Try ARC6: towards distributed computing in a few minutes¶
Scared of distributed computing complexities?
With ARC6 you can setup a Computing Element and try common distributed computing workflows in just a few minutes!
ARC6 comes with so-called zero configuration included and works out of the box without any configuration at all.
Step 1. Enable NorduGrid ARC6 repos¶
Prepare your system to install via the NorduGrid Repositories.
Alpha and release-candidate packages are in testing repository, so please make sure it is enabled, e.g. on RHEL-based systems you can use
yum --enablerepo=nordugrid-testing to enable it for one transaction or
yum-config-manager --enable nordugrid-testing to enable permanently.
If you want to test ARC6 including all latest developments, set up your repository to include the nightly builds following Using ARC packages from nightly builds instructions.
Step 2. Install A-REX¶
ARC Resource-coupled EXecution service (A-REX) is a core component that manages authentication, authorization and job life cycle. It is enough to have A-REX installed to have a minimal computing element:
[root ~]# yum -y install nordugrid-arc-arex
Step 3. Run A-REX¶
To start ARC services just run:
[root ~]# arcctl service start --as-configured
You can check if A-REX is running with:
[root ~]# arcctl service list arc-acix-index (Not installed, Disabled, Stopped) arc-acix-scanner (Not installed, Disabled, Stopped) arc-arex (Installed, Enabled, Running) arc-datadelivery-service (Not installed, Disabled, Stopped) arc-gridftpd (Not installed, Disabled, Stopped) arc-infosys-ldap (Not installed, Disabled, Stopped)
arcctl tool automates many ARC CE operations and is designed with bash-completion in mind.
If you would like to use ARC in production it is advised to have completion enabled:
[root ~]# yum install bash-completion python-argcomplete [root ~]# activate-global-python-argcomplete
Step 4. Generate user certificate and key for testing¶
Grid services and users authentication heavily relies on cryptography and uses certificates/keys for each entity. ARC6 comes with Test Certificate Authority on board that can issue the test user certificates easily.
The ARC6 zero configuration implements a default closed approach defining the special authorization object called authgroup.
During the test-user certificate generation,
arcctl test-ca will automatically add the issued certificate subject to the
testCA.allowed-subjects file, opening the job submission possiblity to the test-user transparently. the testCA.allowed-subjects can be found in your
No other subject will be able to submit to your system before you change the
authgroup settings in
You can test submission from the host running A-REX or from any other host in the network.
Testing from the host running A-REX¶
It is technically possible to submit jobs from the
root account, however it is advised to use a dedicated regular user. Here we assume that you use a dedicated regular user.
To generate test certificate/key and install it to standard location inside local user’s home directory run:
[root ~]# arcctl test-ca usercert --install-user user01 User certificate and key are installed to default /home/user01/.globus location for user user01.
Testing from any other host¶
In order to submit jobs from any other host (not the one running A-REX) you need to transfer the (test) user certificate and the CA-files to this other host.
On the A-REX host generate a user certificate/key:
[root ~]# arcctl test-ca usercert --export-tar User certificate and key are exported to testcert-09160712.tar.gz. To use it with arc* tools on the other machine, copy the tarball and run the following commands: tar xzf testcert-09160712.tar.gz source arc-test-certs/setenv.sh
Transfer the tarball to the client host and on the client host execute the commands suggested in the
[user ~]$ tar xzf /tmp/testcert-09160712.tar.gz [user ~]$ source arc-test-certs/setenv.sh
The zero configured A-REX comes with EMI-ES and REST interfaces enabled. It runs on port
443, so make sure it is not firewalled to be able to be used from another client host.
