Emulab Scripts

Contains several scripts which are used to deploy and run Cassandra on an Emulab cluster.

Scripts

Two major scripts,exec_remote.sh and copy_remote.sh. You need to fill the variable $USER.

Remote Excecute

$ ./exec_remote.sh -f script.sh -h hosts_file [-p]

exec_remote executes a script remotely on all of the hosts which are specified in hosts_file. Besides it can be done in parallel with -p option.

For example, do "hello world" on all the hosts.

$ ./exec_remote.sh -f ./scripts/info.sh -h hosts 

scripts dir contains several scripts that are used at remote hosts.

• info.sh just prints "hello world".
• init.sh installs java and create work dir (/public/${node-id}/) at every remote host.
• deploy.sh decompresses the cassandra tar file, which has been copied to all hosts previously, and injects configuration.
• start.sh starts Cassandra on remote hosts.
• create_keyspace.sh creates lots of keyspaces on Cassandra cluster, usually through seed node.
• stop.sh kills Cassandra daemon on remote hosts.

The hosts file has the format like,

22 node-1.CA-6127.ucare.emulab.net
22 node-10.CA-6127.ucare.emulab.net
22 node-11.CA-6127.ucare.emulab.net
22 node-12.CA-6127.ucare.emulab.net
22 node-13.CA-6127.ucare.emulab.net
22 node-14.CA-6127.ucare.emulab.net

where the first column is ssh port (for compatibility when using virtual nodes), and the second is host name.

Copy to Remote

We still need a script that copies Cassandra tar file to every host.

$ ./copy_remote.sh -s SRC -h hosts_file

The script hard coded the target dir as /public/${node-id}/.

Work Flow

Here's a typical work flow that runs a Cassandra cluster using these scripts.

Create Host File

Beside, we may need other host files like seeds and non_seeds when seed nodes are supposed to start first, and then the non-seed nodes. Like,

all host file,

22 node-1.CA-6127.ucare.emulab.net
22 node-10.CA-6127.ucare.emulab.net
22 node-11.CA-6127.ucare.emulab.net
22 node-12.CA-6127.ucare.emulab.net
22 node-13.CA-6127.ucare.emulab.net
22 node-14.CA-6127.ucare.emulab.net

seed file,

22 node-1.CA-6127.ucare.emulab.net

non-seed file,

22 node-10.CA-6127.ucare.emulab.net
22 node-11.CA-6127.ucare.emulab.net
22 node-12.CA-6127.ucare.emulab.net
22 node-13.CA-6127.ucare.emulab.net
22 node-14.CA-6127.ucare.emulab.net

Test Connection

This could be done by,

$ ./exec_remote.sh -f ./scripts/info.sh -h hosts 

Init Environment

Install packages, create directories, and etc. It would be better using -p parallel option.

$ ./exec_remote.sh -f ./scripts/init.sh -h hosts -p 

Dispatch Tar File

$ ./copt_remote.sh -s cassandra.tgz -h hosts

Deploy

Decompress tar file and inject configuration.

$ ./exec_remote.sh -f ./scripts/deploy.sh -h hosts -p 

Run Seed Node

$ ./exec_remote.sh -f ./scripts/start.sh -h seeds 

Create Keyspaces

$ ./exec_remote.sh -f ./scripts/create_keyspace.sh -h seeds 

Start Non-seed Nodes

Start all other nodes simultanously.

$ ./exec_remote.sh -f ./scripts/start.sh -h non_seeds -p