Advanced Webtier customizations

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 /customroute>
  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 Platform Model. 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 Platform Instances.

Registering the Webtier Template in Myst Studio

We can register our template:

1. Click Administration > Custom Actions > Create New

2. Name: webtier-custom-router but this can be anything you want

3. Resource Type: Plain text

4. Target Location: ohs/custom.conf which we will provide this value to our Platform Blueprint later 

5. Click Save.

NOTE: 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.

Updating the Platform Blueprint to use the Webtier Template

1. Go to the Platform Blueprint > Webtier Configuration.

2. Moduleconf Source Directory: ${myst.workspace}/resources/custom/ohs

3. Save and Commit

4. 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, ssl.conf and admin.conf?

Performing advanced customisations to httpd.conf, admin.conf and ssl.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 as a custom action and register as Plain text type at resources/custom/ohs/httpd.conf)

2. Create a template as a custom action and register as Plain text type at resources/custom/ohs/ssl.conf)

3. Create a template as a custom action and register as Plain text type at resources/custom/ohs/admin.conf)

4. Create a custom action (e.g. webtier-update-conf) which programmatically takes the template and writes it to the desired location

5. Create a global variable in the Platform Blueprint (e.g. action.configure-webtier.post=webtier-update-conf)

6. Run configure-webtier as usual. This will result in configure-webtier running and then the below custom action webtier-update-conf overwriting the conf files with ones defined as Plain text type in the custom action.

Below is an example Jython Action for replacing httpd.conf | ssl.conf | admin.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"])
      
      for file in ["httpd.conf","ssl.conf","admin.conf"]:
        #findAndReplaceFile(srcFile,properties,allowUnresolvedProperties)
        replacedFile = ConfigUtils.findAndReplaceFile(File("resources/custom/ohs/" + file), props, 1)

        LOG.info("Backup " + file + " with suffix .yyyymmdd-HHMM")
        os.system('cp -p' + cfg['ohs.instance.home'] + '/' + file + ' ' + cfg['ohs.instance.home'] + '/' + file + '.`date "+%Y%m%d-%H%M"`')

        LOG.info("Copying " + replacedFile.getAbsolutePath() " to " + cfg['ohs.instance.home'] + "/" + file)
        os.system("cp -p" + replacedFile.getAbsolutePath() + " " + cfg['ohs.instance.home'] + "/" + file)
        
        LOG.info("*****************************\n*****************************")
        LOG.info("Oracle OHS requires the AdminServer to be restarted in order for the conf files to be pushed to OHS nodes.")
        LOG.info("*****************************\n*****************************")