buf.build protoc local exec using container images from custom registry

buf-protoc-plugin-local-exec.sh

#!/usr/bin/env bash
# Symlink this script as ./protoc-gen-<plugin-name>.
# container images should be built as protoc-gen-<plugin-name>
# make sure `buf` is installed and available in your PATH as well 
# as this script and the symlinks. Works both with docker and podman.
# podman is preferred if both are available. (podman is preferred in CI environments)
#
# Example buf.gen.yaml:
# ---
# version: v1
# plugins:
#   - plugin: go # symlink protoc-gen-go to this script
#     out: internal/pb
#     opt:
#       - paths=source_relative
#
# export PROTOC_PLUGIN_REGISTRY environment variable to use a
# custom container registry (e.g. registry.gitlab.com/my-org/protoc-plugins), defaults to localhost.
# export DEBUG environment variable to enable debug logging
#
# Upsteam protoc plugin images can be found here: https://github.com/bufbuild/plugins
set -fe -o pipefail

# log executions if debug is enabled
if [[ -n "${DEBUG}" ]]; then
    set -x
fi

_log() {
    local -r prefix="$1"
    shift
    echo "[${prefix}$(date -u "+%Y-%m-%d %H:%M:%S %Z")] ""$*" >&2
}

info() {
    _log "INFO " "$*"
}

error() {
    _log "ERROR " "$*"
}

check_container_runtime() {
    if command -v podman &>/dev/null; then
        export RUNTIME="podman"
    elif command -v docker &>/dev/null; then
        export RUNTIME="docker"
    else
        error "No container runtime found"
        exit 1
    fi
}

use_container_image_registry() {
    if [[ -n "${PROTOC_PLUGIN_REGISTRY}" ]]; then
        export PROTOC_PLUGIN="${PROTOC_PLUGIN_REGISTRY}/$1"
    else
        export PROTOC_PLUGIN="$1"
    fi
}

main() {
    check_container_runtime
    use_container_image_registry "$1"
    info "Running ${RUNTIME} run ${PROTOC_PLUGIN}"
    exec $RUNTIME run -i "${PROTOC_PLUGIN}"
}

_self=${0##*/}
main "$_self"