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https://github.com/elodina/datastax-enterprise-mesos

DataStax Enterprise on Mesos
https://github.com/elodina/datastax-enterprise-mesos

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DataStax Enterprise on Mesos

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DataStax Enterprise Mesos Framework

==================================



[Description](#description)    

[Installation](#installation)

* [Prerequisites](#prerequisites)

* [Scheduler configuration](#scheduler-configuration)

* [Run the scheduler](#run-the-scheduler)

* [Quick start](#quick-start)



[Typical operations](#typical-operations)

* [Shutting down framework](#shutting-down-framework)

* [Rolling restart](#rolling-restart)

* [Memory configuration](#memory-configuration)

* [Failed node recovery](#failed-node-recovery)

* [Automatic migration mechanism for state between versions](#automatic-migration-mechanism-for-state-between-versions)

* [Upgrading scheduler](#upgrading-scheduler)

* [Launching SOLR](#launching-solr)



[Navigating the CLI](#navigating-the-cli)

* [Requesting help](#requesting-help)

* [Restarting nodes](#restarting-nodes)



Description

-----------



This framework aims to simplify running Datastax Enterprise on Mesos. Being actively developed right now.



Currently this framework supports running Cassandra nodes only.



Open issues here https://github.com/elodina/datastax-enterprise-mesos/issues



Installation

============

Prerequisites

-------------



Minimum supported Mesos version is 0.23.0



Clone and build the project



    # git clone https://github.com/elodina/datastax-enterprise-mesos

    # cd datastax-enterprise-mesos

    # ./gradlew jar

    

Get Java 7 JRE



    # wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/7u79-b15/jre-7u79-linux-x64.tar.gz

    

Get Datastax Enterprise distribution



    # wget --user user --password pass http://downloads.datastax.com/enterprise/dse.tar.gz

    

Scheduler configuration

-----------------------



```

# ./dse-mesos.sh help scheduler

Start scheduler

Usage: scheduler [options]



Option (* = required)  Description

---------------------  -----------

--debug       Run in debug mode. (default: false)

--framework-name       Framework name. Defaults to dse.

--framework-role       Framework role. Defaults to *.

--framework-timeout    Framework failover timeout. Defaults

                         to 30 days.

--jre                  Path to JRE archive.

* --master             Mesos Master addresses.

--principal            Principal (username) used to register

                         framework.

--secret               Secret (password) used to register

                         framework.

* --storage            Storage for cluster state. Examples:

                         file:dse-mesos.json; zk:master:

                         2181/dse-mesos.

--user                 Mesos user. Defaults to current system

                         user.



Generic Options

Option  Description

------  -----------

--api   Binding host:port for http/artifact

          server. Optional if DM_API env is

          set.

```

    

Quick start

-----------



In order not to pass the API url to each CLI call lets export the URL as follows:

```

# export DM_API=http://master:7000

```

First lets start 1 Cassandra node with the default settings. Further you will see how to change node settings.



```

# ./dse-mesos.sh node add 0

node added:

  id: 0

  state: idle

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.5, mem:512

  seed: false

  stickiness: period:30m

```

    

You now have a cluster with 1 Cassandra node that is not started.    



```

# ./dse-mesos.sh node list

node:

  id: 0

  state: idle

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.5, mem:512

  seed: false

  stickiness: period:30m

```



You can configure node with resource requirement like cpu or memory, also you can specify overrides to cassandra.yaml file.



```

# ./dse-mesos.sh node update 0 --cpu 0.8 --cassandra-yaml-configs max_hints_delivery_threads=2,hinted_handoff_enabled=false

node added:

  id: 0

  state: idle

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.8, mem:512

  seed: false

  stickiness: period:30m

  cassandra.yaml overrides: max_hints_delivery_threads=2,hinted_handoff_enabled=false

```



Key-value pairs specified after `--cassandra-yaml-configs` option will override default cassandra.yaml configuration file that comes with 

dse distribution. Note that this way you can override only *key-value* configs from casandra.yaml while there are also arrays,

objects. Also, supplied key-value pairs are "blindly" passed to the Cassandra process, i.e. configs are not validated. 



