buildbucket/proto/config/project_config.proto - infra/luci/luci-go - Git at Google

 // Copyright 2018 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 // Schemas for project configs.

 syntax = "proto3";

 package buildbucket;

 option go_package = "go.chromium.org/luci/buildbucket/proto/config;configpb";

 import "google/protobuf/wrappers.proto";

 // A single access control rule.
 message Acl {

   // A buiildbucket user role.
   // Defines what a user can do.
   //
   // The order of enum member tags is important.
   // A role with a higher tag number can perform any action that a role with a
   // lower tag number can perform.
   enum Role {
     // Can do read-only operations, such as search for builds.
     READER = 0;
     // Same as READER + can schedule and cancel builds.
     SCHEDULER = 1;
     // Can do all write operations.
     WRITER = 2;
   }
   // Role denotes a list of actions that an identity can perform.
   Role role = 1;
   // Name of the group defined in the auth service.
   string group = 2;
   // An email address or a full identity string "kind:name". See auth service
   // on kinds of identities. Anonymous users are "anonymous:anonymous".
   // Either identity or group must be present, not both.
   string identity = 3;
 }

 // A set of Acl messages. Can be referenced in a bucket by name.
 message AclSet {
   // A name of the ACL set. Required. Must match regex '^[a-z0-9_]+$'.
   string name = 1;
   // List of access control rules.
   // The order does not matter.
   repeated Acl acls = 2;
 }


 // Defines a swarmbucket builder or a builder mixin. A builder has a name, a
 // category and specifies what should happen if a build is scheduled to that
 // builder.
 //
 // SECURITY WARNING: if adding more fields to this message, keep in mind that
 // a user that has permissions to schedule a build to the bucket, can override
 // this config.
 //
 // Next tag: 21.
 message Builder {
   reserved 8;  // cipd_packages
   reserved 11; // build_numbers of the old format.
   reserved 13; // auto_builder_dimension of the old format.
   reserved 15; // experimental of the old format.


   // Describes a cache directory persisted on a bot.
   //
   // If a build requested a cache, a cache directory is available on build
   // startup. If the cache was present on the bot, the directory contains files
   // from the previous run.
   // The build can read/write to the cache directory while it runs.
   // After build completes, the cache directory is persisted.
   // Next time another build requests the same cache and runs on the same bot,
   // if the cache wasn't evicted, the files will still be there.
   //
   // One bot can keep multiple caches at the same time and one build can request
   // multiple different caches.
   // A cache is identified by its name and mapped to a path.
   // In recipes-based builds, the path is relative to api.paths['cache'] dir.
   // For example, a cache {"name": "foo", "path": "bar"} maps foo to bar and
   // the cache dir is available at
   //   my_cache = api.path['cache'].join('bar')
   //
   // If the bot is running out of space, caches are evicted in LRU manner.
   //
   // Renaming a cache is equivalent to clearing it from the builder perspective.
   // The files will still be there, but eventually will be purged by GC.
   //
   // Builder cache.
   //
   // Buildbucket implicitly declares cache
   //   {"name": "<hash(bucket/builder)>", "path": "builder"}.
   // This means that any LUCI builder has a "personal disk space" on the bot.
   // Builder cache is often a good start before customizing caching.
   // In recipes, it is available at api.path['cache'].join('builder').
   //
   // In order to share the builder cache among multiple builders, it can be
   // overridden:
   //
   //   builders {
   //     name: "a"
   //     caches {
   //       path: "builder"
   //       name: "my_shared_cache"
   //     }
   //   }
   //   builders {
   //     name: "b"
   //     caches {
   //       path: "builder"
   //       name: "my_shared_cache"
   //     }
   //   }
   //
   // Builders "a" and "b" share their builder cache. If an "a" build ran on a bot
   // and left some files in the builder cache and then a "b" build runs on the
   // same bot, the same files will be available in the builder cache.
   message CacheEntry {
     // Identifier of the cache. Required. Length is limited to 128.
     //
     // If the pool of swarming bots is shared among multiple LUCI projects and
     // projects use same cache name, the cache will be shared across projects.
     // To avoid affecting and being affected by other projects, prefix the cache
     // name with something project-specific, e.g. "v8-".
     string name = 1;
     // Relative path where the cache in mapped into. Required.
     // Must use POSIX format (forward slashes).
     // In most cases, it does not need slashes at all.
     // Must be unique in the given builder.
     string path = 2;
     // Number of seconds to wait for a bot with a warm cache to pick up the
     // task, before falling back to a bot with a cold (non-existent) cache.
     //
     // The default is 0, which means that no preference will be chosen for a bot
     // with this or without this cache, and a bot without this cache may be
     // chosen instead.
     //
     // If no bot has this cache warm, the task will skip this wait and will
     // immediately fallback to a cold cache request.
     //
     // The value must be multiples of 60 seconds.
     int32 wait_for_warm_cache_secs = 3;
   }

