Varnish Installation Guide

rpm --nosignature -i https://repo.varnish-cache.org/redhat/varnish-4.0.el7.rpm
yum install varnish

firewall-cmd --zone=public --add-port=6081/tcp

systemctl start varnish

Error 503 Backend fetch failed

Backend fetch failed

Guru Meditation:

XID: 3

Varnish cache server

systemctl stop varnish

cp /etc/varnish/varnish.params /etc/varnish/varnish.params.bak

vim /etc/varnish/varnish.params

VARNISH_LISTEN_ADDRESS=192.168.1.10
VARNISH_LISTEN_PORT=80
VARNISH_VCL_CONF=/etc/varnish/librenms.vcl
VARNISH_STORAGE="malloc,512M"

# Set this to 1 to make systemd reload try to switch vcl without restart.
RELOAD_VCL=1

# Main configuration file. You probably want to change it.
VARNISH_VCL_CONF=/etc/varnish/librenms.vcl

# Default address and port to bind to. Blank address means all IPv4
# and IPv6 interfaces, otherwise specify a host name, an IPv4 dotted
# quad, or an IPv6 address in brackets.
VARNISH_LISTEN_ADDRESS=192.168.1.10
VARNISH_LISTEN_PORT=80

# Admin interface listen address and port
VARNISH_ADMIN_LISTEN_ADDRESS=127.0.0.1
VARNISH_ADMIN_LISTEN_PORT=6082

# Shared secret file for admin interface
VARNISH_SECRET_FILE=/etc/varnish/secret

# Backend storage specification, see Storage Types in the varnishd(5)
# man page for details.
VARNISH_STORAGE="malloc,512M"

# Default TTL used when the backend does not specify one
VARNISH_TTL=120

# User and group for the varnishd worker processes
VARNISH_USER=varnish
VARNISH_GROUP=varnish

# Other options, see the man page varnishd(1)
DAEMON_OPTS="-p thread_pool_min=5 -p thread_pool_max=500 -p thread_pool_timeout=300"

vim /etc/httpd/conf.d/librenms.conf

vim /etc/httpd/conf/httpd.conf

cd /etc/varnish
touch librenms.vcl

chown varnish:varnish default.vcl varnish.params secret
chmod 644 default.vcl varnish.params secret

vim librenms.vcl

#
# This is an example VCL file for Varnish.
#
# It does not do anything by default, delegating control to the
# builtin VCL. The builtin VCL is called when there is no explicit
# return statement.
#
# See the VCL chapters in the Users Guide at https://www.varnish-cache.org/docs/
# and http://varnish-cache.org/trac/wiki/VCLExamples for more examples.

# Marker to tell the VCL compiler that this VCL has been adapted to the
# new 4.0 format.
vcl 4.0;

# Default backend definition. Set this to point to your Apache server.
backend librenms {
    .host = "127.0.0.1";
    .port = "8080";
}

# In this example our objective is to cache static content with Varnish and temporarily
# cache dynamic content in the client web browser.

sub vcl_recv {
    # HTTP requests from client web browser.
    # Here we remove any cookie HTTP requests for the 'librenms.domain.net' host
    # containing the matching file extensions. We don't have to match by host if you
    # only have LibreNMS running on Apache.
    # If the cookies are not removed from the HTTP request then Varnish will not cache
    # the files. 'else' function is set to 'pass', or don't cache anything that doesn't
    # match.

    if (req.http.host ~ "^librenms.domain.net") {
        set req.backend_hint = librenms;
        if (req.url ~ "\.(png|gif|jpg|jpeg|ico|pdf|js|css|svg|eot|otf|woff|woff2|ttf)$") {
            unset req.http.Cookie;
        }

        else{
            return(pass);
        }
    }
}

sub vcl_backend_response {
    # 'sub vcl_backend_response' is the same function as 'sub vcl_fetch' in Varnish 3, however,
    # the syntax is slightly different
    # This function happens after we read the response headers from the backend (Apache).
    # First function 'if (bereq.url ~ "\' removes cookies from the Apache HTTP responses
    # that match the file extensions that are between the quotes, and cache the files for 24 hours.
    # This assumes you update LibreNMS once a day, otherwise restart Varnish to clear cache.
    # Second function 'if (bereq.url ~ "^/' removes the Pragma no-cache statements and sets the age
    # of how long the client browser will cache the matching urls.
    # LibreNMS graphs are updated every 300 seconds, 'max-age=300' is set to match this behavior.
    # We could cache these URLs in Varnish but it would add to the complexity of the config.

    if (bereq.http.host ~ "^librenms.domain.net") {
        if (bereq.url ~ "\.(png|gif|jpg|jpeg|ico|pdf|js|css|svg|eot|otf|woff|woff2|ttf)$") {
            unset beresp.http.Set-cookie;
            set beresp.ttl = 24h;
        }

        if (bereq.url ~ "^/graph.php" || "^/device/" || "^/iftype/" || "^/customers/" || "^/health/" || "^/apps/" || "^/(plugin)$" || "^/(alert)$" || "^/eventlog/" || "^/graphs/" || "^/ports/" ) {
            unset beresp.http.Pragma;
            set beresp.http.Cache-Control = "max-age=300";
        }
    }
}

sub vcl_deliver {
    # Happens when we have all the pieces we need, and are about to send the
    # response to the client.
    # You can do accounting or modifying the final object here.

    return (deliver);
}

firewall-cmd --reload