fix: return tty size in container_inspect.go by priyanshsao · Pull Request #28579 · containers/podman

priyanshsao · 2026-04-24T14:10:04Z

In the output of podman inspect, there is a field for the container's TTY size (ConsoleSize), which Podman presently only returns [0,0].
This PR updates the tty size for containers which have terminal enabled and are in running state.
For cases where there is an issue with getting the size or the container is not running, suitable warning is given, no update happens and default [0,0] is returned.

Fixes: #28368

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Does this PR introduce a user-facing change?

Fix podman inspect to return console size of a running container.

priyanshsao · 2026-04-24T14:13:14Z

A simple video to see the change quickly

podman_tty.mp4

packit-as-a-service · 2026-04-24T14:25:08Z

tmt tests failed for commit 8f5a4a2. @lsm5, @psss, @thrix please check.

danishprakash

Can you please also add a test case for this?

danishprakash · 2026-04-27T06:09:16Z

+		} else {
+			defer f.Close()
+
+			height, width, err := xterm.GetSize(int(f.Fd()))


GetSize returns (width, height), so the size is flipped.

danishprakash · 2026-04-27T06:14:32Z

+		procPath := fmt.Sprintf("/proc/%d/fd/0", c.state.PID)
+
+		f, err := os.Open(procPath)


That path doesn't exist on FreeBSD, so this would always fail. We could either guard this for Linux or even split this into *_freebsd.go. Bottom line, the behavior on FreeBSD won't change (podman will still return [0,0]), but there's going to be an additional warning, which is superfluous considering we know this won't work.

Probably safest to have _linux and _freebsd files for this

So, for *_freebsd.go the console size should be updated with another method or just simply make it [0,0] ?

0,0 for now, though add a TODO comment saying it should be fixed later

danishprakash · 2026-04-27T06:15:50Z

+		f, err := os.Open(procPath)
+		if err != nil {
+			if c.state.State != define.ContainerStateRunning {
+				logrus.Warnf("container %q is not running, unable to get console size", c.ID())


To me, this seems to be noise.

Maybe debug or exit with an error?

Debug logs safest

danishprakash · 2026-04-27T06:32:33Z

 	"go.podman.io/podman/v6/libpod/driver"
 	"go.podman.io/podman/v6/pkg/signal"
 	"go.podman.io/podman/v6/pkg/util"
+	xterm "golang.org/x/term"


Suggested change

xterm "golang.org/x/term"

"golang.org/x/term"

danishprakash · 2026-04-27T06:39:28Z

+			if c.state.State != define.ContainerStateRunning {
+				logrus.Warnf("container %q is not running, unable to get console size", c.ID())
+			} else {
+				logrus.Warnf("unable to open %s", procPath)


The lack of context here might confuse more than it would help, consider:

Suggested change

logrus.Warnf("unable to open %s", procPath)

logrus.Debugf("unable to get console size for container %s: %v", c.ID(), err)

Honny1 · 2026-04-27T12:31:10Z

+	if c.Terminal() {
+		procPath := fmt.Sprintf("/proc/%d/fd/0", c.state.PID)
+
+		f, err := os.Open(procPath)


What if the container doesn't run, and some other process gets that PID?

According to my knowledege,
PID's are reused only when the prev. process with same PID has already been exited.
Even if another process gets same PID,
the prev. container c.state.pid returns 0 because it is stopped, because without the prev. process stopped same PID cannot be assigned to another.
Also, /proc/0/fd/ access is not allowed, so os.Open("/proc/0/fd/") gives error.
Resulting in debug message and [0,0] consoleSize.

Honny1 · 2026-04-27T12:32:10Z

+		f, err := os.Open(procPath)
+		if err != nil {
+			if c.state.State != define.ContainerStateRunning {
+				logrus.Warnf("container %q is not running, unable to get console size", c.ID())


Maybe debug or exit with an error?

priyanshsao · 2026-05-04T09:29:21Z

Can you please also add a test case for this?

