Build images

docker build -t kevineye/docker-sample-hovers docker-sample-hovers
docker build -t kevineye/docker-sample-slideshow docker-sample-slideshow
docker build -t kevineye/varnish-auto varnish-auto

Start dependencies

In these examples, 192.168.59.103 is the docker host machine.

# start etcd
docker run --name etcd -d -p 4001:4001 -p 7001:7001 quay.io/coreos/etcd:v0.4.6 -addr 192.168.59.103:4001

# start registrator
docker run --name registrator -d --link etcd:etcd -v /var/run/docker.sock:/tmp/docker.sock -h 192.168.59.103 progrium/registrator etcd://etcd:4001/services

Start varnish container and apps

These could be started in any order. Note, the individual servers (apache containers) do not need a link to etcd, do not need a hostname specification (-h), do not need a name (--name), and their ports can be allocated dynamically by docker (-P).

# start varnish container
docker run --name varnish -d --link etcd:etcd -p 80:80 kevineye/varnish-auto

# start sample apps
docker run -d -P kevineye/docker-sample-hovers
docker run -d -P kevineye/docker-sample-slideshow

Note, the default varnish configuration will be used until there are both apps running and app configuration metadata (below).

Add configuration metadata

Without any configuration, the apps will not be accessible through varnish. The configuration can be added before or after varnish or the apps are started. The configuration will not be removed when the apps stop. The configuration will be lost if all clustered etcd containers are destroyed unless a persistent etcd log volume is configured.

The configuration is loaded into etcd using etcdctl. This is run in a container so that etcdctl does not have to be installed on the host machine.

Hovers app configuration

The following JSON is added to mount the hovers sample app at /hovers, and redirect from /.

[
    {
	    "from": "^https?://[^/]+/hovers\\b"
	},
    {
	    "from": "^(https?://[^/]+)/(?:$|index\\b).*",
	    "to": "\\1/hovers/"
	}
]

This can be installed with this command:

docker run --rm -it --link etcd:etcd kevineye/varnish-auto sh -c 'etcdctl --peers $ETCD_PORT_4001_TCP_ADDR:$ETCD_PORT_4001_TCP_PORT set /apps/docker-sample-hovers '\''[ { "from": "^https?://[^/]+/hovers\\b" }, { "from": "^(https?://[^/]+)/(?:$|index\\b).*", "to": "\\1/hovers/" } ]'\'

Slideshow app configuration

The following JSON is added to mount the hovers sample app at /slideshow, and demonstrate an internal redirect from /internal-demo.

[
    {
	    "from": "^https?://[^/]+/slideshow\\b"
	},
    {
	    "from": "^(https?://[^/]+)/internal-demo\\b",
	    "to": "\\1/slideshow",
	    "internal": true
	}
]

This can be installed with this command:

docker run --rm -it --link etcd:etcd kevineye/varnish-auto sh -c 'etcdctl --peers $ETCD_PORT_4001_TCP_ADDR:$ETCD_PORT_4001_TCP_PORT set /apps/docker-sample-slideshow '\''[ { "from": "^https?://[^/]+/slideshow\\b" }, { "from": "^(https?://[^/]+)/internal-demo\\b", "to": "\\1/slideshow", "internal": true } ]'\'

Try it out

Hovers app http://192.168.59.103/hovers

Slideshow app http://192.168.59.103/slideshow

Root redirects to hovers app http://192.168.59.103/

Internal redirect displays slideshow app without redirect http://192.168.59.103/internal-demo

Troubleshooting and extra commands

Peek at services in etcd

curl -sL http://192.168.59.103:4001/v2/keys/services?recursive=true | jq .

List/modify app configuration in etcd

# dump all app configuration JSON
curl -sL http://192.168.59.103:4001/v2/keys/apps?recursive=true | jq .

# just list app configuration keys, using etcdctl
docker run --rm -it --link etcd:etcd kevineye/varnish-auto sh -c 'etcdctl --peers $ETCD_PORT_4001_TCP_ADDR:$ETCD_PORT_4001_TCP_PORT ls /apps'

# remove an app configuration
docker run --rm -it --link etcd:etcd kevineye/varnish-auto sh -c 'etcdctl --peers $ETCD_PORT_4001_TCP_ADDR:$ETCD_PORT_4001_TCP_PORT rmdir /apps/docker-sample-slideshow'

Watch registrator add/remove apps

docker logs -f registrator

Watch confd update varnish configuration

docker exec varnish tail -f /log/confd.log

Peek at current varnish configuration

docker exec varnish cat /etc/varnish/default.vcl

Get inside varnish

docker exec -it varnish varnishadm

Container development

docker run --rm -i -t --link etcd:etcd -p 80:80 -v `pwd`/varnish-auto:/app kevineye/varnish-auto bash

Scaling to multiple docker hosts

Not yet tested, but should work:

1. Start etcd and registrator on each docker host, clustering etcd instances.
2. For redundancy, start varnish container on each docker host, and use a real load balancer or round-robin DNS to direct traffic to all varnish containers. This is not absolutely necessary. Having only one varnish instance will balance among apps on multiple hosts, but will not have redundancy.
3. Start any number of apps on any docker hosts. Apps do not need to run on all hosts, or could run multiple times on the same host.

SSL/TLS Termination

Not tested yet, but should work:

1. Use a separate container running stud, nginx, apache, ... just to handle SSL/TLS unwrapping, then forward to varnish.
2. Probably run one dedicated to each varnish container.
3. This container could also handle authentication (oauth, shibboleth, etc.)