syntax = "proto3";

// Package pb provides the protobuf definition of LLB: low-level builder instruction.
// LLB is DAG-structured; Op represents a vertex, and Definition represents a graph.
package pb;

import "github.com/gogo/protobuf/gogoproto/gogo.proto";

// Op represents a vertex of the LLB DAG.
message Op {
	// inputs is a set of input edges.
	repeated Input inputs = 1;
	oneof op {
		ExecOp exec = 2;
		SourceOp source = 3;
		CopyOp copy = 4;
		BuildOp build = 5;
	 }
}

// Input represents an input edge for an Op.
message Input {
	// digest of the marshaled input Op
	string digest = 1 [(gogoproto.customtype) = "github.com/opencontainers/go-digest.Digest", (gogoproto.nullable) = false];
	// output index of the input Op
	int64 index = 2 [(gogoproto.customtype) = "OutputIndex", (gogoproto.nullable) = false];
}

// ExecOp executes a command in a container.
message ExecOp {
	Meta meta = 1;
	repeated Mount mounts = 2;
}

// Meta is a set of arguments for ExecOp.
// Meta is unrelated to LLB metadata.
// FIXME: rename (ExecContext? ExecArgs?)
message Meta {
	repeated string args = 1;
	repeated string env = 2;
	string cwd = 3;
	string user = 4;
}

// Mount specifies how to mount an input Op as a filesystem.
message Mount {
	int64 input = 1 [(gogoproto.customtype) = "InputIndex", (gogoproto.nullable) = false];
	string selector = 2;
	string dest = 3;
	int64 output = 4 [(gogoproto.customtype) = "OutputIndex", (gogoproto.nullable) = false];
	bool readonly = 5;
	MountType mountType = 6;
	CacheOpt cacheOpt = 20;
}

enum MountType {
	BIND = 0;
	SECRET = 1;
	SSH = 2;
	CACHE = 3;
}

message CacheOpt {
	string ID = 1;
}

// CopyOp copies files across Ops.
message CopyOp {
	repeated CopySource src = 1;
	string dest = 2;
}

// CopySource specifies a source for CopyOp.
message CopySource {
	int64 input = 1 [(gogoproto.customtype) = "InputIndex", (gogoproto.nullable) = false];
	string selector = 2;
}

// SourceOp specifies a source such as build contexts and images.
message SourceOp {
	// TODO: use source type or any type instead of URL protocol.
	// identifier e.g. local://, docker-image://, git://, https://...
	string identifier = 1;
	// attrs are defined in attr.go
	map<string, string> attrs = 2;
}

// BuildOp is used for nested build invocation.
message BuildOp {
	int64 builder = 1 [(gogoproto.customtype) = "InputIndex", (gogoproto.nullable) = false];
	map<string, BuildInput> inputs = 2;
	Definition def = 3;
	map<string, string> attrs = 4;
	// outputs
}

// BuildInput is used for BuildOp.
message BuildInput {
	int64 input = 1 [(gogoproto.customtype) = "InputIndex", (gogoproto.nullable) = false];
}

// OpMetadata is a per-vertex metadata entry, which can be defined for arbitrary Op vertex and overridable on the run time.
message OpMetadata {
	// ignore_cache specifies to ignore the cache for this Op.
	bool ignore_cache = 1;
	// Description can be used for keeping any text fields that builder doesn't parse
	map<string, string> description = 2;  
	WorkerConstraint worker_constraint = 3;
	ExportCache export_cache = 4;
}

message ExportCache {
	bool Value = 1;
};

// WorkerConstraint is experimental and likely to be changed.
message WorkerConstraint {
	repeated string filter = 1; // containerd-style filter
}

// Definition is the LLB definition structure with per-vertex metadata entries
message Definition {
	// def is a list of marshaled Op messages
	repeated bytes def = 1;
	// metadata contains metadata for the each of the Op messages.
	// A key must be an LLB op digest string. Currently, empty string is not expected as a key, but it may change in the future.
	map<string, OpMetadata> metadata = 2 [(gogoproto.castkey) = "github.com/opencontainers/go-digest.Digest", (gogoproto.nullable) = false];
}