Class: Jerbil::Broker

Inherits:
Object
  • Object
show all
Defined in:
lib/jerbil.rb

Overview

The Broker, being a server class that runs on each machine on which Jerbil services will run or will be required. The Broker registers services and interacts with other servers to share information about services across the network.

It is not necessary to use this interface directly. By using the JerbilService::Base class all interaction with the server is done under the hood. See Services Readme for more details.

Key methods are:

  • *#register* to add a service to the broker’s database

  • **#remove** to remove a service from the broker’s database

  • **#find to obtain information about one or more services matching given criteria

Methods used between servers are:

local services known to this server

Methods used to internally:

  • #stop to stop the server gracefully

  • #missing_service? to check if a service is missing and remove it from

the database if it is

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options, pkey) ⇒ Broker

create a new Jerbil server

The options for the server are defined in Config and are best created using this class. This is a [Jeckyl](github.com/osburn-sharp/jeckyl) config file. Further details are provided in the Readme file.

The private key should be unique to this server and is used to authenticate system actions and to authenticate remote servers. Its not very secure so more a way of avoiding mistakes. The key is best created using Support.create_private_key.

Parameters:

  • options (Hash) —

    a hash of various options as defined in Config.

  • pkey (String) —

    a private key generated by the script calling the broker and used to authenticate system calls



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# File 'lib/jerbil.rb', line 87

def initialize(options, pkey) #log_dir, log_level=:system)

  # store details of this server and remote servers
  @env = options[:environment] || :prod
  @private_key = pkey
  @secret = options[:secret]
  
  @local = Jerbil::Servers.create_local_server(@env, @private_key)
  @remote_servers = Array.new


  # who am i
  #@host = Socket.gethostname

  #store local and remote services
  @store = Array.new
  @remote_store = Array.new

  # create a jellog logger that continues any previous log and keeps the last 5 log files
  @app_name = "Jerbil-#{options[:environment].to_s}"
  @log_opts = Jellog::Config.intersection(options)
  #log_opts = @log_opts.dup
  @logger = Jellog::Logger.new(@app_name, @log_opts)
  @logger.mark
  @logger.debug "Started the Logger for Jerbil"
  @logger.debug "Saved logger options: #{@log_opts.inspect}"


  # some statistical data
  @started = Time.now
  @registrations = 0
  @logger.verbose("Searching for remote servers")
  network_servers = [] #Jerbil::Servers.find_servers(@env, options[:net_address], options[:net_mask], options[:scan_timeout])
  #@logger.verbose("Found #{@remote_servers.length} remote servers")

  # now loop round the remote servers to see if any are there
  # DO NOTHING cos its an empty array!
  network_servers.each do |remote_server|
    rjerbil = remote_server.connect
    unless rjerbil.nil?
      @logger.debug "Getting Remote Services. Connecting to : #{remote_server.inspect}"
      # there is a remote server, so tell it about me
      begin
        rkey = rjerbil.register_server(@local, @secret, @env)
        remote_server.set_key(rkey)
        @logger.debug "Key for #{remote_server.fqdn}: #{rkey}"
        rjerbil.get_local_services(rkey).each {|ls| add_service_to_store(@remote_store, ls)}
        # add it to the list of verified servers
        @remote_servers << remote_server
      rescue DRb::DRbConnError
        # assume it is not working
        @logger.verbose("Failed to get remote services from server: #{remote_server.fqdn}")
      rescue JerbilAuthenticationError => jerr
        @logger.warn("Remote server authentication failed, skipping")
        @logger.warn("  #{jerr.message}")
      rescue ArgumentError, NoMethodError
        @logger.warn("Remote server incompatibility, skipping")
      rescue => jerr
        @logger.exception(jerr)
      end

    end
  end

  @logger.system("Started up the Jerbil Server")
  
  @logger.debug "My key: #{@private_key}"
  @logger.debug "Stored remote keys:"
  @remote_servers.each do |rs|
    @logger.debug "   #{rs.fqdn}: #{rs.key}"
  end
  
  #@logger.verbose "Closing logger temporarily"
  #@logger.close
  
rescue => jerr
  @logger.exception(jerr)
  raise
end

Instance Attribute Details

#registrations ⇒ Object (readonly)

the number of registrations since the server started



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# File 'lib/jerbil.rb', line 179

def registrations
  @registrations
end

#remote_servers ⇒ Array (readonly)

the remote servers at any one time

Returns:



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# File 'lib/jerbil.rb', line 184

def remote_servers
  @remote_servers
end

#started ⇒ Object (readonly)

date/time at which the server was started



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# File 'lib/jerbil.rb', line 176

def started
  @started
end

Instance Method Details

#close ⇒ Object

close the logger that Jerbil is using

probably only useful for testing?



