protoc-gen-bq-schema

README

protoc-gen-bq-schema

This is the fork of GoogleCloudPlatform/protoc-gen-bq-schema repository addressing these PRs:

• #12 Use comments as field description (from master branch in this repository)
• #14 Add support for message-level extra_fields
• #17 Added enumsasints plugin parameter – since v1.5
• Add support for recursive messages – since v1.6

Default branch of this repository is develop.

Two satellite repositories:

• protoc-gen-bq-schema-example-proto – example of input Protobuf files
• protoc-gen-bq-schema-example-bq – example of generated Big Schema JSON files

protoc-gen-bq-schema is a plugin for ProtocolBuffer compiler.

It converts messages written in .proto format into schema files in JSON for BigQuery.

So you can reuse existing data definitions in .proto for BigQuery with this plugin.

Installation

go get github.com/chuhlomin/protoc-gen-bq-schema

Usage

protoc --bq-schema_out=path/to/outdir foo.proto

protoc and protoc-gen-bq-schema commands must be found in $PATH.

The generated JSON schema files are suffixed with .schema and their base names are named after their package names and bq_table_name options.

If you do not already have the standard Google Protobuf libraries in your proto_path, you'll need to specify them directly on the command line (and potentially need to copy bq_schema.proto into a proto_path directory as well), like this:

protoc --bq-schema_out=path/to/out/dir foo.proto --proto_path=. --proto_path=<path_to_google_proto_folder>/src

Example

Suppose that we have the following foo.proto.

syntax = "proto3";

package foo;

import "google/type/date.proto";
import "bq/bq_table.proto";
import "bq/bq_field.proto";

message Bar {
  option (gen_bq_schema.bigquery_opts).table_name = "bar_table";
  option (gen_bq_schema.bigquery_opts).extra_fields = "f:INTEGER";
  option (gen_bq_schema.bigquery_opts).extra_fields = "g:RECORD:Baz";

  message Nested {
    repeated int32 a = 1;
  }

  enum EnumAllowingAlias {
    option allow_alias = true;
    UNKNOWN = 0;
    STARTED = 1;
    RUNNING = 1;
  }

  int32 a = 1; // field comment
  Nested b = 2;
  string c = 3;

  bool d = 4 [(gen_bq_schema.bigquery).ignore = true];
  uint64 e = 5 [
    (gen_bq_schema.bigquery) = {
      require: true
      type_override: 'TIMESTAMP'
    }
  ];

  google.type.Date date = 6 [(gen_bq_schema.bigquery).type_override = "DATE"];

  EnumAllowingAlias status = 8;
}

message Baz {
  int32 a = 1;
}

protoc --bq-schema_out=. foo.proto will generate a file named foo/bar_table.schema.

The message foo.Baz is ignored because it doesn't have option gen_bq_schema.bigquery_opts.

Plugin parameter enumsasints=true will marshal all enums into integers instead of strings: protoc --bq-schema_out=enumsasints=true:. foo.proto.

Docker Hub

You can use chuhlomin/protoc-gen-bq-schema image on Docker Hub.

Example Docker run:

mkdir bq_schema
docker run -i -t -v $(pwd):/workdir \
  chuhlomin/protoc-gen-bq-schema:1.6 \
  -I/workdir \
  -I/workdir/bq \
  --bq-schema_out=/workdir/bq_schema \
  /workdir/foo.proto

Example Drone step: .drone.yml

  - name: build
    image: chuhlomin/protoc-gen-bq-schema:1.6
    commands:
      - mkdir bq_schema
      - protoc -I/protobuf/ -I. -Ibq --bq-schema_out=bq_schema foo.proto

Local Development

To test build binaries inside an isolated Docker container (recommended):

docker run -i -t -v $(pwd):/workdir golang:1.12.14-alpine3.10 /bin/sh

apk add --no-cache make git gcc libc-dev protobuf
cd /workdir
make clean test install
make examples

exit

To test and build the plugin binary on your machine run the following commands:

make clean test install

# (optionally) build a Docker image
docker build -t protoc-gen-bq-schema:local .

License

protoc-gen-bq-schema is licensed under the Apache License version 2.0.

This is not an official Google product.

Documentation

Overview

protoc plugin which converts .proto to schema for BigQuery. It is spawned by protoc and generates schema for BigQuery, encoded in JSON.

usage:

$ bin/protoc --bq-schema_out=path/to/outdir foo.proto