THE ADMIN SERVICE

JUST USE COMMANDS THAT ARE DOCUMENTED HERE

Only commands described in this documentation should be used for the administration of a dCache system.

First Steps
Access with SSH
- Public Key Authorization
- Access via gPlazma and the dcache.kpwd file
Hot to use the Admin Interface
Creating a new user
Direct command execution
Use of the SSH Admin Interface by scripts

First Steps

dCache has a powerful administration interface. Administration protocol is implemented as admin cell that embeds ssh server. Once logged to admin interface an administrator can connect or send commands to other cells in the system.

It is useful to run the admin service in its own separate domain. In the example of the section called “Installing a dCache instance” this domain is called adminDoorDomain:

[adminDoorDomain]
[adminDoorDomain/admin]

Note

All configurable values of the ssh admin interface can be found in the /usr/share/dcache/defaults/admin.properties file. Please do NOT change any value in this file. Instead enter the key value combination in the /etc/dcache/dcache.conf.

Access with SSH

The admin service embeds ssh server listening on port 22224 (configurable) and supports the following authentication mechanisms :

kerberos
password
public key authentication.

The mechanisms can be enabled by setting the following variable:

admin.ssh.authn.enabled = password,publickey,kerberos

(that is comma separated mechanism names). By default publickey and password are enabled. To enable kerberos it needs to be added to the list. To complete kerberos setup the following variable needs to be defined:

dcache.authn.kerberos.realm=EXAMPLE.ORG

and admin.ssh.authn.kerberos.keytab-file should point existing keytab file. Default is /etc/krb5.keytab.

There are two ways of authorizing administrators to access the dCache ssh admin interface - public key based authorization and gPlazma based authorization. The configuration of both authorization mechanisms is described below.

Public Key Authorization

To authorize administrators by their public key insert the key into the file authorized_keys2 which should be placed in the directory /etc/dcache/admin as specified in the file /usr/share/dcache/defaults/admin.properties under admin.paths.authorized-keys. Each key has to be one line (no line breaks) and should have a standard format, such as:

ssh-dss AAAAB3....GWvM= /Users/JohnDoe/.ssh/id_dsa

IMPORTANT

Please make sure that the copied key is still in one line. Any line-break will prevent the key from being read.

NOTE

You may omit the part behind the equal sign as it is just a comment and not used by dCache.

Now you can login to the admin interface by

ssh -p 22224 -l admin headnode.example.org
|dCache (6.0.46)
|Type "\?" for help.

Public key based authorization is default with a fallback to gPlazma kpwd plugin.

Access via gPlazma and the `dcache.kpwd` file

To use gPlazma make sure that you added it to your layout file :

[gplazmaDomain]
[gplazmaDomain/gplazma]

The gPlazma configuration file /etc/dcache/gplazma.conf has to look like:

auth    sufficient      kpwd  "kpwd=/etc/dcache/dcache.kpwd"
map     sufficient      kpwd  "kpwd=/etc/dcache/dcache.kpwd"
session sufficient      kpwd  "kpwd=/etc/dcache/dcache.kpwd"

Add a user admin to the /etc/dcache/dcache.kpwd file using the dcache script.

Example:

dcache kpwd dcuseradd admin -u 12345 -g 1000 -h / -r / -f / -w read-write -p password
|writing to /etc/dcache/dcache.kpwd :
|
|done writing to /etc/dcache/dcache.kpwd :

After you ran the above command the following like appears in /etc/dcache/dcache.kpwd file:

passwd admin 4091aba7 read-write 12345 1000 / /

For more information about gPlazma see Chapter 10, Authorization in dCache.

Now the user admin can login to the admin interface with his password password by:

ssh -l admin -p 22224 headnode.example.org
|admin@headnode.example.org's password:
|dCache (6.0.46)
|Type "\?" for help.

To utilize kerberos authentication mechanism the following lines need to be added to /etc/dcache/dcache.kpwd file:

mapping "johndoe@EXAMPLE.ORG" admin

login admin read-write 0 0 / / /
  johndoe@EXAMPLE.ORG

Then, you can access dCache having obtained kerberos ticket:

kinit johndoe@EXAMPLE.ORG
ssh -l admin -p 22224 headnode.example.org
|dCache (6.0.46)
|Type "\?" for help.

To allow other users access to the admin interface add them to the /etc/dcache/dcache.kpwd file as described above.

Just adding a user in the dcache.kpwd file is not sufficient. The generated user also needs access priileges that can only be set within the admin interface itself.

See the section called “Create a new user” to learn how to create the user in the admin interface and set the rights.

Hot to use the Admin Interface

Admin interface allows you to execute shell commands, connect to other cells and execute their supported commands or send supported cell commands to other cells. Once logged in you are prompted to use help Type "\?" for help.