Now lets start the task. This call to CLI will block until the task is actually started but will wait no more than a configured timeout. Timeout can be passed via --timeout flag and defaults to 2 minutes. If a timeout of 0s is passed CLI won't wait for tasks to start at all and will reply with "Scheduled tasks ..." message.



```

# ./dse-mesos.sh node start 0

node started:

  id: 0

  state: running

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.5, mem:512

  seed: true

  stickiness: period:30m, hostname:slave0

  runtime:

    task id: node-0-1449579588537

    executor id: node-0-1449579588537

    slave id: faa6dc48-30d4-4385-8cd4-d0be512e0521-S1

    hostname: slave0

    seeds: slave0

```



By now you should have a single Cassandra node instance running. You should be able to connect to it via `cqlsh ` (in our case `cqlsh slave0` should work).



Here's how you stop it:



```

# ./dse-mesos.sh node stop 0

node stopped:

  id: 0

  state: idle

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.5, mem:512

  seed: true

  stickiness: period:30m, hostname:slave0, expires:2015-12-22 16:23:29+02

```



And remove:



```

# ./dse-mesos.sh node remove 0

node removed

```



OpsCenter support

-----------------

Ensure your OpsCenter version matches DataStax Enterprise version.



In order to integrate OpsCenter with existing Cassandra cluster you need to have a correct `address.yaml` configuration file.

This file is automatically created for you by the framework when you start the node.



DSE Agent (which is started with the Cassandra instance) will monitor the local node and by default

put all OpsCenter data to the local Cassandra cluster.



The only property which needs to be specified is `stomp_interface` - reachable IP address of the opscenterd machine.

You can set this property as part of `address-yaml-configs` cli option:

```

# ./dse-mesos.sh node update 0 --address-yaml-configs "stomp_interface=10.1.131.9"

```

 

Using external Cassandra in HA mode 

-----------------------------------



To run in HA mode (that is tolerate scheduler failures) this framework supports two options for persisting its state:

 

 - zookeeper (`scheduler --storage zk:...`)

 - external cassandra (`scheduler --storage casandra:...`)

 

 (Note: choosing storage type `file` doesn't guarantee you fault tolerance because after failover new scheduler instance may

 be started on a different machine where the initial state file will be not available thus new scheduler instance won't be able to

 recover its state)

 

To use `cassandra` storage type you need to do some preparations:

 

 1. have a running C* instance reachable from machines where you plan to run schedulers

 2. create a keyspace e.g. `dse_mesos` with a replication factor per your needs

 3. create a table e.g. `dse_mesos_framework` in a newly created keyspace, the schema is defined in `vagrant/cassandra_schema.cql`

  

  Last two items can be achieve by executing (cqlsh needs to be in PATH):

  

  ```

  # cqlsh host cql_port -f /vagrant/vagrant/cassandra_schema.cql

  ```

  

After that you can run scheduler with the following command:

  

  ```

  # ./dse-mesos.sh scheduler --master zk://master:2181/mesos --debug true --storage cassandra:9042:192.168.3.5,192.168.3.6 \

   --cassandra-keyspace dse_mesos --cassandra-table dse_mesos_framework

  ```

    

Typical operations

=================

Shutting down framework

-----------------------



While the scheduler has a shutdown hook it doesn't actually finish the framework.

To shutdown the framework completely (e.g. unregister it in Mesos) you may shoot a

`POST` to `/teardown` specifying the framework id to shutdown:



```

# curl -d frameworkId=20150807-094500-84125888-5050-14187-0005 -X POST http://master:5050/teardown

```



Rolling restart

---------------



You already have running nodes.



```

# ./dse-mesos.sh node update 0..1 --data-file-dirs /sstable/xvdv,/sstable/xvdw,/sstable/xvdx



nodes updated:

  id: 0

  state: running

  modified: has pending update

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.7, mem:1024

  seed: true

  data file dirs: /sstable/xvdv,/sstable/xvdw,/sstable/xvdx

  commit log dir: /var/lib/cassandra/commitlog

  ...



  id: 1

  state: running

  modified: has pending update

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.7, mem:1024

  seed: false

  data file dirs: /sstable/xvdv,/sstable/xvdw,/sstable/xvdx

  commit log dir: /var/lib/cassandra/commitlog

  ...



```



Whenever node has none `idle` state (`starting`, `running`, `stopping`, `reconciling`) and you update it,

`modified` flag will communicate that node `has pending update`, to apply update node has to be stopped.



