Avoid server hang on restarts

When restarting, the entrypoint was appending to existing configuration always, without checking if it was already filled. As such, since the 1st restart, frontend and backend names got duplicated and the server stopped working. In an automated restart environment, the file was only growing constantly.

Now we generate the full config and overwrite it always.

Author: yajo

Dockerfile

@@ -6,7 +6,6 @@ CMD ["haproxy", "-f", "/usr/local/etc/haproxy/haproxy.cfg"]
 RUN apk add --no-cache python3 &&\
     pip3 install --no-cache-dir dnspython
 
-COPY haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg
 COPY magic-entrypoint.py /magic-entrypoint
 
 ENV NAMESERVERS="208.67.222.222 8.8.8.8 208.67.220.220 8.8.4.4" \

haproxy.cfg

@@ -17,11 +17,20 @@
 TEMPLATE = """
 backend talk_{index}
     server stupid_{index} {talk}
-
 frontend listen_{index}
     bind {listen}
     default_backend talk_{index}
 """
+config = """
+global
+    log /dev/log local0
+defaults
+    log global
+    mode tcp
+    timeout client 10m
+    timeout connect 10s
+    timeout server 10m
+"""
 
 if len(LISTENS) != len(TALKS):
     sys.exit("Set the same amount of servers in $LISTEN and $TALK")
@@ -47,15 +56,15 @@
         logging.info("Resolved %s to %s", server, ip)
 
     # Render template
-    result = TEMPLATE.format(
+    config += TEMPLATE.format(
         index=index,
         listen=listen,
         talk=f"{ip}:{port}",
     )
 
-    # Write template to haproxy's cfg file
-    with open("/usr/local/etc/haproxy/haproxy.cfg", "a") as cfg:
-        cfg.write(result)
+# Write template to haproxy's cfg file
+with open("/usr/local/etc/haproxy/haproxy.cfg", "w") as cfg:
+    cfg.write(config)
 
 logging.info("Magic ready, executing now: %s", " ".join(sys.argv[1:]))
 os.execv(sys.argv[1], sys.argv[1:])