Managed mode

Managed mode is a feature of buf generate that allows API consumers to control file and field options when generating code from Protobuf files, even without control of the API itself. It's easy to implement and provides a thoughtful set of defaults for these options, with enough granularity to manage them more directly as needed. It hides some of Protobuf's quirks and allows consumers to start generating code quickly.

It removes the need for API producers to make these decisions for consumers. Instead, producers can leave this information out and different types of consumers can rely on managed mode to generate code in the ways that they need to use it.

Enable managed mode

You can enable managed mode with two lines of code in your buf.gen.yaml file:

version: v2
managed:
  enabled: true

If your desired code generation behavior matches managed mode's default behavior, enabling it is all you need to do. When you generate code, these defaults are automatically applied as file options to your Protobuf files.

If you need different behavior, managed mode allows you to selectively override or disable the options necessary to generate the code as you require. The sections below have details about how to construct override and disable rules for each of the options, and this example illustrates a few key interactions:

version: v2
managed:
  enabled: true
  disable:
    # Don't modify any file option or field option for googleapis
    - module: buf.build/googleapis/googleapis
    # Don't modify csharp_namespace for any file
    - file_option: csharp_namespace
    # Don't modify java_package for files in weather/v1beta1/ in this module
    - module: buf.build/acme/weather
      path: weather/v1beta1/
      file_option: java_package
  override:
    # Use this prefix by default for all files
    - file_option: go_package_prefix
      value: company.com/foo/bar
    # Because the last matching rule wins, files in only this module have the prefix x/y/z
    - file_option: go_package_prefix
      module: buf.build/acme/weather
      value: x/y/z
    # For files in this path only, go_package is directly set to this value and the previous
    # go_package_prefix rule isn't applied
    - file_option: go_package
      path: special/path/
      value: special/value/package/v1
    # Same rules apply to field options as well
    # This sets JSType to JS_STRING for package.Message.field
    - field_option: jstype
      field: package.Message.field
      value: JS_STRING

Precedence rules

If a managed mode option has both override and disable specified, disable takes precedence and override settings won't be applied. For options that set package prefixes or suffixes, this means that disabling the base option (such as go_package) also disables any overrides that set a prefix or suffix.

Some of managed mode's options allow you to extend a file option by adding a prefix and/or suffix in addition to modifying it directly—for example, go_package and go_package_prefix. If a file matches multiple rules that modify the same option (go_package in this case), then the last one specified is applied. For example, if you set both Go options like this, only the go_package_prefix value is applied because they're both trying to modify go_package:

managed:
  enabled: true
  override:
    - file_option: go_package
      value: foo/bar
    - file_option: go_package_prefix
      value: data

There is one special case: when the last rules that modify java_package are java_package_prefix and java_package_suffix, java_package is modified to <prefix>.proto_package.<suffix>. In that case, any java_package rules defined before the prefix/suffix rules are ignored for files that match all three.

Override managed mode defaults

You may need to override an option to make your generated code conform to your company's source control directory structure or API endpoints. To override an option, you create a rule with its name and the new value in the override section of your buf.gen.yaml file. If no input is specified in the rule, the value is modified for all inputs, but each rule can specify inputs down to the field level of a single .proto file if you need to be that granular.

For example, managed mode's defaults set java_package to com.<proto_package>, which means that given this configuration and an input with this .proto file package value:

version: v2
managed:
  enabled: true
plugins:
  - remote: buf.build/protocolbuffers/java
    out: gen/proto

syntax = "proto3";

package acme.weather.v1;

it generates code from the buf.build/protocolbuffers/java plugin for the .proto file and puts it in the gen/proto/com/acme/weather/v1 directory of your workspace. Your generated Java code files have a package com.acme.weather.v1; declaration.

However, if you need the code to live in gen/proto/net/acme/weather/v1 with a package net.acme.weather.v1; declaration, you add an override rule for java_package_prefix :

version: v2
managed:
  enabled: true
  override:
    - file_option: java_package_prefix
      value: net
plugins:
  - remote: buf.build/protocolbuffers/java
    out: gen/proto

