Add MySQL cross-DC disaster recovery (DC-DR) guide#940
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📝 WalkthroughWalkthroughThis PR adds four new documentation pages for MySQL cross data-center disaster recovery (DC-DR): a landing index page, a conceptual overview, a detailed user guide, and an operational runbook covering 14 failure/maintenance scenarios. No code or exported entities are changed. ChangesMySQL DC-DR Documentation
Estimated code review effort🎯 2 (Simple) | ⏱️ ~15 minutes Poem
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Actionable comments posted: 1
🧹 Nitpick comments (7)
docs/guides/mysql/dr/overview/index.md (5)
172-179: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueRephrase to avoid "only" repetition in the table.
The last row repeats "only" twice, which reads awkwardly. Rephrase for clarity:
| Two sites, co-located quorum | 2 | 2 | only the one-vote DC | only when the one-vote DC is lost | + | Two sites, co-located quorum | 2 | 2 | the one-vote DC | when the one-vote DC is lost |🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/overview/index.md` around lines 172 - 179, The “At a glance” table in the MySQL DR overview repeats “only” in the last row, so reword that row for smoother readability without changing the meaning. Update the “Two sites, co-located quorum” entry in the markdown table to avoid the double “only” phrasing while keeping the same tolerance and failover conditions, and keep the rest of the table unchanged.Source: Linters/SAST tools
68-71: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueFix hyphenation in "intra standby-DC".
"An intra standby-DC GR election" should be hyphenated as "An intra-standby-DC GR election" for correct compound modifier grammar.
- label loop. An intra standby-DC GR election (which moves the local primary and the + label loop. An intra-standby-DC GR election (which moves the local primary and the🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/overview/index.md` around lines 68 - 71, Fix the compound modifier in the DR overview prose by changing the phrase in the affected paragraph from “intra standby-DC GR election” to “intra-standby-DC GR election”; update the wording in the markdown content near the fence/GR election explanation so the grammar is consistent and no other surrounding text changes are needed.Source: Linters/SAST tools
188-192: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueAdd language specifier to the fenced code block.
<details> <summary>🤖 Prompt for AI Agents</summary>Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.In
@docs/guides/mysql/dr/overview/index.mdaround lines 188 - 192, Add a
language specifier to the fenced CLI snippet in the MySQL DR overview docs so
the markdown code block is explicitly marked as bash; update the existing fenced
block containing the --dc-dr-enabled, --dc-dr-coord-kubeconfig, and
--dc-dr-local-dc flags to use the correct syntax highlighting identifier.</details> <!-- cr-comment:v1:d5ef3d993a54bf923d395618 --> _Source: Linters/SAST tools_ --- `86-89`: _📐 Maintainability & Code Quality_ | _🔵 Trivial_ | _💤 Low value_ **Capitalize "PetSet" correctly.** "petset" should be "PetSet" to match the KubeDB/Kubernetes custom resource naming convention used elsewhere in the document. ```diff - with `role: Arbiter` and empty `replicaIndices`. The petset `Witness` role (a + with `role: Arbiter` and empty `replicaIndices`. The PetSet `Witness` role (a🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/overview/index.md` around lines 86 - 89, Update the MySQL DR overview text to capitalize the Kubernetes resource name consistently: change the lowercase “petset” mention in the explanatory paragraph to “PetSet” so it matches the convention used elsewhere in the document. Keep the rest of the wording unchanged and make the edit in the paragraph discussing the `Witness` role and `replicaIndices`.
315-319: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueClarify the relabeling description.
