
trap finish EXIT;

(
  url="https://registry.hub.docker.com/v2/repositories/${image}/tags/?page_size=100"
  counter=1
  while [ $counter -le $max_pages ] && [ -n "${url}" ]; do
    >&2 echo -n ".";
    content=$(curl -s "${url}");
    ((counter++));
    url=$(jq -r '.next // empty' <<< "${content}");
    echo "${content}";
  done;
  >&2 echo;
) | jq -s '[.[].results[]]' \
  | jq 'map({tag: .name, digest: .images[].digest}) | unique | group_by(.digest) | map(select(.[].digest) | {(.[0].digest): [.[].tag]}) | unique' \
  > "${grouped_tags_tmp}";

# jq -s '[.[].results[]]' will slurp -s the array of all pages in a single big array, somewhat like a flatmap
# jq 'map({tag: .name, digest: .images[].digest}) | unique | group_by(.digest) | map(select(.[].digest) | {(.[0].digest): [.[].tag]})'
# - map({tag: .name, digest: .images[].digest}) will keep only the tag name and the images digest
# - unique will keep unique objects, as it's possible to have to have images digest that are available with various architecture or os
# - group_by(.digest) group tags by their images digest, this creates an array of an array of objects
# - map(select(.[].digest) | {(.[0].digest): [.[].tag]}) change the structure to an array of objects shaped this way
#      {
#        "sha256:518f6c2137b7463272cb1f52488e914b913b92bfe0783acb821c216987959971": [
#          "11",
#          "11-buster",
#          "11-jdk",
#          "11-jdk-buster",
#          "11.0",
#          "11.0-buster",
#          "11.0-jdk",
#          "11.0-jdk-buster",
#          "11.0.8",
#          "11.0.8-buster",
#          "11.0.8-jdk",
#          "11.0.8-jdk-buster"
#        ]
#      }


if [ -n "${wanted_tag}" ]; then
  jq --arg wanted_tag "${wanted_tag}" 'map(to_entries | map(select(.value | index($wanted_tag))) | from_entries | select(length > 0)) | unique' "${grouped_tags_tmp}"
  # 'map(to_entries | map(select(.value | index($wanted_tag))) | from_entries | select(length > 0)) | unique'
  # - first map(...) enable to work on each entries of the input array
  # - to_entries | map(select(.value | index($wanted_tag))) | from_entries | select(length > 0)
  #   - to_entries for each object extract as a dictionary with key : (the digest), value: (the tags array)
  #   - map(select(.value | index($wanted_tag))) will select the entry whose value has the wanted tag in its array
  #   - from_entries will reassemble the dictionary as a object { digest: tags array}
  #   - select(length > 0) will remove empty objects
  # - unique remove possible duplicates
else
  jq '.' "${grouped_tags_tmp}"
fi

Thanks I'll try to come up with something to be able to select architecture. Thanks for the suggestion !

For information I ended up with creating my own function : https://gist.github.com/adrienaury/caa582f17edb399acfa7635afc9d435d
I credited you in the help message :)

$ dtags

Usage:   dtags [OPTIONS] IMAGE

Retrieve a list of tags from dockerhub

Options:
  -r, --repository string     Name of a repository, default: library
  -a, --architecture string   Filter on a specific architecture (e.g.: amd64), this can be a regex expression, default: all architectures
  -o, --os string             Filter on a specific operating system (e.g.: linux), this can be a regex expression, default: linux
  -l, --limit integer         Limit the number of results, this number is counted in hundreds (e.g.: a limit of 1 will return a maximum of 100 results), default to 10
  -c, --cache integer         Cache curl result, default no caching

Example: dtags -l1 -a amd64 alpine

Inspired by https://gist.github.com/bric3
Adapted by https://gist.github.com/adrienaury

You can combine it with this one to cache results : https://gist.github.com/adrienaury/4ec61ae619ec7b68e03cf4ee603a0645

$ cache -- dtags alpine -a amd64 | jq 'select(.tag == "latest")'
{
  "tag": "latest",
  "date": "2021-04-14T19:39:25.049993Z",
  "os": "linux",
  "architecture": "amd64",
  "digest": "sha256:def822f9851ca422481ec6fee59a9966f12b351c62ccb9aca841526ffaa9f748"
}

Thank you ! Your version is really neat !