Is there any description about the algorithm by which Azure DevOps selects the next free agent?
Our scenario is that we will run multiple agents on a single vm and we will have multiple such VMs in our VMSS that we will manually scale in and out (first based on cron schedules).
In order to best utilize the available VMs we would like to make sure that the jobs are evenly distributed on all VMs.
Meaning first run only one job (on the respective agent) per VM. If there are more jobs than VMs than share the jobs so that 2 jobs per VM are processed. Then continue like that until all agents are busy.
What I want to avoid is that the first VM is loaded with jobs until its full and then the next VM.
So I am asking myself how I can influence the selection mechanism to find the next free agent.
Thank you
PS. Such a “load balancing” is already inbuilt in Jenkins.
Related
We are running into the following issue:
We have a job in our pipeline that runs tests. The number of tests need to be distributed over 4 agents to run optimal. It can happen that only one agent is available and the job will start to run all the load on that specific agent, which can then time-out because it takes too long for other agents to become available in time to share in the load.
In essence, if we run with 4 agents, the job will run with optimal efficiency.
My question: is it possible to let a job wait for a specific number of agents to become available before starting the tasks in the job?
That`s not possible through out-of-box features.... But you may create a simple PowerShell script that will query your agents statuses: https://learn.microsoft.com/en-us/rest/api/azure/devops/distributedtask/agents/list?view=azure-devops-rest-7.1
and use includeAssignedRequest
GET https://dev.azure.com/{organization}/_apis/distributedtask/pools/{poolId}/agents?includeAssignedRequest={includeAssignedRequest}&api-version=7.1-preview.1
if you see assignedRequest, your build agent is busy...
I am using Windows Self hosted agent for my Azure DevOps pipelines. Currently the pipelines are executed sequentially. If more than one pipelines triggered from different ADO projects, then it has to wait in queue to get the agent. In order to execute the pipeline in parallel, I came to know from some tutorials if we increase the paid parallel jobs for self hosted agent under billing section of Organization setting. Is my understanding correct? If so what are the precautionary steps I need to take. Do we have any control of when the pipelines to be executed in parallel?
Thanks.
In order to run self-hosted parallel jobs, you need to purchase parallel jobs and register several self-hosted agents.
For parallel jobs, you can register any number of self-hosted agents in your organization. If you want to run 3 jobs in parallel, then you must register at least 3 self-hosted agents in one agent pool. DevOps charges based on the number of jobs you want to run at a time, not the number of agents registered. There are no time limits on self-hosted jobs. For private projects, you can have one job and one additional job for each active Visual Studio Enterprise subscriber who is a member of your organization.
About how to purchase parallel jobs, please refer to Buy parallel jobs.
For how to control the use of parallel jobs, please refer to the following:
For classic pipeline, you can specify when to run the job through dependencies and Run this job in Additional options in the agent job. Then the pipeline will run in sequence according to your settings.
For YAML pipeline, you can specify the conditions under which the job should run with "dependsOn" and "condition".
For example:
For more info about conditions, please refer to Specify conditions
If you don't specify a specific order, the jobs will run in parallel based on the parallel jobs you purchased.
I don't know if my experience can help. I'll try. I started a new job and we use self-hosted TFS / Azure DevOps. I am changing our build process to create 3 product SKUs (it uses conditional compilation). Let's call them Good, Better & Best.
I edited the Build definition. First I switched to the Variables tab. I created a Process variable named SKUs and set it to Good,Better,Best. The commas are important.
Next I switched to the Tasks tab. I located the Agent Phase. Mine was called Phase 1. Select it. On the right, under Parallelism, I selected Multi-configuration. In the Multipliers text field I entered SKUs. I set Maximum number of agents to 3.
What I don't yet know is the TFS back-end administration and options that the company purchased beforehand.
We pay for a number of Microsoft hosted build agents in Azure pipelines. We have a lot of build pipelines, where many of them do jobs in parallel.
Are there any metrics I can use to see the utilization of the build agents and even more interesting, how many jobs are in queue for a free build agent?
Since this would be for the whole Azure Devops instance the Dashboard feature doesn't seems to be appropriate because it only seems to hold project specific metrics.
Got to your Organization Settings-Parallel jobs blade. This will give you the ability to view the jobs in progress.
As for metrics there is a public preview just came out for this; however, I do not have it available yet.
Agent pool usage data is sampled and aggregated by the Analytics service every 10 mins. The number of jobs is plotted based on the max number of running jobs for the specified interval of time.
This feature is enabled by default. To try it out, follow the guidance
below.
Within project settings, navigate to the pipelines “Agent pools” tab
From the agent pool, select a pool (e.g., Azure Pipelines) Within the
pool, select the “Analytics” tab
Is it possible to run multiple Azure Self-hosted build/deploy agents and multiple deployment agents on one server? Also, can these agents service more than one organisation or even multiple Azure AD Tenants?
I do realise the consequences with the server straining under IO bottlenecks and the like, these agents will probably never have to manage more than 3 projects being build and/or deployed at a time, but the sources can be from different projects in different organisations or possibly Tenants.
I have deployed my Deployment Agents to the servers and they function fine with a Microsoft-hosted build agent (my question is about ONE of these servers, it would apply to all of them eventually), but I am afraid to now start deploying the build agents to the same servers now.
This approach is very Do-able and is actually really cost-effective if you do not have continuous deployments or your virtual machine has the IO capacity to handle the planed traffic.
Understand the basics of an Agent. What exactly happens when you host a Windows Agent is that it creates a Windows Service which would run internally a separate new process and perform the actions for the agent.
Since these are independent processes, they are not at all impacted by the operations of other agents. As long as you are not trying to access the same files/resources this approach is actually a great approach and we should surely try this.
I have installed agent on VM and configured a CI build pipeline. The pipeline is triggered and works perfectly fine.
Now I want to use same build pipeline, same agent, but different VM. Is this possible?
How will the execution happen for builds and on which VM will the source be copied?
Thank you.
Like the others I'm also not sure what you're trying to do and also think that the same agent across multiple machines is not possible.
But if you have to alternate or choose easily between VMs, you could set up for each of your VMs (used for this special scenario) an individual agent queue with one agent in that pool. That way you can choose the agent pool at queue time via the agent queue dropdown field. But that would only work if you're triggering manually, not in a typical CI scenario. In that case you would have to edit the definition to enforce any particular VM each time you want to swap VMs.
NO. These private agents are supposed to have a unique name and are assigned to an Agent Pool/Queue. They are polling up to VSTS/Azure Devops server if they have a job to do. Then they execute it. If you clone a machine with the same private build agent, then theoretically the agent that picks it up will execute the job, but that is theoretic. I really don't know how the Agent Queues will handle this.
It depends on what you want to do.
If you want to spread the workload, like 2 build servers and have builds go to whichever build server isn't busy, then you would create 1 Agent Pool/Queue. Create a Private Agent on one server and register it to that Pool, then on the second server un-register the agent and then re-register the agent add it to the SAME pool.
If you want to do work on 2 servers at the exact same time, like a deployment to 2 servers at the same time, then you would create a 'Deployment Group' and add both servers to that. You would unregister both agents from the Agent Pool/Queue. From your 'Deployment Group' copy the PowerShell script snippet and run it on each machine. This way you can use this in your Release Pipeline and deployments in parallel, which take less time to do deployments.
You could set up a variable in the pipeline so you can specify the name of the VM at build-time.
Also, once you have one or more agents, you would add them to an app pool. When builds are run, it will choose one agent from the pool and use that.