start-buildkit.sh

#!/usr/bin/env bash

# This script MUST be sourced (i.e. use `source start-buildkit.sh`).

# Variable used by KraftKit, hence the requirement for sourcing the script
export KRAFTKIT_BUILDKIT_HOST=docker-container://buildkit

# Install container if not already installed.
if [ -n "$(docker ps --all --no-trunc --quiet --filter 'name=^buildkit$')" ]; then
    echo "Container 'buildkit' is already installed. Nothing to do."
else
    echo "Installing 'buildkit' container ... "
    docker run -d --name buildkit --privileged moby/buildkit:latest
    return $?
fi

if [ "$(docker container inspect -f '{{.State.Running}}' buildkit 2> /dev/null)" = "true" ]; then
    echo "Container 'buildkit' is already running. Nothing to do."
else
    echo "Starting 'buildkit' container ... "
    docker start buildkit
    return $?
fi

CACHE_ARGS=()
if [ -n "${CACHE_DIR:-}" ]; then
  mkdir -p "$CACHE_DIR"
  CACHE_ARGS+=(--cache-from type=local,src="$CACHE_DIR")
  CACHE_ARGS+=(--cache-to type=local,dest="$CACHE_DIR",mode=max)
fi
export CACHE_ARGS