How to decode aux of moby.buildkit.trace ?

[punkpeye]

I am trying to get build logs

apocas/dockerode#782

I have trace events like:

event {
  id: 'moby.buildkit.trace',
  aux: 'CosBCkdzaGEyNTY6MTRjODM0ZGEwY2JmMzdiMTAzNDViNjU0OWZkZTYyM2U3YjQwOTdiNmI2ZDYxMjAwNTZiZWQwNmFlYjVhMTcxZRokW2ludGVybmFsXSBsb2FkIHJlbW90ZSBidWlsZCBjb250ZXh0KgwIxY+XuwYQkZGS+AIyDAjFj5e7BhCY05qSAw=='
}

How do I decode them?

I tried:

Buffer.from(event.aux, 'base64').toString();

But this gives me:

Gsha256:14c834da0cbf37b10345b6549fde623e7b4097b6b6d6120056bed06aeb5a171e$[internal] load remote build context*
                                                                                                             ŏ������2
                                                                                                                    ŏ���Ӛ�

and similar gibberish

[cowwoc]

Bump!

[punkpeye]

@cowwoc did you figure out?

[cowwoc]

@punkpeye Yes, I did.

• I download a bunch of protobuf files here: https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/pom.xml#L398
• I modify one of the proto files here: https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/pom.xml#L716
• I convert proto files to Java files here: https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/pom.xml#L738
• I compile the Java files here: https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/pom.xml#L755
• When I receive an "aux" in the HTTP response, I parse it using StatusResponse.parseFrom(aux): https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/src/main/java/com/github/cowwoc/docker/internal/util/ImageBuildListener.java#L52
• Then I log the contents of the StatusResponse here: https://github.com/cowwoc/docker/blob/5d03012fac1d971d55385c9c62504ca4a2c1a441/src/main/java/com/github/cowwoc/docker/internal/util/ImageBuildListener.java#L83

Note, all of this logic is based on trial-and-error. I know for a fact that I don't handle all of the possible cases that may be returned by the server. I plan to add them as I run across concrete cases because I want to compare the output I see in Docker Desktop with the output that my library returns.

I hope this helps!

[punkpeye]

Thank you for sharing!

Spent 5 hours trying to make it work. Then did the same thing just by calling shell commands in 5 minutes.

I was able to get partial response decoded, buy never got fully decoded message.