Adding engines to clusters

To add an engine to a cluster, connect it to the shared database. Then, configure the load balancer to send traffic to it.

Before you begin

Set up a cluster of engines, including setting up a load balancer and shared database. See Setting up clusters of engines.
Each engine must run the same version of IBM® UrbanCode™ Deploy.

About this task

You can add many engine nodes to the cluster as you need.

Procedure

On the new node, install the engine as described in Installing engines. For the public address of the system, specify the IP address of the load balancer. For the Keystone server, use the same Keystone server that you would use if you were installing a single engine.
After you install the engine, stop the Heat services by running the following commands:
```
cd /etc/init.d
```
```
for s in $(ls openstack*); do service $s stop; done
```
Stop the MySQL database and prevent it from starting at system startup by running the following commands:
```
service mysqld stop
```
```
chkconfig mysqld off
```
The engine does not require this service because it must use the shared engine database. If the cluster node does not require MySQL for any other purpose, you can uninstall MySQL from the cluster node.
Open the /etc/heat/heat.conf file in a text editor.
In the /etc/heat/heat.conf file, if you are connecting to a Keystone engine other than the default Keystone engine for the cloud, find the allowed_auth_uris property, and add the complete URL to the Keystone server to the property value. For example, if the engine connects to clouds at cloud1.example.com and cloud2.example.com, the property might look like the following example:
```
allowed_auth_uris=http://cloud1.example.com:5000/v2.0,http://cloud2.example.com:5002/v2
```
Find the sql_connection property, and change it to the location of the shared engine database. For example, if the shared engine database has the host name engine-database.example.com, the property looks as follows:
```
sql_connection=mysql://heat:heat@engine-database.example.com:3306/heat?charset=utf8
```
Find the auth_host property, and update it to point to the load balancer host name, as in the following example:
```
auth_host=ucd-patterns.example.com
```
Find the rabbit_host property, and update it to point to the host name of the shared engine database, as in the following example:
```
rabbit_host=engine-database.example.com
```
Stop the RabbitMQ service:
```
service rabbitmq-server stop
```
Prevent the RabbitMQ service from starting on system startup:
```
chkconfig rabbitmq-server off
```
Open the /etc/keystone/keystone.conf file in a text editor.
In the /etc/keystone/keystone.conf file, find the connection parameter and update it to use shared engine database, as in the following example:
```
connection=mysql://keystone:keystone@engine-database.example.com:3306/keystone?charset=utf8
```

Start the Heat services by running the following commands:

cd /etc/init.d

for s in $(ls openstack*); do service $s start; done

for s in $(ls openstack*); do service $s status; done

Configure the load balancer to send traffic on the following ports to the new engine node:

5000
35357
8004
8000
8003

For example, if you are using HAProxy, the configuration file might have code that is similar to the following snippets. In this code example, it is assumed that the engine nodes have these host names: engine1.example.com, engine2.example.com, and engine3.example.com.

frontend keystone_api
    bind *:5000
    default_backend keystone_api_back

frontend keystone_admin
    bind *:35357
    default_backend keystone_admin_back

frontend heat_api
    bind *:8004
    default_backend heat_api_back

frontend heat_cfn
    bind *:8000
    default_backend heat_cfn_back

frontend heat_cloudwatch
    bind *:8003
    default_backend heat_cloudwatch_back

backend keystone_api_back
    balance     roundrobin
    server      enginenode1 engine1.example.com:5000 check
    server      enginenode2 engine2.example.com:5000 check
    server      enginenode3 engine3.example.com:5000 check
    option      httpchk

backend keystone_admin_back
    balance     roundrobin
    server      enginenode1 engine1.example.com:35357 check
    server      enginenode2 engine2.example.com:35357 check
    server      enginenode3 engine3.example.com:35357 check
    option      httpchk

backend heat_api_back
    balance     roundrobin
    server      enginenode1 engine1.example.com:8004 check
    server      enginenode2 engine2.example.com:8004 check
    server      enginenode3 engine3.example.com:8004 check
    option      httpchk

backend heat_cfn_back
    balance     roundrobin
    server      enginenode1 engine1.example.com:8000 check
    server      enginenode2 engine2.example.com:8000 check
    server      enginenode3 engine3.example.com:8000 check
    option      httpchk

backend heat_cloudwatch_back
    balance     roundrobin
    server      enginenode1 engine1.example.com:8003 check
    server      enginenode2 engine2.example.com:8003 check
    server      enginenode3 engine3.example.com:8003 check
    option      httpchk

Restart the HAProxy service:
```
service haproxy restart
```
On the new engine node, run the following commands to verify that the engine is running:
```
source ˜/clientrc
```
```
heat stack-list
```
```
keystone endpoint-list
```
The endpoints that the keystone endpoint-list command returns must refer to the load balancer and not the engine node.
Verify that the load balancer is sending traffic to the new node. For example, if HAProxy is installed on a system with the host name ucd-patterns.example.com, you can go to the following URL to see the status of the nodes: http://ucd-patterns.example.com:1936/haproxy?stats

Results

The engine is part of the cluster.

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