parse

#!/bin/bash

################################################################
# 
# Apache License 2.0
#
# This file will parse the Environment variables created by
# node containers linked to the varnish container
# and automatically create a default.vcl configuration file
# 
# The configuration file will create a load balancer and add
# each of the node containers linked.
#
# Varnish is not configured to use the reverse proxy features
# that it has, it just a load balancer.
#
################################################################


# Get the Environment variables and save them in the variable envs
envs=`printenv`

# Remove the default.vcl file

echo "vcl 4.0;
backend default {
.host = "127.0.0.1";
.port = "8080";
.connect_timeout = 60s;
.first_byte_timeout = 60s;
.between_bytes_timeout = 60s;
.max_connections = 800;
}
 
acl purge {
"127.0.0.1";
"localhost";
}
 
sub vcl_recv {
set req.grace = 2m;
 
# Set X-Forwarded-For header for logging in nginx
remove req.http.X-Forwarded-For;
set req.http.X-Forwarded-For = client.ip;
 
# Remove has_js and CloudFlare/Google Analytics __* cookies and statcounter is_unique
set req.http.Cookie = regsuball(req.http.Cookie, "(^|;\s*)(_[_a-z]+|has_js|is_unique)=[^;]*", "");
# Remove a ";" prefix, if present.
set req.http.Cookie = regsub(req.http.Cookie, "^;\s*", "");
 
# Either the admin pages or the login
if (req.url ~ "/wp-(login|admin|cron)") {
# Don't cache, pass to backend
return (pass);
}" > /etc/varnish/default.vcl
# Loop through all of our variables
for env in $envs
do
  # separate the name of the variable from the value
  IFS== read name value <<< "$env"  
  
  # if the variable has PORT_80_TCP_ADDR it means this is a
  # variable created by a node container linked to the varnish
  # container
  if [[ $name == *PORT_80_TCP_ADDR* ]]; then

# create a backend for each node container found in the variables
cat >> /etc/varnish/default.vcl << EOF
  backend ${name} {
    .host = "${value}";
    .port = "80";
    .connect_timeout = 60s;
    .first_byte_timeout = 60s;
    .between_bytes_timeout = 60s;
    .max_connections = 800;
  }
  
EOF

  fi
done

# once we have all the containers ready, we create the
# load balancer, since we're gonna loop again, we just
# create the first line
cat >> /etc/varnish/default.vcl << EOF

  
  sub vcl_init {
    new cluster1 = directors.round_robin();

EOF

# loop again to add each backend created
for env in $envs
do
  IFS== read name value <<< "$env"  
  if [[ $name == *PORT_80_TCP_ADDR* ]]; then

# create each backend in the load balancer
cat >> /etc/varnish/default.vcl << EOF
     cluster1.add.backend = (${name}, 1.0); 
EOF

  fi
done

# close the load balancer line
# and add the balancer as the req.backend
cat >> /etc/varnish/default.vcl << EOF

  }
  
sub vcl_fetch {
   if (req.url ~ "\.(css|js|png|gif|jpg)$") {
     unset beresp.http.set-cookie;
     set beresp.ttl = 66h;
  }
}
  
sub vcl_recv {
    set req.backend_hint = cluster1.backend();
}
EOF