Try the Buf Schema Registry

In this tour you will gain understanding of the Buf Schema Registry (BSR) and its APIs, create a repository and push a module with generated documentation. Most of all you'll familiarize yourself with Dependency Management, powered by the BSR, solving one of the greatest challenges of the Protobuf ecosystem. In the end, you will put it all together to build an API client with Remote Packages.

By the end of this tour, you will have a strong understanding of the core components of the BSR, including:

• Create a Repository & Push a Buf Module
• Generate Documentation
• Utilize dependency management for well known types
• Build an API using Remote Packages

Before you begin

It's always a good idea to check if the locally installed version of buf is up-to-date. Open your shell and make sure you have the correct version installed.

$ buf --version
Output
1.21.0

Clone the Git repository

First, clone the Git repository that contains the starter code for the PetStore service. From the development directory of your choice, run this command:

$ git clone https://github.com/bufbuild/buf-tour

You'll notice that the repository contains a start/getting-started-with-bsr directory and a finish/getting-started-with-bsr directory. Here you will find an already configured buf module that define the pet store API, which specifies a way to create, get, and delete pets in the store and some generated code to build an API server and client.

We'll start in the start/getting-started-with-bsr directory

$ cd buf-tour/start/getting-started-with-bsr

1. Log in

If you haven't already, Sign Up for the Buf Schema Registry. Otherwise, visit buf.build/login, and you'll be prompted with a few different login options, including Google, GitHub, and traditional email and password.

After you've successfully authenticated, you'll be prompted to select a username and complete your registration. If successful, you should see that you're logged in and that your username is rendered in the upper right-hand corner.

1.1. Create an API Token

Now that you're logged in:

1. Visit the buf.build/settings/user page.
2. Click the Create New Token button.
3. Select an expiration time. You can optionally add a note for yourself to distinguish this token from others (we recommend that you name this CLI, Development, or something else along those lines).
4. Click Create.
5. Copy the token to your clipboard. You will use this throughout the rest of the guide.

1.2. buf registry login

All you need to log in is the API token created above. Run this command to do so:

$ buf registry login
Output
Log in with your Buf Schema Registry username. If you don't have a username, create one at https://buf.build.

Username: <USERNAME>
Token: <YOUR TOKEN>

2. Push a Module

Now that you've authenticated with the BSR, you can create a repository and push a module that defines the PetStoreService API.

Modules are the core primitive of Buf and the BSR. A module is a collection of Protobuf files that are configured, built, and versioned as a logical unit. You created a module when you initialized a buf.yaml at the beginning of the tour.

2.1. Create a repository

A module is stored in a repository. A repository stores all versions of a module, where each version is identified by a commit, (optionally) a tag, and/or (optionally) a draft. While roughly analogous to Git repositories, a BSR repository is only a remote location - there is no concept of a repository "clone". In other words, repositories do not exist in multiple locations.

Create a new repository:

1. Navigate to the home page
2. Select your username in the top right corner
3. Click "Repositories" from the dropdown
4. Clicking on "Create repository"
5. Name the repository petapis. For the purposes of this guide, we will keep the repository public.

You should now be presented with an empty repository called petapis. Next up, we will find out how to push a module.

2.2. Configure a name

Back in your terminal, move into the proto directory:

$ cd proto

Update your buf.yaml so that its name matches the repository you just created:

version: v1
name: buf.build/<USERNAME>/petapis
breaking:
  use:
    - FILE
lint:
  use:
    - DEFAULT

2.3. Push the module

Push the module to the buf.build/<USERNAME>/petapis repository with this command (in the proto directory containing your buf.yaml):

$ buf push
Output
19bcefa1a736428d9e64d21c9191b213

The pushed module will create a commit, this is included in the CLI output. Your value will differ.

Behind the scenes, buf recognizes the name in your buf.yaml and pushes the module to the buf.build/<USERNAME>/petapis repository. If successful, the generated commit identifies this current version of your module.

3. View generated documentation

You can browse generated documentation for your module in the BSR.

Navigate to the /docs page for the module you just created in your browser. If your <USERNAME> variable is set to acme and you created the buf.build/acme/petapis module, you can visit the buf.build/acme/petapis/docs page (replace acme with your <USERNAME> in this link).

3.1. Add a buf.md

The page you see above serves as the primary entrypoint for your module's documentation. But as you can see from the default buf.md content, we currently don't have any module-level documentation.

You can update the module-level documentation page by creating a buf.md in the same directory as your module's buf.yaml, and pushing it up to the BSR. In this way, the buf.md file is analogous to a GitHub repository's README.md. The buf.md file currently supports all the CommonMark syntax.