[headnode] (local) admin > \?
\? [command]...  # display help for shell commands
\c cell[@domain] [user]  # connect to cell
\exception [trace]  # controls display of stack traces
\h [command]...  # display help for cell commands
\l [cell[@domain]|pool/poolgroup]...  # list cells
\q # quit
\s [OPTIONS] (cell[@domain]|pool/poolgroup)[,(cell[@domain]|pool/poolgroup)]... command...  # send command
\sl [options] pnfsid|path command...  # send to locations
\sn [options] command...  # send pnfsmanager command
\sp [options] command...  # send poolmanager command
\timeout [seconds]  # sets the command timeout

[headnode] (local) admin >

Shell commands are always available at command prompt, whereas in order to execute cell commands you have to either connect to the cell using \c cell[@domain] and execute command or send command to the cell using \s [OPTIONS] (cell[@domain]|pool/poolgroup)[,(cell[@domain]|pool/poolgroup)]... command.... For instance:

[headnode] (local) enstore > \? \c
NAME
       \c -- connect to cell

SYNOPSIS
       \c cell[@domain] [user]

DESCRIPTION
       Connect to new cell. May optionally switch to another user.

ARGUMENTS
       cell[@domain]
              Well known or fully qualified cell name.
       user
              Account to connect with.

[headnode] (local) enstore >

The \l command executed without arguments lists all well-known cells in the system. In general cells are addressed by their full name <name>@<domainName>. For well-known cells the @<domainName> part can be omitted. Executing \l *@* will list everything running in your dCache system.

NOTE

If the cells are well-known, they can be accessed without adding the domain-scope. See Cell Message passing for more information.

Each cell implements help [command] (also aliased as \h [command]) which, when executed without parameters, displays a set of commands supported by the cell. When provided with command name as an argument it shows that command syntax like so:

[headnode] (local) admin > \s pool_1 help log set
Sets the log level of <appender>.

NOTE

You can send (\s) help command to a cell but you can’t send \h command to a cell. The \h command can be executed only after connecting to a cell using \c command:

[headnode] (local) admin > \c pool_1
[headnode] (pool_1@poolDomain) admin > \h log set
Sets the log level of <appender>.

WARNING

Some commands are dangerous. Executing them without understanding what they do may lead to data loss.

The command \q exits the admin shell.

If you want to find out which cells are running on a certain domain, you can issue the command ps in the System cell of the domain.

Example: For example, if you want to list the cells running on the poolDomain, \c to its System cell and issue the ps command.

  (local) admin > \c System@poolDomain
  (System@poolDomain) admin > ps
    Cell List
  ------------------
  c-dCacheDomain-101-102
  System
  pool_2
  c-dCacheDomain-101
  pool_1
  RoutingMgr
  lm

The cells in the domain can be accessed using \c together with the cell-name scoped by the domain-name. So first, one has to get back to the local prompt, as the \c command will not work otherwise.

NOTE

Note that \c only works from the local prompt. If the cell you are trying to access does not exist, the \c command will complain.
Example:
(local) admin > \c nonsense
Cell as it doesn't exist

Connect to the routing manager of the dCacheDomain and use ls command to get a list of all well-known cells, running in each domain:

Example:
  (local) admin > \c RoutingMgr@dCacheDomain
  (RoutingMgr@dCacheDoorDomain) admin > ls
  Our routing knowledge :
   Local : [PoolManager, topo, LoginBroker, info]
   adminDoorDomain : [pam]
  gsidcapDomain : [DCap-gsi-example.dcache.org]
  dcapDomain : [DCap-example.dcache.org]
  utilityDomain : [gsi-pam, PinManager]
  gPlazmaDomain : [gPlazma]
  webdavDomain : [WebDAV-example.dcache.org]
   gridftpDomain : [GFTP-example.dcache.org]
  srmDomain : [RemoteTransferManager, CopyManager, SrmSpaceManager, SRM-example.dcache.org]
   httpdDomain : [billing, srm-LoginBroker, TransferObserver]
  poolDomain : [pool_2, pool_1]
   namespaceDomain : [PnfsManager, dirLookupPool, cleaner]

All cells implement the info command to display general information about the cell and show pinboard command for listing the last lines of the pinboard of the cell. The output of these commands contains useful information for troubleshooting.

The most useful command of the pool cells is rep ls. It lists the file replicas which are stored in the pool by their pnfs IDs:

(RoutingMgr@dCacheDoorDomain) admin >  \s pool_1  rep ls
000100000000000000001120 <-P---------(0)[0]> 485212 si={myStore:STRING}
000100000000000000001230 <C----------(0)[0]> 1222287360 si={myStore:STRING}
(RoutingMgr@dCacheDoorDomain) admin >


(RoutingMgr@dCacheDoorDomain) admin > \c pool_1
(pool_1) admin > rep ls
000100000000000000001120 <-P---------(0)[0]> 485212 si={myStore:STRING}
000100000000000000001230 <C----------(0)[0]> 1222287360 si={myStore:STRING}

Each file replica in a pool has one of the 4 primary states: “cached” (<C—), “precious” (<-P–), “from client” (<–C-), and “from store” (<—S).