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# File 'lib/jerbil.rb', line 477

def close
  @logger.close
end

#detach_server(my_key, server) ⇒ Object

detach a remote server from this server

called when the remote server is closing down. Incorrect keys are silently ignored. The remote server is removed from the database.

Parameters:

  • my_key (String) —

    being the key of the server being called

  • server (Server) —

    being the record for the remote server that is detaching



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# File 'lib/jerbil.rb', line 628

def detach_server(my_key, server)
 
  unless @private_key == my_key
    @logger.warn("Detaching remote server: incorrect key: #{my_key}")
    return false
  end
  
  unless @remote_servers.include?(server)
    @logger.warn "Detaching remote server: server not known: #{server.ident}"
    return false
  end
  
  @logger.verbose("About to detach a remote server: #{server.ident}")
  @remote_store.delete_if {|s| s.host == server.fqdn}
  @remote_servers.delete(server)
  @logger.info("Detached server: #{server.ident}")
end

#find(args = {}) ⇒ Array

return the services that match the given criteria

search for services based on name, environment etc:

broker.find(:name=>'MyService', :env=>:test)

If an option is not specified it will be ignored. Find uses ServiceRecord#matches? to compare services to the given criteria.

Normally this method will log the access to each service found (keeps a count) This can be disabled by setting :ignore_access to true. This is used internally to avoid counting Jerbil operations as service accesses.

There are also various short-cut methods that can be used: get, get_local and get_all

Parameters:

  • args (Hash) (defaults to: {}) —

    search arguments

Options Hash (args):

  • :name (String) —

    to match exactly the name of the service

  • :env (Symbol) —

    to match the services environment (:dev, :test, :prod)

  • :host (String) —

    to match exactly the name of the host on which the service is running

  • :key (String) —

    to match exactly the service key

  • :ignore_access (Boolean) —

    do not count this call as an access

Returns:

  • (Array) —

    Services that match or nil if none



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# File 'lib/jerbil.rb', line 316

def find(args={})
  #options = {:name=>nil, :port=>nil, :env=>nil}.merge(args)
  results = Array.new
  services = @store + @remote_store
  services.each do |service|
    if service.matches?(args) then
      service.log_access unless args[:ignore_access]
      results << service
    end
  end

  @logger.verbose("Searching for services. Found #{results.length} matching.")
  @logger.verbose("  Arguments: #{args.inspect}")

  return results
end

#get(args = {}) ⇒ Array

get the first service that matches the given criteria.

Uses #find to do the real work and returns the first service. There is no guarantee of the order. In addition, unless :ignore_acess is true, this call will check if the service is connected, and will return nil if it is not

Parameters:

  • args (Hash) (defaults to: {}) —

    search arguments

Options Hash (args):

  • :name (String) —

    to match exactly the name of the service

  • :env (Symbol) —

    to match the services environment (:dev, :test, :prod)

  • :host (String) —

    to match exactly the name of the host on which the service is running

  • :key (String) —

    to match exactly the service key

  • :ignore_access (Boolean) —

    do not count this call as an access

Returns:

  • (Array) —

    Services that match or nil if none



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# File 'lib/jerbil.rb', line 343

def get(args={})
  results = Array.new
  results = self.find(args)
  if results.length >= 1 then
    service = results[0]
    @logger.verbose("Get returned #{service.ident}")
    unless args[:ignore_access]
      # check if it is working
      begin
        service.connect
      rescue ServiceCallbackMissing
        @logger.warning("Verifying #{service.ident} failed due to missing callback")
        # missing callback but still return it...
      rescue ServiceConnectError
        @logger.verbose("Verification failed for #{service.ident}")
        return nil
      end
    end
    return service
  else
    return nil
  end
end

#get_all(ignore_access = false) ⇒ Array

return all services

does not require any matching criteria.

