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tt replicaset: add subcommand downgrade
Closes #968 @TarantoolBot document Title: `tt replicaset downgrade` downgrades database schema. The `tt replicaset downgrade` command allows for a automate downgrade of each replicaset in a Tarantool cluster. The process is performed sequentially on the master instance and its replicas to ensure data consistency. Below are the steps involved: For Each Replicaset: - **On the Master Instance**: 1. Run the following commands in sequence to downgrade the schema and take a snapshot: ```lua box.schema.downgrade(<..version..>) box.snapshot() ``` - **On Each Replica**: 1. Wait for the replica to apply all transactions produced by the `box.schema.downgrade` command executed on the master. This is done by monitoring the vector clocks (vclock) to ensure synchronization. 2. Once the repica has caught up, run the following command to take a snapshot: ```lua box.snapshot() ``` > **Error Handling**: If any errors occur during the downgrade process, the operation will halt, and an error report will be generated. --- - Specify the schema version for downgrade The `tt replicaset downgrade` command requires specifying the target version for the schema downgrade. This version should be provided using the `--version` (or `-v`) option. The version must follow the `x.x.x` format, where `x` represents a numerical value. To view the list of available downgrade versions, execute the following command in Tarantool: ```lua box.schema.downgrade_versions() ``` **Example:** ```bash $ tt replicaset downgrade [<APP_NAME> | <URI>] --version 3.0.0 ``` - Timeout for Synchronization Replicas will wait for synchronization for a maximum of `Timeout` seconds. The default timeout is set to 5 seconds, but this can be adjusted manually using the `--timeout` option. **Example:** ```bash $ tt replicaset downgrade [<APP_NAME> | <URI>] -v 3.0.0 --timeout 10 ``` - Selecting Replicasets for Downgrade You can specify which replicaset(s) to downgrade by using the `--replicaset` or `-r` option to target specific replicaset names. **Example:** ```bash $ tt replicaset downgrade [<APP_NAME> | <URI>] -v 3.0.0 replicaset <RS_NAME_1> -r <RS_NAME_2> ... ``` This provides flexibility in downgrading only the desired parts of the cluster without affecting the entire system.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| package replicasetcmd | ||
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| import ( | ||
| _ "embed" | ||
| "fmt" | ||
| "strings" | ||
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| "github.com/mitchellh/mapstructure" | ||
| "github.com/tarantool/tt/cli/connector" | ||
| "github.com/tarantool/tt/cli/replicaset" | ||
| "github.com/tarantool/tt/cli/running" | ||
| ) | ||
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| // DowngradeOpts contains options used for the downgrade process. | ||
| type DowngradeOpts struct { | ||
| // List of replicaset names specified by the user for the downgrade. | ||
| ChosenReplicasetAliases []string | ||
| // Timeout period (in seconds) for waiting on LSN synchronization. | ||
| LsnTimeout int | ||
| // Version to downgrade the schema to. | ||
| DowngradeVersion string | ||
| } | ||
|
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| //go:embed lua/downgrade.lua | ||
| var downgradeMasterLua string | ||
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| func filterComments(script string) string { | ||
| var filteredLines []string | ||
| lines := strings.Split(script, "\n") | ||
| for _, line := range lines { | ||
| trimmedLine := strings.TrimSpace(line) | ||
| if !strings.HasPrefix(trimmedLine, "--") { | ||
| filteredLines = append(filteredLines, line) | ||
| } | ||
| } | ||
| return strings.Join(filteredLines, "\n") | ||
| } | ||
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| // Downgrade downgrades tarantool schema. | ||
| func Downgrade(discoveryCtx DiscoveryCtx, opts DowngradeOpts, | ||
| connOpts connector.ConnectOpts) error { | ||
| replicasets, err := getReplicasets(discoveryCtx) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| replicasets = fillAliases(replicasets) | ||
| replicasetsToDowngrade, err := filterReplicasetsByAliases(replicasets, | ||
| opts.ChosenReplicasetAliases) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| return internalDowngrade(replicasetsToDowngrade, opts.LsnTimeout, | ||
| opts.DowngradeVersion, connOpts) | ||
| } | ||
