fix the panic error in dashboard proxy

[TianxiangShen]

Changes

fix the panic error in dashboard proxy which is due to null pointer. The external log server might returns an empty response. We need to check the response first before returns the status code.

{"level":"error","ts":1724741273.0200272,"caller":"utils/proxy.go:46","msg":"Failed to execute request: Get \"http://pod-logs-server:80/tnet-cd/d89f4a51-6439-11ef-bac3-7ee28d663481-pr-checkout-pod/step-pr-checkout?startTime=2024-08-27T06%3A01%3A48Z&completionTime=2024-08-27T06%3A02%3A22Z\": context canceled","stacktrace":"github.com/tektoncd/dashboard/pkg/utils.Proxy\n\tgithub.com/tektoncd/dashboard/pkg/utils/proxy.go:46\ngithub.com/tektoncd/dashboard/pkg/endpoints.Resource.LogsProxy\n\tgithub.com/tektoncd/dashboard/pkg/endpoints/externallogs.go:34\nnet/http.HandlerFunc.ServeHTTP\n\tnet/http/server.go:2109\nnet/http.(*ServeMux).ServeHTTP\n\tnet/http/server.go:2487\ngithub.com/tektoncd/dashboard/pkg/csrf.(*csrf).ServeHTTP\n\tgithub.com/tektoncd/dashboard/pkg/csrf/csrf.go:74\nnet/http.serverHandler.ServeHTTP\n\tnet/http/server.go:2947\nnet/http.(*conn).serve\n\tnet/http/server.go:1991"}
2024/08/27 06:47:53 http: panic serving 10.222.16.105:29181: runtime error: invalid memory address or nil pointer dereference
goroutine 82193969 [running]:
net/http.(*conn).serve.func1()
	net/http/server.go:1850 +0xbf
panic({0x15f31e0, 0x252e9f0})
	runtime/panic.go:890 +0x262
github.com/tektoncd/dashboard/pkg/utils.Proxy(0xc002709a00, {0x1a23098, 0xc000a26e00}, {0xc0022069c0, 0xb2}, 0xc00220695d?)
	github.com/tektoncd/dashboard/pkg/utils/proxy.go:47 +0x537
github.com/tektoncd/dashboard/pkg/endpoints.Resource.LogsProxy({0xc0004f4240, {0x1a35fb8, 0xc00058a340}, {{0xc000046074, 0x10}, {0x7ffd15ea4508, 0x10}, {0x7ffd15ea452e, 0x10}, {0x7ffd15ea4575, ...}, ...}}, ...)
	github.com/tektoncd/dashboard/pkg/endpoints/externallogs.go:34 +0x13d
net/http.HandlerFunc.ServeHTTP(0x4a?, {0x1a23098?, 0xc000a26e00?}, 0x0?)
	net/http/server.go:2109 +0x2f
net/http.(*ServeMux).ServeHTTP(0x15d8600?, {0x1a23098, 0xc000a26e00}, 0xc002709a00)
	net/http/server.go:2487 +0x149
github.com/tektoncd/dashboard/pkg/csrf.(*csrf).ServeHTTP(0xc000379410, {0x1a23098, 0xc000a26e00}, 0xc002709a00)
	github.com/tektoncd/dashboard/pkg/csrf/csrf.go:74 +0x94
net/http.serverHandler.ServeHTTP({0xc001f38450?}, {0x1a23098, 0xc000a26e00}, 0xc002709a00)
	net/http/server.go:2947 +0x30c
net/http.(*conn).serve(0xc0010a77c0, {0x1a23ba0, 0xc000379500})
	net/http/server.go:1991 +0x607
created by net/http.(*Server).Serve
	net/http/server.go:3102 +0x4db

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Release Notes

Fix the panic error in dashboard proxy

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: TianxiangShen / name: Tianxiang Shen (b026fce)

[tekton-robot]

Hi @TianxiangShen. Thanks for your PR.

I'm waiting for a tektoncd 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.

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[TianxiangShen]

/kind bug

[AlanGreene]

Thanks for the PR @TianxiangShen. Can you share some details about how to reproduce the issue?

We'll be delivering a complete rewrite of the backend in an upcoming release so it would be good to verify the new version is not affected by the same issue.

/ok-to-test

[TianxiangShen]

Thanks for the PR @TianxiangShen. Can you share some details about how to reproduce the issue?

We'll be delivering a complete rewrite of the backend in an upcoming release so it would be good to verify the new version is not affected by the same issue.

/ok-to-test

Hi Alan, sorry for the late reply. This issue happens when dashboard backend trys to access the external-logs server and that server send backs an empty respons. here's my setting for the dashboard pod:

spec:
  containers:
  - args:
    - --port=9097
    - --logout-url=
    - --pipelines-namespace=tekton-pipelines
    - --triggers-namespace=tekton-pipelines
    - --read-only=true
    - --log-level=info
    - --log-format=json
    - --namespace=
    - --stream-logs=true
    - --external-logs=http://pod-logs-server:80
...

when the external-logs server http://pod-logs-server:80 failed to fetch the logs from our storage bucket, it shows following error and the response will be empty.

2024/08/16 02:18:03 failed to check existence of py-cd/abc-pod/step-checkout: failed to stat object: Head "https://bucket.nuobject.io/tekton-logs/py-cd/abc-pod/step-checkout": context deadline exceeded

[AlanGreene]

Thanks for the extra info @TianxiangShen, this is good to know.

/approve
/lgtm

[tekton-robot]

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This pull-request has been approved by: AlanGreene

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