Parameters:

  • ignore_access (Boolean) (defaults to: false) —

    is the same as :ignore_access for #find

Returns:

  • (Array) —

    Services that match or nil if none



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# File 'lib/jerbil.rb', line 384

def get_all(ignore_access=false)
  self.find(:ignore_access => ignore_access)
end

#get_all_by_server ⇒ Object 



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# File 'lib/jerbil.rb', line 388

def get_all_by_server
  services = self.find(ignore_access: true)
  servers = Hash.new
  services.each do |serv|
    unless servers.has_key?(serv.host)
      servers[serv.host] = Array.new
    end
    servers[serv.host] << serv
  end
  return servers
end

#get_local(args = {}) ⇒ Array

get the first service that matches the given criteria and is running on the same processor

Parameters:

  • args (Hash) (defaults to: {}) —

    search arguments

Options Hash (args):

  • :name (String) —

    to match exactly the name of the service

  • :env (Symbol) —

    to match the services environment (:dev, :test, :prod)

  • :host (String) —

    to match exactly the name of the host on which the service is running

  • :key (String) —

    to match exactly the service key

  • :ignore_access (Boolean) —

    do not count this call as an access

Returns:

  • (Array) —

    Services that match or nil if none



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# File 'lib/jerbil.rb', line 373

def get_local(args={})
  new_args = args.merge({:host=>@host})
  return get(new_args)
end

#get_local_services(my_key) ⇒ Array

get all of the local services registered with this server

Parameters:

  • my_key (String) —

    must be the called servers private key shared with a remote server through #register_server.

Returns:

Raises:



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# File 'lib/jerbil.rb', line 572

def get_local_services(my_key)
  raise InvalidServerKey, @logger.error("get_local_services: incorrect key: #{my_key}") unless @private_key == my_key
  return @store.dup
end

#local_service_count ⇒ Numeric

the number of local services registered with the server

Returns:

  • (Numeric) —

    count of services



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# File 'lib/jerbil.rb', line 210

def local_service_count
  @store.length
end

#register(service) ⇒ Object

register a service to the local server

The caller registers the given service. The server will check that the service is not already registered before adding it. It will then inform all the other servers it is aware of about this service so that anyone on the network can reach it. See #register_remote to see what happens when this methods registers a service with a remote server.

Parameters:

Raises:



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# File 'lib/jerbil.rb', line 234

def register(service)
  @logger.verbose("About to register a local service: #{service.ident}")
  if service.local? then
    service.register
    add_service_to_store(@store, service)
    @registrations += 1
    @logger.system("Registered Local Service: #{service.ident}")

    @remote_servers.each do |rserver|
      rjerbil = rserver.connect
      unless rjerbil.nil?
        @logger.debug("Registering remote. Connected to #{rserver.fqdn}")
        begin
          rjerbil.register_remote(rserver.key, service)
          @logger.verbose("Registered Service: #{service.name} on server: #{rserver.fqdn}")
        rescue DRb::DRbConnError
          # assume it is not working
        end
      end
    end
  else
    # someone is attempting to register a service that is not local
    @logger.warn("Attempt to register non-local service: #{service.ident}")
    raise ServiceNotLocal
  end
end

#register_remote(my_key, service) ⇒ Object

register a remote service

This is called by a jerbil service when it wants to register a service local to it with all the other servers. This will siltenly delete any existing service record.

Parameters:

  • my_key (String) —

    • the caller must provide this server’s private key

  • service (Service) —

    • the service to be registered

Raises:

  • ServiceAlreadyRegistered if the service is a duplicate



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# File 'lib/jerbil.rb', line 587

def register_remote(my_key, service)
  @logger.debug "About to register a remote service:"
  @logger.debug "   #{service.inspect}"
 
  unless @private_key == my_key
    @logger.warn("register remote: incorrect key: #{my_key}, ignoring")
    return true
  end
  
  # perhaps there is a stale record for this service? Stops add below from assuming it is missing etc
  @remote_store.delete_if {|rservice| rservice.same_service?(service)}
  
  add_service_to_store(@remote_store, service)
  @logger.info("Registered Remote Service: #{service.ident}")
  return true

end

#register_server(server, secret, env) ⇒ String

Register a remote server, providing limited authentication.

