#!/bin/bash
# -*- sh -*-

: << =cut

=head1 NAME

pvc - Plugin to monitor a PVC cluster.

=head1 CONFIGURATION

Note that due to how Munin thresholds work, these values must always be slightly less than 1 or 2 respectively,
or the alerts will never be triggered.

Defaults (no config required):

[pvc]
env.warning 1.99
env.critical 1.99

Make degraded cluster WARN only (max value is 2, so 3 effectively disables):

[pvc]
env.pvc_cluster_warning 1.99
env.pvc_cluster_critical 3

=head1 AUTHOR

Joshua Boniface <joshua@boniface.me>

=head1 LICENSE

GPLv3

=head1 BUGS

=back

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=cut

. "$MUNIN_LIBDIR/plugins/plugin.sh"

warning=1.99
critical=1.99

export PVC_CLIENT_DIR="/run/shm/munin-pvc"
PVC_CMD="/usr/bin/pvc --quiet --cluster local status --format json-pretty"
JQ_CMD="/usr/bin/jq"

output_usage() {
    echo "This plugin outputs numerical values based on the health of the PVC cluster."
    echo
    echo "There are separate outputs for both the PVC cluster itself as well as the Ceph storage cluster."
    echo "In normal operation, i.e. when both clusters are in 'Optimal' state, the plugin returns 0 for"
    echo "each cluster. When the cluster is placed into 'Maintenance' mode,the plugin returns 1 for each"
    echo "cluster, and goes into WARN state (limit 0.99); this can be adjusted by overriding the WARNING"
    echo "threshold of the plugin to something other than 0.99 - note that due to Munin's alerting design,"
    echo "the warning value must always be very slightly below the whole number. When either cluster"
    echo "element becomes 'Degraded', the plugin returns 2 for the relevant cluster, which is treated as a"
    echo "critical. Like the WARNING threshold, this can be overridden, and with the same caveat about limit."
    exit 0
}

output_autoconf() {
    $PVC_CMD &>/dev/null
    pvc_ret=$?
    $JQ_CMD --version &>/dev/null
    jq_ret=$?

    if [[ ${pvc_ret} -eq 0 && ${jq_ret} -eq 0 ]]; then
        echo "yes"
    elif [[ ${pvc_ret} -ne 0 ]]; then
        echo "no (no 'pvc' command found or local cluster not usable)"
    elif [[ ${jq_ret} -ne 0 ]]; then
        echo "no (no 'jq' command found)"
    else
        echo "no (generic failure)"
    fi
}

output_config() {
    echo 'graph_title PVC Clusters'
    echo 'graph_args --base 1000'
    echo 'graph_vlabel Count'
    echo 'graph_category pvc'
    echo 'graph_period second'
    echo 'graph_info This graph shows the nodes in the PVC cluster.'

    echo 'pvc_cluster.label Cluster Degradation'
    echo 'pvc_cluster.type GAUGE'
    echo 'pvc_cluster.max 2'
    echo 'pvc_cluster.info Whether the PVC cluster is in a degraded state.'
    print_warning pvc_cluster
    print_critical pvc_cluster

    echo 'pvc_storage.label Storage Degradation'
    echo 'pvc_storage.type GAUGE'
    echo 'pvc_storage.max 2'
    echo 'pvc_storage.info Whether the storage cluster is in a degraded state.'
    print_warning pvc_storage
    print_critical pvc_storage

    exit 0
}

output_values() {
    PVC_OUTPUT="$( $PVC_CMD )"

    cluster_health="$( $JQ_CMD '.health' <<<"${PVC_OUTPUT}" | tr -d '"' )"
    case $cluster_health in
        "Optimal")
            cluster_value="0"
            ;;
        "Maintenance")
            cluster_value="1"
            ;;
        "Degraded")
            cluster_value="2"
    esac

    storage_health="$( $JQ_CMD '.storage_health' <<<"${PVC_OUTPUT}" | tr -d '"' )"
    case $storage_health in
        "Optimal")
            storage_value="0"
            ;;
        "Maintenance")
            storage_value="1"
            ;;
        "Degraded")
            storage_value="2"
    esac


    echo "pvc_cluster.value $cluster_value"
    echo "pvc_storage.value $storage_value"
}

case $# in
    0)
        output_values
        ;;
    1)
        case $1 in
            autoconf)
                output_autoconf
                ;;
            config)
                output_config
                ;;
            *)
                output_usage
                exit 1
                ;;
        esac
        ;;
    *)
        output_usage
        exit 1
esac