The autoradio service aims to provide a reliable, fault-tolerant Icecast streaming service for audio and video. It provides all the necessary components to ensure that the traffic from the source to the clients is uninterrupted, even in face of high load or server crashes. All this, if possible, without any operator intervention.
It is a full-stack service, meaning that it includes its own DNS and HTTP servers, for full control of the request flow.
Autoradio works by using etcd to coordinate the various nodes and store the global mount configuration. The intended target is a set of homogeneous servers (or virtual machines) dedicated to this purpose. Autoradio also needs a dedicated DNS domain (or a delegation for a subdomain).
The simplest installation method is probably to use the pre-built
Debian packages (only available for amd64 at the moment), by placing
this line in
deb http://www.incal.net/ale/debian autoradio/
And then running:
$ sudo apt-key adv --recv-key 0xC0EAC2F9CE9ED9B0 $ sudo apt-get update $ sudo apt-get install etcd autoradio-server
Full cluster install procedure
Note: this procedure assumes a Debian distribution, it should work either with Wheezy (oldstable) or Jessie (stable).
This assumes that you have an existing domain name (here example.com) that you control, and that you will run the cluster under a sub-domain (radio.example.com). The procedure will install an etcd server on each node, so it will work best for a small, odd number of machines.
Having said that, follow these steps to bootstrap a new streaming cluster:
Make sure that, on each of your servers, the output of
hostname -fis the fully-qualified hostname of the machine, and that it resolves to its public IP (possibly using
/etc/hosts). This way autoradio can detect the IP address that peers should use when communicating with each host. Also, for simplicity, we're going to assume that each host can resolve the IP address of each other just by using its short name.
Pick one of your servers, say host1, and add a delegation for radio.example.com to it. For instance, in a
bind-formatted zone file:
radio IN NS 3600 host1.example.com.
On host1, edit
/etc/default/etcdwith the following contents:
ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380 ETCD_INITIAL_ADVERTISE_PEER_URLS=http://host1:2380 ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379 ETCD_ADVERTISE_CLIENT_URLS=http://host1:2379 ETCD_INITIAL_CLUSTER_STATE=new ETCD_INITIAL_CLUSTER=node1=http://host1:2380
Once you save the file, restart the etcd daemon: this will initialize an empty database:
$ service etcd restart
On host1, edit
Run the steps in the Installation section above to set up the APT repository and install the
autoradiopackages using the configuration you just wrote.
This will start the radiod and redirectord daemons, and you will be able to serve DNS records for the radio.example.com zone.
Check that the service is healthy with:
$ ping -c1 radio.example.com This should send a ping to *host1*.
Now that the first node is up and running, set up the remaining machines. For every host:
Set up etcd. First, run the following command on the first machine (host1):
$ etcdctl member add host2 http://host2:2380
(remember not to include a final slash on the node URL).
This will print out some environment variables. You should copy
ETCD_INITIAL_CLUSTER line into
the new host. The other lines of that file should be identical to
what shown in step 4 of the previous checklist, replacing the host
name where necessary.
Note that you will need to wait for etcd on the new machine to
start successfully before you can run
etcdctl member add for the
next one. For further instructions on how to change the etcd
cluster configuration at runtime, see
the etcd documentation.
/etc/default/autoradio(as shown in step 5 of the previous checklist above), and the daemons will start automatically.
Install the autoradio packages, see Installation section above. The daemons should start automatically with the new configuration.
Building from source
To build autoradio from source, you should have a Go environment set up properly on your machine. Autoradio uses godep to manage its dependencies, so make sure you have that installed as well. Building autoradio should then be as simple as running, from the top-level source directory:
$ godep go install ./...
This should install the radiod, redirectord and radioctl
In order to create a new stream (mount, in the Icecast terminology),
assuming you are running autoradio on the
On any node, run:
$ radioctl create-mount /path/to/mount.ogg
this will output the username and password used to authenticate the source. Take note of them.
The cluster will be automatically reconfigured with the new mount in a few seconds at most.
Configure the source, using the username/password provided in the previous step, and point it at the following URL:
Tell your users to listen to the stream at:
Note: some sources are unable to handle HTTP redirects: in that case, you might want to enable proxying on autoradio, and tell the client to use the direct-path URL:
DNS zone delegation
Since we can't modify the DNS glue records for the zone delegation in real-time, we have to restrict slightly the assumptions on the availability of nodes in the cluster: you have to assume that at least N of your nodes will be partially available at any one time (i.e. at least one of a chosen subset of N servers will be reachable). The number N should be fairly low, say 3. Then, you can use those 3 servers as the nameservers for zone delegation, and the other nodes are free to have dynamic membership.
The autoradio HTTP server can operate in one of two modes:
clients connect directly to Icecast
When a client connects to the service on port 80, it is sent a redirect to an Icecast server on port 8000. Unfortunately some older clients (especially sources) don't handle redirects too well.
connections to Icecast are proxied by autoradio
Clients talk to the autoradio HTTP server, which proxies connections to the back-end Icecast servers. This way the clients only need to talk to port 80, which not only avoids using redirects but might simplify access for people behind corporate proxies and such.
This behavior is controlled by the
command-line flag to redirectord. It is set to true by default.
The users should be able to reach ports 53/tcp, 53/udp, 80/tcp and 8000/tcp (the latter only if proxying is disabled) on all nodes. Nodes should be able to reach 2379/tcp and 2380/tcp (the etcd ports) on each other; these two ports can be public if you've set up X509-based authentication for etcd.
In a production cluster, you will want to limit access to the etcd daemons so that only the other nodes can connect to it. While it is possible to do this with firewall rules, the dynamic membership of the cluster may make this difficult. We suggest using instead etcd's support for X509 client authentication, together with a tool to manage an online CA (such as autoca. This way, enrolling a new machine in the cluster only requires generating a new client certificate, and no other configuration.
Install the CA certificate in
/etc/autoradio/etcd_ca.pem, the client
/etc/autoradio/etcd_client.pem and its private key in
/etc/autoradio/etcd_client.key, and the clients will connect to
etcd using SSL authentication.
The radiod and redirectord daemons can send runtime metrics to a statsd server (by default on localhost:8125).
It is possible to set up a mount to relay an upstream mount re-encoded
with different parameters, using the
create-transcoding-mount command. In this case, autoradio will
automatically start up a process (a
liquidsoap instance) to perform the
re-encoding, which will connect as the mount source. A master-election
protocol is used to ensure that only one such process per mount is
started in the whole cluster.
There's a Vagrant environment in the
vagrant-test subdirectory that will set up a test three-node cluster
(with Debian Jessie as the base system) using pre-packaged binaries.
To run it:
$ cd vagrant-test $ vagrant up
It will take a while to download the base image the first time, then
it will turn up three nodes called node1, node2 and node3.
vagrant ssh to inspect them.
If you want to test a locally-built package, copy the
etcd Debian packages in the
vagrant-test directory and, in that
same directory, run
$ dpkg-scanpackages -m . >Packages
the provisioning process will automatically use the local packages if they are available.