List Docker Image Tags using bash

docker_tags.sh

#!/usr/bin/env bash

# Gets all tags for a given docker image.

# Examples:

# retrieve all tags for a single library
# docker-tags "library/redis" | jq --raw-output '.[]'

# retrieve all tags for multiple libraries
# docker-tags "library/mongo" "library/redis" "microsoft/nanoserver" "microsoft/dotnet" | jq --raw-output '.[]'

# retrieve first 10 tags for multiple libraries
# docker-tags "library/mongo" "library/redis" "microsoft/nanoserver" "microsoft/dotnet" | jq --raw-output '.[][0:9]'

docker-tags() {
    arr=("$@")

    for item in "${arr[@]}";
    do
        tokenUri="https://auth.docker.io/token"
        data=("service=registry.docker.io" "scope=repository:$item:pull")
        token="$(curl --silent --get --data-urlencode ${data[0]} --data-urlencode ${data[1]} $tokenUri | jq --raw-output '.token')"
        listUri="https://registry-1.docker.io/v2/$item/tags/list"
        authz="Authorization: Bearer $token"
        result="$(curl --silent --get -H "Accept: application/json" -H "Authorization: Bearer $token" $listUri | jq --raw-output '.')"
        echo $result
    done
}

arr=("$@")
for item in "${arr[@]}";

This is just a clumsy and memory-squandering way to say for item in "$@";

images=($@)
for image in "${images[@]}"; do

This adds a quoting error (you want "$@", always, not a bare $@).

Thx for this script. I used a bit of jq/sort/sed to get the version number of the "latest" tag like so. Given that an image can have many tags going way back one probably needs to know apriori which major version is the "latest" and supply that.

docker_latest_image() {
    image=$1
    major=${2:-1}
    tokenUri="https://auth.docker.io/token"
    data=("service=registry.docker.io" "scope=repository:$image:pull")
    token="$(curl --silent --get --data-urlencode ${data[0]} --data-urlencode ${data[1]} $tokenUri | jq --raw-output '.token')"
    listUri="https://registry-1.docker.io/v2/$image/tags/list"
    curl --silent --get -H "Accept: application/json" -H "Authorization: Bearer $token" $listUri \
    | jq --raw-output ".tags[] | select(. | startswith(\"$major.\"))" | sort -V | sed -n \$p
   }

docker_latest_image  library/alpine 3
3.18.4