Bash script to pull latest Docker container, (re)start container if needed, and clean up dangling images

control.sh

#!/usr/bin/env bash

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" > /dev/null && pwd )"
IMAGE=
TAG='latest'
CONTAINER=

function printf() {
    format="\e[1;31m$1\e[m"
    shift
    /usr/bin/printf "$format" $*
}

if [[ -z "$1" ]]; then
    printf 'Please specify a service\n'
    exit 1;
fi
SERVICE="$DIR/services/$1.sh"
if [[ ! -f "$SERVICE" ]]; then
    printf 'Service file %s does not exist\n' "$SERVICE"
    exit 1
fi

# shellcheck disable=1090
source "$SERVICE"
if [[ -z "$IMAGE" ]] || [[ -z "$CONTAINER" ]] || [[ "$(type -t docker_start_new)" != "function" ]]; then
    printf 'Erroneous service file (IMAGE=%s, TAG=%s, CONTAINER=%s, docker_start_new=%s)\n' "$IMAGE" "$CONTAINER" "$TAG" "$(type -t docker_start_new)"
    exit 1
fi

function docker_start() {
    if [[ "$(type -t docker_prestart)" == "function" ]]; then
        printf 'Running pre-start script\n'
        docker_prestart
    fi

    printf 'Pulling latest image %s:%s\n' "$IMAGE" "$TAG"
    docker pull "$IMAGE:$TAG"
    CURRENT_IMAGE="$(docker container ls -a --filter="name=$CONTAINER" --format='{{.Image}}')"

    if [[ -z "$CURRENT_IMAGE" ]]; then
        printf '%s container not found\n' "$CONTAINER"
    elif [[ "$CURRENT_IMAGE" != "$IMAGE:$TAG" ]]; then
        printf 'Container %s is not running latest %s, gonna remove it\n' "$CONTAINER" "$IMAGE"
        docker rm -f "$CONTAINER"
    else
        printf 'Container %s is already running the latest %s\n' "$CONTAINER" "$IMAGE"
        printf 'Starting container %s\n' "$CONTAINER"
        docker start "$CONTAINER"
        exit 0
    fi
    printf 'Cleaning up dangling images\n'
    DANGLING="$(docker image ls --filter=dangling=true -q "$IMAGE")"
    if [[ -n "$DANGLING" ]]; then
        docker rmi "$DANGLING"
    else
        printf 'No dangling images\n'
    fi
    docker_start_new
}

function docker_stop() {
    printf 'Stopping container %s\n' "$CONTAINER"
    docker stop "$CONTAINER"
    if [[ "$(type -t docker_poststop)" == "function" ]]; then
        printf 'Running post-stop script\n'
        docker_poststop
    fi
}

case "$2" in
    start)
        docker_start
        ;;
    stop)
        docker_stop
        ;;
    restart)
        docker_stop
        docker_start
        ;;
    remove|rm)
        docker_stop
        docker rm "$CONTAINER"
        ;;
    *)
        printf 'Unknown operation\n'
        exit 1
        ;;
esac

runner.sh

#!/usr/bin/env bash

export IMAGE='gitlab/gitlab-runner'
export CONTAINER='gitlab-runner'

function docker_start_new() {
    docker run -d --name "$CONTAINER" --restart unless-stopped \
        -v /srv/gitlab-runner/config:/etc/gitlab-runner \
        -v /var/run/docker.sock:/var/run/docker.sock \
        --log-driver json-file --log-opt max-size=10m --log-opt max-file=3 \
        "$IMAGE:$TAG"
}