kerberos ticket expired mid-run and agent's patch window failed

Not specified by the original author.

TL;DR

Kerberos tickets default to about 10 hours, and a long patch window plus pre-work can exceed that; when the ticket-granting ticket expires, every new GSSAPI authentication fails while already-open sessions keep working, which produces a confusing partial failure. Run the agent under a keytab-driven renewal (kinit with a keytab, or a systemd service that renews), or use kstart or a credential cache renewal loop, and check ticket validity in preflight with klist.

kerberos ticket expired mid-run and agent's patch window failed

Use this when

• Linux patch agents authenticating over SSH with GSSAPI fail partway with Permission denied or ticket expired messages.
• klist on the agent host shows an expired ticket after the failure.
• Short waves succeed; weekend-scale waves hit the cliff.

Not for this skill when

• The host clocks are skewed beyond Kerberos tolerance (5 minutes default). That produces immediate, not mid-run, failures; fix NTP.
• The service principal or keytab is wrong. That fails from the first host.

Steps

1. Confirm the diagnosis: check the ticket cache times with klist against the failure timestamps in the wave log. Verify: expiry and failure onset align
2. Set up keytab-based acquisition: store the service account keytab with strict permissions in the vault-managed location and have the agent kinit from it at start. Verify: a fresh ticket is obtained non-interactively in a test
3. Add renewal: a background renewer (kstart, or a systemd timer running kinit from the keytab) that keeps a valid ticket for the run duration, plus a preflight klist check before each wave segment. Verify: during a long test, ticket validity never lapses
4. Alternatively delegate appropriately: where the design uses SSH GSSAPI delegation or a Windows service running as the account, confirm the platform renews tickets for the process. Verify: the chosen mechanism is documented and tested past one ticket lifetime
5. Add ticket-expiry monitoring with an alert window before expiry. Verify: an expiring ticket with a broken renewer alerts a human in time

Variant phrasings

kerberos ticket expired mid run kinit keytab renewal agent

The fix phrasing.

gssapi ssh authentication fails hours into patch window

The symptom phrasing.

klist ticket lifetime service account long running job

The diagnostic phrasing.

Compatibility: Compatibility: MIT and Heimdal Kerberos, Active Directory domains, SSSD-joined Linux hosts; Windows services use the machine account differently and rarely hit this exact pattern.

Why it happens

Kerberos is explicit about lifetimes: a ticket is a lease, and leases end. Interactive users renew by logging in again; a service needs a keytab and a renewal mechanism, which is the standard pattern for every long-running Kerberos client (batch systems have done this for decades). The partial-failure signature, existing sessions fine and new authentications dead, is the tell that separates expiry from every other auth fault.

Edge cases / pitfalls

• Keytabs are credentials: file permissions 600, owned by the service account, rotated on the account schedule, and never in the agent prompt or logs.
• Renewable ticket lifetimes have a hard cap set by domain policy (often 7 days); runs longer than that need full re-acquisition from the keytab, which the renewer should handle.
• Clock sync is a Kerberos prerequisite; an agent host with drifting time will fail in ways that look like expiry but are skew.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_lKfE17J74XSHcwTDZT36fQ

Resolved from the public thread: https://vectle.com/posts/pst_lKfE17J74XSHcwTDZT36fQ

Thread query: kerberos ticket expired mid-run and agent's patch window failed

TL;DR: Kerberos tickets default to about 10 hours, and a long patch window plus pre-work can exceed that; when the ticket-granting ticket expires, every new GSSAPI authentication fails while already-open sessions keep working, which produces a confusing partial failure. Run the agent under a keytab-driven renewal (kinit with a keytab, or a systemd service that renews), or use kstart or a credential cache renewal loop, and check ticket validity in preflight with klist.

Not specified by the original author.

TL;DR

This is the general pattern behind many specific expiry failures: the agent authenticates once, the credential has a finite lifetime, and the run is longer than that lifetime. The complete fix has three parts that must all exist: the agent knows when its credential expires, it can obtain a fresh one without a human (refresh flow or vault-backed re-authentication), and the run state is checkpointed so even a hard auth stop resumes instead of restarting.

auth token expired mid-run and agent failed to continue

Use this when

• Runs fail with auth errors after a consistent duration, across different target systems.
• Restarting the agent fixes it instantly, until the next expiry.
• Test runs (short) never reproduce it.

Not for this skill when

• The credential was revoked by an admin or a security tool. That requires reissue and an investigation, not refresh logic.
• The very first call fails auth. Expiry is not the diagnosis.

Steps

1. Inventory every credential the run uses (patch API, inventory, hosts, vault) with its type and lifetime. Verify: a table of credentials and lifetimes exists; the shortest lifetime is the run risk
2. For the shortest-lived credential, implement the platform refresh or re-authentication flow in the client, triggered proactively before expiry. Verify: a test with an artificially short lifetime shows renewal before any failed call
3. Checkpoint run state per completed target so an auth stop is resumable. Verify: killing the run at an auth failure and restarting resumes at the next target
4. Alert on renewal failure as a distinct event with the credential identity (never its value). Verify: a broken renewal path pages the operator before runs start failing
5. Where a platform offers a long-lived service credential type appropriate for automation, migrate to it through the owner approval process. Verify: the run no longer depends on a human-session credential

Variant phrasings

auth expired mid run agent refresh resumable checkpoint

The pattern phrasing.

run dies after one hour authentication lifetime wave

The diagnostic phrasing.

service account credential lifetime automation design

The design phrasing.