   // Specifies a recipe to run.
   message Recipe {
     // Repository URL of the recipe package.
     // Value "-" is treated as unset.
   string repository = 1;
     // Name of the recipe to run.
     string name = 2;

     // If set, will use CIPD to fetch the recipes, rather than using git. This
     // obsoletes the `repository` parameter.
     //
     // Typically the package will look like:
     //
     //   infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build
     //
     // Recipes bundled from internal repositories are typically under
     // `infra_internal/recipe_bundles/...`.
     //
     // But if you're building your own recipe bundles, they could be located
     // elsewhere.
     string cipd_package = 6;

     // The CIPD version to fetch. This can be a lower-cased git ref (like
     // `refs/heads/master` or `head`), or it can be a cipd tag (like
     // `git_revision:dead...beef`).
     //
     // The default is `head`, which corresponds to the git repo's HEAD ref. This
     // is typically (but not always) a symbolic ref for `refs/heads/master`.
     string cipd_version = 5;

     // Colon-separated build properties to set.
     // A property can be overriden by "properties" build parameter.
     //
     // Use this field for string properties and use properties_j for other
     // types.
     repeated string properties = 3;
     // Same as properties, but the value must valid JSON. For example
     //   properties_j: "a:1"
     // means property a is a number 1, not string "1".
     //
     // If null, it means no property must be defined. In particular, it removes
     // a default value for the property, if any.
     //
     // Fields properties and properties_j can be used together, but cannot both
     // specify values for same property.
     repeated string properties_j = 4;
   }