Registering a server will purge any old server record and any old services for that server

Parameters:

  • server (Servers) —

    • the remote server’s Servers record

  • secret (String) —

    shared between all servers on the net

  • env (Symbol) —

    of the calling server, just to ensure it is the same

Returns:

  • (String) —

    private key of the called server to be used for further interactions

Raises:



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# File 'lib/jerbil.rb', line 543

def register_server(server, secret, env)
  @logger.debug("Attempting to register server: #{server.ident}")
  unless secret == @secret
    @logger.debug "mismatching secret: #{secret}"
    raise JerbilAuthenticationError, @logger.error("Secret key from #{server.fqdn} does not match")
  end
  unless env = @env
    raise JerbilAuthenticationError, @logger.error("Registering server with #{env}, against #{@env}")
  end
  # need to delete any stale existing record
  @remote_servers.delete_if {|rserver| rserver.fqdn == server.fqdn}
  
  # registering this new server, but there may be stale services as well
  @remote_store.delete_if {|rservice| rservice.host == server.fqdn}
  
  @remote_servers << server 
  @logger.debug "Registered a new server"
  @logger.debug "   #{server.ident}: #{server.key}"
    
  return @private_key
end

#remote_service_count ⇒ Numeric

the number of remote services registered with the server

Returns:

  • (Numeric) —

    count of services



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# File 'lib/jerbil.rb', line 216

def remote_service_count
  @remote_store.length
end

#remove(service) ⇒ Object

remove a service from the register

does nothing if the service is not registered, otherwise removes it locally and then calls #remove_remote for each registered server.

Parameters:



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# File 'lib/jerbil.rb', line 268

def remove(service)
  if @store.include?(service) then
    # its a local one
    @store.delete(service)
    @logger.system("Deleted Service: #{service.ident}")
  else
    @logger.warn("Attempt was made to remove a service that is not registered: #{service.ident}")
    @logger.warn("Trying to remove it remotely anyway")
  end
  @remote_servers.each do |rserver|
    rjerbil = rserver.connect
    unless rjerbil.nil?
      @logger.debug("Connected to #{rserver.fqdn}")
      begin
        rjerbil.remove_remote(rserver.key, service)
        @logger.verbose("Removed Service from remote server: #{service.ident}")
      rescue DRb::DRbConnError
        # assume it is not working
        @logger.debug("Skipping over remove_remote for #{rserver.fqdn} while removing #{service.ident}")
      end
    end
  end
end

#remove_remote(my_key, service) ⇒ Object

delete a remote service from this server

Parameters:

  • my_key (String) —

    • the caller must provide this server’s private key

  • service (Service) —

    • the service to be registered



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# File 'lib/jerbil.rb', line 608

def remove_remote(my_key, service)
  @logger.debug "About to remove a remote service:"
  @logger.debug "   #{service.inspect}"
 
  unless @private_key == my_key
    @logger.warn("remove_remote: incorrect key: #{my_key}")
    return true
  end
  @remote_store.delete_if {|s| s == service}
  @logger.info("Deleted Remote Service: #{service.ident}")
  return true
end

#restart_logger ⇒ Object

restart the logger on the other side of daemonising it

NOT NEEDED!



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# File 'lib/jerbil.rb', line 170

def restart_logger
  @logger = Jellog::Logger.new(@app_name, @log_opts)     
  @logger.debug "Restarted Logger"
end

#ruby_version ⇒ Object

tell remote users about what version of Ruby we are running



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# File 'lib/jerbil.rb', line 192

def ruby_version
  RUBY_VERSION
end

#server ⇒ Object

provide access to the local server record



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# File 'lib/jerbil.rb', line 187

def server
  @local
end

#service_count ⇒ Numeric

the total number of services currently registered with the server

Returns:

  • (Numeric) —

    count of services



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# File 'lib/jerbil.rb', line 204

def service_count
  @store.length + @remote_store.length
end

#service_missing?(service) ⇒ Boolean

Checks for a potentially missing service and removes it if it cannot be found.

