This branch is for Varnish-Cache 7.6 and later.
Notice that as of Release 7.6.0, issue 4183 causes panics when this VMOD is used. This has been fixed in 7.6.1 via PR 4186.
Use branch 7.5 with Varnish-Cache 7.5.x.
See CHANGES.rst to stay informed about important changes between versions.
This module provides a varnish director for dynamic creation of backends based on calls to
- the system's network address resolution service which, in turn,
typically use information from the
/etc/hostsfile and the Domain Name Service (DNS), but can be configured to use other sources like LDAP (see nsswitch.conf(5)). - or more advanced DNS resolution where getdns is available.
While standard varnish backends defined in VCL may also be defined in terms of host names, changes of the name service information will only be picked up with a VCL reload.
In contrast, for dynamic backends provided by this module,
- name resolution information will be refreshed by background threads after a configurable time to live (ttl) or after the ttl from DNS with a getdns vmod_dynamic.resolver.
- resolution to multiple network addresses is supported
In addition, with a getdns vmod_dynamic.resolver, service discovery by DNS SRV records is possible, in which case this module also allows to configure host names (targets), their ports, priority and weight though DNS. See https://en.wikipedia.org/wiki/SRV_record for a good basic explanation and vmod_dynamic.director.service for details.
Further documentation is available in the manual page vmod_dynamic(3).
We encourage the use of open source operating systems and primarily support Linux and FreeBSD / OpenBSD.
This vmod should also work on any other sane UNIX-ish platform like the Solaris Descendents and MacOS.
We specifically do not support any Windows based environments, also not Docker on Windows. Feel free to use the VMOD, but do not expect us to support you, unless you are willing to put substantial amounts of money into a sponsorship.
The source tree is based on autotools to configure the building, and
does also have the necessary bits in place to do functional unit tests
using the varnishtest tool.
For extended resolver functionality, getdns is required both during installation and at runtime. Before building, install getdns from source or install developer packages, e.g.:
apt-get install libgetdns-dev
At runtime, only the library itself is required, e.g.:
apt-get install libgetdns1
Building requires the Varnish header files and uses pkg-config to find the necessary paths.
Usage:
./autogen.sh ./configure
If you have installed Varnish to a non-standard directory, call
autogen.sh and configure with PKG_CONFIG_PATH pointing to
the appropriate path. For instance, when varnishd configure was called
with --prefix=$PREFIX, use
export PKG_CONFIG_PATH=${PREFIX}/lib/pkgconfig
export ACLOCAL_PATH=${PREFIX}/share/aclocal
The module will inherit its prefix from Varnish, unless you specify a
different --prefix when running the configure script for this
module.
Make targets:
- make - builds the vmod.
- make install - installs your vmod.
- make check - runs the unit tests in
src/tests/*.vtc. - make distcheck - run check and prepare a tarball of the vmod.
If you build a dist tarball, you don't need any of the autotools, only pkg-config and Varnish. You can build the module simply by running:
./configure make
For the test suite to work, please add this line to your /etc/hosts:
127.0.0.1 www.localhost img.localhost
then run:
make check
Also, the service tests require direct access to public DNS (for now).
Alternatively, the make check can also be skipped.
You can then proceed with the installation:
sudo make install
By default, the vmod configure script installs the built vmod in the
directory relevant to the prefix. The vmod installation directory can be
overridden by passing the vmoddir variable to make install.
FreeBSD users may install from either the ports tree or via packages:
via the Ports Tree
cd /usr/ports/www/varnish-libvmod-dynamic/ && make install cleanvia the Package
pkg install varnish-libvmod-dynamic
Binary, debuginfo and source RPMs for VMOD dynamic are available at:
https://pkg.uplex.de/
The packages are built for Enterprise Linux 7 (el7), and hence will run on compatible distros (such as RHEL7, Fedora, CentOS 7 and Amazon Linux).
To set up your YUM repository for the RPMs:
yum-config-manager --add-repo https://pkg.uplex.de/rpm/7/uplex-varnish/x86_64/
The RPMs are compatible with Varnish versions 6.3.2 and 6.4.0. They
also require the getdns library, as discussed above. The library
is not necessarily available in the distributions' standard
repositories, but can be installed from EPEL7:
yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
If you have problems or questions concerning the RPMs, post an issue to one of the source repository web sites, or contact <[email protected]>.
To report bugs, use github.com issues.
For enquiries about professional service and support, please contact [email protected].
To contribute to the project, please use pull requests on github.com.
To support the project's development and maintenance, there are several options:
- Donate money through paypal. If you wish to receive a commercial invoice, please add your details (address, email, any requirements on the invoice text) to the message sent with your donation.
- Become a github sponsor.
- Contact [email protected] to receive a commercial invoice for SWIFT payment.
If you want to learn more about DNS, you can start with RFC 1034 and other RFCs that updated it over time. You may also have DNS already in place, or may be interested in setting up a name server in your infrastructure. Below is a non-exhaustive list of tools and services, but for free software name servers you can have a look at debianadmin.
DNS in the cloud (in alphabetic order):
DNS and containers (in alphabetic order):
- DC/OS (Mesos)
- Docker Machine (sort of)
- Kubernetes
We thank the various people and companies having made vmod_dynamic a reality:
vmod_dynamic is based upon vmod_named developed and maintained from 2015 to 2017 by Dridi Boukelmoune (github @dridi) and supported by Varnish Software.
Maintenance and improvements 2017 - 2019 were sponsored by various unnamed UPLEX clients and authored by Geoffrey Simmons and Nils Goroll from UPLEX.
SRV record support and getdns integration in 2019 was supported by GOG.com
vmod_dynamic also contains contributions by: Ricardo Nabinger Sanchez, Ryan Steinmetz