display logs for multiple containers at the same time

[baude]

add the ability for users to specify more than one container at a time
while using podman logs. If more than one container is being displayed,
podman will also prepend a shortened container id of the container on
the log line.

also, enabled the podman-remote logs command during the refactoring of
the above ability.

fixes issue #2219

Signed-off-by: baude bbaude@redhat.com

[openshift-ci-robot]

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[baude]

@TomasTomecek ptal

[mheon]

To preserve conversation from IRC, this isn't completely parsing the Kube log format, so it can't interpret P vs F lines and prints extra newlines. Also prints a few timestamp for each character when --follow and --timestamps are specified together.

Handling of control characters also seems wonky.

[TomasTomecek]

@baude oh my, thank you so much for working on this! Can't comment on the code, but this seems to be exactly what I was asking for. One question: will --follow arg still work?

[mheon]

Another thing I noticed here - when following a single container, podman logs will exit immediately when the container exits currently, while this will hang forever waiting for new logs.

[baude]

@baude oh my, thank you so much for working on this! Can't comment on the code, but this seems to be exactly what I was asking for. One question: will --follow arg still work?

yup!

[rhatdan]

I like the idea that it hangs forever, that way if I start the container, the output will start up again.

[mheon]

@baude We can probably remove pkg/logs as part of this - that code shouldn't be used elsewhere

[baude]

bot, retest this please

[mheon]

One more thing I noticed: in the old implementation, logs --follow first printed all the logs already there, then began following; with this PR, we don't print anything old, just new log lines as they come up

[mheon]

Otherwise, my major concerns are addressed, output looks fine

[rhatdan]

bot, retest this please

[TomasTomecek]

Nicely done, @baude. Just tested it locally, very nice work!

$ ./bin/podman run --rm -d --name cont1 fedora:29 bash -c 'while true; do date; sleep 1; done'
40e06045c6971c4c8452f2780e588ac468942ab3db7fcb9647435d15c8fdc453

$ ./bin/podman run --rm -d --name cont2 fedora:29 bash -c 'while true; do date; sleep 1; done'
2d66875579d62dedb0f0fdfedbeb5ba28dfad7fbe9f2b99b745e17d5f4ce940e

$ ./bin/podman logs -f cont1 cont2
40e06045c697 Fri Mar 15 16:13:43 UTC 2019
40e06045c697 Fri Mar 15 16:13:44 UTC 2019
40e06045c697 Fri Mar 15 16:13:45 UTC 2019
40e06045c697 Fri Mar 15 16:13:46 UTC 2019
40e06045c697 Fri Mar 15 16:13:47 UTC 2019
2d66875579d6 Fri Mar 15 16:13:47 UTC 2019
2d66875579d6 Fri Mar 15 16:13:48 UTC 2019

[baude]

bot, retest this please

[mheon]

Latest version seems to properly print all logs before following

[rhatdan]

/lgtm