Add prototype

ask_for_jobs

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+# coding=utf-8
+
+
+import json
+import os
+import subprocess
+from threading import Thread
+import urllib.parse
+import urllib.request
+
+
+ERRORRMESSAGE = urllib.parse.quote("Bei der Verarbeitung der Daten ist ein Fehler aufgetreten.")
+VRE_MANAGER = "http://localhost:5000/vre/jobs"
+IMAGES = {
+    "nlp": "gitlab.ub.uni-bielefeld.de:4567/pjentsch/vre_nlp_node",
+    "ocr": "gitlab.ub.uni-bielefeld.de:4567/pjentsch/vre_ocr_node"
+}
+
+
+def manage_jobs(service):
+    # Get queued jobs
+    queued = json.load(
+        urllib.request.urlopen(VRE_MANAGER + "?service=" + service + "&status=queued")
+    )
+
+    # Return if no jobs are available
+    if len(queued) == 0:
+        return
+
+    # Get a list of compute nodes
+    compute_nodes = subprocess.run(
+        ["docker", "ps", "--filter", "ancestor=" + IMAGES[service], "--format", "{{.Names}}"],
+        encoding="utf-8",
+        stdout=subprocess.PIPE
+    ).stdout.split()
+
+    # Filter occupied compute nodes out
+    compute_nodes = [compute_node for compute_node in compute_nodes if bool(subprocess.run(["docker", "exec", compute_node, "test", "-f", "pyflow.data/active_pyflow_process.txt"]).returncode)]
+
+    # Return if no compute nodes are available
+    if len(compute_nodes) == 0:
+        return
+
+    # Assign jobs to compute nodes
+    job_assignments = zip(queued, compute_nodes)
+
+    for job_assignment in job_assignments:
+        # Prepare and start the assigned jobs
+        jobThread = Thread(target=start_job, args=(service, job_assignment[1], job_assignment[0]))
+        jobThread.start()
+
+
+def start_job(service, compute_node, job):
+    # Update job status to "running"
+    urllib.request.urlopen(
+        urllib.request.Request(url=VRE_MANAGER + "/" + job["id"] + "?status=running", method="PUT")
+    )
+
+    # Start the service
+    process = subprocess.run(
+        ["docker", "exec", compute_node, service, "-i", "/root/vre_files/jobs/" + job["id"], "-o", "/root/vre_files/jobs/" + job["id"], "-l", job["language"]],
+        stderr=subprocess.DEVNULL,
+        stdout=subprocess.DEVNULL
+    )
+    if process.returncode != 0:
+        urllib.request.urlopen(
+            urllib.request.Request(url=VRE_MANAGER + "/" + job["id"] + "?status=failed&report=" + ERRORRMESSAGE, method="PUT")
+        )
+        return
+
+    # Update job status to "finished"
+    urllib.request.urlopen(
+        urllib.request.Request(url=VRE_MANAGER + "/" + job["id"] + "?status=finished", method="PUT")
+    )
+
+    # TODO: Send E-Mail to user
+
+
+manage_jobs("ocr")
+manage_jobs("nlp")