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| func internalDowngrade(replicasets []replicaset.Replicaset, lsnTimeout int, version string, | ||
| connOpts connector.ConnectOpts) error { | ||
| for _, replicaset := range replicasets { | ||
| err := downgradeReplicaset(replicaset, lsnTimeout, version, connOpts) | ||
| if err != nil { | ||
| fmt.Printf("• %s: error\n", replicaset.Alias) | ||
| return fmt.Errorf("replicaset %s: %w", replicaset.Alias, err) | ||
| } | ||
| fmt.Printf("• %s: ok\n", replicaset.Alias) | ||
| } | ||
| return nil | ||
| } | ||
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| func downgradeMaster(master *instanceMeta, version string) (syncInfo, error) { | ||
| var downgradeInfo syncInfo | ||
| fullMasterName := running.GetAppInstanceName(master.run) | ||
| res, err := master.conn.Eval(filterComments(downgradeMasterLua), | ||
| []interface{}{version}, connector.RequestOpts{}) | ||
| if err != nil { | ||
| return downgradeInfo, fmt.Errorf( | ||
| "failed to execute downgrade script on master instance - %s: %w", | ||
| fullMasterName, err) | ||
| } | ||
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| if err := mapstructure.Decode(res[0], &downgradeInfo); err != nil { | ||
| return downgradeInfo, fmt.Errorf( | ||
| "failed to decode response from master instance - %s: %w", | ||
| fullMasterName, err) | ||
| } | ||
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| if downgradeInfo.Err != nil { | ||
| return downgradeInfo, fmt.Errorf( | ||
| "master instance downgrade failed - %s: %s", | ||
| fullMasterName, *downgradeInfo.Err) | ||
| } | ||
| return downgradeInfo, nil | ||
| } | ||
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| func downgradeReplicaset(replicaset replicaset.Replicaset, lsnTimeout int, version string, | ||
| connOpts connector.ConnectOpts) error { | ||
| master, replicas, err := collectRWROInfo(replicaset, connOpts) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| defer closeConnectors(master, replicas) | ||
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| // Downgrade master instance, collect LSN and IID from master instance. | ||
| downgradeInfo, err := downgradeMaster(master, version) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| // Downgrade replica instances. | ||
| masterLSN := downgradeInfo.LSN | ||
| masterIID := downgradeInfo.IID | ||
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| for _, replica := range replicas { | ||
| fullReplicaName := running.GetAppInstanceName(replica.run) | ||
| err := waitLSN(replica.conn, masterIID, masterLSN, lsnTimeout) | ||
| if err != nil { | ||
| return fmt.Errorf("can't ensure that downgrade operations performed on "+ | ||
| "%s are replicated to %s to perform snapshotting on it: error "+ | ||
| "waiting LSN %d in vclock component %d: %w", | ||
| running.GetAppInstanceName(master.run), fullReplicaName, | ||
| masterLSN, masterIID, err) | ||
| } | ||
| err = snapshot(&replica) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| } | ||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| local version = ... | ||
| local allowed_versions = box.schema.downgrade_versions() | ||
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| local function is_version_allowed(version, allowed_versions) | ||
| for _, allowed_version in ipairs(allowed_versions) do | ||
| if allowed_version == version then | ||
| return true | ||
| end | ||
| end | ||
| return false | ||
| end | ||
|
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| local function format_allowed_versions(versions) | ||
| return "[" .. table.concat(versions, ", ") .. "]" | ||
| end | ||
|
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| local function downgrade_schema(version) | ||
| if not is_version_allowed(version, allowed_versions) then | ||
| local err = ("Version '%s' is not allowed.\nAllowed versions: %s"):format( | ||
| version, format_allowed_versions(allowed_versions) | ||
| ) | ||
| return { | ||
| lsn = box.info.lsn, | ||
| iid = box.info.id, | ||
| err = err, | ||
| } | ||
| end | ||
|
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| local ok, err = pcall(function() | ||
| box.schema.downgrade(version) | ||
| box.snapshot() | ||
| end) | ||
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| return { | ||
| lsn = box.info.lsn, | ||
| iid = box.info.id, | ||
| err = not ok and tostring(err) or nil, | ||
| } | ||
| end | ||
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| return downgrade_schema(version) |
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