Table of Contents

• Introduction
• Contributing
• Reporting Issues
• Installation
• Quick Start
• Configuration
• Shell Access
• Upgrading

Introduction

Dockerfile to build a squid image.

Contributing

If you find this image useful here's how you can help:

• Send a Pull Request with your awesome new features and bug fixes
• Help new users with Issues they may encounter
• Send me a tip on Gittip or using Bitcoin at 16rDxVqJPyYAFYPLduTaSiwe7ZiY1hHqKM

Reporting Issues

Docker is a relatively new project and is active being developed and tested by a thriving community of developers and testers and every release of docker features many enhancements and bugfixes.

Given the nature of the development and release cycle it is very important that you have the latest version of docker installed because any issue that you encounter might have already been fixed with a newer docker release.

For ubuntu users I suggest installing docker using docker's own package repository since the version of docker packaged in the ubuntu repositories are a little dated.

Here is the shortform of the installation of an updated version of docker on ubuntu.

sudo apt-get purge docker.io
curl -s https://get.docker.io/ubuntu/ | sudo sh
sudo apt-get update
sudo apt-get install lxc-docker

Fedora and RHEL/CentOS users should try disabling selinux with setenforce 0 and check if resolves the issue. If it does than there is not much that I can help you with. You can either stick with selinux disabled (not recommended by redhat) or switch to using ubuntu.

If using the latest docker version and/or disabling selinux does not fix the issue then please file a issue request on the issues page.

In your issue report please make sure you provide the following information:

• The host ditribution and release version.
• Output of the docker version command
• Output of the docker info command
• The docker run command you used to run the image (mask out the sensitive bits).

Installation

Pull the latest version of the image from the docker index. This is the recommended method of installation as it is easier to update image in the future. These builds are performed by the Docker Trusted Build service.

docker pull sameersbn/squid:latest

Alternately you can build the image locally.

git clone https://github.com/sameersbn/docker-squid.git
cd docker-squid
docker build --tag="$USER/squid" .

Quick Start

Run the image

docker run --name='squid' -it --rm -p 3128:3128 \
  sameersbn/squid:latest

You now have a squid proxy server listening on port 3128. Just configure your browser / applications to use the proxy and your good to go.

Additionally you can mount a volume at the /var/spool/squid3 path to have a persistent cache, else the cache will be purged when the container is removed. For example, -v /opt/squid/cache:/var/spool/squid3 will store the cache at the /opt/squid/cache path on the host.

Configuration

Squid is a full featured caching proxy server and has hundreds of configuration parameters.

The proper way to configure squid to your liking is by editing the squid.conf file and volume mounting the updated configuration at the /etc/squid3/squid.user.conf path in the container by specifying the -v /path/on/host/to/squid.conf:/etc/squid3/squid.user.conf flag in the docker run command. You can use the squid.conf from the repository as a template to base your configurations.

For basic installations I have added a couple of configuration options which should help serve simple usage scenarios.

Please refer the docker run command options for the --env-file flag where you can specify all required environment variables in a single file. This will save you from writing a potentially long docker run command. Alternately you can specify these configurations using the -e docker run flag

• CACHE_MAX_SIZE: Maximum amount of storage (MB) to use for the cache store. Defaults to 100 MB
• CACHE_MAX_OBJECT_SIZE: Maximum size of an object (MB) in the cache. Defaults to 4 MB
• CACHE_MAX_MEM: Maximum amount of system memory squid is allowed to use to cached objects in the RAM
• OVERALL_SPEED_KBPS: The speed limit (Kbps) for the aggregate bucket. Defaults to -1 (unlimited)
• INDIVIDUAL_SPEED_KBPS: The speed limit (Kbps) for the individual bucket. Defaults to -1 (unlimited)

Shell Access

For debugging and maintenance purposes you may want access the container shell. Since the container does not allow interactive login over the SSH protocol, you can use the nsenter linux tool (part of the util-linux package) to access the container shell.

Some linux distros (e.g. ubuntu) use older versions of the util-linux which do not include the nsenter tool. To get around this @jpetazzo has created a nice docker image that allows you to install the nsenter utility and a helper script named docker-enter on these distros.

To install the nsenter tool on your host execute the following command.

docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter

Now you can access the container shell using the command

sudo docker-enter squid

For more information refer https://github.com/jpetazzo/nsenter

Another tool named nsinit can also be used for the same purpose. Please refer https://jpetazzo.github.io/2014/03/23/lxc-attach-nsinit-nsenter-docker-0-9/ for more information.

Upgrading

To upgrade the image simply follow this 3 step upgrade procedure.

• Step 1: Update the docker image.

docker pull sameersbn/squid:latest

• Step 2: Stop and remove the currently running image

docker stop squid
docker rm squid

• Step 3: Start the image

docker run --name=squid -d [OPTIONS] sameersbn/squid:latest