   // Name of the builder or builder mixin.
   //
   // If a builder name, will be propagated to "builder" build tag and
   // "buildername" recipe property.
   string name = 1;
   // Names of mixins to apply to this builder definition.
   //
   // FLATTENING
   //
   // Final builder/mixin values are computed as follows:
   // - start with an empty builder definition.
   // - if this is a builder, apply values in a bucket's builder_defaults,
   //   flattened in advance.
   // - apply each mixin, flattened in advance, in the same order.
   // - apply values in this builder/mixin.
   //
   // EXAMPLE
   //
   //   A definition
   //
   //     builder_mixins {
   //       name: "foo"
   //       dimensions: "os:Linux"
   //       dimensions: "cpu:x86"
   //       recipe {
   //         repository: "https://example.com"
   //         name: "x"
   //       }
   //     }
   //     builder_mixins {
   //       name: "bar"
   //       dimensions: "cores:8"
   //       dimensions: "cpu:x86-64"
   //     }
   //     bucket {
   //       name: "luci.x.try"
   //       swarming {
   //         builders {
   //           name: "release"
   //           mixins: "foo"
   //           mixins: "bar"
   //           recipe {
   //             name: "y"
   //           }
   //         }
   //       }
   //     }
   //
   //   is equivalent to
   //
   //     bucket {
   //      name: "luci.x.try"
   //      swarming {
   //         builders {
   //           name: "release"
   //           dimensions: "os:Linux"
   //           dimensions: "cpu:x86-64"
   //           dimensions: "cores:8"
   //           recipe {
   //             repository: "https://example.com"
   //             name: "y"
   //           }
   //         }
   //       }
   //     }
   //
   // A NOTE ON DIAMOND MERGES
   //
   // Given
   //   B mixes in A and overrides some values defined in A
   //   C mixes in A
   //   D mixes in B and C
   // B's overrides won't affect D because D mixes in C after B.
   //
   //   builder_mixins {
   //     name: "A"
   //     dimensions: "dim:a"
   //   }
   //   builder_mixins {
   //     name: "B"
   //     mixins: "A"
   //     dimensions: "dim:b"
   //   }
   //   builder_mixins {
   //     name: "C"
   //     mixins: "A"
   //   }
   //   ...
   //   builders {
   //     name: "D"
   //     mixins: "B"
   //     mixins: "C"
   //   }
   //
   // D's dim will be "a", not "b" because it is "a" in C which is applied after
   // B.
   //
   // OTHER
   //
   // Circular references are prohibited.
   repeated string mixins = 10;
   // Builder category. Will be used for visual grouping, for example in Code Review.
   string category = 6;
   // Will be become to swarming task tags.
   // Each tag will end up in "swarming_tag" buildbucket tag, for example
   // "swarming_tag:builder:release"
   repeated string swarming_tags = 2;
   // Colon-delimited key-value pair of task dimensions.
   //
   // If value is not specified ("<key>:"), then it excludes a default value.
   //
   // If this builder is defined in a bucket, dimension "pool" is defaulted
   // to the name of the bucket. See Bucket message below.
   repeated string dimensions = 3;
   // Specifies that a recipe to run.
   Recipe recipe = 4;
   // Swarming task priority.
   uint32 priority = 5;
   // Maximum build execution time. Not to be confused with pending time.
   uint32 execution_timeout_secs = 7;
   // Maximum build pending time.
   uint32 expiration_secs = 20;
   // Caches that should be present on the bot.
   repeated CacheEntry caches = 9;
   // If YES, generate monotonically increasing contiguous numbers for each
   // build, unique within the builder.
   // Note: this limits the build creation rate in this builder to 5 per second.
   Toggle build_numbers = 16;
   // Email of a service account to run the build as or literal 'bot' string to
   // use Swarming bot's account (if available). Passed directly to Swarming.
   // Subject to Swarming's ACLs.
   string service_account = 12;
   // If YES, each builder will get extra dimension "builder:<builder name>"
   // added. Default is UNSET.
   //
   // For example, this config
   //
   //   builder {
   //     name: "linux-compiler"
   //     dimension: "builder:linux-compiler"
   //   }
   //
   // is equivalent to this:
   //
   //   builders {
   //     name: "linux-compiler"
   //     auto_builder_dimension: YES
   //   }
   //
   // We've considered providing interpolation like this
   //   builder_defaults {
   //     dimensions: "builder:${BUILDER}"
   //   }
   // (see also http://docs.buildbot.net/0.8.9/manual/cfg-properties.html#interpolate)
   // but are currently against complicating config with this.
   Toggle auto_builder_dimension = 17;
   // If YES, by default a new build in this builder will be marked as
   // experimental.
   // This is useful for inherently experimental builders that use production
   // recipes.
   // See also luci_migration_host field.
   Toggle experimental = 18;
   // If not empty and not "-", and a build request is not marked as
   // experimental/prod explicitly and has "mastername" property, buildbucket
   // will contact this instance of luci-migration app to determine whether the
   // builder is experimental.
   // On success, this takes precedence over Builder.experimental proto field
   // (above).
   //
   // Special value "-" means no luci_migration_host specified.
   // Useful in a builder that wants to override luci_migration_host
   // specified in builder_defaults or mixin.
   string luci_migration_host = 19;
 }

