Merge pull request #9 from YunoHost/queue_worker_to_avoid_useless_ios

[enh] queue/worker pattern to avoid hammering the server with ios

dynette.cron.py

@@ -2,6 +2,7 @@
 
 ### Configuration ###
 
+postgresql_dsn = "dbname=dynette user=dynette password=myPassword"
 conf_file = '/etc/bind/named.conf.local'    # Include this filename in '/etc/bind/named.conf'
 zone_dir  = '/var/lib/bind/'                # Do not forget the trailing '/'
 subs_urls = ['https://dyndns.yunohost.org']  # 127.0.0.1 if you install subscribe server locally
@@ -25,9 +26,12 @@ allowed_operations = {
 ### Script ###
 
 import os
+import sys
 import json
+import psycopg2
 from urllib import urlopen
 
+
 # Get master key
 master_key_path = os.path.join(os.path.dirname(__file__), 'master.key')
 master_key = open(master_key_path).read().rstrip()
@@ -35,6 +39,33 @@ master_key = open(master_key_path).read().rstrip()
 # Bind configuration
 lines = ['// Generated by Dynette CRON']
 
+with psycopg2.connect(postgresql_dsn) as postgresql_connection:
+    with postgresql_connection.cursor() as psql:
+        # look in the job queue if we have tasks to handle
+        need_rewrite = False
+        need_bind9_cache_flush = False
+
+        # DataMapper convert table names to lower cases and add a "s" at the
+        # end
+        # consume all available tasks at once to merge them and avoir doing
+        # useless jobs
+        psql.execute("SELECT task FROM jobqueues ORDER BY id ASC;")
+
+        for task in psql.fetchall():
+            task = task[0]
+            if task == "conf_rewrite":
+                need_rewrite = True
+            elif task == "bind9_cache_flush":
+                need_bind9_cache_flush = True
+
+        if not need_rewrite and not need_bind9_cache_flush:
+            sys.exit(0)
+
+        # we have consume all the jobs, flush it
+        # because we are in a SQL transaction we won't have situation where a
+        # job could be added just after we read them all
+        psql.execute("DELETE FROM jobqueues;")
+
         # Loop through Dynette servers
         for url in subs_urls:
 
@@ -100,6 +131,8 @@ for url in subs_urls:
                         '};',
                     ])
 
+        # update bind9 zone
+        if need_rewrite:
             # Backup old Bind configuration file.
             os.system('cp '+ conf_file +' '+ conf_file +'.back')
 
@@ -111,17 +144,14 @@ with open(conf_file, 'w') as zone:
             os.system('chown -R bind:bind '+ zone_dir +' '+ conf_file)
 
             # Reload Bind
-if os.system('/usr/sbin/rndc reload') == 0:
-    exit(0)
-else:
+            if os.system('/usr/sbin/rndc reload') != 0:
                 os.system('cp '+ conf_file +' '+ conf_file +'.bad')
                 os.system('cp '+ conf_file +'.back '+ conf_file)
                 os.system('/usr/sbin/rndc reload')
                 print("An error occured ! Please check daemon.log and your conf.bad")
-    exit(1)
+                sys.exit(1)
 
-# mein got this is so awful
-if os.path.exists('/tmp/dynette_flush_bind_cache'):
+        # flush bind9 cache (mostly because we got a hmac-sha512 key migration
+        if need_bind9_cache_flush:
             os.system('/usr/sbin/rndc flush')
             os.system('/usr/sbin/rndc reload')
-    os.system('rm /tmp/dynette_flush_bind_cache')

dynette.rb

@@ -68,6 +68,25 @@ class Ipban
     property :ip_addr, String, :key => true
 end
 
+################
+### JobQueue ###
+################
+
+# JobQueue to communicate with the conf updater
+class Jobqueue
+    include DataMapper::Resource
+
+    property :id, Serial, :key => true
+    property :task, String
+end
+
+def schedule_conf_rewrite()
+    Jobqueue.create(:task => "conf_rewrite")
+end
+
+def schedule_bind9_cache_flush()
+    Jobqueue.create(:task => "bind9_cache_flush")
+end
 
 ################
 ### Handlers ###
@@ -198,6 +217,7 @@ post '/key/:public_key' do
     entry.ips << Ip.create(:ip_addr => request.ip)
 
     if entry.save
+        schedule_conf_rewrite
         halt 201, { :public_key => entry.public_key, :subdomain => entry.subdomain, :current_ip => entry.current_ip }.to_json
     else
         halt 412, { :error => "A problem occured during DNS registration" }.to_json
@@ -237,11 +257,8 @@ put '/migrate_key_to_sha512/' do
         halt 412, { :error => "A problem occured during key algo migration" }.to_json
     end
 
-    # I don't have any other way of communicating with this dynette.cron.py
-    # this is awful
-    File.open("/tmp/dynette_flush_bind_cache", "w").close
-    # let's try flusing here, hope that could help ... (this design is so awful)
-    `/usr/sbin/rndc flush`
+    schedule_conf_rewrite
+    schedule_bind9_cache_flush
 
     halt 201, { :public_key => entry.public_key, :subdomain => entry.subdomain, :current_ip => entry.current_ip }.to_json
 end
@@ -255,6 +272,7 @@ put '/key/:public_key' do
     end
     entry.current_ip = request.ip
     if entry.save
+        schedule_conf_rewrite
         halt 201, { :public_key => entry.public_key, :subdomain => entry.subdomain, :current_ip => entry.current_ip }.to_json
     else
         halt 412, { :error => "A problem occured during DNS update" }.to_json
@@ -270,6 +288,7 @@ delete '/key/:public_key' do
     if entry = Entry.first(:public_key => params[:public_key])
         Ip.first(:entry_id => entry.id).destroy
         if entry.destroy
+            schedule_conf_rewrite
             halt 200, "OK".to_json
         else
             halt 412, { :error => "A problem occured during DNS deletion" }.to_json
@@ -296,6 +315,7 @@ delete '/domains/:subdomain' do
 
         Ip.first(:entry_id => entry.id).destroy
         if entry.destroy
+            schedule_conf_rewrite
             halt 200, "OK".to_json
         else
             halt 412, { :error => "A problem occured during DNS deletion" }.to_json