Configuring the AMGA Server and the Replicatin Daemon

The AMGA metadata server amgad the AMGA replication daemon mdservermt.config are configured using the amgad.config file. By default, they share the same configuration file, but by using the -c command line option it is possible to specify a different configuration file for each. Nevertheless, the format of the configuration is similar for both programs.

Format of the Configuration File

Every line of the file contains a key value pair seperated by an equal (=) sign. Blank space is ignored around the equal sign and the end of the line. Keys may not contain any white space but white space in the value is allowed. To have white space at the beginning of a value (after the =) or at the end (at the end of the line), escape it with a backslash (\ ). Lines can be continued with a backslash (\) at the end of a line (white space after the \ is ignored). Comments can be put at the beginning or end of a line after a hash-sign (#). The escape character is the backslash (\). The following escape sequences exist:

• \ : Gives \
• # : Gives #
• \ (): Insert a space at beginning/end of option

The configuration file is divided into two sections. The first, consisting of settings defined in the global section, contains generic server options. The second section is called Replication and contains all the settings controlling replication. Sections are opened like this:

[SectionA]
...

[SectionB]
...

Example of a server configuration file

  # Server options
  Port=8822 # Default 8822
  MinProcesses = 2
  MaxProcesses = 50 # Default: 50
  Mode = process # process (default) or thread mode
  # initThreadNumber = 8
  # MaxConnectsPerProcess = 1000000

  Report = enable

  # Database options
  # The DataSource option must match a data source name in the odbc.ini file
  #DataSource=sqlitedb
  #DataSource=Oracle10g
  DataSource=PSQL
  DBUser=arda

  # Session options
  Sessions = allow       # Values are: no allow force
  IdleTimeout = 1200     # Timeout for a connection/query in sec [20m default]
  SessionTimeout = 86400 # Timeout for a session in the cache in sec
  MaxSessionSize = 3000  # The maximum size that pesistent session info can have

  # Connection limits
  #MaxConnectsPerUser = -1  # Maximum concurrent connections per user
  #ReservedConnections = -1 # Number of connections reserved for root

  # Secure Connections
  UseSSL = 1

  # Authentication options
  RequireAuthentication = 0 # If this is off, no authentication is done!
  AllowCertificateAuthentication = 1
  AllowPasswordAuthentication = 1
  # If you use SSL, you need to load server certificates:
  CertFile = cert.pem
  KeyFile = key.pem
  # If Certificate based authentication allowed, you need to load server certs
  # TrustedCertDir = /etc/grid-security/certificates
  # AllowGridProxyLogin = 1            # Requires also AllowCertificateAuthentication

  # Authorization options, choose 0 or more
  #MapFile = /etc/grid-map-file       # Authorization based on certs
  # Authorization based on certifictes, put a list of VOMS URL and assigned users, here:
  #VOMSGroups = https://lcg-voms.cern.ch:8443/voms/lhcb/services/VOMSAdmin?method=listMembers, lhcb, \
  #             https://kuiken.nikhef.nl:8443/voms/picard/services/VOMSAdmin?method=listMembers, picard
  UserDB = 1 # Authorization based on certs & passwords
  #VOGroupMap =
  #VirtualOrganizations = gildav(gilda) # vo1(defaultUser1), vo2, vo3(defaultUser2)...
  #VOGroupMap = gildav:/gildav(gildav:users)
  #VOUserMap = gildav:/gildav/Role=TrailersManager(gildav)
  #MyProxyHack = 1 # Allow roles in MyProxy certificates for login


  ########################
  # Replication settings
  ########################
  [Replication]
  # Settings for the master
  EnableMaster = 0
  ReplicationDaemonPort=8833

  # The remaining slaves are for slave nodes
  EnableSlave = 1
  NodeName=gridpc1

Description of the server options

The following options are supported:

