Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

exec credential provider: use stdin to detect user interaction #99654

Merged
merged 1 commit into from Mar 3, 2021
Merged

exec credential provider: use stdin to detect user interaction #99654

merged 1 commit into from Mar 3, 2021

Conversation

ankeesler
Copy link
Contributor

@ankeesler ankeesler commented Mar 2, 2021 •
edited by liggitt

What type of PR is this?

/kind bug

What this PR does / why we need it:

We are not sure why this was stdout, since stdin is what the user uses to pass
information to the exec plugin.

There is a question of backwards compatibility here. Our take is that this is a
bug, and so we are ameliorating behavior instead of breaking behavior. There are
2 main cases to consider with respect to backwards compatibility:

  1. an existing exec plugin depended on stdin being hooked up to them if stdout
    was a terminal (e.g., echo foo | client-go-command-line-tool); we believe
    this is an anti-pattern, since the client-go-command-line-tool could be using
    stdin elsewhere (e.g., echo foo | kubectl apply -f -)

  2. an existing exec plugin depended on stdin not being hooked up to them if
    stdout was not a terminal (e.g., client-go-command-line-tool >/dev/null);
    hopefully there are very few plugins that have tried to base logic off of
    whether stdin returned EOF immediately, since this could also happen when
    something else is wrong with stdin

We hope to apply a stronger fix to this exec plugin user interaction stuff in a
future release.

Which issue(s) this PR fixes:

Fixes #98451

Special notes for your reviewer:

Does this PR introduce a user-facing change?

stdin is now only passed to client-go exec credential plugins when it is detected to be an interactive terminal. Previously, it was passed to client-go exec plugins when **stdout** was detected to be an interactive terminal.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

@ankeesler
exec credential provider: use stdin to detect user interaction
aea995c 
We are not sure why this was stdout, since stdin is what the user uses to pass
information to the exec plugin.

There is a question of backwards compatibility here. Our take is that this is a
bug, and so we are ameliorating behavior instead of breaking behavior. There are
2 main cases to consider with respect to backwards compatibility:

1. an existing exec plugin depended on stdin being hooked up to them if stdout
   was a terminal (e.g., echo foo | client-go-command-line-tool); we believe
   this is an anti-pattern, since the client-go-command-line-tool could be using
   stdin elsewhere (e.g., echo foo | kubectl apply -f -)

2. an existing exec plugin depended on stdin not being hooked up to them if
   stdout was not a terminal (e.g., client-go-command-line-tool >/dev/null);
   hopefully there are very few plugins that have tried to base logic off of
   whether stdin returned EOF immediately, since this could also happen when
   something else is wrong with stdin

We hope to apply a stronger fix to this exec plugin user interaction stuff in a
future release.

Signed-off-by: Andrew Keesler <akeesler@vmware.com>
@k8s-ci-robot k8s-ci-robot added release-note Denotes a PR that will be considered when it comes time to generate release notes. kind/bug Categorizes issue or PR as related to a bug. size/XS Denotes a PR that changes 0-9 lines, ignoring generated files. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. do-not-merge/needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. needs-triage Indicates an issue or PR lacks a `triage/foo` label and requires one. labels Mar 2, 2021
@k8s-ci-robot
Copy link
Contributor

Hi @ankeesler. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

@k8s-ci-robot k8s-ci-robot added needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. needs-priority Indicates a PR lacks a `priority/foo` label and requires one. labels Mar 2, 2021
@ankeesler
Copy link
Contributor Author