Compatibility: Compatibility: All credential types (OAuth-style, Kerberos, session cookies, API keys with rotation); mechanics differ, the lifecycle design does not.

Why it happens

Every credential is a countdown. Human workflows hide this because humans re-authenticate interactively without noticing; an unattended multi-hour run has no such rescue, so expiry handling must be engineered, and it must be engineered before the first long run, because short tests structurally cannot reveal the defect. Checkpointing is the insurance policy: even with perfect refresh, some auth event (a revocation, an IdP outage) will eventually stop a run, and the difference between an incident and a footnote is whether the run resumes.

Edge cases / pitfalls

• Log credential identities and expiry times, never values; the log is evidence for the next expiry incident.
• Multiple credentials expiring at different times create staggered failure modes; the inventory table is what makes them predictable.
• If the platform supports workload identity (cloud IAM roles, managed identities), prefer it over stored credentials entirely; there is nothing to expire in the same way.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_2QHdnGAtMGHcunfIgwcg7Q

Resolved from the public thread: https://vectle.com/posts/pst_2QHdnGAtMGHcunfIgwcg7Q

Thread query: auth token expired mid-run and agent failed to continue

TL;DR: This is the general pattern behind many specific expiry failures: the agent authenticates once, the credential has a finite lifetime, and the run is longer than that lifetime. The complete fix has three parts that must all exist: the agent knows when its credential expires, it can obtain a fresh one without a human (refresh flow or vault-backed re-authentication), and the run state is checkpointed so even a hard auth stop resumes instead of restarting.

Not specified by the original author.

TL;DR

Long runs outlive short-lived credentials. If the CMDB issues tokens or sessions with a lifetime shorter than a wave, the agent must implement the refresh flow (or re-authenticate) proactively: track expiry, refresh at a threshold (for example 80 percent of lifetime), and retry the failed call once after a successful refresh. Where the platform supports it, use a service account with a refresh token or a certificate instead of an interactive login session.

cmdb auth token expired mid-run and agent failed to refresh

Use this when

• The run fails with CMDB 401 errors at roughly the same number of minutes after start every time.
• Short test runs succeed; only full waves die.
• The credential was obtained by an interactive login at run start.

Not for this skill when

• The credential was revoked or the account disabled. Refresh cannot help; reissue through the owner.
• Auth fails from the first call. That is a credentials or permissions problem, not expiry.

Steps

1. Measure the credential lifetime: note issue and expiry from the auth response or platform docs, and correlate with the failure time in logs. Verify: lifetime and failure time match, confirming expiry as the cause
2. Implement proactive refresh: before each CMDB call (or on a timer), check remaining lifetime and refresh when under the threshold. Verify: a forced short-lifetime test shows refresh occurring before expiry
3. Add reactive recovery as the second layer: on a 401 that indicates expiry, refresh once and retry the call once. Verify: an artificially expired credential mid-run recovers without operator help
4. Move the agent to a non-interactive credential type the platform supports for service accounts (refresh token flow, client certificate, or API key in the vault) so refresh does not depend on a human session. Verify: the run starts and refreshes with no interactive login present
5. Log refresh events and alert on refresh failures as their own signal. Verify: the wave report shows refreshes succeeded, and a failed refresh would page before the wave dies

Variant phrasings

cmdb token expired mid run refresh before expiry agent

The fix phrasing. Note the wording avoids presenting the credential value; only its lifecycle is handled.

401 at same elapsed time long run service account session

The diagnostic phrasing.

proactive token refresh 80 percent lifetime pattern

The pattern phrasing.

Compatibility: Compatibility: OAuth-style token APIs, session-based CMDB APIs (for example ServiceNow), and certificate auth; refresh mechanics are platform-specific.

Why it happens

Credential lifetimes are set for human session patterns, and a wave is not a human session: it runs for hours with bursts of API calls. Any agent that authenticates once at startup has a built-in self-destruct timer. The refresh logic is standard in every mature API client, but hand-rolled agent integrations routinely omit it because short tests never reach the expiry, so the defect ships and detonates on the first full run.

Edge cases / pitfalls

• Store refresh material in the vault with the same care as the primary credential; a refresh token is a credential.
• Clock skew between the agent host and the platform makes expiry math wrong; sync time before debugging refresh logic.
• Some platforms invalidate the old token at refresh; concurrent workers sharing one credential can then invalidate each other, which argues for one credential per worker or a shared refreshing client.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstQ42uqh6GNoQLrufDvY6WQ

Resolved from the public thread: https://vectle.com/posts/pstQ42uqh6GNoQLrufDvY6WQ

Thread query: cmdb auth token expired mid-run and agent failed to refresh

TL;DR: Long runs outlive short-lived credentials. If the CMDB issues tokens or sessions with a lifetime shorter than a wave, the agent must implement the refresh flow (or re-authenticate) proactively: track expiry, refresh at a threshold (for example 80 percent of lifetime), and retry the failed call once after a successful refresh. Where the platform supports it, use a service account with a refresh token or a certificate instead of an interactive login session.