Gathering vSphere VM performance metrics with Perl, docker and VMware PhotonPosted: November 11, 2015
In a previous post I described how to gather vSphere performance metrics with Powershell. In that post the main focus was getting vSphere virtual machine performance data concurrently. After that post I wanted to use Ruby so that I could get some experience using Ruby threads, but there wasn’t much documentation on getting vSphere performance metrics with Ruby. However, I remembered seeing some example scripts in Perl for getting vSphere performance metrics, but I really didn’t want to try to get up to speed with using threads in Perl. At the time, I was also learning docker so I had the thought that instead of using multiple threads to get vSphere performance metrics concurrently, I could spin up a docker container for each virtual machine that I want to get data on. This isn’t the same thing as using threads and I’m not even sure it’s a good idea, but it would give me more experience with docker.
I used the full ISO of Photon and installed it onto a vSphere VM using these instructions.
ssh into the VM and create the directory where we will build our docker image from. My folder is named /root/docker-files/vsphere-perf-6. This folder will need the following files, which I’ll cover in the rest of this post:
I’m not going to cover docker too much in this post. If you’d like to learn more about it, check out James Turnbull’s excellent The Docker Book. The Dockerfile is a set of instructions that describe how to build our docker image and you can probably pick up most of what is going on. Here are the contents of my Dockerfile:
FROM centos:centos6 MAINTAINER Chris Greene <email@example.com> ENV REFRESHED_AT 10-20-2015 RUN yum -y install tar perl kmod-14-10.el7 openssl-devel uuid e2fsprogs perl-XML-LibXML perl-Crypt-SSLeay util-linux-ng which perl-Time-HiRes ADD VMware-vSphere-CLI-6.0.0-2503617.x86_64.tar.gz /tmp/ RUN yes | /tmp/vmware-vsphere-cli-distrib/vmware-install.pl --default RUN mkdir /tmp/vsphere-perf-data/ ADD get-vm-metrics.pl / RUN chmod 700 /get-vm-metrics.pl ENTRYPOINT ["/get-vm-metrics.pl"]
I do want to cover a few of these options.
FROM specifies that the image will use CentOS 6 as a base. In checking the vSphere CLI Release Notes you will see which OSes are supported. If your curious, I tried CentOS 7 and had a variety of issues.
RUN runs the specified command in the docker image.
ADD copies the specified file into the image as well as unpack it if it’s an archive.
ENTRYPOINT specifies the file/command that we want to run when we enter the container. Any additional arguments that we specify when starting the container will be passed into this command. I use this so that I don’t need to specify the perl script each time I start a container.
vSphere CLI Archive
We will need to download and copy the VMware-vSphere-CLI-6.0.0-2503617.x86_64.tar.gz into this directory. You can download the file at vSphere CLI 6.0 GA. I used WinSCP to copy the file from my Windows machine to the Photon VM, but you can use any method to get the file into the VM.
This is the workhouse of the solution and can be found on github. If you’re not familiar with vSphere performance data, and even maybe if you are, this script can be pretty cryptic. The vSphere CLI comes with a couple of sample performance scripts and on Windows can be found in C:\Program Files (x86)\VMware\VMware vSphere CLI\Perl\samples\performance. If you really want to find out how this works, I’d suggest experimenting with those scripts and using Perl’s Data::Dumper module to print out data structures such as $all_counters and %counters_by_name. I printed these to files so I could see how the data was arrange. I think I wrote this in June and can’t even remember what all data is in each data structure. I can’t imagine too many people will really be interested in how the script works, but if anyone does, they can leave a comment.
The script simply outputs the performance metrics into a CSV file having the name of the VM’s UUID.
Building the docker image
Now that we have all of the necessary files we can build the docker image:
docker build -t “chrisgreene/vsphere-vm-perf” .
The -t is specified a tag and the dot at the end says to build the image from the current directory. You should see a lot of info fly similar to:
Sending build context to Docker daemon 54.6 MB Step 0 : FROM centos:centos6 ---> 3bbbf0aca359 Step 1 : MAINTAINER Chris Greene <firstname.lastname@example.org> ---> Using cache ---> 61988029d210 Step 2 : ENV REFRESHED_AT 10-20-2015 ---> Using cache ---> e9cc98bcc314 Step 3 : RUN yum -y install tar perl kmod-14-10.el7 openssl-devel uuid e2fsprogs perl-XML-LibXML perl-Crypt-SSLeay util-linux-ng which perl-Time-HiRes ---> Using cache ---> cf7ae0f75ac1 Step 4 : ADD VMware-vSphere-CLI-6.0.0-2503617.x86_64.tar.gz /tmp/ ---> Using cache ---> 5ac95667c360 Step 5 : RUN yes | /tmp/vmware-vsphere-cli-distrib/vmware-install.pl --default ---> Using cache ---> c18e84cda077 Step 6 : RUN mkdir /tmp/vsphere-perf-data/ ---> Using cache ---> 525369fe6d26 Step 7 : ADD get-vm-metrics.pl / ---> Using cache ---> a121b473e867 Step 8 : RUN chmod 700 /get-vm-metrics.pl ---> Using cache ---> c54032fad81d Step 9 : ENTRYPOINT /get-vm-metrics.pl ---> Using cache ---> 40de5fab2fe9 Successfully built 40de5fab2fe9
We can view our image by running the docker images command:
root [ ~/docker-files/vsphere-perf-6-]# docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE chrisgreene/vsphere-vm-perf latest 40de5fab2fe9 About a minute ago 729.1 MB
Running our container
After the docker image has been built, we can start containers based off of it. As previously mentioned, the get-vm-metrics.pl script outputs a VM’s performance metrics into a CSV file having the name of the VM’s UUID. In this example I’m going to have that CSV file created in a directory named /tmp/vsphere-perf-data on the docker host’s (Photon VM) filesystem.
docker run --rm -v /tmp/vsphere-perf-data:/tmp chrisgreene/vsphere-vm-perf --server vc5c.vmware.local --vm db3 --username 'vmware\api' --password 'vmware123' Start: 2015-11-11T05:34:2100:00 - End: 2015-11-11T05:34:2400:00
–rm specifies to delete the container once it exits.
-v say that I want to map the /tmp/vsphere-perf-data directory on the docker host to the /tmp directory on the container. The script creates the CSV file in the /tmp directory which is mapped to the /tmp/vsphere-perf-data directory on the docker host.
chrisgreene/vsphere-vm-perf is the name of the image I want to start the container from.
The rest of the parameters are options that are passed into the get-vm-metrics.pl script. I’m requesting to retrieve the performance metrics from a VM named db3 on vCenter vc5c.vmware.local.
If I look in the docker host’s /tmp/vsphere-perf-data/ directory, I’ll see the CSV file:
root [ ~/docker-files/vsphere-perf-6]# ll /tmp/vsphere-perf-data/ total 4864 -rw-r--r-- 1 root root 4979479 Nov 11 05:34 502a96ed-d2bb-be58-c079-43cd79503660.txt
I didn’t take this further since I was only using it as an intermediate step in the final goal of gathering the data with Ruby (rbvmomi). I thought I’d use the provided examples written in Perl instead of trying to figure out everything from scratch, which I’d probably have to do if I used rbvmomi. I did figure out how to get the data using rbvmomi, but unfortunately the project that was requiring this data has been cancelled so I don’t know if I’ll get a chance to revisit it. I’d still like to learn a little about multi-threading in Ruby or concurrency in Go so maybe I can use gathering VM performance data as an exercise.
The docker image can be found at https://hub.docker.com/r/chrisgreene/vsphere-vm-perf/