docker context and DOCKER_HOST support

README.md

@@ -129,7 +129,9 @@ Ran on 1 node in 1.54 seconds
 
 Given an docker image name it will spin up that container and setup external ssh on that platform. For helpful docker tips look [here](https://github.com/puppetlabs/litmus_image/blob/main/README.md)
 
-provision
+Containers by default will be managed in the current [docker context](https://docs.docker.com/engine/context/working-with-contexts/), on the [DOCKER_HOST](https://docs.docker.com/engine/reference/commandline/cli/#environment-variables), or on localhost if nether are configured.
+
+#### Provision
 
 ```ruby
 $ bundle exec bolt --modulepath /Users/tp/workspace/git/ task run provision::docker --targets localhost  action=provision platform=ubuntu:14.04 inventory=/Users/tp/workspace/git/provision
@@ -162,7 +164,7 @@ These defaults can be overriden by passing the flags with different values i.e.
 bundle exec bolt --modulepath /Users/tp/workspace/git/ task run provision::docker --targets localhost  action=provision platform=ubuntu:14.04 inventory=/Users/tp/workspace/git/provision vars='{ "docker_run_opts": ["-p 8086:8086", "-p 3000:3000"]}'
 ```
 
-tear_down
+#### Tear down
 
 ```ruby
 $ bundle exec bolt --modulepath /Users/tp/workspace/git/ task run provision::docker --targets localhost  action=tear_down inventory=/Users/tp/workspace/git/provision node_name=localhost:2222

tasks/docker.rb

@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require 'json'
+require 'uri'
 require 'yaml'
 require 'puppet_litmus'
 require_relative '../lib/task_helper'
@@ -152,7 +153,16 @@ def provision(image, inventory_location, vars)
   os_release_facts = get_image_os_release_facts(image)
   distro = os_release_facts['ID']
   version = os_release_facts['VERSION_ID']
-  hostname = 'localhost'
+
+  hostname = (ENV['DOCKER_HOST'].nil? || ENV['DOCKER_HOST'].empty?) ? 'localhost' : URI.parse(ENV['DOCKER_HOST']).host || ENV['DOCKER_HOST']
+  begin
+    # Use the current docker context to determine the docker hostname
+    docker_context = JSON.parse(run_local_command('docker context inspect'))[0]
+    hostname = URI.parse(docker_context['Endpoints']['docker']['Host']).host || hostname
+  rescue RuntimeError
+    # old clients may not support docker context
+  end
+
   group_name = 'ssh_nodes'
   warn '!!! Using private port forwarding!!!'
   front_facing_port = random_ssh_forwarding_port