 // Configuration of buildbucket-swarming integration for one bucket.
 message Swarming {
   // Hostname of the swarming instance, e.g. "chromium-swarm.appspot.com".
   string hostname = 1;
   // DEPRECATED, IGNORED.
   // Used to generate a URL for Build, may contain parameters
   // {swarming_hostname}, {task_id}, {bucket} and {builder}. Defaults to:
   // https://{swarming_hostname}/user/task/{task_id}
   string url_format = 2;

   // Defines default values for builders.
   Builder builder_defaults = 3;

   // Configuration for each builder.
   // Swarming tasks are created only for builds for builders that are not
   // explicitly specified.
   repeated Builder builders = 4;

   // Percentage of builds that should use a canary swarming task template.
   // A value from 0 to 100.
   // If omitted, default percentage is used.
   google.protobuf.UInt32Value task_template_canary_percentage = 5;
 }

 // Defines one bucket in buildbucket.cfg
 message Bucket {
   // Name of the bucket. Names are unique within one instance of buildbucket.
   // If another project already uses this name, a config will be rejected.
   // Name reservation is first-come first-serve.
   string name = 1;
   // List of access control rules for the bucket.
   // The order does not matter.
   repeated Acl acls = 2;
   // A list of ACL set names. Each ACL in each referenced ACL set will be
   // included in this bucket.
   // The order does not matter.
   repeated string acl_sets = 4;
   // Buildbucket-swarming integration.
   Swarming swarming = 3;
 }

 // Schema of buildbucket.cfg file, a project config.
 message BuildbucketCfg {
   // All buckets defined for this project.
   repeated Bucket buckets = 1;
   // A list of ACL sets. Names must be unique.
   repeated AclSet acl_sets = 2;
   // A list of builder mixin definitions.
   // A mixin can be referenced in any builder defined within the BuildbucketCfg.
   // See also Buider.mixins field.
   repeated Builder builder_mixins = 3;
 }

 // Toggle is a boolean with an extra state UNSET.
 // When protobuf messages are merged, UNSET does not overwrite an existing
 // value.
 // TODO(nodir): replace with Trinary in ../common.proto.
 enum Toggle {
   UNSET = 0;
   YES = 1;
   NO = 2;
 }
	// Copyright 2018 The LUCI Authors.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	// Schemas for project configs.

	syntax = "proto3";

	package buildbucket;

	option go_package = "go.chromium.org/luci/buildbucket/proto/config;configpb";

	import "google/protobuf/wrappers.proto";

	// A single access control rule.
	message Acl {

	// A buiildbucket user role.
	// Defines what a user can do.
	//
	// The order of enum member tags is important.
	// A role with a higher tag number can perform any action that a role with a
	// lower tag number can perform.
	enum Role {
	// Can do read-only operations, such as search for builds.
	READER = 0;
	// Same as READER + can schedule and cancel builds.
	SCHEDULER = 1;
	// Can do all write operations.
	WRITER = 2;
	}
	// Role denotes a list of actions that an identity can perform.
	Role role = 1;
	// Name of the group defined in the auth service.
	string group = 2;
	// An email address or a full identity string "kind:name". See auth service
	// on kinds of identities. Anonymous users are "anonymous:anonymous".
	// Either identity or group must be present, not both.
	string identity = 3;
	}

	// A set of Acl messages. Can be referenced in a bucket by name.
	message AclSet {
	// A name of the ACL set. Required. Must match regex '^[a-z0-9_]+$'.
	string name = 1;
	// List of access control rules.
	// The order does not matter.
	repeated Acl acls = 2;
	}


	// Defines a swarmbucket builder or a builder mixin. A builder has a name, a
	// category and specifies what should happen if a build is scheduled to that
	// builder.
	//
	// SECURITY WARNING: if adding more fields to this message, keep in mind that
	// a user that has permissions to schedule a build to the bucket, can override
	// this config.
	//
	// Next tag: 21.
	message Builder {
	reserved 8; // cipd_packages
	reserved 11; // build_numbers of the old format.
	reserved 13; // auto_builder_dimension of the old format.
	reserved 15; // experimental of the old format.


