Docker CLI Plugin to interact with a registry

docker-distribution

#!/usr/bin/env bash

docker_cli_plugin_metadata() {
        local vendor="nicholasdille"
        local version="v0.0.1"
        local url="https://dille.name"
        local description="Interact with a Docker registry"
        cat <<-EOF
        {"SchemaVersion":"0.1.0","Vendor":"${vendor}","Version":"${version}","ShortDescription":"${description}","URL":"${url}"}
EOF
}

parse_image_reference() {
        local image=$1

        # Match arbitrary image
        if [[ "${image}" =~ ^([^/]+)/([^:]+)(:(.+))?$ ]]; then
		registry=${BASH_REMATCH[1]}
		repository=${BASH_REMATCH[2]}
		reference=${BASH_REMATCH[4]}

        # Match image from Docker Hub
    elif [[ "${image}" =~ ^([^:]+)(:(.+))?$ ]]; then
		registry=registry.hub.docker.com
		repository=${BASH_REMATCH[1]}
		reference=${BASH_REMATCH[3]}
		if [[ "${repository}" != */* ]]; then
			repository=library/${repository}
		fi

	else
		>&2 echo "Unable to parse image name <${image}>"
		exit 1
	fi

        if [[ "${reference}" == "" ]]; then
                reference=latest
        fi

        echo registry=${registry}
        echo repository=${repository}
        echo reference=${reference}
}

get_docker_credentials() {
        local registry=$1

        cat ~/.docker/config.json | jq --raw-output ".auths.\"${registry}\".auth" | base64 -d
}

list_tags() {
        local image=$1
        eval $(parse_image_reference ${image})

	if [[ "${registry}" == "registry.hub.docker.com" ]]; then
		local credentials=$(get_docker_credentials https://index.docker.io/v1/)
		local response=$(curl -su "${credentials}" "https://auth.docker.io/token?service=registry.docker.io&scope=repository:${repository}:pull")
		if echo ${response} | jq --raw-output '.details' | grep -q "incorrect username or password"; then
			echo "Unable to retrieve token from Docker Hub. Please do 'docker login' first."
			exit 1
                fi
		local token=$(echo ${response} | jq --raw-output '.token')
		curl -sH "Authorization: Bearer $token" -H "Accept: ${content_type}" "https://${registry}/v2/${repository}/tags/list" | jq --raw-output '.tags[]'

	else
		local credentials=$(get_docker_credentials ${registry})
		curl -su "${credentials}" -H "Accept: application/json" "https://${registry}/v2/${repository}/tags/list" | jq --raw-output '.tags[]'
	fi
}

delete_tag() {
        local image=$1
        eval $(parse_image_reference ${image})

	if [[ "${registry}" == "registry.hub.docker.com" ]]; then
		local credentials=$(get_docker_credentials https://index.docker.io/v1/)
		local response=$(curl -su "${credentials}" "https://auth.docker.io/token?service=registry.docker.io&scope=repository:${repository}:pull")
		if echo ${response} | jq --raw-output '.details' | grep -q "incorrect username or password"; then
			echo "Unable to retrieve token from Docker Hub. Please do 'docker login' first."
			exit 1
                fi
		local token=$(echo ${response} | jq --raw-output '.token')
		curl -sX DELETE -H "Authorization: Bearer $token" "https://${registry}/v2/${repository}/manifests/${reference}"

	else
		local credentials=$(get_docker_credentials ${registry})
		curl -sX DELETE -u "${credentials}" "https://${registry}/v2/${repository}/manifests/${reference}"
	fi
}

get_manifest() {
	local image=$1
        eval $(parse_image_reference ${image})
	local content_type="application/vnd.docker.distribution.manifest.v2+json"

	if [[ "${registry}" == "registry.hub.docker.com" ]]; then
		local credentials=$(get_docker_credentials https://index.docker.io/v1/)
		local response=$(curl -su "${credentials}" "https://auth.docker.io/token?service=registry.docker.io&scope=repository:${repository}:pull")
		if echo ${response} | jq --raw-output '.details' | grep -q "incorrect username or password"; then
			echo "Unable to retrieve token from Docker Hub. Please do 'docker login' first."
			exit 1
                fi
		local token=$(echo ${response} | jq --raw-output '.token')
		curl -sH "Authorization: Bearer $token" -H "Accept: ${content_type}" "https://${registry}/v2/${repository}/manifests/${reference}"

	else
		local credentials=$(get_docker_credentials ${registry})
		curl -su "${credentials}" -H "Accept: ${content_type}" "https://${registry}/v2/${repository}/manifests/${reference}"
	fi
}

put_manifest() {
	local image=$1
        eval $(parse_image_reference ${image})
	local content_type="application/vnd.docker.distribution.manifest.v2+json"

	if [[ "${registry}" == "registry.hub.docker.com" ]]; then
		local credentials=$(get_docker_credentials https://index.docker.io/v1/)
		local response=$(curl -su "${credentials}" "https://auth.docker.io/token?service=registry.docker.io&scope=repository:${repository}:push")
		if echo ${response} | jq --raw-output '.details' | grep -q "incorrect username or password"; then
			echo "Unable to retrieve token from Docker Hub. Please do 'docker login' first."
			exit 1
                fi
                local token=$(echo ${response} | jq --raw-output '.token')
                curl -sH "Authorization: Bearer $token" -H "Accept: ${content_type}" "https://${registry}/v2/${repository}/manifests/${reference}"

	else
		local credentials=$(get_docker_credentials ${registry})
                cat - | curl -fX PUT -u "${credentials}" -H "Content-Type: ${content_type}" -d @- "https://${registry}/v2/${repository}/manifests/${reference}"
	fi
}

case "$1" in
        docker-cli-plugin-metadata)
                docker_cli_plugin_metadata
                ;;
        *)
		shift
		case "$1" in
                        list-tags)
                                shift
                                list_tags "$@"
                                ;;

                        delete-tag)
                                shift
                                delete_tag "$@"
                                ;;

			get-manifest)
				shift
				get_manifest "$@"
				;;

			put-manifest)
				shift
				put_manifest "$@"
				;;

			*)
				echo
				echo "Usage: docker distribution"
				echo
				echo "Commands:"
				echo "  list-tags     List all tags in the specified image repository"
				echo "  delete-tag    Delete a tag from the specified image repository"
				echo "  get-manifest  Download image manifest from Docker registry"
                                echo "  put-manifest  Upload image manifest to Docker registry"
                                echo
		esac
                ;;
esac