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Last pushed: 21 days ago
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CentOS-6 6.9 x86_64 - Varnish Cache.
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Docker Image including CentOS-6 6.9 x86_64 and Varnish Cache 4.1.

Overview & links


The latest CentOS-6 based release can be pulled from the centos-6 Docker tag. It is recommended to select a specific release tag - the convention is centos-6-1.4.0or 1.4.0 for the 1.4.0 release tag.

Included in the build are the SCL, EPEL and IUS repositories. Installed packages include OpenSSH secure shell, vim-minimal, are installed along with python-setuptools, supervisor and supervisor-stdout.

Supervisor is used to start the varnishd (and optionally the sshd) daemon when a docker container based on this image is run. To enable simple viewing of stdout for the service's subprocess, supervisor-stdout is included. This allows you to see output from the supervisord controlled subprocesses with docker logs {docker-container-name}.

If enabling and configuring SSH access, it is by public key authentication and, by default, the Vagrant insecure private key is required.

SSH Alternatives

SSH is not required in order to access a terminal for the running container. The simplest method is to use the docker exec command to run bash (or sh) as follows:

$ docker exec -it {docker-name-or-id} bash

For cases where access to docker exec is not possible the preferred method is to use Command Keys and the nsenter command. See for details on how to set this up.

Quick Example

Run up a container named varnish.pool-1.1.1 from the docker image jdeathe/centos-ssh-varnish on port 80 of your docker host. 1 backend host is defined with the IP address; this is required to identify the backend hosts from within the Varnish VCL file.

$ docker run -d -t \
  --name varnish.pool-1.1.1 \
  -p 80:80 \
  --add-host httpd_1: \

Now you can verify it is initialised and running successfully by inspecting the container's logs.

$ docker logs varnish.pool-1.1.1



To run the a docker container from this image you can use the standard docker commands. Alternatively, if you have a checkout of the source repository, and have make installed the Makefile provides targets to build, install, start, stop etc. where environment variables can be used to configure the container options and set custom docker run parameters.

In the following example the http service is bound to port 8000 and offloaded https on port 8500 of the docker host. Also, the environment variable VARNISH_STORAGE has been used to set up a 256M memory based storage instead of the default file based type.

Using environment variables

$ docker stop varnish.pool-1.1.1 && \
  docker rm varnish.pool-1.1.1
$ docker run \
  --detach \
  --tty \
  --name varnish.pool-1.1.1 \
  --publish 8000:80 \
  --publish 8500:8443 \
  --ulimit memlock=82000 \
  --ulimit nofile=131072 \
  --ulimit nproc=65535 \
  --env "VARNISH_STORAGE=malloc,256M" \
  --add-host httpd_1: \

Now you can verify it is initialised and running successfully by inspecting the container's logs:

$ docker logs varnish.pool-1.1.1

Environment Variables

There are several environmental variables defined at runtime which allows the operator to customise the running container. This may become necessary under special circumstances and the following show those that are most likely to be considered for review, the rest should be left unaltered and for clarification refer to the varnishd documentation.


The Varnish VCL configuration file path, (or base64 encoded string of the configuration file contents), is set using VARNISH_VCL_CONF. The default configuration supplied is located at the path /etc/varnish/docker-default.vcl.


The VARNISH_TTL can be used to set a hard minimum time to live for cached documents. The default is 120 seconds.


Start at least VARNISH_MIN_THREADS but no more than VARNISH_MAX_THREADS worker threads with the VARNISH_THREAD_TIMEOUT idle timeout.


Use VARNISH_STORAGE to specify the storage backend. See the varnishd documentation for the types and parameters available. The default is a file type backend but it is recommended to use malloc if there is enough RAM available.

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