Nodes will be restarted one by one, scheduler stops node then starts it, same applied to rest of the nodes.



```

# ./dse-mesos.sh node restart 0..1 --timeout 8min

stopping node 0 ... done

starting node 0 ... done

stopping node 1 ... done

starting node 1 ... done

nodes restarted:

  id: 0

  state: running

  data file dirs: /sstable/xvdv,/sstable/xvdw,/sstable/xvdx

  commit log dir: /var/lib/cassandra/commitlog

  ...



  id: 1

  state: running

  data file dirs: /sstable/xvdv,/sstable/xvdw,/sstable/xvdx

  commit log dir: /var/lib/cassandra/commitlog

  ...

```



Some times node could timeout on start or stop, in such case restart halts with notice:



```

./dse-mesos.sh node restart 0..1 --timeout 8min

stopping node 0 ... done

starting node 0 ... done

stopping node 1 ... done

starting node 1 ... Error: node 1 timeout on start

```



Memory configuration

--------------------



Given by `--mem` option RAM will be consumed by executor, DSE process, DSE agent.

DSE process capped by Xmx, however also consumes `offheap` memory. By default

- Xmx = max(min(1/2 mem, 1024MB), min(1/4 mem, 8GB))

- Xmn = min(100 * cpu, 1/4 * Xmx)



To override default Xmx and/or Xmn calculation specify it via `--cassandra-jvm-options`, for instance:

```

./dse-mesos.sh node update 0 --cassandra-jvm-options "-Xmx1024M"

```

in this case `Xmn` will be calculated by default (according to given `Xmx` in `--cassandra-jvm-options`), or override only `Xmn`

```

./dse-mesos.sh node update 0 --cassandra-jvm-options "-Xmn100M"

```

or both

```

./dse-mesos.sh node update 0 --cassandra-jvm-options "-Xmx2048M -Xmn100M"

```

`Xmx`, `Xmn` correspond to env variables `MAX_HEAP_SIZE`, `HEAP_NEWSIZE` and will be set in `cassandra-env.sh`



Failed node recovery

--------------------

When a node fails, DSE mesos scheduler assumes that the failure is recoverable. The scheduler will try

to restart the node after waiting failover-delay (i.e. 30s, 2m). The initial waiting delay is equal to failover-delay setting.

After each consecutive failure this delay is doubled until it reaches failover-max-delay value.



If failover-max-tries is defined and the consecutive failure count exceeds it, the node will be deactivated.



The following failover settings exists:

```

--failover-delay     - initial failover delay to wait after failure (option value is required)

--failover-max-delay - max failover delay (option value is required)

--failover-max-tries - max failover tries to deactivate broker (to reset to unbound pass --failover-max-tries "")

```



Upgrading scheduler

-------------------

Scheduler of version 0.2.1.3 is able to migrate state between versions for all types

of storages (file, zk, cassandra) from version 0.2.1.2. For example you are running 0.2.1.2 version and want

to update to 0.2.1.3 then you have to stop scheduler (for C* storage stop all running

schedulers that share state table) and then start new scheduler (for C* start schedulers

sequentially, first one will migrate state table, next will just start without migrating

anything).



Launching SOLR

--------------



Just pass option `--solr-enabled true` when creating



```

./dse-mesos.sh node add 0 --solr-enabled true



node added:

  id: 0

  state: idle

  topology: cluster:default, dc:default, rack:default

  resources: cpu:0.5, mem:512

  seed: false

  solr: true

  dirs: data:, commit:, caches:

  failover: delay:3m, max-delay:30m

  stickiness: period:30m

```



or updating node configuration via CLI (NOTE: `solr: true` means node with SOLR),



```

./dse-mesos.sh node update 0 --solr-enabled true

```



in order to disable launching SOLR on node pass `--solr-enabled false` (don't forget to restart updated node).



SOLR requires two ports `HTTP` and `Shard`, configure them via `./dse-mesos cluster ` with options

`--solr-http-port` and `--solr-shard-port`.



Navigating the CLI

==================

Requesting help

--------------



```

# ./dse-mesos.sh help

Usage:  ...



Commands:

  help [cmd [cmd]] - print general or command-specific help

  scheduler        - start scheduler

  node             - node management commands

  cluster          - cluster management commands



Run `help ` to see details of specific command

```



You may also run `./dse-mesos.sh help  []` to view help of specific command/sub-command.



Restarting nodes

----------------



```

# ./dse-mesos.sh help node restart

Restart node

Usage: node restart  [options]



Option     Description

------     -----------

--timeout  Time to wait until node restart.

             Should be a parsable Scala Duration

             value. Defaults to 4m.



Generic Options

Option  Description

------  -----------

--api   Binding host:port for http/artifact

          server. Optional if DM_API env is

          set.



```