	// Describes a cache directory persisted on a bot.
	//
	// If a build requested a cache, a cache directory is available on build
	// startup. If the cache was present on the bot, the directory contains files
	// from the previous run.
	// The build can read/write to the cache directory while it runs.
	// After build completes, the cache directory is persisted.
	// Next time another build requests the same cache and runs on the same bot,
	// if the cache wasn't evicted, the files will still be there.
	//
	// One bot can keep multiple caches at the same time and one build can request
	// multiple different caches.
	// A cache is identified by its name and mapped to a path.
	// In recipes-based builds, the path is relative to api.paths['cache'] dir.
	// For example, a cache {"name": "foo", "path": "bar"} maps foo to bar and
	// the cache dir is available at
	// my_cache = api.path['cache'].join('bar')
	//
	// If the bot is running out of space, caches are evicted in LRU manner.
	//
	// Renaming a cache is equivalent to clearing it from the builder perspective.
	// The files will still be there, but eventually will be purged by GC.
	//
	// Builder cache.
	//
	// Buildbucket implicitly declares cache
	// {"name": "<hash(bucket/builder)>", "path": "builder"}.
	// This means that any LUCI builder has a "personal disk space" on the bot.
	// Builder cache is often a good start before customizing caching.
	// In recipes, it is available at api.path['cache'].join('builder').
	//
	// In order to share the builder cache among multiple builders, it can be
	// overridden:
	//
	// builders {
	// name: "a"
	// caches {
	// path: "builder"
	// name: "my_shared_cache"
	// }
	// }
	// builders {
	// name: "b"
	// caches {
	// path: "builder"
	// name: "my_shared_cache"
	// }
	// }
	//
	// Builders "a" and "b" share their builder cache. If an "a" build ran on a bot
	// and left some files in the builder cache and then a "b" build runs on the
	// same bot, the same files will be available in the builder cache.
	message CacheEntry {
	// Identifier of the cache. Required. Length is limited to 128.
	//
	// If the pool of swarming bots is shared among multiple LUCI projects and
	// projects use same cache name, the cache will be shared across projects.
	// To avoid affecting and being affected by other projects, prefix the cache
	// name with something project-specific, e.g. "v8-".
	string name = 1;
	// Relative path where the cache in mapped into. Required.
	// Must use POSIX format (forward slashes).
	// In most cases, it does not need slashes at all.
	// Must be unique in the given builder.
	string path = 2;
	// Number of seconds to wait for a bot with a warm cache to pick up the
	// task, before falling back to a bot with a cold (non-existent) cache.
	//
	// The default is 0, which means that no preference will be chosen for a bot
	// with this or without this cache, and a bot without this cache may be
	// chosen instead.
	//
	// If no bot has this cache warm, the task will skip this wait and will
	// immediately fallback to a cold cache request.
	//
	// The value must be multiples of 60 seconds.
	int32 wait_for_warm_cache_secs = 3;
	}

	// Specifies a recipe to run.
	message Recipe {
	// Repository URL of the recipe package.
	// Value "-" is treated as unset.
	string repository = 1;
	// Name of the recipe to run.
	string name = 2;

	// If set, will use CIPD to fetch the recipes, rather than using git. This
	// obsoletes the `repository` parameter.
	//
	// Typically the package will look like:
	//
	// infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build
	//
	// Recipes bundled from internal repositories are typically under
	// `infra_internal/recipe_bundles/...`.
	//
	// But if you're building your own recipe bundles, they could be located
	// elsewhere.
	string cipd_package = 6;

	// The CIPD version to fetch. This can be a lower-cased git ref (like
	// `refs/heads/master` or `head`), or it can be a cipd tag (like
	// `git_revision:dead...beef`).
	//
	// The default is `head`, which corresponds to the git repo's HEAD ref. This
	// is typically (but not always) a symbolic ref for `refs/heads/master`.
	string cipd_version = 5;