"relabels the survivor's GR primary
primary" is telegraphic. Specify the label being set:- primary `primary`, sets `super_read_only = OFF`, stops the survivor's inbound channel, + primary as `primary`, sets `super_read_only = OFF`, stops the survivor's inbound channel,Or more precisely:
- primary `primary`, sets `super_read_only = OFF`, stops the survivor's inbound channel, + primary to `kubedb.com/role: primary`, sets `super_read_only = OFF`, stops the survivor's inbound channel,🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/overview/index.md` around lines 315 - 319, The wording in the DR overview is too terse around the survivor relabeling step; update the sentence describing the survivor’s GR primary so it explicitly states that the label being set is `primary` (for example, “sets the survivor’s GR primary label to `primary`”). Keep the rest of the recovery flow description unchanged, and adjust the surrounding text near the `primary Service` and `AppBinding` references only if needed for readability.docs/guides/mysql/dr/runbook/index.md (1)
191-191: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueRephrase for clarity: "only once it does" is ambiguous.
The pronoun "it does" is distant from its antecedent. Replace with explicit reference:
- the coordinator clears `super_read_only` only once it does. + the coordinator clears `super_read_only` only once that condition is met.🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/runbook/index.md` at line 191, The sentence in the MySQL DR runbook is ambiguous because “it does” does not clearly refer back to the fresh `renewTime`. Rephrase the text in the surrounding runbook section to use an explicit subject, likely by naming `renewTime` directly in the clause about when the coordinator clears `super_read_only`, so the timing condition is immediately clear.docs/guides/mysql/dr/guide/index.md (1)
64-68: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low valueAdd shell language tag to the operator flags block.
The fenced code block at lines 64-68 lacks a language specifier. Add
bashafter the opening backticks to satisfy markdownlint and enable syntax highlighting.+```bash
--dc-dr-enabled
--dc-dr-coord-kubeconfig=
--dc-dr-local-dc=🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@docs/guides/mysql/dr/guide/index.md` around lines 64 - 68, Add the missing shell language specifier to the fenced operator flags block in the MySQL DR guide so the markdown lint passes and syntax highlighting works. Update the code fence that contains the dc-dr flag examples to use the bash language tag, keeping the flag contents unchanged and preserving the existing section formatting in the guide.
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@docs/guides/mysql/dr/runbook/index.md`:
- Line 15: The runbook text uses an unhyphenated compound modifier, so update
the phrasing in the MySQL DR guide to use “cross-data-center disaster recovery
(DC-DR) mode.” Fix the wording in the affected documentation sentence so the
compound adjective is hyphenated consistently and the terminology matches the
intended disaster recovery label.
---
Nitpick comments:
In `@docs/guides/mysql/dr/guide/index.md`:
- Around line 64-68: Add the missing shell language specifier to the fenced
operator flags block in the MySQL DR guide so the markdown lint passes and
syntax highlighting works. Update the code fence that contains the dc-dr flag
examples to use the bash language tag, keeping the flag contents unchanged and
preserving the existing section formatting in the guide.
In `@docs/guides/mysql/dr/overview/index.md`:
- Around line 172-179: The “At a glance” table in the MySQL DR overview repeats
“only” in the last row, so reword that row for smoother readability without
changing the meaning. Update the “Two sites, co-located quorum” entry in the
markdown table to avoid the double “only” phrasing while keeping the same
tolerance and failover conditions, and keep the rest of the table unchanged.
- Around line 68-71: Fix the compound modifier in the DR overview prose by
changing the phrase in the affected paragraph from “intra standby-DC GR
election” to “intra-standby-DC GR election”; update the wording in the markdown
content near the fence/GR election explanation so the grammar is consistent and
no other surrounding text changes are needed.
- Around line 188-192: Add a language specifier to the fenced CLI snippet in the
MySQL DR overview docs so the markdown code block is explicitly marked as bash;
update the existing fenced block containing the --dc-dr-enabled,
--dc-dr-coord-kubeconfig, and --dc-dr-local-dc flags to use the correct syntax
highlighting identifier.
- Around line 86-89: Update the MySQL DR overview text to capitalize the
Kubernetes resource name consistently: change the lowercase “petset” mention in
the explanatory paragraph to “PetSet” so it matches the convention used
elsewhere in the document. Keep the rest of the wording unchanged and make the
edit in the paragraph discussing the `Witness` role and `replicaIndices`.
