wglass/lighthouse

import collections
import datetime
import logging

import six

from .stanzas.section import Section
from .stanzas.meta import MetaFrontendStanza
from .stanzas.frontend import FrontendStanza
from .stanzas.backend import BackendStanza
from .stanzas.peers import PeersStanza


logger = logging.getLogger(__name__)


class HAProxyConfig(object):
    """
    Class for generating HAProxy config file content.

    Requires global and defaults stanzas to be passed, can optionally take
    a `stats_stanza` for enabling a stats portal.
    """

    def __init__(
            self,
            global_stanza, defaults_stanza,
            proxy_stanzas=None, stats_stanza=None, meta_clusters=None,
            bind_address=None
    ):
        self.global_stanza = global_stanza
        self.defaults_stanza = defaults_stanza
        self.proxy_stanzas = proxy_stanzas or []
        self.stats_stanza = stats_stanza
        self.meta_clusters = meta_clusters or {}
        self.bind_address = bind_address

    def generate(self, clusters, version=None):
        """
        Generates HAProxy config file content based on a given list of
        clusters.
        """
        now = datetime.datetime.now()

        sections = [
            Section(
                "Auto-generated by Lighthouse (%s)" % now.strftime("%c"),
                self.global_stanza,
                self.defaults_stanza
            )
        ]

        meta_stanzas = [
            MetaFrontendStanza(
                name, self.meta_clusters[name]["port"],
                self.meta_clusters[name].get("frontend", []), members,
                self.bind_address
            )
            for name, members
            in six.iteritems(self.get_meta_clusters(clusters))
        ]
        frontend_stanzas = [
            FrontendStanza(cluster, self.bind_address)
            for cluster in clusters
            if "port" in cluster.haproxy
        ]
        backend_stanzas = [BackendStanza(cluster) for cluster in clusters]

        if version and version >= (1, 5, 0):
            peers_stanzas = [PeersStanza(cluster) for cluster in clusters]
        else:
            peers_stanzas = []

        sections.extend([
            Section("Frontend stanzas for ACL meta clusters", *meta_stanzas),
            Section("Per-cluster frontend definitions", *frontend_stanzas),
            Section("Per-cluster backend definitions", *backend_stanzas),
            Section("Per-cluster peer listings", *peers_stanzas),
            Section("Individual proxy definitions", *self.proxy_stanzas),
        ])
        if self.stats_stanza:
            sections.append(
                Section("Listener for stats web interface", self.stats_stanza)
            )

        return "\n\n\n".join([str(section) for section in sections]) + "\n"

    def get_meta_clusters(self, clusters):
        """
        Returns a dictionary keyed off of meta cluster names, where the values
        are lists of clusters associated with the meta cluster name.

        If a meta cluster name doesn't have a port defined in the
        `meta_cluster_ports` attribute an error is given and the meta cluster
        is removed from the mapping.
        """
        meta_clusters = collections.defaultdict(list)

        for cluster in clusters:
            if not cluster.meta_cluster:
                continue
            meta_clusters[cluster.meta_cluster].append(cluster)

        unconfigured_meta_clusters = [
            name for name in meta_clusters.keys()
            if name not in self.meta_clusters
        ]

        for name in unconfigured_meta_clusters:
            logger.error("Meta cluster %s not configured!")
            del meta_clusters[name]

        return meta_clusters