Layer4 "Connection refused" with haproxy

I need some advise on how to setup haproxy. I have two web-servers up and running. For testing they run a simple node server on port 8080.

Now on my haproxy server I start haproxy which gives me the following:

$> /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg [WARNING] 325/202628 (16) : Server node-backend/server-a is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.[WARNING] 325/202631 (16) : Server node-backend/server-b is DOWN, reason: Layer4 timeout, check duration: 2001ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.[ALERT] 325/202631 (16) : backend 'node-backend' has no server available!

Just one note: If I do: 

haproxy$> wget server-a:8080

I get the response from the node server.

Here is my haproxy.cfg:

#--------------------------------------------------------------------- # Global settings#---------------------------------------------------------------------globallog 127.0.0.1 local2chroot /var/lib/haproxypidfile /var/run/haproxy.pidmaxconn 4000user haproxygroup haproxystats socket /var/lib/haproxy/stats#---------------------------------------------------------------------# common defaults that all the 'listen' and 'backend' sections will# use if not designated in their block#---------------------------------------------------------------------defaultsmode tcplog globaloption tcplogoption dontlognulloption http-server-close# option forwardfor except 127.0.0.0/8option redispatchretries 3timeout http-request 10stimeout queue 1mtimeout connect 10stimeout client 1mtimeout server 1mtimeout http-keep-alive 10stimeout check 10smaxconn 3000#---------------------------------------------------------------------# main frontend which proxys to the backends#---------------------------------------------------------------------frontend wwwbind *:80default_backend node-backend#---------------------------------------------------------------------# round robin balancing between the various backends#--------------------------------------------------------------------backend node-backendbalance roundrobinmode tcpserver server-a 172.19.0.2:8080 checkserver server-b 172.19.0.3:8080 check

If I remove the check option it seems to work. Any suggestions how I can fix this checking mechanism of haproxy?

4

Best Answer

You need to get exact ip address of your server with the help of command

ifconfig

and correct the below address in your haproxy.cfg file:

172.19.0.2:8080172.19.0.3:8080

or modify line like below

server server-a server-a:8080 checkserver server-b server-b:8080 check

Remove "mode tcp" and change it to "mode http".
Im just guessing here but i suppose haproxy is doing a tcp check against your web server and the web server can not respond to it.
in "mode http" it checks the web server in http mode and expects a "response 200" for L4 checkand expects a string (whatever you defined) as a L7 check

eg. L4

backend node-backendbalance roundrobinmode http #(NOT NEEDED IF DEFINED IN DEFAULTS)option httpchkserver server-a 172.19.0.2:8080 checkserver server-b 172.19.0.3:8080 check
eg. L7

backend node-backendbalance roundrobinmode http #(NOT NEEDED IF DEFINED IN DEFAULTS)option httpchk get /SOME_URIhttp-check expect status 200server server-a 172.19.0.2:8080 checkserver server-b 172.19.0.3:8080 check

Another note related to @basickarl's comment on docker. If you are sending into a docker (docker-compose) instance (namely where you have multiple instances of service running) you likely need to define the docker resolver and use it for dns resolution on your backend:

resolver:

resolvers docker_resolvernameserver dns 127.0.0.11:53

backend usage of resolver:

backend mainbalance roundrobinoption http-keep-aliveserver haproxyapp app:80 check inter 10s resolvers docker_resolver resolve-prefer ipv4

i tryied all this answers nothing works for me. only put the gateway IP of network work, for default bridge is 172.17.0.1.

In the servers put the : and with this haproxy connects with success.

My example of custom network with fixed ips and gateway:

----- haproxy configbackend be_pe_8545mode httpbalance roundrobinserver p1 172.20.0.254:18545 check inter 10sserver p2 172.20.0.254:28545 check inter 10s----- docker app / networkdocker_app: ... networks:public_network:ipv4_address: 172.20.0.50 public_network:name: public_networkdriver: bridgeipam:driver: defaultconfig:- subnet: 172.20.0.0/24gateway: 172.20.0.254

Random Posts

How to pad the left side of a list of tensors in pytorch to the size of the largest list?Convert List to Pandas Dataframe ColumnSquash in SourceTreeTrust Store vs Key Store - creating with keytoolHow can I convert bool true or false to string "True" or "False"Why is iCloud blocking some of my applications emails?long to wide with dplyr [duplicate]Override Mantine styles to only one elementWhat is torch.randn((1, 5))?what library to use for stoi keyword in c++Why is my background color not filling all of my table?Elegant grid search in python/numpyTemplate based C / C++ code generationUnderstanding what QHash does when key not foundWhy Error: Signature verification failed?What's the difference between a CRC and a checksum?How do you or a vector with a single bit in verilog?Ionic v6 Ion-accordion open first item by defaultare there side effects of running jest with --detectOpenHandles --forceExit?conda init doesn't initialize shell?