- Around line 315-319: The wording in the DR overview is too terse around the
survivor relabeling step; update the sentence describing the survivor’s GR
primary so it explicitly states that the label being set is `primary` (for
example, “sets the survivor’s GR primary label to `primary`”). Keep the rest of
the recovery flow description unchanged, and adjust the surrounding text near
the `primary Service` and `AppBinding` references only if needed for
readability.
In `@docs/guides/mysql/dr/runbook/index.md`:
- Line 191: The sentence in the MySQL DR runbook is ambiguous because “it does”
does not clearly refer back to the fresh `renewTime`. Rephrase the text in the
surrounding runbook section to use an explicit subject, likely by naming
`renewTime` directly in the clause about when the coordinator clears
`super_read_only`, so the timing condition is immediately clear.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
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docs/guides/mysql/dr/_index.mddocs/guides/mysql/dr/guide/index.mddocs/guides/mysql/dr/overview/index.mddocs/guides/mysql/dr/runbook/index.md
Document running a single distributed MySQL across data centers for cross data center disaster recovery. Mirrors the Postgres DR section, adapted to MySQL Group Replication: each Member data center is its own self contained GR cluster, the dr-controlplane primary DC Lease picks the one writable data center, and every standby data center streams a named async replication channel (CHANGE REPLICATION SOURCE ... SOURCE_AUTO_POSITION = 1) from the active data center's primary while GR distributes intra-DC. Adds docs/guides/mysql/dr: - overview: architecture, the GR-never-crosses-DC rule, data center roles, 2-DC vs 3-DC topologies, deploy, status.disasterRecovery, failover, switchover. - guide: components, the DC-name contract, fence (super_read_only, re-asserted after every GR election), GTID and seconds lag, timing invariant, per-DC scaling, DC-aware health, day-2 ops. - runbook: scenario by scenario procedures (active DC loss, partition, planned switchover and failback, stuck switchover, lag, fence tripped, split-brain). Signed-off-by: Tamal Saha <tamal@appscode.com>
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What
Documents running a single distributed
MySQLacross multiple data centers for cross data center disaster recovery (DC-DR). Adds a newdocs/guides/mysql/dr/section, mirroring the Postgres DR section but adapted to MySQL Group Replication.The companion feature work: apimachinery
status.disasterRecovery+spec.distributed(kubedb/apimachinery#1796) and the coordinator fence + cross-DC channel (kubedb/mysql-coordinator#186).Pages
overview/index.md— architecture (the GR-never-crosses-DC rule, each Member DC a self contained GR cluster, thedr-controlplaneLease as the single cross-DC authority, the fail-closedsuper_read_onlyfence, the nameddcdrasync channel viaCHANGE REPLICATION SOURCE ... SOURCE_AUTO_POSITION = 1), data center roles, 2-DC vs 3-DC topologies, deploy,status.disasterRecovery, unplanned failover, planned switchover.guide/index.md— components and where they run, the DC-name contract, operator flags, deploy, connecting, monitoring, replication/lag (GTID gap +Seconds_Behind_Source), the timing invariant, quorum/roles (odd GR group sizes, fence re-assertion after every GR election), switchover/failback (GTID catch-up, clone re-seed), per-DC horizontal scaling, DC-aware health, day-2 ops.runbook/index.md— 14 scenario-by-scenario procedures (active DC loss, partition, planned switchover/failback, coordination-plane down, stuck switchover, growing lag, fence tripped, re-add a DC, scaling, version upgrade, suspected split-brain) plus an escalation checklist.MySQL specifics vs the Postgres DR docs
RemoteReplica), with GR distributing intra-DC; lag is the GTID gap plusSeconds_Behind_Source.super_read_only = ONand is re-asserted after every GR election (GR clears it on its elected primary).Notes
This is forward-looking docs that land with the MySQL DC-DR feature (sibling to the in-flight Postgres DR docs). The one
/docs/guides/postgres/dr/cross-link (SemiSync mode pointer) resolves once the Postgres DR docs section merges.Summary by CodeRabbit