Let's start by adding a quick note:

$ touch buf.md

## PetAPIs

This module contains all the APIs required to interact with the `PetStoreService`.

Your proto directory should now look like this:

proto/
├── buf.md
├── buf.yaml
├── google
│   └── type
│       └── datetime.proto
└── pet
    └── v1
        └── pet.proto

Now if you push your module again, you'll notice a new commit and that the documentation has been updated to reflect the latest changes:

$ buf push
Output
4514ddced0584e73a100e82096c7958c

If you refresh the documentation page you visited above, you should see the changes you just introduced with your buf.md documentation.

3.2. Package documentation

As you can see from the module documentation page, both the pet.v1 and google.type packages are available as links. Click on the pet.v1 link to navigate to its package documentation at buf.build/acme/petapis/docs/4514ddced0584e73a100e82096c7958c/pet.v1. From here, you can click through each of the Protobuf type definitions and see all the comments associated with each type. In fact, if you click on the google.type.DateTime message referenced in the Pet message, you'll be brought to the google.type.v1 package documentation for the same commit.

For an example of API documentation, check out buf.build/googleapis/googleapis.

4. Add a dependency

Without the BSR, you can only depend on other Protobuf APIs by manually fetching the .proto files you need. Historically, if you wanted to use googleapis, for example, you'd need to clone the right Git repository and copy the .proto file(s) you need in order to compile your own .proto files. And if googleapis has its own external dependencies, then you need to fetch those as well.

Even worse, this way of managing dependencies is prone to API drift, where the googleapis code may evolve over time, leaving your local copies inconsistent with the latest version and your modules thus out of date. It turns out that this is exactly what you did with the PetStoreService: the google/type/datetime.proto file is actually present in your local directory and currently used to build your module.

Now that you're familiar with the BSR, you can simplify this entire workflow immensely.

4.1. Remove the datetime.proto file

Start by removing the google/type/datetime.proto file from your module altogether. From within the proto directory, run this command to remove_all_ the local google dependencies:

$ rm -r google

Now remove the google/type/datetime.proto reference from your buf.yaml:

 version: v1
 name: buf.build/<USERNAME>/petapis
 breaking:
   use:
     - FILE
 lint:
   use:
     - DEFAULT
 -  ignore:
 -    - google/type/datetime.proto

If you try to build the module in its current state, you will notice an error:

$ buf build
Output
pet/v1/pet.proto:7:8:google/type/datetime.proto: does not exist

4.2. Depend on googleapis

You can resolve this error by configuring a dependency in your buf.yaml's deps key. The google/type/datetime.proto file is provided by the buf.build/googleapis/googleapis module, so you can configure it like this:

 version: v1
 name: buf.build/<USERNAME>/petapis
 +deps:
 +  - buf.build/googleapis/googleapis
 breaking:
   use:
     - FILE
 lint:
   use:
     - DEFAULT

Now, if you try to build the module again, you'll notice this:

$ buf build
Output
WARN  Specified deps are not covered in your buf.lock, run "buf mod update":
  - buf.build/googleapis/googleapis
pet/v1/pet.proto:7:8:google/type/datetime.proto: does not exist

buf detected that you specified a dependency that isn't included in the module' s buf.lock file. This file is a dependency manifest for your module, representing a single reproducible build of your module's dependencies. You don't have a buf.lock file yet because you haven't specified any external dependencies, but you can create one with the command that buf recommended above:

$ buf mod update

The buf mod update command updates all of your deps to their latest version. The generated buf.lock should look similar to this (the commit may vary):

# Generated by buf. DO NOT EDIT.
version: v1
deps:
  - remote: buf.build
    owner: googleapis
    repository: googleapis
    commit: 62f35d8aed1149c291d606d958a7ce32

Now, if you try to build the module again, you'll notice that it's successful:

$ buf build
Output
buf: downloading buf.build/googleapis/googleapis:62f35d8aed1149c291d606d958a7ce32

This is the BSR's dependency management in action! A few things happened here, so let's break it down:

1. buf noticed that a new dependency was added to the deps key.
2. buf resolved the latest version of the buf.build/googleapis/googleapis module and wrote it to the module's buf.lock.
3. When another buf command is run, buf downloads the buf.build/googleapis/googleapis module to the local module cache.
4. Finally, now that buf has all the dependencies it needs, it can successfully build the module ( as google/type/datetime.proto is included).

In summary, buf can resolve the dependencies specified in your buf.yaml's deps key and include the imports required to build your module. You don't have to manually copy .proto files anymore!

4.3. Push Your Changes

Now that you've updated your module to depend on buf.build/googleapis/googleapis instead of vendoring the google/type/datetime.proto yourself, you can push the module to the BSR:

$ buf push
Output
b2917eb692064beb92ad1e38dba6c25e

Navigate back to your repository on the BSR and see your packages have changed, the Google package is no longer a first-class citizen of your module - it is now a third-party dependency.

