Makefile – Start, Stop or Delete 20 VMs at once

Last time I created 20 virtual machines at once.  Now I want to stop those machines, or start them back up, or delete them. Basically, I want to do bulk operations on all of the machines that I am using in this scenario.

If you look at the create 20 VMs post, I gave each one of them a similar name, based on the pattern “load-xxx” where load is the operation I am using them for and xxx is a three digit sequential id with 0s prefixed. (This makes them order correctly in our UI.)

Because I know their names, I can count them up and not have to explicitly tell these operations how many machines I want to operate on.  To do that, I create a make variable that contains the count of all VMs prefixed by “load.”

COUNT = $$(( $(shell gcloud compute instances list | grep 'load-' | wc -l | xargs) ))

Once I have that, I can perform batch operations very simply.

To stop 20 running VMs:

    @echo "Initiate Stop loop"
    @i=1 ; 
    while [[ $$i -le $(COUNT) ]] ; 
        do server=`printf "load-%03d" $$i` ; 
        ($(call stop-node,$$server) &) ; 
        ((i = i + 1)) ; 
define stop-node
   echo "Stop Compute Engine Instance - " $(1) ; 
   (gcloud compute instances stop $(1) ) 

Just to explain, like the previous post, we loop from i to COUNT, creating a variable that contains the name of our server, and running a function call to execute the gcloud stop instances command.  Why is this a separate function?  Because I usually do more than just stop the VM.

I also wrap the call in parentheses and append the & to allow multiple calls to execute in parallel.

To start them back up:

    @echo "Initiate Start loop"
    @i=1 ; 
    while [[ $$i -le $(COUNT) ]] ; 
        do server=`printf "load-%03d" $$i` ; 
        ($(call start-node,$$server) &) ; 
        ((i = i + 1)) ; 
define start-node
   echo "Start Compute Engine Instance - " $(1) ; 
   (gcloud compute instances start $(1))      

To delete them all:

    @echo "Initiate Delete loop"
    @i=1 ; 
    while [[ $$i -le $(COUNT) ]] ; 
        do server=`printf "load-%03d" $$i` ; 
        ($(call delete-node,$$server) &) ; 
        ((i = i + 1)) ; 
define delete-node
   echo "DELETE Compute Engine Instance - " $(1) ;
    (gcloud compute instances delete $(1) --delete-disks "all" --quiet )

And in this case, I do a little bit more here in delete.  I make sure all of the disks are deleted, and I set the request to quiet. Why? Because I don’t want to confirm this 20 times, silly.

In any case, doing batch operations on my set of VMs is as easy as:

make start
make stop
make delete

There you have it, fleets of VMs responding in concert to your requests.  As it should be.

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