feat: add support for python3

- Use jq where possible
- Drop unused function (no usage across entire codebase nor in any github repository

Closes #3689

plugins/app-json/internal-functions

@@ -17,7 +17,7 @@ get_phase_script() {
     return 0
   fi
 
-  get_json_value "scripts.dokku.${PHASE_SCRIPT_KEY}" <"$APP_JSON_FILE"
+  get_json_value ".scripts.dokku.${PHASE_SCRIPT_KEY}" <"$APP_JSON_FILE"
 }
 
 get_release_cmd() {

plugins/common/functions

@@ -923,24 +923,10 @@ internal_get_app_urls() {
 get_json_value() {
   declare desc="return value of provided json key from a json stream on stdin"
   # JSON_NODE should be expresses as either a top-level object that has no children
-  # or in the format of json.node.path
+  # or in the format of .json.node.path
   local JSON_NODE="$1"
-  local JSON_NODE=${JSON_NODE//\./\"][\"}
-  local JSON_NODE="[\"${JSON_NODE}\"]"
-  cat | python2.7 -c 'import json,sys;obj=json.load(sys.stdin);print json.dumps(obj'"${JSON_NODE}"').strip("\"")'
-}
 
-get_json_keys() {
-  declare desc="return space-separated list of json keys from json provided on stdin"
-  # JSON_NODE should be expressed as json.node.path and is expected to have children
-  local JSON_NODE="$1"
-  local JSON_NODE=${JSON_NODE//\./\"][\"}
-  local JSON_NODE="[\"${JSON_NODE}\"]"
-  if [[ "$JSON_NODE" == "[\"\"]" ]]; then
-    cat | python2.7 -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj.keys())'
-  else
-    cat | python2.7 -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj'"${JSON_NODE}"'.keys())'
-  fi
+  cat | jq -r "${JSON_NODE} | select (.!=null)" 2>/dev/null
 }
 
 strip_inline_comments() {

plugins/scheduler-docker-local/scheduler-inspect

@@ -40,7 +40,7 @@ for container in data:
     container['Config']['Env'] = env
     output.append(container)
 
-print json.dumps(data, sort_keys=True, indent=4)
+print(json.dumps(data, sort_keys=True, indent=4))
 EOF
 
   local CONTAINER_FILES="$(find "$DOKKU_ROOT/$APP" -maxdepth 1 -name "CONTAINER.*" -printf "%f\n" 2>/dev/null | sort -t . -k 2 -n | xargs)"