Docker-Compose logging to variable

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Question, Bug, or Feature?
Type: Feature/Question

Enter Task Name: Docker-Compose

list here (V# not needed): 0 https://github.com/Microsoft/azure-pipelines-tasks/tree/master/Tasks

Environment

• Server - Azure Pipelines or TFS on-premises? Azure Pipeline

  • If using Azure Pipelines, provide the account name, team project name, build definition name/build number: N/A

• Agent - Hosted or Private: Hosted agent

  • If using Hosted agent, provide agent queue name: N/A
  • If using private agent, provide the OS of the machine running the agent and the agent version: N/A

Issue Description

I’m trying to build a script that is able to cache images even on a Hosted Agent. Something similar to this: https://github.com/marketplace/actions/build-docker-images-using-cache and https://testdriven.io/blog/faster-ci-builds-with-docker-cache/

However for this to nicely integrate into Azure DevOps I would like to be able to read out the created identifiers per stage. This can be done quite easily by reading through the log file. E.g.:

In the image above I want to get the Id so that I can execute a docker tag afterwards and tag this specific image as something like devemazegenerator-stages:0

So my main question would be, if it’s possible to somehow storage all logging to a variable during a docker-compose build or docker build.

Regarding directly targeting a stage instead

So in regards to directly targeting a stage instead, like for example calling:

docker build . --stage build

I first thought about using this, but the issue here is that you’re basically doing a docker build twice. I would like to be able to kick-off docker-compose, have all variables / configuration setup there and then afterwards pick-up the stages that I want to push to the registry.

Next to that, it currently seems to be impossible to target an unnamed stage. See: https://forums.docker.com/t/docker-build-first-stage-in-multi-stage-pipeline/91167

Task logs

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Troubleshooting

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Error logs

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[devedse]

Another update, I just found out that apparently the lines Building .... are being written to STDERR. I’ve created a bug report for that:

https://github.com/docker/compose/issues/7346

[thesattiraju]

@ds-ms, how would you pipe the output to an environment variable that can be used in a follow up task? I’ve been reading through the documentation but what I’ve only found is this:

If you want to share the contents within a job, you could simply pipe the logs to a file. And use that file path in your scripts within the job.

I checked with @azooinmyluggage, I’ll take your PR forward; it seems like a good addition. 😃