@danishprakash @mheon,
I was looking at the test files for container_inspect.go, I have found this integration test container_inspect_test.go, do I need to add test case in this file?
can you please provide more details.

mheon · 2026-05-04T13:04:51Z

Probably not necessary. You could add an E2E test instead, maybe in test/e2e/inspect_test.go, and just verify the numbers are non-zero when a container is started with a TTY and 0 when it is not?

priyanshsao · 2026-05-05T11:54:57Z

Probably not necessary. You could add an E2E test instead, maybe in test/e2e/inspect_test.go, and just verify the numbers are non-zero when a container is started with a TTY and 0 when it is not?

I think this test would fail in FreeBSD, because we return zero in both case. What do you think?

danishprakash · 2026-05-05T13:47:57Z

You could skip the test on freebsd, or check that it returns [0,0]:

if runtime.GOOS == "freebsd" {
    Skip("ConsoleSize not implemented on FreeBSD")
}

In the output of podman inspect, there is a field for the container's TTY size (ConsoleSize), which Podman presently only returns [0,0]. This PR updates the console size field for containers with terminal enabled. For cases where there is an issue with getting the size, suitable debug information is given, no update happens and default [0,0] is returned. This implementation is only for Linux systems. For FreeBSD, the console size is not implemented yet so, adds a todo for that. Fixes: containers#28368 Signed-off-by: Priyansh Sao <saopriyansh06@gmail.com>

priyanshsao · 2026-05-07T06:23:07Z

Implemented all the changes related to implementation asked by reviewers.
For tests I will make another commit.

Just a small change from my side, I replaced the Warnf with Debugf for this
logrus.Debugf("could not get terminal size: %v", err)
I thought, the users shouldn't be bothered, if for some reason we were unable to get size.

If that's not a good change, I would fix that when I would make commit for tests.

priyanshsao · 2026-05-07T06:24:35Z

For tests, the problem I'm facing is that, to get the consoleSize field updated

container's terminal should be enabled + a real terminal should be attached.

But this doesn't work in podman test:
session := podmanTest.Podman([]string{"run", "-it", "--name", ctrName, FEDORA_MINIMAL, "sleep", "+Inf"})

So I tried this:
session := podmanTest.Podman([]string{"run", "-dt", "--name", ctrName, FEDORA_MINIMAL, "sleep", "+Inf"})

But the thing is even with terminal enabled the console size is 0 because no terminal is attached.

priyanshsao · 2026-05-07T06:26:27Z

Very Sorry for this, my keys got wrongly pressed and this pr got closed.

Honny1 · 2026-05-07T08:17:02Z

@priyanshsao I think you forgot to push the new test. Can you check your changes once more? Thanks.

priyanshsao · 2026-05-07T08:58:48Z

@priyanshsao I think you forgot to push the new test. Can you check your changes once more? Thanks.

There are some issues I'm facing related to tests, once those are resolved I will add another commit with changes.

priyanshsao · 2026-05-11T13:48:57Z

For tests, the problem I'm facing is that, to get the consoleSize field updated

container's terminal should be enabled + a real terminal should be attached.

But this doesn't work in podman test: session := podmanTest.Podman([]string{"run", "-it", "--name", ctrName, FEDORA_MINIMAL, "sleep", "+Inf"})

So I tried this: session := podmanTest.Podman([]string{"run", "-dt", "--name", ctrName, FEDORA_MINIMAL, "sleep", "+Inf"})

But the thing is even with terminal enabled the console size is 0 because no terminal is attached.

@mheon @danishprakash, Do I need to use some external lib for creating a real terminal or podman tests has some functions for this, can you please provide your thoughts on this.

mheon · 2026-05-11T14:39:27Z

Hm. I don't know if we've encountered this one before. It looks like the system tests can create terminals.

mheon · 2026-05-11T15:36:55Z

Yeah, system tests might be safer - see tests like https://github.com/containers/podman/blob/main/test/system/450-interactive.bats#L51-L81

danishprakash reviewed Apr 27, 2026

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Honny1 reviewed Apr 27, 2026

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priyanshsao force-pushed the inspect-tty-size branch from 8f5a4a2 to 4728ce1 Compare May 7, 2026 06:15

priyanshsao closed this May 7, 2026

priyanshsao reopened this May 7, 2026

		procPath := fmt.Sprintf("/proc/%d/fd/0", c.state.PID)

		f, err := os.Open(procPath)

	logrus.Warnf("unable to open %s", procPath)
	logrus.Debugf("unable to get console size for container %s: %v", c.ID(), err)

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