root / doc / examples / dumb-allocator @ 7d26425f
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#!/usr/bin/python |
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# |
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# Copyright (C) 2008 Google Inc. |
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# |
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# This program is free software; you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation; either version 2 of the License, or |
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# (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, but |
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# WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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# General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with this program; if not, write to the Free Software |
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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# 02110-1301, USA. |
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|
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"""Simple first-fit allocator for ganeti instance allocation framework. |
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|
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This allocator just iterates over the nodes and selects the first one |
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that fits in both memory and disk space, without any consideration for |
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equal spread or VCPU oversubscription. |
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|
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""" |
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|
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import simplejson |
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import sys |
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|
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|
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def SelectNode(nodes, request, to_skip): |
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"""Select a node for the given instance |
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|
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""" |
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disk_size = request["disk_space_total"] |
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selected = None |
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for nname, ninfo in nodes.iteritems(): |
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if nname in to_skip: |
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continue |
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if request["memory"] > ninfo["free_memory"]: |
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continue |
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if disk_size > ninfo["free_disk"]: |
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continue |
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selected = nname |
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break |
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return selected |
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|
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|
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def OutputError(text, exit_code=1): |
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"""Builds an error response with a given info message. |
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|
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""" |
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error = { |
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"success": False, |
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"info": text, |
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"nodes": [], |
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} |
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print simplejson.dumps(error, indent=2) |
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return exit_code |
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|
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|
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def main(): |
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"""Main function. |
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|
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""" |
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if len(sys.argv) < 2: |
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print >> sys.stderr, "Usage: %s cluster.json" % (sys.argv[0]) |
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return 1 |
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|
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data = simplejson.load(open(sys.argv[1])) |
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|
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nodes = data["nodes"] |
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request = data["request"] |
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req_type = request["type"] |
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offline_nodes = [name for name in nodes if nodes[name]["offline"]] |
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drained_nodes = [name for name in nodes if nodes[name]["offline"]] |
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if req_type == "allocate": |
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forbidden_nodes = offline_nodes |
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inst_data = request |
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elif req_type == "relocate": |
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idict = data["instances"][request["name"]] |
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forbidden_nodes = idict["nodes"] + offline_nodes + drained_nodes |
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inst_data = idict |
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inst_data["disk_space_total"] = request["disk_space_total"] |
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else: |
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return OutputError("Unsupported allocator mode '%s'" % req_type) |
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|
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result_nodes = [] |
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while len(result_nodes) < request["required_nodes"]: |
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new_selection = SelectNode(nodes, inst_data, result_nodes+forbidden_nodes) |
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if new_selection is None: |
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return OutputError("Can't find a suitable node for position %s" |
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" (already selected: %s)" % |
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(len(result_nodes) + 1, ", ".join(result_nodes)), |
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exit_code=0) |
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result_nodes.append(new_selection) |
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|
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result = { |
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"success": True, |
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"info": "Allocation successful", |
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"nodes": result_nodes, |
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} |
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print simplejson.dumps(result, indent=2) |
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return 0 |
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|
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if __name__ == "__main__": |
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sys.exit(main()) |