fix: allow DNS failover during CSE connectivity checks#8985
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Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 8618f8d1-4a31-43a9-92d7-0ba79b33675f
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July 20, 2026 15:13
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Pull request overview
This PR adjusts the Linux CSE outbound connectivity preflight retry parameters in cse_main.sh to better tolerate DNS failover scenarios (e.g., an unresponsive primary custom DNS server) while slightly reducing the overall worst-case retry window. It fits into the Linux node provisioning path (nodePrep) where outbound connectivity checks are performed during cluster integration.
Changes:
- Update the outbound preflight retry shape from
60 x 5sto20 x 15sinparts/linux/cloud-init/artifacts/cse_main.sh. - Add a ShellSpec assertion to ensure the outbound preflight uses the intended retry parameters.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| parts/linux/cloud-init/artifacts/cse_main.sh | Adjusts outbound connectivity preflight retry/timeout parameters to allow DNS fallback within an attempt. |
| spec/parts/linux/cloud-init/artifacts/cse_main_spec.sh | Adds a test that validates the retry parameters embedded in cse_main.sh. |
cameronmeissner
approved these changes
Jul 20, 2026
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 8618f8d1-4a31-43a9-92d7-0ba79b33675f
r2k1
changed the title
| fi | ||
| else | ||
| logs_to_events "AKS.CSE.apiserverCurl" "retrycmd_if_failure ${API_SERVER_CONN_RETRIES} 1 10 curl -v --cacert /etc/kubernetes/certs/ca.crt https://${API_SERVER_NAME}:443" || time curl -v --cacert /etc/kubernetes/certs/ca.crt "https://${API_SERVER_NAME}:443" || VALIDATION_ERR=$ERR_K8S_API_SERVER_CONN_FAIL | ||
| logs_to_events "AKS.CSE.apiserverCurl" "retrycmd_if_failure ${API_SERVER_CONN_RETRIES} 1 15 curl -v --cacert /etc/kubernetes/certs/ca.crt https://${API_SERVER_NAME}:443" || time curl -v --cacert /etc/kubernetes/certs/ca.crt "https://${API_SERVER_NAME}:443" || VALIDATION_ERR=$ERR_K8S_API_SERVER_CONN_FAIL |
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Existing behaviour. I have no willpower to change it
cameronmeissner
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Jul 20, 2026
cameronmeissner
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Jul 20, 2026
r2k1
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July 20, 2026 23:36
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What this PR does / why we need it:
The Linux CSE wraps hostname-based connectivity checks with per-attempt timeouts. With multiple custom DNS servers, an unresponsive primary can consume the timeout before libc tries a responsive secondary.
This gives both affected checks 15 seconds per attempt while preserving or reducing their total retry budgets:
Each attempt can now cover the normal primary DNS timeout, secondary DNS fallback, and TCP/TLS setup. The rendered endpoints and failure behavior are unchanged.
Tests:
spec/parts/linux/cloud-init/artifacts/cse_main_spec.shGENERATE_TEST_DATA=true go test ./pkg/agent...cse_main.shWhich issue(s) this PR fixes:
N/A