Overrides are applied in the order you specify in the buf.gen.yaml file, which allows you to start with more general rules and then be more specific for a subset of inputs. Using this flexibility, you can create very specific sets of outputs. For example, this series of rules creates different generated code directories for each input:

version: v2
managed:
  enabled: true
  override:
    # Modify the java_package value to '<net>.<proto_package>' for all files
    - file_option: java_package_prefix
      value: net
    # Modify the java_package value to '<com>.<proto_package>.<com>' for all files
    # in buf.build/acme/petapis. These rules take precedence over the rule above.
    # Note that both the prefix and suffix are applied because the rules specify
    # the same module.
    - file_option: java_package_prefix
      module: buf.build/acme/petapis
      value: com
    - file_option: java_package_suffix
      module: buf.build/acme/petapis
      value: com
    # For the file foo/bar/baz.proto, set java_package specifically to
    # 'com.x.y.z'. This takes precedence over the previous rules above.
    - file_option: java_package
      path: foo/bar/baz.proto
      value: com.x.y.z
plugins:
  - remote: buf.build/protocolbuffers/java
    out: gen/proto
inputs:
  - directory: proto
  - module: buf.build/acme/petapis

Assuming the workspace is structured as below and the package values in the .proto files match the directory structure:

workspace_root
├── buf.gen.yaml
├── buf.yaml
├── gen
│   └── proto
└── proto
    ├── acme
    │   └── weather
    │       └── v1
    │           └── weather.proto
    └── foo
        └── bar
            └── baz.proto

the directory structure of the generated code looks like this, and the package declarations in the generated Java files match the directory structure they're contained within:

workspace_root
├── buf.gen.yaml
├── buf.yaml
├── gen
│   └── proto
│       ├── com
│       │   └── pet
│       │       └── v1
│       │           └── com
│       │               # buf.build/acme/petapis Java files
│       │               # package com.pet.v1.com;
│       ├── x
│       │   └── y
│       │       └── z
│       │           # baz.proto Java files
│       │           # package com.x.y.z;
│       └── net
│           └── acme
│               └── weather
│                   └── v1
│                       # weather.proto Java files
│                       # package net.acme.weather.v1;
└── proto
    ├── acme
    │   └── weather
    │       └── v1
    │           └── weather.proto
    └── foo
       └── bar
           └── baz.proto

The examples above show how to override file options, and field options work similarly. The only Protobuf field option that managed mode supports is JSType.

version: v2
managed:
  enabled: true
  override:
    # For all fields in the buf.build/acme/paymentapis module where the field is
    # one of the compatible types, set 'jstype' to 'JS_NORMAL'.
    - field_option: jstype
      module: buf.build/acme/paymentapis
      value: JS_NORMAL
    # Set the package.Message.field field 'jstype' value to 'JS_STRING'.
    # You can additionally specify the module and path, but the field name
    # is sufficient.
    - field_option: jstype
      value: JS_STRING
      field: package.Message.field

Disable managed mode for specific inputs

In addition to overriding specific options, you can also disable managed mode entirely for any combination of inputs by input, file, and/or field. Commonly this is used to keep managed mode from overriding options for inputs like the buf.build/googleapis/googleapis module.

To disable a specific option for all inputs, list it under the disable key:

version: v2
managed:
  enabled: true
  disable:
    - file_option: csharp_namespace

To disable managed mode entirely for specific inputs, list the inputs under the disablekey:

version: v2
managed:
  enabled: true
  disable:
    # Don't modify any files in buf.build/googleapis/googleapis
    - module: buf.build/googleapis/googleapis
    # Don't modify any files in the foo/v1 directory within this workspace.
    # This can be a path to a directory or a .proto file. If it's a directory
    # path, all .proto files in the directory are ignored.
    - path: foo/v1

From there, you can set rules that are as specific as you need to target the combinations of options, inputs, and fields that you want:

version: v2
managed:
  enabled: true
  disable:
    # Don't modify the field options for the foo.bar.Baz.field_name field.
    - field: foo.bar.Baz.field_name

version: v2
managed:
  enabled: true
  disable:
    # Don't modify the java_package file option for files in foo/v1 in
    # buf.build/acme/weather
    - module: buf.build/acme/weather
      path: foo/v1
      file_option: java_package

version: v2
managed:
  enabled: true
  disable:
    # disable jstype for all files that match the module, path, and field name.
    - module: buf.build/acme/petapis
      field: foo.bar.Baz.field_name
      path: foo/v1
      field_option: jstype

Defaults and override behavior

Managed mode usually modifies several aspects of your generated code based on the package name in your .proto files. Specifically, it often changes the directory structure and package references in the generated files. The examples below show the output of the following workspace, .proto file, and managed mode options, with these assumptions:

