kubernetes/common/cassandra/resources/config/docker-entrypoint.sh

#!/bin/bash
set -e

# first arg is `-f` or `--some-option`
# or there are no args
if [ "$#" -eq 0 ] || [ "${1#-}" != "$1" ]; then
        set -- cassandra -f "$@"
fi

# allow the container to be started with `--user`
if [ "$1" = 'cassandra' -a "$(id -u)" = '0' ]; then
        find /var/lib/cassandra /var/log/cassandra "$CASSANDRA_CONFIG" \
                \! -user cassandra -exec chown cassandra '{}' +
        exec gosu cassandra "$0" "$@"
fi

_ip_address() {
        # scrape the first non-localhost IP address of the container
        # in Swarm Mode, we often get two IPs -- the container IP, and the (shared) VIP, and the container IP should always be first
        ip address | awk '
                $1 == "inet" && $NF != "lo" {
                        gsub(/\/.+$/, "", $2)
                        print $2
                        exit
                }
        '
}

# "sed -i", but without "mv" (which doesn't work on a bind-mounted file, for example)
_sed-in-place() {
        local filename="$1"; shift
        local tempFile
        tempFile="$(mktemp)"
        sed "$@" "$filename" > "$tempFile"
        cat "$tempFile" > "$filename"
        rm "$tempFile"
}

if [ "$1" = 'cassandra' ]; then
        : ${CASSANDRA_RPC_ADDRESS='0.0.0.0'}

        : ${CASSANDRA_LISTEN_ADDRESS='auto'}
        if [ "$CASSANDRA_LISTEN_ADDRESS" = 'auto' ]; then
                CASSANDRA_LISTEN_ADDRESS="$(_ip_address)"
        fi

        : ${CASSANDRA_BROADCAST_ADDRESS="$CASSANDRA_LISTEN_ADDRESS"}

        if [ "$CASSANDRA_BROADCAST_ADDRESS" = 'auto' ]; then
                CASSANDRA_BROADCAST_ADDRESS="$(_ip_address)"
        fi
        : ${CASSANDRA_BROADCAST_RPC_ADDRESS:=$CASSANDRA_BROADCAST_ADDRESS}

        if [ -n "${CASSANDRA_NAME:+1}" ]; then
                : ${CASSANDRA_SEEDS:="cassandra"}
        fi
        : ${CASSANDRA_SEEDS:="$CASSANDRA_BROADCAST_ADDRESS"}

        _sed-in-place "$CASSANDRA_CONFIG/cassandra.yaml" \
                -r 's/(- seeds:).*/\1 "'"$CASSANDRA_SEEDS"'"/'

        for yaml in \
                broadcast_address \
                broadcast_rpc_address \
                cluster_name \
                endpoint_snitch \
                listen_address \
                num_tokens \
                rpc_address \
                start_rpc \
                authenticator \
        ; do
                var="CASSANDRA_${yaml^^}"
                val="${!var}"
                if [ "$val" ]; then
                        _sed-in-place "$CASSANDRA_CONFIG/cassandra.yaml" \
                                -r 's/^(# )?('"$yaml"':).*/\2 '"$val"'/'
                fi
        done

        for rackdc in dc rack; do
                var="CASSANDRA_${rackdc^^}"
                val="${!var}"
                if [ "$val" ]; then
                        _sed-in-place "$CASSANDRA_CONFIG/cassandra-rackdc.properties" \
                                -r 's/^('"$rackdc"'=).*/\1 '"$val"'/'
                fi
        done
fi

exec "$@"