f602ed0d86
The queue runner used to special-case `localhost` as a remote builder: Rather than using the normal remote-build (using the `cmdBuildDerivation` command), it was using the (generally less efficient, except when running against localhost) `cmdBuildPaths` command because the latter didn't require a privileged Nix user (so made testing easier − allowing to run hydra in a container in particular). However: 1. this means that the build loop can follow two discint code paths depending on the setup, the irony being that the most commonly used one in production (the “non-localhost” case) isn't the one used in the testsuite (because all the tests run against a local store); 2. It turns out that the “localhost” version is buggy in relatively obvious ways − in particular a failure in a fixed-output derivation or a hash mismatch isn't reported properly; 3. If the “run in a container” use-case is indeed that important, it can be (partially) restored using a chroot store (which wouldn't behave excactly the same way of course, but would be more than good-enough for testing) |
||
|---|---|---|
| .github | ||
| datadog | ||
| doc | ||
| examples | ||
| foreman | ||
| src | ||
| tests | ||
| .gitignore | ||
| bootstrap | ||
| configure.ac | ||
| COPYING | ||
| default.nix | ||
| flake.lock | ||
| flake.nix | ||
| hydra-api.yaml | ||
| hydra-module.nix | ||
| INSTALL | ||
| Makefile.am | ||
| Procfile | ||
| README.md | ||
| shell.nix | ||
| version | ||
Hydra
Hydra is a Continuous Integration service for Nix based projects.
Installation And Setup
Note: The instructions provided below are intended to enable new users to get a simple, local installation up and running. They are by no means sufficient for running a production server, let alone a public instance.
Enabling The Service
Running Hydra is currently only supported on NixOS. The hydra module allows for an easy setup. The following configuration can be used for a simple setup that performs all builds on localhost (Please refer to the Options page for all available options):
{
services.hydra = {
enable = true;
hydraURL = "http://localhost:3000";
notificationSender = "hydra@localhost";
buildMachinesFiles = [];
useSubstitutes = true;
};
}
Creating An Admin User
Once the Hydra service has been configured as above and activate you should already be able to access the UI interface at the specified URL. However some actions require an admin user which has to be created first:
$ su - hydra
$ hydra-create-user <USER> --full-name '<NAME>' \
--email-address '<EMAIL>' --password <PASSWORD> --role admin
Afterwards you should be able to log by clicking on "Sign In" on the top right of the web interface using the credentials specified by hydra-crate-user. Once you are logged in you can click "Admin -> Create Project" to configure your first project.
Creating A Simple Project And Jobset
In order to evaluate and build anything you need to crate projects that contain jobsets. Hydra supports imperative and declarative projects and many different configurations. The steps below will guide you through the required steps to creating a minimal imperative project configuration.
Creating A Project
Log in as adminstrator, click "Admin" and select "Create project". Fill the form as follows:
- Identifier:
hello - Display name:
hello - Description:
hello project
Click "Create project".
Creating A Jobset
After creating a project you are forwarded to the project page. Click "Actions" and choose "Create jobset". Fill the form with the following values:
- Identifier:
hello - Nix expression:
examples/hello.nixinhydra - Check interval: 60
- Scheduling shares: 1
We have to add two inputs for this jobset. One for nixpkgs and one for hydra (which we are referrencing in the Nix expression above):
-
Input name:
nixpkgs -
Type:
Git checkout -
Value:
https://github.com/nixos/nixpkgs-channels nixos-20.03 -
Input name:
hydra -
Type:
Git checkout -
Value:
https://github.com/nixos/hydra
Make sure State at the top of the page is set to "Enabled" and click on "Create jobset". This concludes the creation of a jobset that evaluates ./examples/hello.nix once a minute. Clicking "Evaluations" should list the first evaluation of the newly created jobset after a brief delay.
Building And Developing
Building Hydra
You can build Hydra via nix-build using the provided default.nix:
$ nix-build
Development Environment
You can use the provided shell.nix to get a working development environment:
$ nix-shell
$ ./bootstrap
$ configurePhase # NOTE: not ./configure
$ make
Executing Hydra During Development
When working on new features or bug fixes you need to be able to run Hydra from your working copy. This can be done using foreman:
$ nix-shell
$ # hack hack
$ make
$ foreman start
Have a look at the Procfile if you want to see how the processes are being started. In order to avoid conflicts with services that might be running on your host, hydra and postgress are started on custom ports:
- hydra-server: 63333 with the username "alice" and the password "foobar"
- postgresql: 64444
Note that this is only ever meant as an ad-hoc way of executing Hydra during development. Please make use of the NixOS module for actually running Hydra in production.
JSON API
You can also interface with Hydra through a JSON API. The API is defined in hydra-api.yaml and you can test and explore via the swagger editor
Additional Resources
- Hydra User's Guide
- Hydra on the NixOS Wiki
- hydra-cli
- Peter Simons - Hydra: Setting up your own build farm (NixOS)
License
Hydra is licensed under GPL-3.0
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