Add service that will watch on balancer configMap

Co-authored-by: danilapog <danil.titarenko@onlyoffice.com>
Co-committed-by: danilapog <danil.titarenko@onlyoffice.com>

Dockerfile.balancer

@@ -15,8 +15,7 @@ RUN apt-get update -y && \
     rm -rf /var/lib/apt/lists/* && \
     wget -O /usr/local/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v1.2.5/dumb-init_1.2.5_$(uname -m) && \
     chmod +x /usr/local/bin/dumb-init && \
-    mkdir -p /ds_ep_observer \
-             /cm_observer \
+    mkdir -p /scripts \
              /var/tmp/docs_cache \
              /etc/nginx/mnt_config \
              /etc/nginx/lua && \
@@ -25,13 +24,15 @@ RUN apt-get update -y && \
 
 COPY scripts/ds-ep-observer.py \
      scripts/ds-pod-observer.py \
-     /ds_ep_observer/
-COPY scripts/balancer-shutdown.py /
+     scripts/balancer-shutdown.py \
+     scripts/balancer-cm-observer.py \
+     /scripts/
 COPY config/balancer/conf.d/balancer-server.conf /etc/nginx/conf.d/
 COPY config/balancer/conf.d/handler-server.conf /etc/nginx/conf.d/
 COPY config/balancer/nginx.conf /usr/local/openresty/nginx/conf/
 COPY config/balancer/lua/configuration.lua /etc/nginx/lua/
 COPY config/balancer/lua/docs_balancer.lua /etc/nginx/lua/
+COPY config/balancer/balancer-lua.conf /etc/nginx/mnt_config/
 COPY --chmod=755 balancer-docker-entrypoint.py /docker_entrypoint.py
 
 EXPOSE 80 443

balancer-docker-entrypoint.py

@@ -38,9 +38,10 @@ def set_nginx_parameter():
 def running_services():
     try:
         running_nginx = ["/usr/local/openresty/bin/openresty", "-g", "daemon off;"]
-        running_get_ds_ep = ["python3", "/ds_ep_observer/ds-ep-observer.py"]
-        running_get_ds_pod = ["python3", "/ds_ep_observer/ds-pod-observer.py"]
-        all_cmd = [running_nginx, running_get_ds_ep, running_get_ds_pod]
+        running_cm_observer = ["python3", "/scripts/balancer-cm-observer.py"]
+        running_get_ds_ep = ["python3", "/scripts/ds-ep-observer.py"]
+        running_get_ds_pod = ["python3", "/scripts/ds-pod-observer.py"]
+        all_cmd = [running_nginx, running_cm_observer, running_get_ds_ep, running_get_ds_pod]
         for cmd in all_cmd:
             cmd_process = subprocess.Popen(cmd)
             logger_endpoints_ds.info(f'The "{cmd_process.pid}" process has been running')

config/balancer/balancer-lua.conf

@@ -0,0 +1,3 @@
+default_type text/plain;
+return 200 "Hello, app is not ready. Please wait...\n";
+# Just simple placeholder that return 200 until configMap is not initiated;

scripts/balancer-cm-observer.py

@@ -0,0 +1,75 @@
+from kubernetes import client, watch
+import os
+import logging
+import requests
+import json
+import time
+import subprocess
+
+cm_name = "balancer-lua-config"
+cm_key = "balancer-lua.conf"
+cm_path = "/etc/nginx/mnt_config/balancer-lua.conf"
+
+k8s_host = os.environ["KUBERNETES_SERVICE_HOST"]
+api_server = f'https://{k8s_host}'
+pathCrt = '/run/secrets/kubernetes.io/serviceaccount/ca.crt'
+pathToken = '/run/secrets/kubernetes.io/serviceaccount/token'
+pathNS = '/run/secrets/kubernetes.io/serviceaccount/namespace'
+
+with open(pathToken, "r") as f_tok:
+    token = f_tok.read()
+
+with open(pathNS, "r") as f_ns:
+    ns = f_ns.read()
+
+configuration = client.Configuration()
+configuration.ssl_ca_cert = pathCrt
+configuration.host = api_server
+configuration.verify_ssl = True
+configuration.debug = False
+configuration.api_key = {"authorization": "Bearer " + token}
+client.Configuration.set_default(configuration)
+
+v1 = client.CoreV1Api()
+
+def init_logger(name):
+    logger = logging.getLogger(name)
+    formatter = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
+    logger.setLevel(logging.DEBUG)
+    stdout = logging.StreamHandler()
+    stdout.setFormatter(logging.Formatter(formatter))
+    stdout.setLevel(logging.DEBUG)
+    logger.addHandler(stdout)
+    logger.info('Running Docs-Balancer configMap observer service...')
+
+# Watch for changes in the ConfigMap
+def watch_configmap_changes():
+    field_selector = f"metadata.name={cm_name}"
+    while True:
+        try:
+            w = watch.Watch()
+            for event in w.stream(v1.list_namespaced_config_map, namespace=ns, field_selector=field_selector):
+                try:
+                    f = open(cm_path, "w")
+                    f.write(event['object'].data[cm_key])
+                    f.close()
+                    reload_nginx()
+                except Exception as msg_write_cm:
+                    logger_cm_observer.error(f'Cant write in config file...{msg_write_cm}')
+        except Exception as msg_get_cm:
+            logger_cm_observer.warning(f'Trying to get cm data...{msg_get_cm}')
+            time.sleep(1)
+
+
+def reload_nginx():
+    try:
+        subprocess.run(['nginx', '-s', 'reload'], check=True)
+    except Exception as quit_msg:
+        logger_cm_observer.error(f'Failed nginx reload attempt: "{quit_msg}"\n')
+
+# Init logger
+init_logger('balancer')
+logger_cm_observer = logging.getLogger('balancer.cm')
+
+# Start watching for changes
+watch_configmap_changes()

scripts/balancer-shutdown.py

@@ -93,7 +93,8 @@ def ngx_shutdown():
 def shutdown_services():
     services = [
             'ds-ep-observer.py',
-            'ds-pod-observer.py'
+            'ds-pod-observer.py',
+            'balancer-cm-observer.py'
             ]
     try:
         for service in services: