Cluster sync adj in p&a flavour#1814
Cluster sync adj in p&a flavour#1814M4KIF wants to merge 2 commits intofeature/database-controllersfrom
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| CNPG cluster | ||
| Poolers | ||
| Access resources (configmap and secret) | ||
| And all of them needs to be set to Ready for our PostgresCluster phase to become Ready? |
| rewrite to consider taking state of other objects into account | ||
| before declaring readyness. | ||
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| CNPG cluster |
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Correct me if I'm wrong, but what I'm missing in the code is checking if CNPG cluster is ready and if yes then updating our ClusterReady condition to true, so at the end (here) we can check if all conditions are true and set whole custom resource status ready to true
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Currently? Yes, currently It's mostly a scaffolding to which I will place any business logic.
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| return ctrl.Result{}, patchErr | ||
| default: | ||
| if statusErr := updateStatus(clusterReady, metav1.ConditionFalse, reasonClusterBuildSucceeded, |
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Here we are updating the status with clusterReady condition False if we patched CNPG Cluster and requeue.
Shouldnt we in the next reconciliation go again to this check again if CNPG cluster is in desired state:
!equality.Semantic.DeepEqual(currentNormalized, desiredNormalized)and if it is (we are not going inside this if), set the clusterReady condition to true?
Something like:
statusErr := updateStatus(clusterReady, metav1.ConditionTrue...just after this big if block?
Maybe one more CNPG cluster check is needed, just to be sure it's in healthy and ready state, if not then requeue or leave with error?
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actually after thinking about it, it should be probably after reconcileManagedRoles as it's the last thing we are doing with CNPG cluster.
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In general I think It's a bit misleading that we do cluster ready and condtion == false. At least for me, It should be sth like ClusterErrorRetry, like http codes.
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Sorry I think I don't not fully understand that. By cluster do you mean our PostgresClusterCR or Cluster Ready condition (actual CNPG cluster)?
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In general I think It's a bit misleading that we do cluster ready and condtion == false. At least for me, It should be sth like ClusterErrorRetry, like http codes.
This is standard pattern in k8s, we should stick to it. Take a look at our design docs where we map phases and conditions to current situation
| // return ctrl.Result{}, nil | ||
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| type clusterReadynessCheck interface { |
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sound like a great thing to add to the specific port capabilities :-)
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Then the interface here would be implemented by the ports. Clean and nice idea
| pgcConstants "github.com/splunk/splunk-operator/pkg/postgresql/cluster/business/core/types/constants" | ||
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| type Provisioner interface { |
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I think our secondary ports should reflect that we create cluster and database and we should map our interfaces around it.
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| // basically a sync logic | ||
| state := pgcConstants.EmptyState |
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I think the idea here was to decouple status check from cnpg status, At the same time we also check health after every stage and we move forward only if we are ok, if it is still in progress we requeue or raise error. Here we have a code we can use to check where we are with status iteratively, but I dont see yet how it solve our core problem
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we build our state here, after checking all ports for readyness/not dying there is the moment for us to decide what happened and how It happened.
We don't set our state as state == cnpgVariable mapped to ours, we decide what do we want to do with the fact that cm's, secrets, provisioner etc. are ready.
| cnpgv1 "github.com/cloudnative-pg/cloudnative-pg/api/v1" | ||
| enterprisev4 "github.com/splunk/splunk-operator/api/v4" | ||
| clustercore "github.com/splunk/splunk-operator/pkg/postgresql/cluster/core" | ||
| clustercore "github.com/splunk/splunk-operator/pkg/postgresql/cluster/business/core" |
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tbh business string is redundat here. Core itself is already a domain
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I agree It's redundant, here It's a tradeoff for verbosity and segregation of components. And a service pattern at once, ie. the service/ is the primary port (reconciler that we provide) implementation. core/ is core, and ports/ are the contracts that we need for the core to work. They can grow large, hence the whole separate dir for ports.
| cnpgCluster *cnpgv1.Cluster | ||
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| func (c *provisionerHealthCheck) Condition() (pgcConstants.State, error) { |
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I think all of this conditions check should be part of our Ports, also how you want to map condition to phase?
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I agree, they were placed here as what I need. Solving It like you say is the thing I'm hoping for. For the provisioner/cluster etc. ports to include an interface for checking It's state.
Then the adapter would be essentially mapping the dependency state to our abstraction of It's state. Ie. we have cluster ready, provisioning, failover, cupcake, coffee etc.
Mapping condition to phase would be the job of the facade, ie. the cluster.go. That would be the whole operational brain behind. Ie. lot's of individual pieces funneled into our business decisions.
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Sth. like a stateMapper, or another objects that specialises in deciding on what phase/condition we're in could also be born. The bit mask could be used for covering the phase 1, ie. state = FinaliserNotAdded && !ClusterProvisioning etc.
Phase 2 -> state == Finaliser && ClusterReady etc.
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| func (p *poolerHealthCheck) Condition() (pgcConstants.State, error) { | ||
| return pgcConstants.PoolerReady, nil |
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how do we want to check the actual condition component has in status?
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wdym? It's kind of the job of the adapter to test and provide that the state is actual. Ie. If we place this as a method of a port, and implement It via adapters. We actually won't work on the real state of the component in our core. Only on our understanding of It.
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Currently It would be just to copy paste the thing that we do inside cluster.go, ie. the resource obj. of the Pooler, k8s.Get(obj, ...) and all similar. As there is no abstraction currently.
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| const ( | ||
| ComponentsReady = PoolerReady | ProvisionerReady | SecretReady | ConfigMapReady |
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what we try to achieve here? Is it a bitmask? Since you use IOTA we endup in having just random integer?
That would be probably simpler to just use struct with keeping the state like that:
type ClusterState struct {
Provisioner ComponentPhase
Pooler ComponentPhase
ConfigMap ComponentPhase
Secret ComponentPhase
}
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It's a bitmask. And It does the same job of keeping a struct with aditional field.
And It kinda solves the case of having to create new types just for each component.
Just adding additional states to the state machine, ie. the values in the "enum". The iota usage is an enum in go: https://yourbasic.org/golang/iota/
It's the first usage in this file, hence It's basically an enum from 0
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And It kinda solves the case of having to create new types just for each component.
We already create types for a new component for many reasons, so what problem it really solve? I agree it is smart way of doing this, but neverthless if new component arise you need to add it to the const and extend types. I feel like we trade go readability for a really small c-like optimisation especially with this model of bitwise comparision later:
state |= componentHealth.State
if state&pgcConstants.ComponentsReady == pgcConstants.ComponentsReady
Also, if we build state incrementally it means that the LAST successful state in state machine is an final success. With this in mind we dont need to check every other component state afterwards.
Can we do this simpler so when Im wake up at 5am in the morning I easily understand the code?
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I agree that this state check, after the iteration health check passes is redundant here.
And taking into consideration the potential future work. Which could include a file division.
I could expand the *healthCheck types with them returning the *(component)StateDto instead of relying on generic state bits.
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Because later, in the very near future It seems that the project could follow this footstep of having some separation in phases and It's crucial elements. Like we've discussed on the p&a ideas brainstorm.
| rc.emitPoolerReadyTransition(postgresCluster, poolerOldConditions) | ||
| } | ||
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| if state&pgcConstants.ComponentsReady != 0 { |
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Not sure if this logic is not broken. What happens if we set ProvisionerReady but later in stage we set failed for something. Sue to way we set state and components this would pass. I think it is because iota incrementing by 1 not by power of 2? I think we should rely not on bitmasking here, but simple struct with state for every stage and if all is good we are good
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with unsetting the bit's at any space, this condition starts failing. As well as with not setting the bits, the values don't AND, hence if we mark ProvisionerReady and then set masks for ConfigMapFailed, it won't fire.
And to prove how this logic would work, there would be tests that would make sure any misfires aren't possible.
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| oldPhase = *postgresCluster.Status.Phase | ||
| // Aggregate component readiness from iterative health checks. | ||
| state := pgcConstants.EmptyState | ||
| conditions := []clusterReadynessCheck{ |
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so after every phase that is not immediate like cluster creation we should also incorporate state check rediness. I think we discussed that we dont really need to check at the end assuming we check intermediary statuses per phase?
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I agree with that, but Isn't then the scope == refactor the reconciler?
I've tried to stick with changing the sync logic and doing the ground prep for more changes in coming tickets and potential p&a rework.
| for _, check := range conditions { | ||
| componentHealth, err := check.Condition(ctx) | ||
| if err != nil { | ||
| if statusErr := updateStatus(componentHealth.Condition, metav1.ConditionFalse, componentHealth.Reason, componentHealth.Message, componentHealth.Phase); statusErr != nil { |
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If we run this at the end of reconcillation it seems that some of the code is dead i.e if we are here, we cannot have a configmap or secret orphaned. If we do it should be discovered during this phase and requeue/err
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| return ctrl.Result{}, statusErr | ||
| } | ||
| logger.Error(err, "Component health check reported issues", |
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Please follow our logging strategy: https://splunk.atlassian.net/wiki/spaces/CCP/pages/1079831167399/PostgreSQL+Controllers+Logging+Strategy
| return componentHealth.Result, err | ||
| } | ||
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| if isPendingState(componentHealth.State) { |
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If we run this code on every phase separately, here we should requeue
| if postgresCluster.Status.Phase != nil { | ||
| newPhase = *postgresCluster.Status.Phase | ||
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| if state&pgcConstants.ComponentsReady == pgcConstants.ComponentsReady { |
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thois could be potentially method on a state so it reads natually at 4 am i.e
func (s State) HasAll(required State) bool {
return s&required == required
}
if state.HasAll(pgcConstants.ComponentsReady) {}
| return &provisionerHealthCheck{cluster: cluster, cnpgCluster: cnpgCluster} | ||
| } | ||
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| func (c *provisionerHealthCheck) Condition(_ context.Context) (StateInformationDto, error) { |
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I like providing interface like that! One doubt I have is about pureness and responsiblity of those condition methods. They check conditions but also fetch k8s objects. IMO k8s objects should be evaluated and the reconciller kickoff and propagated
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I like the direction we are heading two!
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Description
Rewritten the sync logic
Key Changes
Testing and Verification
local integ suite passes (make test) and units (pkg/postgres/cluster/core go test) passes
Related Issues
Jira tickets, GitHub issues, Support tickets...
PR Checklist