Using HaProxy environmental variables in haproxy.cfg not working

Trying to figure out why environmental variables in haproxy.cfg aren't working in HA-Proxy version 1.5.2

on the command line, using Printenv I get a list of environmental variables like FE_PORT_8000_TCP_ADDR=172.17.0.4

Which I need to use in the haproxy.cfg. According to this and the docs How can I use environment variables in haproxy.conf using $FE_PORT_8000_TCP_ADDR or ${FE_PORT_8000_TCP_ADDR} should work. However that is not working.

In Haporxy.cfg hardcoding DOES work, and accessed in a browser it shows as expected:

backend FE
   # balance     roundrobin
    server      FE1 172.17.0.4:8000  maxconn 256

But environmental variable with same supposed value doesn't, in the browser it gives 503 Service Unavailable.

backend FE
   # balance     roundrobin
    server      FE1 $FE_PORT_8000_TCP_ADDR:8000  maxconn 256

Any ideas on what is being done wrong?

UPDATE: This person has what looks like the same issue How can I use environment variables in haproxy.conf

Solution 1:

Since you're stopping/starting with the service command, you need to specify the environment variables in your init script (e.g. /etc/init.d/haproxy on ubuntu) not in your interactive terminal session where you're controlling the service (service haproxy start). You can verify the environment variables available to a specific pid in the proc filesytem. If you check yours for haproxy, it'll likely be only TERM and LANG, because that's the only environment which gets passed via service to the init script (manpage for service).

# cat /proc/$(pgrep haproxy)/environ

If instead of starting daemonized haproxy from the init script you directly run haproxy you'll likely see the behavior you're looking for:

# haproxy -f /etc/haproxy/haproxy.cfg

To solve this, edit the init script /etc/init.d/haproxy and set your variables there:

export FE_PORT_8000_TCP_ADDR=172.17.0.4

Solution 2:

Had the same problem. Fixed it by adding double quotes around the environment variable.

As explained here (2.3. Environment variables)

HAProxy's configuration supports environment variables. Those variables are interpreted only within double quotes. Variables are expanded during the configuration parsing. Variable names must be preceded by a dollar ("$") and optionally enclosed with braces ("{}") similarly to what is done in Bourne shell. Variable names can contain alphanumerical characters or the character underscore ("_") but should not start with a digit.

Solution 3:

I had the same problem but on Debian 8 (Jessie) and setting it in /etc/init.d/haproxy did not work. I fixed it by setting the variable in /etc/default/haproxy like this (no export needed)

FE_PORT_8000_TCP_ADDR=172.17.0.4

For more info see my question and answer about my issue.