• A plugin has been set for each language where managed mode is relevant: C++, C#, Go, Java, Objective-C, PHP, and Ruby
• The output directory (out) for each language is gen/proto/<language>
• Default behavior refers to the option's results when managed mode is enabled, but no other settings have been specified.

workspace_root
├── buf.gen.yaml
├── buf.yaml
├── gen
│   └── proto
│       ├── csharp
│       ├── go
│       ├── java
│       ├── objc
│       ├── php
│       └── ruby
└── proto
    └── acme
        └── weather
            └── v1
                └── weather.proto

syntax = "proto3";

package acme.weather.v1;

enum Condition {
  CONDITION_UNSPECIFIED = 0;
  CONDITION_SUNNY = 1;
  CONDITION_RAINY = 2;
}

message GetWeatherRequest {
  float latitude = 1;
  float longitude = 2;
}

message GetWeatherResponse {
  float temperature = 1;
  Condition conditions = 2;
}

service WeatherService {
  rpc GetWeather (GetWeatherRequest) returns (GetWeatherResponse);
}

C++

C++ only has one option that managed mode supports: cc_enable_arenas. This option is now enabled by default in Protobuf, and changing its value no longer has an effect. However, the descriptor byte array in the generated code will differ on this byte.

C#

C# has two options: csharp_namespace and csharp_namespace_prefix. It makes no changes to directory structure (files are output to the out path), and it sets the namespace as follows:

managed:
  enabled: true

namespace Acme.Weather.V1

managed:
  enabled: true
  override:
    - file_option: csharp_namespace
      value: weather.v1

namespace weather.v1

managed:
  enabled: true
  override:
    - file_option: csharp_namespace_prefix
      value: data

namespace data.Acme.Weather.V1

Go

Go has two options: go_package and go_package_prefix. It requires you to specify a Go import path using go_package, but managed mode doesn't set a default, so you must set a value for one of these options in the override section. If go_package_prefix is set, managed mode defaults to building out directories for each part of the package name. The examples below show the output of these two options, and assume that the Go plugin's opt value is the default of paths=import.

managed:
  enabled: true
  override:
    - file_option: go_package_prefix
      value: data

package weatherv1

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── go
            └── data
                └── acme
                    └── weather
                        └── v1
                            └── weather.pb.go

managed:
  enabled: true
  override:
    - file_option: go_package
      value: foo/bar

package bar

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── go
            └── foo
                └── bar
                    └── weather.pb.go

Java

Java has several options—managed mode sets the following default values:

Similar to Go, java_package can't be combined with java_package_prefix or java_package_suffix , and if it's specified with either of them, the last one wins. However, java_package_prefix and java_package_suffix can be combined with each other to output <prefix>.<proto_package>.<suffix>.

managed:
  enabled: true

package com.acme.weather.v1;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── java
            └── com
                └── acme
                    └── weather
                        └── v1
                            └── Condition.java
                            └── GetWeatherRequest.java
                            └── GetWeatherRequestOrBuilder.java
                            └── GetWeatherResponse.java
                            └── GetWeatherResponseOrBuilder.java
                            └── WeatherProto.java

managed:
  enabled: true
  override:
    - file_option: java_multiple_files
      value: false

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── java
            └── com
                └── acme
                    └── weather
                        └── v1
                            └── WeatherProto.java

managed:
  enabled: true
  override:
    - file_option: java_package_prefix
      value: net
    - file_option: java_package_suffix
      value: data

package net.acme.weather.v1.data;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── java
            └── net
                └── acme
                    └── weather
                        └── v1
                            └── data
                                └── Condition.java
                                └── GetWeatherRequest.java
                                └── GetWeatherRequestOrBuilder.java
                                └── GetWeatherResponse.java
                                └── GetWeatherResponseOrBuilder.java
                                └── WeatherProto.java

managed:
  enabled: true
  override:
    - file_option: java_outer_classname
      value: Allweather

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── java
            └── com
                └── acme
                    └── weather
                        └── v1
                            └── Allweather.java
                            └── Condition.java
                            └── GetWeatherRequest.java
                            └── GetWeatherRequestOrBuilder.java
                            └── GetWeatherResponse.java
                            └── GetWeatherResponseOrBuilder.java

Objective-C

Objective-C has one option: objc_class_prefix., which controls the prefix of all classes in the generated code. Managed mode sets its default value according to the following rules:

