Installing the OSDF Origin¶

This document describes how to install an Open Science Data Federation (OSDF) origin service. This service allows an organization to export its data to the data federation.

Minimum version for this documentation

This document describes features introduced in XCache 3.3.0, released on 2022-12-08. When installing, ensure that your version of the stash-origin RPM is at least 3.3.0.

Note

The OSDF Origin was previously named "Stash Origin" and some documentation and software may use the old name.

Note

The origin must be registered with the OSG prior to joining the data federation. You may start the registration process prior to finishing the installation by using this link along with information like:

Resource name and hostname
VO associated with this origin server (which will be used to determine the origin's namespace prefix)
Administrative and security contact(s)
Who (or what) will be allowed to access the VO's data
Which caches will be allowed to cache the VO data

Before Starting¶

Before starting the installation process, consider the following requirements:

Operating system: A RHEL 7 or RHEL 8 or compatible operating systems.
User IDs: If they do not exist already, the installation will create the Linux user IDs condor and xrootd; only the xrootd user is utilized for the running daemons.
Host certificate: Required for authentication. See our host certificate documentation for instructions on how to request and install host certificates.
Network ports: The origin service requires the following ports open:
Inbound TCP port 1094 for unauthenticated file access via the XRoot or HTTP protocols (if serving public data)
Inbound TCP port 1095 for authenticated file access via the XRoot or HTTPS protocols (if serving authenticated data)
Outbound TCP port 1213 to redirector.osgstorage.org for connecting to the data federation
Outbound UDP port 9930 for reporting to xrd-report.osgstorage.org and xrd-mon.osgstorage.org for monitoring.
Hardware requirements: We recommend that an origin has at least 1Gbps connectivity and 8GB of RAM. We suggest that several gigabytes of local disk space be available for log files, although some logging verbosity can be reduced.

As with all OSG software installations, there are some one-time steps to prepare in advance:

Obtain root access to the host
Prepare the required Yum repositories
Install CA certificates

Installing the Origin¶

The origin service consists of one or more XRootD daemons and their dependencies for the authentication infrastructure. To simplify installation, OSG provides convenience RPMs that install all required software with a single command:

root@host # yum install stash-origin

For this installation guide, we assume that the data to be exported to the federation is mounted at /mnt/stash and owned by the xrootd:xrootd user.

Configuring the Origin Server¶

The stash-origin package provides a default configuration files in /etc/xrootd/xrootd-stash-origin.cfg and /etc/xrootd/config.d. Administrators may provide additional configuration by placing files in /etc/xrootd/config.d of the form /etc/xrootd/config.d/1*.cfg (for directives that need to be processed BEFORE the OSG configuration) or /etc/xrootd/config.d/9*.cfg (for directives that are processed AFTER the OSG configuration).

You must configure every variable in /etc/xrootd/config.d/10-common-site-local.cfg and /etc/xrootd/config.d/10-origin-site-local.cfg.

The mandatory variables to configure are:

File	Config line	Description
10-common-site-local.cfg	`set rootdir = /mnt/stash`	The mounted filesystem path to export; this document calls it `/mnt/stash`
10-common-site-local.cfg	`set resourcename = YOUR_RESOURCE_NAME`	The resource name registered with OSG
10-origin-site-local.cfg	`set PublicOriginExport = /VO/PUBLIC`	The directory relative to `rootdir` that is the top of the exported namespace for public (unauthenticated) origin services
10-origin-site-local.cfg	`set AuthOriginExport = /VO/PUBLIC`	The directory relative to `rootdir` that is the top of the exported namespace for authenticated origin services

For example, if the HCC VO would like to set up an origin server exporting from the mount point /mnt/stash, and HCC has a public registered namespace at /hcc/PUBLIC, then the following would be set in 10-common-site-local.cfg:

set rootdir = /mnt/stash
set resourcename = HCC_OSDF_ORIGIN

And the following would be set in 10-origin-site-local.cfg:

set PublicOriginExport = /hcc/PUBLIC

With this configuration, the data under /mnt/stash/hcc/PUBLIC/bio/datasets would be available under the path /hcc/PUBLIC/bio/datasets in the OSDF namespace and the data under /mnt/stash/hcc/PUBLIC/hep/generators would be available under the path /hcc/PUBLIC/hep/generators in the OSDF namespace.