• Port: The number of the port the server will listen on. This can be overridden on the command line with the -p switch. The default port is 8822.
• MinProcesses: This is the minimum number of processes waiting for client connections the server must offer. When the server starts up or there are no client connections for some time, MinProcesses is the number of processes spawned waiting for connections.
• MaxProcesses: This is the maximum number of processes the server will spawn in total. The server always tries to have 1/3 of the processes in the awaiting connection state. To achieve this, the server will spawn new processes until the number of MaxProcess is reached. Please make sure that your database backend can support as many client connections.
• Mode : This define the execute mode of AMGA daemon. In process mode, each AMGA process is created and responses one client request. In thread mode, each AMGA process several has threads to response requests. The default value is process.
• initThreadNumber : The number of threads each process has. When the server start up initThreadNumber is the number of threads spawned waiting for connection if Mode value is thread. The default is 4.
• Report : AMGA contains statistics collection functionality. When the server start up AMGA sends statistics such as AMGA version, Daemon mode and so on to the collection server on kisti.re.kr. This is enabled by default.
• MaxConnectsPerProcess: To prevent any very rare memory leaks or other resource leaks to reduce the stability of the service, server processes can be asked to terminate themselves after serving a certain number of connections. The default is not to do this.
• DataSource: An ODBC database source which you need to have configured in an odbc.ini file. Note: you can use programs like gODBCConfig or iodbcadm-gtk to configure ODBC. The underlying database needs to be prepared for AMGA by running the createInitial.sql script in the scripts directory of the AMGA distribution.
• DBUser: The user with which the server will contact the database backend. The user name given in the odbci.ini file is the default.
• DBPass: The password the server will give when contacting to the database backend. The password in odbc.ini is the default.
• DBSchema: The schema within the database AMGA shall use for its own tables. Via the import feature it is possible to then access tables in different schemas. The default depends on the database backend and is the user-name on Oracle, the database name on MySQL and for SQLite and PostgreSQL it is the default schema of the database.
• Sessions: This defines whether you want to allow sessions. Sessions create an overhead on the protocol if they are enforced, so the performance of individual clients may reduce while you will be able to support more clients which share the available connections (there is a maximum of MaxProcesses connections, if they are all hogged by a client, then no new clients will be able to connect). Such a denial-of-service situation can be prevented by forcing sessions. Values are: no, allow, force. Default is allow.
• IdleTimeout: Timeout for an idle connection (that is a connection that waits for a client command) in seconds. There are no timeouts currently for database queries apart from how the database is configured. The default is 20 minutes. This is what will make your mdclient command line tool time out.
• SessionTimeout: Timeouts for session. The lifetime of a session in seconds. Default is 1 day.
• MaxSessionSize: Maximum size a session can have when persistently stored on the server between connections. Default is 3000 bytes. This should be sufficient for most certificates used. Rember that the total shared memory needed by the amgad is Sessions*MaxSessionSize.
• MaxConnectsPerUser: Maximum number of concurrent connections for a user. Default is -1: No limits.
• ReservedConnections: Number of connections reserved for the root user. Default is -1: No reserved connections.
• UseSSL: Whether the server will offer SSL as a connection protocol. This is also required to allow certificate based authentication and if you want to use passwords this is recommended if you want to be sure no one listens in. Values are 0 and 1, default is 1. Note that you cannot force the client to use an SSL connection.
• RequireAuthentication: Whether users need to be authenticated. Default is 0: no.
• AllowCertificateAuthentication: Whether you allow users to authenticate with their certificate. You will need to have CA sertificates loaded for the server for this to work in order to be able to verify the client's certificate. See TrustedCertDir. You should also look at User Management because you will need to have a user manager module running for this to work. Default is 0: no.
• AllowPasswordAuthentication: Allow authentication with a password. You need a user manager module running for this to work. See User Management . Default is 0: no.
• CertFile: The path to the server certificate in PEM format. Preferably without encryption. Necessary to use SSL.
• KeyFile: The path to the private key of the server in PEM file format. Necessary to use SSL.
• TrustedCertDir: Path to a directory with trusted CA certificates. Needed to verify a client certificate.
• AllowGridProxyLogin: Whether you allow users to authenticate with a proxy certificate. Default is 0: no.

Replication Settings

The following options control the replication system. They should be defined on the replication section of the configuration file, otherwise AMGA will either not recognize them or will understand them as referring to one of the generic settings, since some names are equal.

These two settings are used by master nodes:

• EnableMaster: Allow this node to act as a master for replication. In particular, this setting activates saving of replication logs to the hard disk. Therefore, if the node is not going to be used as a master, this setting should be disabled for performance reasons. Default: 0. (Disabled)
• ReplicationDaemonPort: The port used by the replication daemon to listen for connections from slaves. Default: 8823.

The following settings are used by slave nodes:

• EnableSlave: Allow this node to act as a slave for replication. Leaving this setting active has no impact on performance, the only different is that it allows the use of the client side replication commands. Default: 0. (Disabled)
• NodeName: The identifier of the local node. Should be unique among all the nodes on the system.

For the rest of the options see User Management .

Federation Settings

The following options control the federation system.

• ServerSideFed: Allow the AMGA server to do actual federation work. Otherwise, the AMGA server just sends information of federated hosts to clients, and the client does the actual federation. For the detail, refer Federation in AMGA. Default: 1. (enabled)
• AllowFedConnFail: Allows connection failures while federating data. Default: 1 (enabled).
• AllowFedExecFail: Allows command execution failures while federating data. Default: 1 (enabled).

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