GIT to MQTT

mqtt.post-update

#!/bin/bash
#
# GIT to MQTT Publishing hook
#
# This script provides a post-update hook solution which is intended to be self-contained and simply publish to
# a mosquitto server the current most recent commit ref for each branch.
#
# Once the branch is published clients subscribed to that specific topic will be informed of their necessity to
# update.
#
# Requirements
# - mosquitto clients 1.6.8+
# - avahi-clients
# - a mosquitto server which is advertised over avahi, and not password protected*
#
# /etc/avahi/services/mqtt.service
# <?xml version="1.0" standalone='no'?><!--*-nxml-*-->
# <!DOCTYPE service-group SYSTEM "avahi-service.dtd">
# <service-group>
#   <name replace-wildcards="yes">Mosquitto Service on %h</name>
#   <service>
#     <type>_mqtt._tcp</type>
#     <port>1883</port>
#   </service>
# </service-group>
#
# * Authentication can be easily added, but this is generally intended simply as notification
#   on local networks for deploying code to hardware.

T=`pwd`
echo "Post update in $T"
REPO_URL=`basename $T`
REPO_NAME=${REPO_URL%.git}
REPO_CHECKOUT="$REPO_NAME.git-temp"

# Discover our local mqtt server
echo "Searching for MQTT service"
MQTT_HOST=`avahi-browse -d local _mqtt._tcp --resolve -p -t | grep '^=' | cut -d ';' -f 8 | grep -v '::'`
MQTT_PORT=`avahi-browse -d local _mqtt._tcp --resolve -p -t | grep '^=' | cut -d ';' -f 9 | grep -v '::'`

if [ "$MQTT_HOST" == "" ]; then
    echo "Fatal, cannot find advertised mosquitto service _mqtt._tcp"
    exit 1
fi

if [ "$MQTT_PORT" == "" ]; then
    $MQTT_PORT = "1883"
fi

echo "Found mosquitto server $MQTT_HOST:$MQTT_PORT"

unset GIT_DIR
if [ -d "$REPO_CHECKOUT" ]; then
    echo "Updating repository"
    cd $REPO_CHECKOUT
    git pull
else
    echo "Cloning repository"
    git clone $T $REPO_CHECKOUT
    cd $REPO_CHECKOUT
fi

# Publish the newest commit ref
BRANCHES=`git branch --list -a | grep remotes/origin | grep -v HEAD`

for BRANCH_FULL in $BRANCHES; do
    BRANCH=${BRANCH_FULL#"remotes/origin/"}
    COMMIT_REF=`git show origin/$BRANCH | head -n 1 | cut -d ' ' -f 2`
    TOPIC="/Git/$REPO_NAME/branches/$BRANCH"

    # Retrieve the current value for the topic
    LAST_COMMIT_REF=`mosquitto_sub -h $MQTT_HOST -t $TOPIC -C 1 -W 1`
    echo "$LAST_COMMIT_REF -> $COMMIT_REF"

    if [ "$LAST_COMMIT_REF" != "$COMMIT_REF" ]; then
        echo "Publishing $BRANCH:$COMMIT_REF to $TOPIC"
        mosquitto_pub -r -h $MQTT_HOST -t $TOPIC -m $COMMIT_REF
    fi
done