Step 5. Submit job and check it is running¶
Install ARC client tools on the client host:
[root ~]# yum -y install nordugrid-arc-client
To submit a job, or perform any other action towards the ARC server you need a so-called proxy-certificate which is a Single Sign-On token for distributed grid-infrastructure. It is generated in the following way:
[user ~]$ arcproxy Your identity: /DC=org/DC=nordugrid/DC=ARC/O=TestCA/CN=Test Cert 08272152 Proxy generation succeeded Your proxy is valid until: 2018-08-28 09:54:24
You can start with the information query about your newly installed ARC computing element :
[user ~]$ arcinfo -c https://arc.example.org/arex Computing service: Information endpoint: https://arc.example.org:443/arex Information endpoint: https://arc.example.org:443/arex Information endpoint: https://arc.example.org:443/arex Submission endpoint: https://arc.example.org:443/arex (status: ok, interface: org.ogf.glue.emies.activitycreation) Submission endpoint: https://arc.example.org:443/arex (status: ok, interface: org.ogf.bes) Submission endpoint: https://arc.example.org:443/arex (status: ok, interface: org.nordugrid.arcrest)
|||Examples uses |
A simple job can be submitted with the
[user ~]$ arctest -J 2 -c https://arc.example.org/arex Submitting test-job 2: &( executable = "/usr/bin/env" )( stdout = "stdout" )( stderr = "stdout" )( gmlog = "gmlog" )( jobname = "arctest2" )( clientxrsl = "&( executable = ""/usr/bin/env"" )( jobname = ""arctest2"" )( stdout = ""stdout"" )( join = ""yes"" )( gmlog = ""gmlog"" )" ) Client version: nordugrid-arc-20180822231219 Test submitted with jobid: https://arc.example.org:443/arex/NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm
The job status can be checked with the
[user ~]$ arcstat https://arc.example.org:443/arex/NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm Job: https://arc.example.org:443/arex/NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm Name: arctest2 State: Running Status of 1 jobs was queried, 1 jobs returned information
To fetch the job’s stdout run
[user ~]$ arccat https://arc.example.org:443/arex/NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm GRIDMAP=/dev/null HOSTNAME=arc.zero TMPDIR=/tmp GLOBUS_LOCATION=/usr <output omitted>
Step 6. Play more with the ARC Computing Element¶
As an admin you might frequently need to extract information from the logs and directories that ARC computing element uses. The brief list of the relevant paths can be obtained from:
[root ~]# arcctl config brief ARC Storage Areas: Control directory: /var/spool/arc/jobstatus Session directories: /var/spool/arc/sessiondir Scratch directory on Worker Node: Not configured Additional user-defined RTE directories: Not configured ARC Log Files: A-REX Service log: /var/log/arc/arex.log A-REX Jobs log: /var/log/arc/arex-jobs.log A-REX Helpers log: /var/log/arc/job.helper.errors A-REX WS Interface log: /var/log/arc/ws-interface.log Infosys Infoproviders log: /var/log/arc/infoprovider.log
To get information and manage jobs on A-REX server, the
arcctl job is useful.
Operations include but is not limited to:
- Listing jobs:
[root ~]# arcctl job list NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm zb0LDm7RfEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmDBFKDme1CYXm <output omitted> [root ~]# arcctl job list --long NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm FINISHED arctest2 /DC=org/DC=nordugrid/DC=ARC/O=TestCA/CN=Test Cert 08272152 zb0LDm7RfEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmDBFKDme1CYXm FINISHED arctest2 /DC=org/DC=nordugrid/DC=ARC/O=TestCA/CN=Test Cert 08272234 <output omitted>
- Job general information:
[root ~]# arcctl job info NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm Name : arctest2 Owner : /DC=org/DC=nordugrid/DC=ARC/O=TestCA/CN=Test Cert 08272152 State : FINISHED LRMS ID : 16890 Modified : 2018-08-27 22:06:34
- Job log:
[root ~]# arcctl job log NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm 2018-08-27T22:03:34Z Job state change UNDEFINED -> ACCEPTED Reason: (Re)Accepting new job 2018-08-27T22:03:34Z Job state change ACCEPTED -> PREPARING Reason: Starting job processing 2018-08-27T22:03:34Z Job state change PREPARING -> SUBMIT Reason: Pre-staging finished, passing job to LRMS 2018-08-27T22:03:36Z Job state change SUBMIT -> INLRMS Reason: Job is passed to LRMS 2018-08-27T22:06:34Z Job state change INLRMS -> FINISHING Reason: Job finished executing in LRMS 2018-08-27T22:06:34Z Job state change FINISHING -> FINISHED Reason: Stage-out finished.
- A-REX logs that mentions the job:
[root ~]# arcctl job log NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm --service ### /var/log/arc/arex.log: [2018-08-27 22:03:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: ACCEPTED: parsing job description [2018-08-27 22:03:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: ACCEPTED: moving to PREPARING [2018-08-27 22:03:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: PREPARING from ACCEPTED [2018-08-27 22:03:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: SUBMIT from PREPARING [2018-08-27 22:03:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: state SUBMIT: starting child: /usr/share/arc/submit-fork-job [2018-08-27 22:03:36] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: state SUBMIT: child exited with code 0 [2018-08-27 22:03:36] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: INLRMS from SUBMIT [2018-08-27 22:06:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: Job finished [2018-08-27 22:06:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: FINISHING from INLRMS [2018-08-27 22:06:34] [Arc] [INFO] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: State: FINISHED from FINISHING [2018-08-27 22:06:34] [Arc] [ERROR] [16298/4] NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm: Job monitoring stop requested with 1 active references ### /var/log/arc/ws-interface.log: [2018-08-27 22:05:32] [Arc.A-REX] [INFO] [16298/42] GET: id NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm path stdout [2018-08-27 22:05:49] [Arc.A-REX] [INFO] [16298/43] GET: id NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm path stdout
- Getting job attributes:
[root ~]# arcctl job attr NhlKDmsmeEtnPSAtDmVmuSEmABFKDmABFKDm2PJKDmBBFKDmxDyQbm jobname arctest2
Now you are ready to Install production ARC6 Computing Element!