Hi, when I use dns resolvers combined with http health checks, the backend either never goes to 'UP' when haproxy starts before the backend, or the backend stays 'DOWN' when it wasn't resolvable for a while.
--> starting haproxy: [WARNING] 348/224658 (10) : Server phoenix-backend/phoenix is DOWN, reason: Layer4 timeout, check duration: 1001ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue. [ALERT] 348/224658 (10) : backend 'phoenix-backend' has no server available! [WARNING] 348/224727 (10) : Server phoenix-backend/phoenix was DOWN and now enters maintenance (DNS timeout status). --> starting container: [WARNING] 348/224914 (10) : phoenix-backend/phoenix changed its IP from 46.38.243.234 to 172.19.0.7 by docker/docker. [WARNING] 348/224914 (10) : Server phoenix-backend/phoenix administratively READY thanks to valid DNS answer. then the process starts and is healthy, but backend stays 'down', no health checks got logged and I needed to restart haproxy which fixed everything. --> stopping the process: [WARNING] 348/225537 (10) : Server phoenix-backend/phoenix is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue. [ALERT] 348/225537 (10) : backend 'phoenix-backend' has no server available! --> starting process: [WARNING] 348/225735 (10) : Server phoenix-backend/phoenix is UP, reason: Layer7 check passed, code: 200, info: "OK", check duration: 171ms. 1 active and 0 backup servers online. 0 sessions requeued, 0 total in queue. --> stopping process and container and waiting a few seconds until 'DOWN' message appears [WARNING] 348/225847 (10) : Server phoenix-backend/phoenix is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue. [ALERT] 348/225847 (10) : backend 'phoenix-backend' has no serverver available! [WARNING] 348/225923 (10) : Server phoenix-backend/phoenix was DOWN and now enters maintenance (DNS timeout status). --> starting container again: [WARNING] 348/230028 (10) : Server phoenix-backend/phoenix administratively READY thanks to valid DNS answer. and starting the process, but nothing happens. again backend stays 'DOWN' and no health checks got logged. > haproxy -vv HA-Proxy version 1.8.1 2017/12/03 Copyright 2000-2017 Willy Tarreau <[email protected]> Build options : TARGET = linux2628 CPU = generic CC = gcc CFLAGS = -O2 -g -fno-strict-aliasing -Wdeclaration-after-statement -fwrapv -Wno-null-dereference -Wno-unused-label OPTIONS = USE_LINUX_SPLICE=1 USE_LIBCRYPT=1 USE_ZLIB=1 USE_OPENSSL=1 USE_PCRE=1 Default settings : maxconn = 2000, bufsize = 16384, maxrewrite = 1024, maxpollevents = 200 Built with OpenSSL version : OpenSSL 1.1.0f 25 May 2017 Running on OpenSSL version : OpenSSL 1.1.0f 25 May 2017 OpenSSL library supports TLS extensions : yes OpenSSL library supports SNI : yes OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2 Built with transparent proxy support using: IP_TRANSPARENT IPV6_TRANSPARENT IP_FREEBIND Encrypted password support via crypt(3): yes Built with multi-threading support. Built with PCRE version : 8.39 2016-06-14 Running on PCRE version : 8.39 2016-06-14 PCRE library supports JIT : no (USE_PCRE_JIT not set) Built with zlib version : 1.2.8 Running on zlib version : 1.2.8 Compression algorithms supported : identity("identity"), deflate("deflate"), raw-deflate("deflate"), gzip("gzip") Built with network namespace support. Available polling systems : epoll : pref=300, test result OK poll : pref=200, test result OK select : pref=150, test result OK Total: 3 (3 usable), will use epoll. Available filters : [SPOE] spoe [COMP] compression [TRACE] trace global log /dev/log local0 log /dev/log local1 info defaults log global mode http timeout connect 3s timeout client 30s timeout server 120s timeout tunnel 3600s timeout http-keep-alive 1s timeout http-request 15s option http-server-close option httplog option forwardfor errorfile 503 /code/docker/haproxy/503.html errorfile 408 /dev/null resolvers docker nameserver docker 127.0.0.11:53 hold valid 2s listen stats bind :8444 mode http stats enable stats realm Haproxy\ Statistics stats uri / frontend http bind 0.0.0.0:80 reqadd X-Forwarded-Proto:\ http default_backend phoenix-backend frontend https bind 0.0.0.0:443 ssl crt "/code/certs/dev/dev-server-combined.pem" alpn h2,http/1.1 no-sslv3 reqadd X-Forwarded-Proto:\ https default_backend phoenix-backend backend phoenix-backend option httpchk GET /_check server phoenix phoenix:4000 resolvers docker init-addr libc,last,none check inter 1000