See the section called “How to Store-/Restore files via the Admin Interface” for more information about rep ls.

The most important commands in the PoolManager are: rc ls and cm ls -r.

rc ls lists the requests currently handled by the PoolManager. A typical line of output for a read request with an error condition is (all in one line):

(pool_1) admin > \c PoolManger
(PoolManager) admin > rc ls
000100000000000000001230@0.0.0.0/0.0.0.0 m=1 r=1 [<unknown>]
[Waiting 08.28 19:14:16]
{149,No pool candidates available or configured for 'staging'}

As the error message at the end of the line indicates, no pool was found containing the file replica and no pool could be used for staging the file from a tertiary storage system.

See the section called “Obtain information via the dCache Command Line Admin Interface” for more information about the command rc ls

Finally, cm ls with the option -r gives the information about the pools currently stored in the cost module of the pool manager. A typical output is:

(PoolManager) admin > cm ls -r
pool_1={R={a=0;m=2;q=0};S={a=0;m=2;q=0};M={a=0;m=100;q=0};PS={a=0;m=20;q=0};PC={a=0;m=20;q=0};
    (...continues...)   SP={t=2147483648;f=924711076;p=1222772572;r=0;lru=0;{g=20000000;b=0.5}}}
pool_1={Tag={{hostname=example.org}};size=0;SC=0.16221282938326134;CC=0.0;}
pool_2={R={a=0;m=2;q=0};S={a=0;m=2;q=0};M={a=0;m=100;q=0};PS={a=0;m=20;q=0};PC={a=0;m=20;q=0};
    (...continues...)   SP={t=2147483648;f=2147483648;p=0;r=0;lru=0;{g=4294967296;b=250.0}}}
pool_2={Tag={{hostname=example.org}};size=0;SC=2.7939677238464355E-4;CC=0.0;}

While the first line for each pool gives the information stored in the cache of the cost module, the second line gives the costs (SC: space cost, CC: performance cost) calculated for a (hypothetical) file of zero size. For details on how these are calculated and their meaning, see the section called “Classic Partitions”.

Creating a new user

To create a new user, and set a new password for the user \c from the local prompt ((local) admin >) to the acm, the access control manager, and run following command sequence:

(local) admin > \c acm
(acm) admin > create user <new-user>
(acm) admin > set passwd -user=<new-user> <newPasswd> <newPasswd>

For the newly created users there will be an entry in the directory /etc/dcache/admin/users/meta.

NOTE

As the initial user admin has not been created with the above command you will not find him in the directory /etc/dcache/admin/users/meta.

Give the new user access to the PnfsManager.

(acm) admin > create acl cell.<cellName>.execute
(acm) admin > add access -allowed cell.<cellName>.execute <new-user>

Example: Give the new user access to the PnfsManager.

(acm) admin > create acl cell.PnfsManager.execute
(acm) admin > add access -allowed cell.PnfsManager.execute <new-user>

Now you can check the permissions by:

(acm) admin > check cell.PnfsManager.execute <new-user>
Allowed
(acm) admin > show acl cell.PnfsManager.execute
<noinheritance>
<new-user> -> true

The following commands allow access to every cell for a user :

(acm) admin > create acl cell.*.execute
(acm) admin > add access -allowed cell.*.execute <new-user>

The following command makes a user as powerful as admin (dCache’s equivalent to the root user):

(acm) admin > create acl *.*.*
(acm) admin > add access -allowed *.*.* <new-user>

Direct command execution

Admin ssh server allows direct command execution like so:

ssh -p 22224 admin@adminNode  "command1; command2; command3"

That is it accepts semicolon (‘;’) separated list of commands. Spaces between commands and command separators do not matter.

Use of the SSH Admin Interface by scripts

In scripts, one can use a “Here Document” to list the commands, or supply them to ssh as standard-input (stdin). The following demonstrates using a Here Document:

#!/bin/sh
#
#  Script to automate dCache administrative activity

outfile=/tmp/$(basename $0).$$.out

ssh -p 22224 admin@adminNode  > $outfile << EOF
\c PoolManager
cm ls -r
\q
EOF

or, the equivalent as stdin.

#!/bin/bash
#
#   Script to automate dCache administrative activity.

echo -e '\c pool_1\nrep ls\n(more commands here)\n\q' \
  | ssh -p 22224 admin@adminNode \
  | tr -d '\r' > rep_ls.out