If the HCC has a protected registered namespace at /hcc/PROTECTED then set the following in 10-origin-site-local.cfg:

set AuthOriginExport = /hcc/PROTECTED

If you are serving public data from the origin, you must set PublicOriginExport and use the xrootd@stash-origin service. If you are serving protected data from the origin, you must set AuthOriginExport and use the xrootd@stash-origin-auth service (if not using xrootd-multiuser) or xrootd-privileged@stash-origin-auth service (if using xrootd-multiuser).

Warning

The OSDF namespace is a global namespace. Directories you export must not collide with directories provided by other origin servers; this is why the explicit registration is required.

Manually Setting the FQDN (optional)¶

The FQDN of the origin server that you registered in Topology may be different than its internal hostname (as reported by hostname -f). For example, this may be the case if your origin is behind a load balancer such as LVS. In this case, you must manually tell the origin services which FQDN to use for topology lookups.

Create the file /etc/systemd/system/[email protected]/override.conf with the following contents:
```
[Service]
Environment=ORIGIN_FQDN=<Topology-registered FQDN>
```
Run systemctl daemon-reload after modifying the file.

Managing the Origin Services¶

Serving data for an origin is done by the xrootd daemon. There can be multiple instances of xrootd, running on different ports. The instance that serves unauthenticated data will run on port 1094. The instance that serves authenticated data will run on port 1095. If your origin serves both authenticated and unauthenticated data, you will run both instances.

Use of multiuser plugin

Some of the service names are different if you have configured the XRootD Multiuser plugin: - xrootd-privileged is used instead of xrootd - cmsd-privileged is used instead of cmsd

The privileged and non-privileged services are mutually exclusive.

The origin services consist of the following SystemD units that you must directly manage:

Service name	Notes
`[email protected]`	Performs data transfers (unauthenticated instance)
`[email protected]`	Performs data transfers (authenticated instance without multiuser)
`[email protected]`	Performs data transfers (authenticated instance with multiuser)

These services must be managed with systemctl and may start additional services as dependencies. As a reminder, here are common service commands (all run as root):

To...	Run the command...
Start a service	`systemctl start <SERVICE-NAME>`
Stop a service	`systemctl stop <SERVICE-NAME>`
Enable a service to start on boot	`systemctl enable <SERVICE-NAME>`
Disable a service from starting on boot	`systemctl disable <SERVICE-NAME>`

In addition, the origin service automatically uses the following SystemD units:

Service name	Notes
`[email protected]`	Integrates the origin into the data federation (unauthenticated instance)
`[email protected]`	Integrates the origin into the data federation (authenticated instance without multiuser)
`[email protected]`	Integrates the origin into the data federation (authenticated instance with multiuser)
`[email protected]`	Updates the authorization files periodically (unauthenticated instance)
`[email protected]`	Updates the authorization files periodically (authenticated instance)

Verifying the Origin Server¶

Once your server has been registered with the OSG and started, perform the following steps to verify that it is functional.

Testing availability¶

To verify that your origin is correctly advertising its availability, run the following command from the origin server:

[user@server ~]$ xrdmapc -r --list s redirector.osgstorage.org:1094
0**** redirector.osgstorage.org:1094
      Srv ceph-gridftp1.grid.uchicago.edu:1094
      Srv stashcache.fnal.gov:1094
      Srv stash.osgconnect.net:1094
      Srv origin.ligo.caltech.edu:1094
      Srv csiu.grid.iu.edu:1094

The output should list the hostname of your origin server.