	// Colon-separated build properties to set.
	// A property can be overriden by "properties" build parameter.
	//
	// Use this field for string properties and use properties_j for other
	// types.
	repeated string properties = 3;
	// Same as properties, but the value must valid JSON. For example
	// properties_j: "a:1"
	// means property a is a number 1, not string "1".
	//
	// If null, it means no property must be defined. In particular, it removes
	// a default value for the property, if any.
	//
	// Fields properties and properties_j can be used together, but cannot both
	// specify values for same property.
	repeated string properties_j = 4;
	}

	// Name of the builder or builder mixin.
	//
	// If a builder name, will be propagated to "builder" build tag and
	// "buildername" recipe property.
	string name = 1;
	// Names of mixins to apply to this builder definition.
	//
	// FLATTENING
	//
	// Final builder/mixin values are computed as follows:
	// - start with an empty builder definition.
	// - if this is a builder, apply values in a bucket's builder_defaults,
	// flattened in advance.
	// - apply each mixin, flattened in advance, in the same order.
	// - apply values in this builder/mixin.
	//
	// EXAMPLE
	//
	// A definition
	//
	// builder_mixins {
	// name: "foo"
	// dimensions: "os:Linux"
	// dimensions: "cpu:x86"
	// recipe {
	// repository: "https://example.com"
	// name: "x"
	// }
	// }
	// builder_mixins {
	// name: "bar"
	// dimensions: "cores:8"
	// dimensions: "cpu:x86-64"
	// }
	// bucket {
	// name: "luci.x.try"
	// swarming {
	// builders {
	// name: "release"
	// mixins: "foo"
	// mixins: "bar"
	// recipe {
	// name: "y"
	// }
	// }
	// }
	// }
	//
	// is equivalent to
	//
	// bucket {
	// name: "luci.x.try"
	// swarming {
	// builders {
	// name: "release"
	// dimensions: "os:Linux"
	// dimensions: "cpu:x86-64"
	// dimensions: "cores:8"
	// recipe {
	// repository: "https://example.com"
	// name: "y"
	// }
	// }
	// }
	// }
	//
	// A NOTE ON DIAMOND MERGES
	//
	// Given
	// B mixes in A and overrides some values defined in A
	// C mixes in A
	// D mixes in B and C
	// B's overrides won't affect D because D mixes in C after B.
	//
	// builder_mixins {
	// name: "A"
	// dimensions: "dim:a"
	// }
	// builder_mixins {
	// name: "B"
	// mixins: "A"
	// dimensions: "dim:b"
	// }
	// builder_mixins {
	// name: "C"
	// mixins: "A"
	// }
	// ...
	// builders {
	// name: "D"
	// mixins: "B"
	// mixins: "C"
	// }
	//
	// D's dim will be "a", not "b" because it is "a" in C which is applied after
	// B.
	//
	// OTHER
	//
	// Circular references are prohibited.
	repeated string mixins = 10;
	// Builder category. Will be used for visual grouping, for example in Code Review.
	string category = 6;
	// Will be become to swarming task tags.
	// Each tag will end up in "swarming_tag" buildbucket tag, for example
	// "swarming_tag:builder:release"
	repeated string swarming_tags = 2;
	// Colon-delimited key-value pair of task dimensions.
	//
	// If value is not specified ("<key>:"), then it excludes a default value.
	//
	// If this builder is defined in a bucket, dimension "pool" is defaulted
	// to the name of the bucket. See Bucket message below.
	repeated string dimensions = 3;
	// Specifies that a recipe to run.
	Recipe recipe = 4;
	// Swarming task priority.
	uint32 priority = 5;
	// Maximum build execution time. Not to be confused with pending time.
	uint32 execution_timeout_secs = 7;
	// Maximum build pending time.
	uint32 expiration_secs = 20;
	// Caches that should be present on the bot.
	repeated CacheEntry caches = 9;
	// If YES, generate monotonically increasing contiguous numbers for each
	// build, unique within the builder.
	// Note: this limits the build creation rate in this builder to 5 per second.
	Toggle build_numbers = 16;
	// Email of a service account to run the build as or literal 'bot' string to
	// use Swarming bot's account (if available). Passed directly to Swarming.
	// Subject to Swarming's ACLs.
	string service_account = 12;
	// If YES, each builder will get extra dimension "builder:<builder name>"
	// added. Default is UNSET.
	//
	// For example, this config
	//
	// builder {
	// name: "linux-compiler"
	// dimension: "builder:linux-compiler"
	// }
	//
	// is equivalent to this:
	//
	// builders {
	// name: "linux-compiler"
	// auto_builder_dimension: YES
	// }
	//
	// We've considered providing interpolation like this
	// builder_defaults {
	// dimensions: "builder:${BUILDER}"
	// }
	// (see also http://docs.buildbot.net/0.8.9/manual/cfg-properties.html#interpolate)
	// but are currently against complicating config with this.
	Toggle auto_builder_dimension = 17;
	// If YES, by default a new build in this builder will be marked as
	// experimental.
	// This is useful for inherently experimental builders that use production
	// recipes.
	// See also luci_migration_host field.
	Toggle experimental = 18;
	// If not empty and not "-", and a build request is not marked as
	// experimental/prod explicitly and has "mastername" property, buildbucket
	// will contact this instance of luci-migration app to determine whether the
	// builder is experimental.
	// On success, this takes precedence over Builder.experimental proto field
	// (above).
	//
	// Special value "-" means no luci_migration_host specified.
	// Useful in a builder that wants to override luci_migration_host
	// specified in builder_defaults or mixin.
	string luci_migration_host = 19;
	}

