DNSCluster (dns_cluster v0.2.0)
View SourceSimple DNS based cluster discovery.
A DNS query is made every :interval milliseconds to discover new ips.
Default node discovery
Nodes will only be joined if their node basename matches the basename of the current node.
For example, if node() is myapp-123@fdaa:1:36c9:a7b:198:c4b1:73c6:1, it will try to connect
to every IP from the DNS query with Node.connect/1. But this will only work if the remote node
has the same basename, like myapp-123@fdaa:1:36c9:a7b:198:c4b1:73c6:2. If the remote node's
basename is different, the nodes will not connect.
Specifying remote basenames
If you want to connect to nodes with different basenames, use a tuple with the basename and query.
For example, to connect to a node named remote, use {"remote", "remote-app.internal"}.
Multiple queries
Sometimes you might want to cluster apps with different domain names. Just pass a list of queries
for this. For instance: ["app-one.internal", "app-two.internal", {"other-basename", "other.internal"}].
Remember, all nodes need to share the same secret cookie to connect successfully.
Examples
To start in your supervision tree, add the child:
children = [
...,
{DNSCluster, query: "myapp.internal"}
]See the start_link/1 docs for all available options.
If you require more advanced clustering options and strategies, see the libcluster library.
Summary
Functions
Returns a specification to start this module under a supervisor.
Starts DNS based cluster discovery.
Functions
Returns a specification to start this module under a supervisor.
See Supervisor.
Starts DNS based cluster discovery.
Options
:name- the name of the cluster. Defaults toDNSCluster.:query- the required DNS query for node discovery, for example:"myapp.internal"or["foo.internal", "bar.internal"]. If the basename differs between nodes, a tuple of{basename, query}can be provided as well. The value:ignorecan be used to ignore starting the DNSCluster.:interval- the millisec interval between DNS queries. Defaults to5000.:connect_timeout- the millisec timeout to allow discovered nodes to connect. Defaults to10_000.
Examples
iex> DNSCluster.start_link(query: "myapp.internal")
{:ok, pid}
iex> DNSCluster.start_link(query: :ignore)
:ignore