Question

From python, I am using knife to launch a server.

e.g.

knife ec2 server create -r "role[nginx_server]" --region ap-southeast-1 -Z ap-southeast-1a -I ami-ae1a5dfc --flavor t1.micro -G nginx -x ubuntu -S sg_development -i  /home/ubuntu/.ec2/sg_development.pem -N webserver1

I will then use the chef-server api to check for when the bootstrap is complete so I can then use boto and other tools to configure the newly created server. Pseudo code will look like this:

cmd = """knife ec2 server create -r "role[nginx_server]...."""
os.system(cmd)
boot = False
while boot==False:
    chefTrigger = getStatusFromChefApi()
    if chefTrigger==True:
       boot=True

continue with code for further proccessing

My question is: What is the trigger in the chef-server that will indicate when the node is fully processed by chef? Note, I used the -N to name the server and will query its properties, but what do I look for? Is there a bool? A status?

Thanks

Answer 1

TL;DR: Use a report/exception handler instead.

When the node has finished running chef-client successfully, it will save the node object to the Chef Server. One of the attributes automatically generated by ohai every time Chef runs is node['ohai_time'], which is the Unix epoch timestamp when ohai was executed (at the beginning of the Chef run). A node that has not successfully saved itself to the server will not have the ohai_time at all. However, this attribute merely tracks the time when ohai ran, not necessarily when chef-client saved to the server (since that can be a few seconds to minutes depending on what your recipes are doing). Note if the chef run exits due to an unhandled exception, it won’t save to the server by default.

A more reliable way to be notified when a node has completed is to use a Report/Exception handler, which can send a message to a variety of places and APIs. See the documentation for more information.