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Resolve "get "panic: EOF" when register runners run in a container"

Niklas Janz requested to merge 29078-get-panic-eof-when-register-runners-run-in-a-container into main

What does this MR do?

This MR wraps io.EOF errors in the askOnce function, to avoid the panic condition down the line.
It provides an error message with a suggestion on how to avoid this.

Why was this MR needed?

To prevent a panic condition with a known fix.

What's the best way to test this MR?

Running the register command in a Docker container, without allocating an interactive terminal, and omitting the --non-interactive-flag:

podman run --rm gitlab/gitlab-runner:alpine register --url https://gitlab.com --token glrt-derpfooba
docker run --rm gitlab/gitlab-runner:alpine register --url https://gitlab.com --token glrt-derpfooba
Pass / Fail output

Pass

❯ docker run --rm gitlab/gitlab-runner:alpine register --url https://gitlab.com --token glrt-derpfooba
Runtime platform                                    arch=arm64 os=linux pid=1 revision=582bd361 version=17.4.0~pre.152.g582bd361
Running in system-mode.                            
                                                   
Created missing unique system ID                    system_id=r_JoVraPIpx3IV
Enter the GitLab instance URL (for example, https://gitlab.com/):
[https://gitlab.com]: PANIC: Unexpected EOF. Did you mean to use --non-interactive?

Fail

❯ docker run --rm gitlab/gitlab-runner:alpine register --url https://gitlab.com --token glrt-derpfooba
Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg.
Runtime platform                                    arch=arm64 os=linux pid=2 revision=66269445 version=17.3.1
Running in system-mode.

Created missing unique system ID                    system_id=r_kXTNV8xZBil3
Enter the GitLab instance URL (for example, https://gitlab.com/):
[https://gitlab.com]: panic: EOF [recovered]
	panic: EOF

goroutine 1 [running]:
main.main.func1()
	/builds/gitlab-org/gitlab-runner/main.go:52 +0x60
panic({0x1baf960?, 0x37af010?})
	/usr/local/go/src/runtime/panic.go:770 +0x124
gitlab.com/gitlab-org/gitlab-runner/commands.(*RegisterCommand).askOnce(0x4000175508, {0x2094a06, 0x41}, 0x400128f278, 0x0)
	/builds/gitlab-org/gitlab-runner/commands/register.go:120 +0x230
gitlab.com/gitlab-org/gitlab-runner/commands.(*RegisterCommand).ask(0x4000175508, {0x1ff20ce, 0x3}, {0x2094a06, 0x41}, {0x0?, 0x4001217620?, 0x24?})
	/builds/gitlab-org/gitlab-runner/commands/register.go:150 +0x12c
gitlab.com/gitlab-org/gitlab-runner/commands.(*RegisterCommand).askRunner(0x4000175508)
	/builds/gitlab-org/gitlab-runner/commands/register.go:263 +0x4c
gitlab.com/gitlab-org/gitlab-runner/commands.(*RegisterCommand).Execute(0x4000175508, 0x40008ed340)
	/builds/gitlab-org/gitlab-runner/commands/register.go:432 +0x170
github.com/urfave/cli.HandleAction({0x1aab8c0?, 0x4001312000?}, 0x8?)
	/go/pkg/mod/github.com/urfave/cli@v1.22.14/app.go:526 +0x94
github.com/urfave/cli.Command.Run({{0x1ffa952, 0x8}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x201aea6, 0x15}, {0x0, ...}, ...}, ...)
	/go/pkg/mod/github.com/urfave/cli@v1.22.14/command.go:175 +0x534
github.com/urfave/cli.(*App).Run(0x4001302a80, {0x400004c2a0, 0x6, 0x6})
	/go/pkg/mod/github.com/urfave/cli@v1.22.14/app.go:277 +0x7f8
main.main()
	/builds/gitlab-org/gitlab-runner/main.go:82 +0x63

What are the relevant issue numbers?

Edited by Niklas Janz

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