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Last pushed: a year ago
Short Description
Cassandra standalone and cluster deployment made easy
Full Description

Cassandra

Cassandra 2.2.0

Usage

In the simplest case, you can start a single node with docker run jeremyot/cassandra. The new node
will be configured to listen on the address asigned to the eth0 interface and will accept RPC connectons
on all interfaces.

Deploying a cluster is almost as easy. The container includes tooling to automatically bootstrap a cluster
using etcd. For example:

ETCD=`docker run -d jeremyot/etcd`
ETCD_ADDR=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' ${ETCD}`
docker run -d jeremyot/cassandra autoscale "${ETCD_ADDR}:4001" service/cassandra
docker run -d jeremyot/cassandra autoscale "${ETCD_ADDR}:4001" service/cassandra --join
docker run -d jeremyot/cassandra autoscale "${ETCD_ADDR}:4001" service/cassandra --join

will start a three node cassandra cluster. You can verify with

CASSANDRA_ADDR=`docker inspect --format "{{ .NetworkSettings.IPAddress }}" \`docker ps -lq\``
docker run -it --rm jeremyot/cassandra nodetool -h $CASSANDRA_ADDR status

You should see a normal nodetool status printout displaying information on all three nodes.

To persist data across restarts, be sure to mount Cassandra's data directory with -v /host/path/to/cassandra:/var/cassandra.

Configuration

Cassandra may be configured by passing arguments when starting the container. A YAML library is included which will convert
arbitrary arguments to YAML and write to cassandra.yaml. YAML paths passed as arguments are flattened and prefixed with --.

For example: --rpc_address=0.0.0.0 becomes rpc_address: 0.0.0.0 and --some.key=value becomes some: {key: value}. To
support complex structures, values may also be passed as YAML strings. --some.key="{k1: [1, 2, 3], k2: [2, 3, 4]}" becomes

some:
  key:
    k1: [1, 2, 3]
    k2: [2, 3, 4]

Special parameters

For convenience, a few special arguments are supported:

  • --listen_interface="etho": configures cassandra to bind to the specified interface.
  • --seeds="10.0.0.2, 10.0.0.3": a shortcut for using SimpleSeedProvider with the specified seeds.
  • --etc_seeds="127.0.0.1:4001/v2/keys/service/key": queries etcd for the initial list of keys, registered at the specified path.
    (used by autoscale). Will start as a standalone node if no results are found.
  • --logger=INFO,stdout,R: sets the logger in log4j-server.properties.
  • --infer_address=google.com: uses a connection to the specified address to infer which address Cassandra should bind to. useful
    for containers with multiple ethernet devices. Allows you to specify a remote host (e.g. another node in the Cassandra cluster)
    and know that Cassandra will be accessible to it.
  • --join: Used with --etc_seeds to prevent bootstrapping as a standalone node. Will wait until some seeds are returned from etcd
    before continuing.

Tools

Along with Cassandra, there are a few tools included with this container. They are as follows:

  • autoscale: as shown above, uses etcd to bootstrap a cluster. May be followed by the standard cassandra configuration arguments.
  • etcdmon: a subcomponent of autoscale, uses etcdmon (https://github.com/JeremyOT/etcdmon) to register the server's
    status with etcd. Additional arguments may be passed in the form <ETCDMON_PARAMS> -- <CASSANDRA_PARAMS>.
  • nodetool: runs nodetool and supports any standard nodetool arguments.
  • cqlsh: runs cqlsh and supports any standard cqlsh arguments.

autoscale

Autoscaling may be used in a few different ways. Called with autoscale 10.0.0.8:4001 service/cassandra, Cassandra will infer its
listen_address by making a connection to 10.0.0.8. It will then attempt to retrieve a list of seeds by querying
http://10.0.0.8:4001/v2/keys/service/cassandra, using its own address as the only seed if none are found. Finally, etcdmon will
update http://10.0.0.8:4001/v2/keys/service/cassandra/<node_address> with value={"host": <node_address>}&ttl=30, pinging etcd every 10
seconds. Alternatively autoscale 10.0.0.8:4001 service/cassandra <interface_name> may be used to bind to the specified interface,
and autoscale 10.0.0.8:4001 service/cassandra <remote_address> will infer the address by making a connection to the specified
remote address. If the third argument does not begin with --, it will first be treated as an interface, then used to infer
the address if no matching interface is found. In all three cases, standard configuration options may be appended.

Note: The address executable, used by the autoscale commands, is built from https://github.com/JeremyOT/address. It is pre-compiled to avoid the need to install Go inside the container.

Snapshots

This container can be used to create and export Cassandra snapshots as tar files (optionall compressed) with the following command:

docker run -i --volumes-from=<running_cassandra_container_id> --net=container:<running_cassandra_container_id> jeremyot/cassandra snapshot <options> (<keyspace> ... ) (> <output.tar>)

Additional options let you specify compression, keyspaces and/or an output file to write to instead of stdout.

Use docker run -i jeremyot/cassandra snapshot --help for more information.

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Comments (1)
depend
3 years ago

Just out of curiosity, are you deploying C* this way in production?