bash_dockerhub

#!/bin/bash

####################################################################################
# This tool provides cli for private dockerhub registry.
# It depends on the "jq" tool for parsing the JSON reponse from Dockerhub rest API. 
# See https://stedolan.github.io/jq/ for installing jq tool.
# Below environment variables need to be configured for the tool to function.
####################################################################################
# DOCKERHUB_USERNAME - Dockerhub username
# DOCKERHUB_PASSWORD - Dockerhub password
# DOCKERHUB_REGISTRY_URL - Dockerhub hosted URL
####################################################################################


# main method
dh() {
	case $1 in 
		repo) get_dh_repo_list;;
		tags) get_dh_repo_tags $2;;
		*) echo "Usage: dh repo|tags [<repo-name>]" ;;
	esac
}


######### Helper methods #############################
get_docker_auth_token() {
	local url auth_challenge auth_url auth_scope auth_service
	url=$1
	auth_challenge=`curl -s -I -X GET $url | awk 'IGNORECASE = 1; /www-authenticate/ {print $0}' | awk -F 'Bearer ' '{print $2}' | awk -F ',' '{for(i=1;i<=NF;i++){print $i}}' | awk -F '=' '{print "\""$1"\":" $2}' | paste -s -d, - | awk '{printf("{%s}",$0)}'`
	auth_url=`echo $auth_challenge | jq -r '.realm'`
	auth_scope=`echo $auth_challenge | jq -r '.scope' | url_encode`
	auth_service=`echo $auth_challenge | jq -r '.service' | url_encode`
	auth_header=`echo -n "$DOCKERHUB_USERNAME:$DOCKERHUB_PASSWORD" | base64`
	curl -s -X GET -H "Authorization: Basic $auth_header" "$auth_url?service=$auth_service&scope=$auth_scope" | jq -r '.access_token'
}

url_encode() {
	str="${1:-$(</dev/stdin)}";
	jq -nr --arg v "$str" '$v|@uri'
}

get_dh_resource() {
	local url token
	url=$1
	token=`get_docker_auth_token "$url"`
	curl -s -X GET -H "Authorization: Bearer $token" "$url"
}

get_dh_repo_list() {
	local url
	url="${DOCKERHUB_REGISTRY_URL}/v2/_catalog"
	get_dh_resource "$url" | jq  -r '.repositories[]'
}

get_dh_repo_tags() {
	local url repo
	if [[ $# -eq 0 ]]; then
		echo "Repository name required to get the tags!"
		return
	fi
	repo=$1
	url="${DOCKERHUB_REGISTRY_URL}/v2/$repo/tags/list"
	get_dh_resource "$url" | jq -r '.tags[]'
}