https://github.com/nixos/hydra-provisioner
On-demand provisioning tool for Hydra
https://github.com/nixos/hydra-provisioner
Last synced: 9 months ago
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On-demand provisioning tool for Hydra
- Host: GitHub
- URL: https://github.com/nixos/hydra-provisioner
- Owner: NixOS
- Archived: true
- Created: 2015-08-26T14:55:28.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2019-04-25T09:19:53.000Z (about 7 years ago)
- Last Synced: 2024-10-30T08:26:13.659Z (over 1 year ago)
- Language: Python
- Size: 14.6 KB
- Stars: 29
- Watchers: 8
- Forks: 11
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# Hydra provisioner
`hydra-provisioner` is a script that automatically creates and destroys build machines (typically EC2 instances) for a Hydra server based on the state of the Hydra queue runner. For instance, if there are many runnable build steps for a particular system type (e.g. `x86_64-linux`), it will create additional build machines, then destroy them when they are no longer needed. The machines are managed using NixOps.
To run this script:
```bash
$ hydra-provisioner conf.nix
```
This command should be run periodically (e.g. every 5 minutes). `conf.nix` is a Nix expression containing a specification of when and how to create machines. For example:
```nix
{
# Tag used for NixOps deployments created by the provisioner. Useful
# if you're running multiple provisioners.
#tag = "hydra-provisioned";
# The spec must contain one or more sets named systemTypes.,
# where is a Nix system type such as "x86_64-linux". You
# can also list system features (e.g. "x86_64-linux:benchmark"), in
# which case only build steps that have "requiredSystemFeatures" set to
# the listed features will be executed on the machines created here.
systemTypes.x86_64-linux = {
# Path to NixOps module defining the deployment for this type.
nixopsExpr = builtins.toPath ./deployment.nix;
# The minimum number of machines to keep around for this type.
#minMachines = 0;
# The maximum number of machines to provision for this type.
#maxMachines = 1;
# Value subtracted from the number of runnables of this type. This
# is the number of runnables to be performed by non-provisioned
# machines, before the provisioner kicks in to create more
# machines.
#ignoredRunnables = 0;
# How many machines should be created given the number of
# runnables. For instance, if there are 10 runnables and
# runnablesPerMachine is 5, then 2 machines will be created.
#runnablesPerMachine = 10;
# How many jobs can be run concurrently on machines of this type.
#maxJobs = 1;
# The speed factor.
#speedFactor = 1;
# The path of the SSH private key.
#sshKey = "/var/lib/hydra/queue-runner/.ssh/id_buildfarm";
# Whether to stop or destroy the machine when it's idle.
#stopOnIdle = false;
# Grace period in seconds before an idle machine is stopped or
# destroyed. Thus, if Hydra load increases in the meantime, the
# machine can be put back in action. Note that regardless of this
# setting, EC2 instances are not stopped or destroyed until their
# current hour of execution time has nearly expired.
#gracePeriod = 0;
};
# Command for getting the Hydra queue status. Useful if the provisioner
# runs on a different machine from the queue runner.
#sshCommand = ["hydra-queue-runner", "--status"]
# Command for writing the queue runner's machines file. The contents are
# passed via stdin.
#updateCommand = [ "/bin/sh" "-c" "cat > /var/lib/hydra/provisioner/machines" ];
}
```
The NixOps specification (e.g. `deployment.nix`) must declare one machine named `machine`. The provisioner will create a separate NixOps deployment for each machine that it creates. A typical NixOps specification looks like this:
```nix
# The "type" argument corresponds to the system type (such as
# "x86_64-linux:benchmark"), and can be used for creating different
# kinds of machines from the same NixOps specification.
{ type, tag, ... }:
{
machine =
{ config, lib, pkgs, ... }:
{
deployment.targetEnv = "virtualbox";
# The queue runner will perform build actions via "nix-store --serve"
# on root@, so this machine needs an authorized key for that.
users.extraUsers.root.openssh.authorizedKeys.keys = lib.singleton ''
command="nix-store --serve --write" ssh-dss AAAAB3NzaC1...
'';
# Currently, Hydra works better with the Nix 1.10 prerelease.
nix.package = pkgs.nixUnstable;
# Frequent garbage collection is a good idea for build machines.
nix.gc.automatic = true;
nix.gc.dates = "*:0/30";
};
}
```
A real-world configuration (for `hydra.nixos.org`) can be found at https://github.com/NixOS/nixos-org-configurations/tree/master/hydra-provisioner.