/sig auth

/cc @enj @liggitt

@k8s-ci-robot k8s-ci-robot requested review from enj and liggitt March 2, 2021 19:44
@k8s-ci-robot k8s-ci-robot added sig/auth Categorizes an issue or PR as relevant to SIG Auth. sig/api-machinery Categorizes an issue or PR as relevant to SIG API Machinery. and removed do-not-merge/needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. labels Mar 2, 2021
@ankeesler ankeesler mentioned this pull request Mar 2, 2021
Closed
@enj
Copy link
Member

enj commented Mar 2, 2021

/triage accepted
/priority important-soon
/ok-to-test
/milestone v1.21
/lgtm

@k8s-ci-robot k8s-ci-robot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. triage/accepted Indicates an issue or PR is ready to be actively worked on. priority/important-soon Must be staffed and worked on either currently, or very soon, ideally in time for the next release. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Mar 2, 2021
@k8s-ci-robot k8s-ci-robot added this to the v1.21 milestone Mar 2, 2021
@k8s-ci-robot k8s-ci-robot removed needs-triage Indicates an issue or PR lacks a `triage/foo` label and requires one. needs-priority Indicates a PR lacks a `priority/foo` label and requires one. labels Mar 2, 2021
@k8s-ci-robot k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Mar 2, 2021
@enj
Copy link
Member

enj commented Mar 2, 2021

/assign @liggitt

@ankeesler ankeesler mentioned this pull request Mar 2, 2021
Closed
liggitt
liggitt reviewed Mar 3, 2021
View reviewed changes
staging/src/k8s.io/client-go/plugin/pkg/client/auth/exec/exec.go
@@ -198,7 +198,7 @@ func newAuthenticator(c *cache, config *api.ExecConfig, cluster *clientauthentic

stdin: os.Stdin,
stderr: os.Stderr,
interactive: term.IsTerminal(int(os.Stdout.Fd())),
interactive: term.IsTerminal(int(os.Stdin.Fd())),
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I wonder if the rationale here was that unless stdout was visible to the user, the exec plugin couldn't reasonably prompt for input?

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

talked with @enj, who pointed out that even if that were the case, this check wouldn't make sense, since the plugins prompted on stderr

@liggitt
Copy link
Member

liggitt commented Mar 3, 2021

/approve

@k8s-ci-robot
Copy link
Contributor

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ankeesler, liggitt

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

@k8s-ci-robot k8s-ci-robot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Mar 3, 2021
@erismaster
Copy link

Hello! I am from the Bug Triage team! Friendly reminder that code freeze is starting March 9th, 2021 (about 1 week from now). We want to ensure that each PR has a chance to be merged before code freeze. This looks close to being merged (pending some failed tests), but commenting for awareness of the code freeze date.

@fejta-bot
Copy link

/retest
This bot automatically retries jobs that failed/flaked on approved PRs (send feedback to fejta).

Review the full test history for this PR.

Silence the bot with an /lgtm cancel or /hold comment for consistent failures.

@k8s-ci-robot k8s-ci-robot merged commit e2eb9f0 into kubernetes:master Mar 3, 2021
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@liggitt liggitt liggitt left review comments

@enj enj Awaiting requested review from enj

@deads2k deads2k Awaiting requested review from deads2k

@sttts sttts Awaiting requested review from sttts

Assignees

@liggitt liggitt

@enj enj

Labels
approved Indicates a PR has been approved by an approver from all required OWNERS files. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. kind/bug Categorizes issue or PR as related to a bug. lgtm "Looks good to me", indicates that a PR is ready to be merged. ok-to-test Indicates a non-member PR verified by an org member that is safe to test. priority/important-soon Must be staffed and worked on either currently, or very soon, ideally in time for the next release. release-note Denotes a PR that will be considered when it comes time to generate release notes. sig/api-machinery Categorizes an issue or PR as relevant to SIG API Machinery. sig/auth Categorizes an issue or PR as relevant to SIG Auth. size/XS Denotes a PR that changes 0-9 lines, ignoring generated files. triage/accepted Indicates an issue or PR is ready to be actively worked on.
Projects
None yet
Milestone
v1.21
Development

Successfully merging this pull request may close these issues.

"exec" auth client plugin checks whether STDOUT is interactive to decide whether to forward STDIN
6 participants
@ankeesler @k8s-ci-robot @enj @liggitt @erismaster @fejta-bot