• Start with the first letter of each sub-package combined to one string, all upper case.
• If the result is shorter than 3 letters, append an X until it's three letters long. For example, acme.weather.v1 becomes AWX.
• If the result is GPB, change it to GPX.

managed:
  enabled: true

static GPBFileDescription AWXWeatherRoot_FileDescription = {
  .package = "acme.weather.v1",
  .prefix = "AWX",
  .syntax = GPBFileSyntaxProto3
};

managed:
  enabled: true
  override:
    - file_option: objc_class_prefix
      value: AWD

static GPBFileDescription AWDWeatherRoot_FileDescription = {
  .package = "acme.weather.v1",
  .prefix = "AWD",
  .syntax = GPBFileSyntaxProto3
};

PHP

PHP has three options: php_namespace, php_metadata_namespace , and php_metadata_namespace_suffix. Only one of these options should be set; if all are set, the last one specified wins. Managed mode sets their default values as follows:

• php_namespace: Package name connected by \ ,with each part in Pascal Case (if a part is a reserved keyword, appends _ at the end)
• php_metadata_namespace : <default_php_namespace>\GPBMetadata
• php_metadata_namespace_suffix : Has no default value, but if set, modifies php_metadata_namespace to <default_php_namespace>\<suffix>.

managed:
  enabled: true

namespace Acme\Weather\V1;

namespace Acme\Weather\V1\GPBMetadata;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── php
            └── Acme
                └── Weather
                    └── V1
                        └── Condition.php
                        └── GetWeatherRequest.php
                        └── GetWeatherResponse.php
                        └── GPBMetadata
                            └── Weather.php

managed:
  enabled: true
  override:
    - file_option: php_namespace
      value: weather.v1

namespace weather.v1;

namespace Acme\Weather\V1\GPBMetadata;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── php
            ├── Acme
            │   └── Weather
            │       └── V1
            │           └── GPBMetadata
            │               └── Weather.php
            └── weather.v1
                └── Condition.php
                └── GetWeatherRequest.php
                └── GetWeatherResponse.php

managed:
  enabled: true
  override:
    - file_option: php_metadata_namespace
      value: Metadata

namespace Acme\Weather\V1;

namespace Metadata;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── php
            ├── Acme
            │   └── Weather
            │       └── V1
            │           └── Condition.php
            │           └── GetWeatherRequest.php
            │           └── GetWeatherResponse.php
            └── Metadata
                └── Weather.php

managed:
  enabled: true
  override:
    - file_option: php_metadata_namespace_suffix
      value: Data

namespace Acme\Weather\V1;

namespace Acme\Weather\V1\Data;

workspace_root
├── buf.gen.yaml
├── buf.yaml
└── gen
    └── proto
        └── php
            └── Acme
                └── Weather
                    └── V1
                        ├── Condition.php
                        ├─── Data
                        │   └── Weather.php
                        ├── GetWeatherRequest.php
                        └── GetWeatherResponse.php

Ruby

Ruby has two options: ruby_package and ruby_package_suffix. Neither option changes the directory structure, but both change the nesting of the Ruby modules in the generated files.

managed:
  enabled: true

module Acme
  module Weather
    module V1
      …
    end
  end
end

managed:
  enabled: true
  override:
    - file_option: ruby_package
      value: Acme::Weather::FooBar::V1

module Acme
  module Weather
    module FooBar
      module V1
        …
      end
    end
  end
end

managed:
  enabled: true
  override:
    - file_option: ruby_package_suffix
      value: data

module Acme
  module Weather
    module V1
      module Data
        …
      end
    end
  end
end

Optimization and field options

These options aren't specific to the languages you generate and don't affect directory structure.

optimize_for

This option doesn't have a default value.

• If set, it expects a value from SPEED, CODE_SIZE and LITE_RUNTIME, and modifies its file option namesake to this value.
• Not all code generators use this option. For example, the generators for C# and Go don't, but Java's does.
• If a.proto imports b.proto, and b.proto sets LITE_RUNTIME, then a.proto must set LITE_RUNTIME or it won't compile.
• In Java, SPEED and LITE_RUNTIME have no difference but there is a difference between SPEED and CODE_SIZE.

jstype field option

This option doesn't have a default value. The accepted values are JS_NORMAL, JS_NUMBER and JS_STRING.

Related docs

• Try out code generation with the buf generate tutorial
• Browse the buf.gen.yaml reference
• Browse the buf generate command reference