Installation ============ This chapter explains how to install Hydra on your own build farm server. Prerequisites ------------- To install and use Hydra you need to have installed the following dependencies: - Nix - PostgreSQL - many Perl packages, notably Catalyst, EmailSender, and NixPerl (see the [Hydra expression in Nixpkgs](https://github.com/NixOS/hydra/blob/master/release.nix) for the complete list) At the moment, Hydra runs only on GNU/Linux (*i686-linux* and *x86\_64\_linux*). For small projects, Hydra can be run on any reasonably modern machine. For individual projects you can even run Hydra on a laptop. However, the charm of a buildfarm server is usually that it operates without disturbing the developer\'s working environment and can serve releases over the internet. In conjunction you should typically have your source code administered in a version management system, such as subversion. Therefore, you will probably want to install a server that is connected to the internet. To scale up to large and/or many projects, you will need at least a considerable amount of diskspace to store builds. Since Hydra can schedule multiple simultaneous build jobs, it can be useful to have a multi-core machine, and/or attach multiple build machines in a network to the central Hydra server. Of course we think it is a good idea to use the [NixOS](http://nixos.org/nixos) GNU/Linux distribution for your buildfarm server. But this is not a requirement. The Nix software deployment system can be installed on any GNU/Linux distribution in parallel to the regular package management system. Thus, you can use Hydra on a Debian, Fedora, SuSE, or Ubuntu system. Getting Nix ----------- If your server runs NixOS you are all set to continue with installation of Hydra. Otherwise you first need to install Nix. The latest stable version can be found one [the Nix web site](http://nixos.org/nix/download.html), along with a manual, which includes installation instructions. Installation ------------ The latest development snapshot of Hydra can be installed by visiting the URL [`http://hydra.nixos.org/view/hydra/unstable`](http://hydra.nixos.org/view/hydra/unstable) and using the one-click install available at one of the build pages. You can also install Hydra through the channel by performing the following commands: nix-channel --add http://hydra.nixos.org/jobset/hydra/master/channel/latest nix-channel --update nix-env -i hydra Command completion should reveal a number of command-line tools from Hydra, such as `hydra-queue-runner`. Creating the database --------------------- Hydra stores its results in a PostgreSQL database. To setup a PostgreSQL database with *hydra* as database name and user name, issue the following commands on the PostgreSQL server: ```console createuser -S -D -R -P hydra createdb -O hydra hydra ``` Note that *\$prefix* is the location of Hydra in the nix store. Hydra uses an environment variable to know which database should be used, and a variable which point to a location that holds some state. To set these variables for a PostgreSQL database, add the following to the file `~/.profile` of the user running the Hydra services. ```console export HYDRA_DBI="dbi:Pg:dbname=hydra;host=dbserver.example.org;user=hydra;" export HYDRA_DATA=/var/lib/hydra ``` You can provide the username and password in the file `~/.pgpass`, e.g. ``` dbserver.example.org:*:hydra:hydra:password ``` Make sure that the *HYDRA\_DATA* directory exists and is writable for the user which will run the Hydra services. Having set these environment variables, you can now initialise the database by doing: ```console hydra-init ``` To create projects, you need to create a user with *admin* privileges. This can be done using the command `hydra-create-user`: ```console $ hydra-create-user alice --full-name 'Alice Q. User' \ --email-address 'alice@example.org' --password foobar --role admin ``` Additional users can be created through the web interface. Upgrading --------- If you\'re upgrading Hydra from a previous version, you should do the following to perform any necessary database schema migrations: ```console hydra-init ``` Getting Started --------------- To start the Hydra web server, execute: ```console hydra-server ``` When the server is started, you can browse to [http://localhost:3000/]() to start configuring your Hydra instance. The `hydra-server` command launches the web server. There are two other processes that come into play: - The evaluator is responsible for periodically evaluating job sets, checking out their dependencies off their version control systems (VCS), and queueing new builds if the result of the evaluation changed. It is launched by the hydra-evaluator command. - The queue runner launches builds (using Nix) as they are queued by the evaluator, scheduling them onto the configured Nix hosts. It is launched using the hydra-queue-runner command. All three processes must be running for Hydra to be fully functional, though it\'s possible to temporarily stop any one of them for maintenance purposes, for instance. Serving behind reverse proxy ---------------------------- To serve hydra web server behind reverse proxy like *nginx* or *httpd* some additional configuration must be made. Edit your `hydra.conf` file in a similar way to this example: ```conf using_frontend_proxy 1 base_uri example.com ``` `base_uri` should be your hydra servers proxied URL. If you are using Hydra nixos module then setting `hydraURL` option should be enough. If you want to serve Hydra with a prefix path, for example [http://example.com/hydra]() then you need to configure your reverse proxy to pass `X-Request-Base` to hydra, with prefix path as value. For example if you are using nginx, then use configuration similar to following: server { listen 433 ssl; server_name example.com; .. other configuration .. location /hydra/ { proxy_pass http://127.0.0.1:3000; proxy_redirect http://127.0.0.1:3000 https://example.com/hydra; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Request-Base /hydra; } } Statsd Configuration -------------------- By default, Hydra will send stats to statsd at `localhost:8125`. Point Hydra to a different server via: ``` host = alternative.host port = 18125 ``` Using LDAP as authentication backend (optional) ----------------------------------------------- Instead of using Hydra\'s built-in user management you can optionally use LDAP to manage roles and users. The `hydra-server` accepts the environment variable *HYDRA\_LDAP\_CONFIG*. The value of the variable should point to a valid YAML file containing the Catalyst LDAP configuration. The format of the configuration file is describe in the [*Catalyst::Authentication::Store::LDAP* documentation](https://metacpan.org/pod/Catalyst::Authentication::Store::LDAP#CONFIGURATION-OPTIONS). An example is given below. Roles can be assigned to users based on their LDAP group membership (*use\_roles: 1* in the below example). For a user to have the role *admin* assigned to them they should be in the group *hydra\_admin*. In general any LDAP group of the form *hydra\_some\_role* (notice the *hydra\_* prefix) will work. credential: class: Password password_field: password password_type: self_check store: class: LDAP ldap_server: localhost ldap_server_options.timeout: 30 binddn: "cn=root,dc=example" bindpw: notapassword start_tls: 0 start_tls_options verify: none user_basedn: "ou=users,dc=example" user_filter: "(&(objectClass=inetOrgPerson)(cn=%s))" user_scope: one user_field: cn user_search_options: deref: always use_roles: 1 role_basedn: "ou=groups,dc=example" role_filter: "(&(objectClass=groupOfNames)(member=%s))" role_scope: one role_field: cn role_value: dn role_search_options: deref: always