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MyST has out of the box support for customising webtier routing rules and standard settings as described here. This approach takes the inputs from attributes defined in the MyST Platform Definition and uses these to generate the moduleconf\*.conf files and httpd.conf, admin.conf and sshd.conf. But what if you want full control over the files being created?

In this case, you may find it more fitting to define a template file for replacement when the webtier is configured at provision-time.

MyST Webtier Template - A working example

Let's say for instance, that you wanted to create a file called moduleconf/custom.conf with the following:

<Location /customrout>
SetHandler weblogic-handler
WeblogicCluster osb02.acme:9011,osb02.acme:9011
DynamicServerList ON
RequestHeader set REQUESTORDN "%{SSL_CLIENT_S_DN}s"
Debug ERR
WLLogFile /u01/app/oracle/user_projects/instances/ohs_instance_osb_domain/diagnostics/logs/OHS/osb_domain/wlproxy_advies.log
DebugConfigInfo OFF
WLTempDir /tmp/_wl_proxy_12c
</Location>

Whilst the above could be achieved entirely through the Routing Rules construct in the MyST Platform Definition, it may be easier to use a template. Let's look at the templated version of our custom.conf.

<Location /customroute>
SetHandler weblogic-handler
WeblogicCluster ${core.domain.cluster[osb].cluster-address}
DynamicServerList ON
RequestHeader set REQUESTORDN "%{SSL_CLIENT_S_DN}s"
Debug ERR
WLLogFile /u01/app/oracle/user_projects/instances/ohs_instance_${core.domain.name}/diagnostics/logs/OHS/${core.domain.name}/wlproxy_advies.log
DebugConfigInfo OFF
WLTempDir /tmp/_wl_proxy_12c
</Location>

Notice that we have replaced osb_domain with ${core.domain.name} so that it takes the value from the MyST Platform Definition. Similarly, we have replaced osb02.acme:9011,osb02.acme:9011 with ${core.domain.cluster[osb].cluster-address}. This ensures that the template can be reusable across multiple MyST Platform Instances.

Registering our Webtier Template in MyST Studio

We can register our template with MyST as follows:

1. Click Administration > Custom Actions > Create New
2. Fill in the mandatory/optional fields. Be sure to choose Plain text for the Resource Type and take note of the Target Location, we will provide this value to our Platform Blueprint later. The name is for display only, choose something that will make it clear what the action is to be used for.

1. Click Save.

The name of the file can be anything as long as .conf is the file extension. Oracle Webtier will dynamically discover any files under moduleconf with this extension and MyST will copy any files to moduleconf that exist in the source directory which we indicate in the next step.

Updating our Platform Blueprint to use the Webtier template

1. In the Platform Blueprint editor, navigate to Webtier Configuration. Enter the value of Moduleconf Source > Directory to ${myst.workspace}/resources/custom/ohs
2. Save the changes
3. During a provision, the custom webtier routing rules will be taken from the Webtier template.

To apply the changes without doing a reprovision:

1. Run configure-webtier as a custom action
2. Restart all servers
3. Notice that any moduleconf files have been replaced and automatically copied to all servers.

What about httpd.conf, ssh.conf and admin.conf?

Performing advanced customisations to httpd.conf, admin.conf and sshd.conf is not as straight forward as defining custom routing rules under moduleconf. For this reason, it is preferable to define all customisation via moduleconf. In an event this approach is not feasible, it would be possible to customise these files using the combination of a template and a custom action which executes the template customisation.
To update these files you would need to

1. create a template and register it as a custom action (e.g. Plain text type at resources/custom/httpd/httpd.conf)
2. create a custom action (e.g. update-webtier-httpd-conf) which programmatically takes the template and writes it to the desired location
3. reference the custom action after configure-webtier (e.g. action.configure-webtier.post=update-webtier-httpd-conf)

Below is an example Jython Action for replacing httpd.conf with a template

from com.rubiconred.myst.config import ConfigUtils
from java.io import File
from java.util import Properties
import os

def myst(cfg):
   webtier = cfg.configuration.getModel().getCore().getWebtier()
   node_list = webtier.getNodeList()
   if node_list:
       nodes = node_list.getNodeArray()
       for node in nodes:
           ohs_node = node.getId()
           props = Properties()
           props.setProperty("ohs.instance.host",cfg["core.node["+ohs_node+"].host"])
           props.setProperty("ohs.component.name",cfg["core.webtier.node["+ohs_node+"].component-name"])
           props.setProperty("ohs.instance.home",cfg["core.webtier.node["+ohs_node+"].instance-home"])
           replacedFile = ConfigUtils.findAndReplaceFile(File("resources/custom/httpd/httpd.conf"), props, 1)
           os.system("cp "+replacedFile.getAbsolutePath()+" "+cfg['ohs.instance.home']+"/httpd.conf")

Note: The 1 flag for the 3rd argument of findAndReplaceFile indicates to allow for unresolved properties. This can be useful if you have webtier properties that are in the same property reference syntax as what MyST expects. To cause MyST to fail if properties are not replaced you can use 0 instead.

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