buildctl: add dump

[AkihiroSuda]

The last PR today 😄

Example output:

$ go run examples/llboput/example.go > a.llb
$ buildctl dump < a.llb
2017/06/12 09:51:52 ([]main.llbOp) (len=4 cap=4) {
 (main.llbOp) {
  Op: (pb.Op) &Op{Inputs:[],Op:&Op_Source{Source:&SourceOp{Identifier:docker-image://docker.io/library/busybox:latest,},},},
  Digest: (digest.Digest) (len=71) sha256:74ecb5d790c33a213ba00f8f43d62947df1d4dea72f5ec13353a9b943f469f0f
 },
 (main.llbOp) {
  Op: (pb.Op) &Op{Inputs:[&Input{Digest:sha256:74ecb5d790c33a213ba00f8f43d62947df1d4dea72f5ec13353a9b943f469f0f,Index:0,}],Op:&Op_Exec{Exec:&ExecOp{Meta:&Meta{Args:[/bin/sleep 1],Env:[],Cwd:/,},Mounts:[&Mount{Input:0,Selector:,Dest:/,Output:0,}],},},},
  Digest: (digest.Digest) (len=71) sha256:1de5701b93648843bf2cf6ebf982b4f63ea55dcb9259e73a5bd6737505660d06
 },
 (main.llbOp) {
  Op: (pb.Op) &Op{Inputs:[&Input{Digest:sha256:1de5701b93648843bf2cf6ebf982b4f63ea55dcb9259e73a5bd6737505660d06,Index:0,}],Op:&Op_Exec{Exec:&ExecOp{Meta:&Meta{Args:[/bin/sh -c echo foo > /bar],Env:[],Cwd:/,},Mounts:[&Mount{Input:0,Selector:,Dest:/,Output:0,}],},},},
  Digest: (digest.Digest) (len=71) sha256:dcfef0f97703c4df76cba8f40891d2a851ae78d3bedce839e43e2e505e691341
 },
 (main.llbOp) {
  Op: (pb.Op) &Op{Inputs:[&Input{Digest:sha256:dcfef0f97703c4df76cba8f40891d2a851ae78d3bedce839e43e2e505e691341,Index:0,}],Op:&Op_Exec{Exec:&ExecOp{Meta:&Meta{Args:[/bin/ls -l /],Env:[],Cwd:/,},Mounts:[&Mount{Input:0,Selector:,Dest:/,Output:0,}],},},},
  Digest: (digest.Digest) (len=71) sha256:cec673a11a7de1687f9626850bfbd802ee8fe964e9b07f2ebbb365ae650fab09
 }
}

I'm also planning graphviz output (buildctl dump --mode dot) in another PR.

Signed-off-by: Akihiro Suda [email protected]

[tonistiigi]

Thanks. As a follow up can you group this behind a debug command? I'm not sure if we want the end user to ever realize that this format exists.

[tonistiigi]

The actual visualization of graph could be something like ./buildctl build --dry-run --graph=dot , so it would be returned from the daemon with the information about the cache hits etc. and would also work with Dockerfiles and other frontends.