If one or more dependencies are pinned to a draft commit, pushing the module will not be allowed.

4.4. Update buf.gen.yaml

Your gen/ directory should look like this

gen
├── google
│   └── type
│       └── datetime.pb.go
└── pet
    └── v1
        ├── pet.pb.go
        └── petv1connect
            └── pet.connect.go

Now that you have exchanged your local copy of the Google proto for one on the BSR, you can now remove the generated code, also.

$ cd ..
$ rm -r gen

Start by updating the buf.gen.yaml to exclude overriding any Go import statements related to googleapis.

 version: v1
 managed:
   enabled: true
   go_package_prefix:
     default: github.com/bufbuild/buf-tour/petstore/gen
 +    except:
 +      - buf.build/googleapis/googleapis
 plugins:
 -  - plugin: buf.build/protocolbuffers/go
 -    out: gen
 -    opt: paths=source_relative
   - plugin: buf.build/bufbuild/connect-go
     out: gen
     opt: paths=source_relative

$ buf generate proto

Now, your gen/ directory should look like this:

gen
└── pet
    └── v1
        ├── pet.pb.go
        └── petv1connect
            └── pet.connect.go

5. Implement the API

In this section, you'll implement a PetStoreService client, which you can run on the command line.

5.1. Fetch Remote Packages

The Buf Schema Registry provides remote packages for Golang: consume generated SDKs from modules and plugins using go get, just like any other Golang library. This means if you use the BSR, there's no need to manage generated code. You can view all of your modules Remote Package options in the assets tab of its repository.

let's fetch a few packages for the client we are building, in this example, we will get the Go base-types in protocolbuffers/go and Connect API stubs in bufbuild/connect-go.

$ go get buf.build/gen/go/<USERNAME>/petapis/protocolbuffers/go
$ go get buf.build/gen/go/<USERNAME>/petapis/bufbuild/connect-go

5.3. Implement the client

You can start implementing a client by creating a client/main.go file:

$ mkdir client
$ touch client/main.go

Copy and paste this content into that file:

package main

import (
  "context"
  "log"
  "net/http"

    // replace <USERNAME> with your BSR username
  "buf.build/gen/go/<USERNAME>/petapis/bufbuild/connect-go/pet/v1/petv1connect"
  petv1 "buf.build/gen/go/<USERNAME>/petapis/protocolbuffers/go/pet/v1"
  "github.com/bufbuild/connect-go"
)

func main() {
  client := petv1connect.NewPetStoreServiceClient(
    http.DefaultClient,
    "http://localhost:8080",
  )
  res, err := client.PutPet(
    context.Background(),
    connect.NewRequest(&petv1.PutPetRequest{
      PetType: petv1.PetType_PET_TYPE_SNAKE,
      Name:    "Ekans",
    }),
  )
  if err != nil {
    log.Println(err)
    return
  }
  log.Println(res.Msg)
}

5.4. Resolve Go dependencies

Now that you have code for both a client and a server, run this command to resolve some of the dependencies you need for the generated code:

$ go mod tidy

You should notice these changes (the version pins may differ):

module github.com/bufbuild/buf-tour/petstore

go 1.19

require (
  buf.build/gen/go/<USERNAME>/petapis/bufbuild/connect-go v1.5.1-20230203192357-a60a321c3624.1
  buf.build/gen/go/<USERNAME>/petapis/protocolbuffers/go v1.28.1-20230203192357-a60a321c3624.4
  github.com/bufbuild/connect-go v1.5.1
  golang.org/x/net v0.5.0
  google.golang.org/genproto v0.0.0-20230202175211-008b39050e57
  google.golang.org/protobuf v1.28.1
)

require golang.org/x/text v0.6.0 // indirect

5.5. Call PutPet

With the server/main.go and client/main.go implementations shown above, run the server and call the PutPet endpoint from the client.

First, run the server:

$ go run server/main.go
Output
... Listening on 127.0.0.1:8080

In a separate terminal, run the client and you should see a success message:

$ go run client/main.go
Output
... Connected to 127.0.0.1:8080
... Successfully PutPet

You'll also notice this in the server logs (in the other terminal running the server):

... Listening on 127.0.0.1:8080
... Got a request to create a PET_TYPE_SNAKE named Ekans

That's it! that's all you need to do to build a module, publish it to the world and build an API server and client using Buf. Try and imagine this at scale, the Buf Schema Registry is your central hub collaborate and share APIs, SDKs and documentation.

To find out more about how you can build better with Buf, check out some of our other guides just like this one:

• Getting Started with the Buf CLI