Testing directory export¶

To verify that the directories you are exporting are visible from the redirector, run the following command from the origin server:

[user@server ~]$ xrdmapc -r --verify --list s redirector.osgstorage.org:1094 <EXPORTED DIR>
0*rv* redirector.osgstorage.org:1094
  >+  Srv ceph-gridftp1.grid.uchicago.edu:1094
   ?  Srv stashcache.fnal.gov:1094 [not authorized]
  >+  Srv stash.osgconnect.net:1094
   -  Srv origin.ligo.caltech.edu:1094
   ?  Srv csiu.grid.iu.edu:1094 [connect error]

Change <EXPORTED_DIR> for the directory the service is suppose to export. Your server should be marked with a >+ to indicate that it contains the given path and the path was accessible.

Testing file access (unauthenticated origin)¶

To verify that you can download a file from the origin server, use the stashcp tool, which is available in the stashcp RPM. Place a <TEST FILE> in <EXPORTED DIR>, where <TEST FILE> can be any file in a publicly accessible path. Run the following command:

[user@host]$ stashcp <TEST FILE> /tmp/testfile

If successful, there should be a file at /tmp/testfile with the contents of the test file on your origin server. If unsuccessful, you can pass the -d flag to stashcp for debug info.

You can also test directly downloading from the origin via xrdcp, which is available in the xrootd-client RPM. Run the following command:

[user@host]$ xrdcp xroot://<origin server>:1094/<TEST FILE> /tmp/testfile

Testing file access (authenticated origin)¶

In order to download files from the origin, caches must be able to access the origin via SSL certificates. To test SSL authentication, use the curl command. Place a <TEST FILE> in <EXPORTED DIR>, where <TEST FILE> can be any file in a protected location. As root on your origin, run the following command:

[root@host]# curl --cert /etc/grid-security/hostcert.pem \
                  --key /etc/grid-security/hostkey.pem \
                  https://<origin server>:1095/<TEST FILE> \
                  -o /tmp/testfile

If successful, there should be a file at /tmp/testfile with the contents of the test file on your origin server.

Note

This test requires including the DN of your origin in your origin's OSG Topology registration.

To verify that a user can download a file from the origin server, use the stashcp tool, which is available in the stashcp RPM. Obtain a credential (a SciToken or WLCG Token, depending on your origin's configuration). Place a <TEST FILE> in <EXPORTED DIR>, where <TEST FILE> can be any file in a path you expect to be accessible using the credential you just obtained. Run the following command:

[user@host]$ stashcp <TEST FILE> /tmp/testfile

If successful, there should be a file at /tmp/testfile with the contents of the test file on your origin server. If unsuccessful, you can pass the -d flag to stashcp for debug info.

Registering the Origin¶

To be part of the Open Science Data Federation, your origin must be registered with the OSG. The service type is XRootD origin server.

The resource must also specify which VOs it will serve data from. To do this, add an AllowedVOs list, with each line specifying a VO whose data the resource is willing to host. For example:

  MY_OSDF_ORIGIN:
    Services:
      XRootD origin server:
        Description: OSDF origin server
    AllowedVOs:
      - GLOW
      - OSG
    DN: /DC=org/DC=opensciencegrid/O=Open Science Grid/OU=Services/CN=my-osdf-origin.example.net

You can use the special value ANY to indicate that the origin will serve data from any VO that puts data on it.

In addition to the origin allowing a VOs via the AllowedVOs list, that VO must also allow the origin in one of its AllowedOrigins lists in DataFederation/StashCache/Namespaces. See the page on getting your VO's data into OSDF.

Specifying the DN of your origin is not required but it is useful for testing.

Updating to OSG 3.6¶

The OSG 3.5 series reached end-of-life on May 1, 2022. Admins are strongly encouraged to move their origins to OSG 3.6.

See general update instructions.

Unauthenticated origins (xrootd@stash-origin service) do not need any configuration changes.

Authenticated origins (xrootd@stash-origin-auth service) may need the configuration changes described in the updating to OSG 3.6 section of the XRootD authorization configuration document.

Getting Help¶

To get assistance, please use the this page.