What to do if you cannot connect to a service that Jerbil thinks is there? check if its local, try to connect and if OK then return false to allow retries otherwise remove the service and return true.

If the service is not local, find its server and ask it the same question. if the server is not there, then fake being that server and remove_remote from everyone. Don’t forget to remove it from here too!

Parameters:

Returns:

  • (Boolean) —

    true if service was missing



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# File 'lib/jerbil.rb', line 412

def service_missing?(service)
  # is it one of mine?
  if service.local? then
    #yes
    @logger.verbose("Local service missing for #{service.ident}?")
    begin
      service.connect
      # seems to be fine
      @logger.info("Missing service was found to be OK: #{service.ident}")
      return false
    rescue
      # failed to connect for some reason.
      # trying to stop the service
      @logger.debug("Local service appears to be missing: #{service.ident}")
      # and now remove it from the record
      self.remove(service)
      @logger.system("Removed missing local service: #{service.ident}")
      return true
    end
  else
    # not one of mine, so who owns it
    @logger.verbose("Missing service is not local: #{service.ident}")
    failed_remote_server = nil
    @remote_servers.each do |rserver|
      if rserver.fqdn == service.host then
        # found it, so try to warn it
        @logger.debug("Service: #{service.ident} belongs to #{rserver.fqdn}")
        begin
          rjerbil = rserver.connect
          return rjerbil.service_missing?(service)
        rescue
          # whoops, failed to connect to remote server
          # so assume it has gone and allow method to continue
          # so that it removes the service as if it was the remote server
          failed_remote_server = rserver
        end
      end
    end
    # only got here because could not connect to the server
    unless failed_remote_server.nil?
      @logger.warn("Failed to connect to server: #{failed_remote_server.fqdn}, removing service for it")
      rkey = failed_remote_server.key
      self.remove_remote(rkey, service)
      @remote_servers.each do |rserver|
        begin
          rjerbil = rserver.connect
          rjerbil.remove_remote(rkey, service)
          @logger.debug("Removed service: #{service.ident} from server #{rserver.fqdn}")
        rescue
          # server not up, so ignore
          @logger.debug("Failed to connect to server to remove service: #{rserver.fqdn}, but who cares!")
        end
      end
      return true
    else
      # strange? Should not have a service for which there is no server...
      @logger.warn("Could not find a server for #{service.ident}. How could this happen?")
      return false
    end
  end
end

#stop(private_key) ⇒ Object

stop the Jerbil server

Need to make sure the caller knows what they are doing so requires the server’s private key.

Parameters:

  • private_key (String) —

    • as given to the server at start-up.



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# File 'lib/jerbil.rb', line 493

def stop(private_key)
  if @private_key == private_key then
    @logger.info("About to stop the Jerbil Server")
    @remote_servers.each do |rserver|
      begin
        rjerbil = rserver.connect
        @logger.verbose("Closing connection to: #{rserver.ident}")
        rjerbil.detach_server(rserver.key, @local) 
      rescue ServerConnectError, DRb::DRbConnError
        @logger.error("Failed to connect to #{rserver.ident}")
      end
    end
    @logger.system("Stopping the Jerbil Server now")
    @logger.close
    DRb.stop_service
    #exit!
  else
    @logger.system("Stop called with incorrect private key")
    @logger.debug(" Private Key provided:")
    @logger.debug("#{private_key}")
    @logger.debug(" Private Key required")
    @logger.debug("#{@private_key}")
    raise InvalidPrivateKey
  end
rescue ServerConnectError
  @logger.error("Connection to remote server failed")
rescue InvalidPrivateKey
  raise
rescue => err
  @logger.exception(err)
end

#verify ⇒ Object

simple method to check that the server is running from a remote client



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# File 'lib/jerbil.rb', line 482

def verify
  return true
end

#version ⇒ String

The current version of the Jerbil Server

Returns:

  • (String) —

    version number in the form N.N.N



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# File 'lib/jerbil.rb', line 198

def version
  Jerbil::Version
end