	// Configuration of buildbucket-swarming integration for one bucket.
	message Swarming {
	// Hostname of the swarming instance, e.g. "chromium-swarm.appspot.com".
	string hostname = 1;
	// DEPRECATED, IGNORED.
	// Used to generate a URL for Build, may contain parameters
	// {swarming_hostname}, {task_id}, {bucket} and {builder}. Defaults to:
	// https://{swarming_hostname}/user/task/{task_id}
	string url_format = 2;

	// Defines default values for builders.
	Builder builder_defaults = 3;

	// Configuration for each builder.
	// Swarming tasks are created only for builds for builders that are not
	// explicitly specified.
	repeated Builder builders = 4;

	// Percentage of builds that should use a canary swarming task template.
	// A value from 0 to 100.
	// If omitted, default percentage is used.
	google.protobuf.UInt32Value task_template_canary_percentage = 5;
	}

	// Defines one bucket in buildbucket.cfg
	message Bucket {
	// Name of the bucket. Names are unique within one instance of buildbucket.
	// If another project already uses this name, a config will be rejected.
	// Name reservation is first-come first-serve.
	string name = 1;
	// List of access control rules for the bucket.
	// The order does not matter.
	repeated Acl acls = 2;
	// A list of ACL set names. Each ACL in each referenced ACL set will be
	// included in this bucket.
	// The order does not matter.
	repeated string acl_sets = 4;
	// Buildbucket-swarming integration.
	Swarming swarming = 3;
	}

	// Schema of buildbucket.cfg file, a project config.
	message BuildbucketCfg {
	// All buckets defined for this project.
	repeated Bucket buckets = 1;
	// A list of ACL sets. Names must be unique.
	repeated AclSet acl_sets = 2;
	// A list of builder mixin definitions.
	// A mixin can be referenced in any builder defined within the BuildbucketCfg.
	// See also Buider.mixins field.
	repeated Builder builder_mixins = 3;
	}

	// Toggle is a boolean with an extra state UNSET.
	// When protobuf messages are merged, UNSET does not overwrite an existing
	// value.
	// TODO(nodir): replace with Trinary in ../common.proto.
	enum Toggle {
	UNSET = 0;
	YES = 1;
	NO = 2;
	}