updates to flowchart

docs/DESIGN.md

@@ -7,64 +7,67 @@ primitives and gives an overview of the underlying implementation.
 
 ```mermaid
 flowchart TD
- Start(Start) --> A0[Ensure service.]
- A0 --> A1[Connect to the cluster\nand fetch all statuses.]
- A1 --> |Got some response| AA{All reachable\nmembers have the\nsame cluster ID?}
- AA --> |Yes| AAA{Is cluster\nin quorum?}
- AAA --> |Yes| AAAA{Are all members \nmanaged by the operator?}
- AAAA --> |Yes| AAAAA0[Promote any learners.]
- AAAAA0 --> |OK| AAAAA1[Ensure configmap with initial cluster\nmatching existing members and\ncluster state=existing]
- AAAAA1 --> |OK| AAAAA2[Ensure StatefulSet with\nreplicas = max member ordinal + 1]
- AAAAA2 --> |OK| AAAAAA{Are all\nmembers healthy?}
- AAAAAA --> |Yes| AAAAAAA{Are all STS pods present\nin the member list?}
- AAAAAAA --> |Yes| AAAAAAAA{Is the\nEtcdCluster\nsize equal to the\nStatefulSet\nsize?}
- AAAAAAAA -->|Yes| AAAAAAAAA[Set cluster\nstatus to ready.]
- AAAAAAAAA --> HappyStop([Stop])
-
- AAAAAAAA --> |No, desired\nsize larger| AAAAAAAAB[Ensure ConfigMap with\ninitial cluster state existing\nand initial cluster URLs\nequal to current cluster\nplus one member, do\n'member add' API call and\nincrement StatefulSet size.]
- AAAAAAAAB --> ScaleUpStop([Stop])
-
- AAAAAAAA --> |No, desired\nsize smaller| AAAAAAAAC[Member remove API\ncall, then decrement\nStatefulSet size\nthen delete PVC.]
- AAAAAAAAC --> ScaleDownStop([Stop])
-
- AAAAAAAA --> |Etcd replicas=0\nSTS replicas=1| AAAAAAAAD[Decrement\nSTS to zero]
- AAAAAAAAD --> ScaleToZeroStop([Stop])
-
- AAAAAA --> |No| AAAAAAB1[On timeout evict member.]
- AAAAAAB1 --> AAAAAAB2[Delete PVC, ensure ConfigMap with\nmembers + this one and delete pod.]
-
- AAAAAAA --> |No| AAAAAAB2
-
- AAAAA0 -->|Error| AAAAAB([Requeue])
- AAAAA1 -->|Error| AAAAAB([Requeue])
- AAAAA2 -->|Error| AAAAAB([Requeue])
-
- AAAA --> |No| AAAAB([Not implemented,\nstop.])
-
- AAA --> |No| AAAB([Either the cluster will\nsoon recover when\nall pods are back online\nor something caused\ndata loss and majority\n failure simultaneously.])
-
- AA --> |No| AAB[Cluster is in\nsplit-brain. Set\nerror status.]
- AAB --> AABStop([Stop])
-
- A1 --> |No members\nreached| AB{Is the correct\nzero-replica STS\npresent?}
- AB --> |Yes| ABA{EtcdCluster\n.spec.replicas==0?}
- ABA --> |Yes| ABAA([Cluster successfully\nscaled to zero, stop.])
- ABA --> |No| ABAB[Ensure ConfigMap with\ninitial cluster = new,\ninitial cluster peers with\nsingle member `name`-0]
- ABAB --> |OK| ABABA[Increment STS size.]
- ABABA --> |OK| ABABAA([Stop])
- ABABA --> |Error| ABABAB([Requeue])
-
- ABAB --> |Error| ABABAB
-
- AB --> |No| ABB{Is the STS\npresent at all?}
- ABB --> |Yes| ABBA[Patch the STS,\nexcept for replicas]
- ABBA --> |OK| ABBAA([Stop])
- ABBA --> |Error| ABBAB([Requeue])
-
- ABB --> |No| ABBB[Create a zero-\nreplica STS]
- ABBB --> |OK| ABBBA([Stop])
- ABBB --> |Error| ABBBB([Requeue])
-
- A0 --> |Unexpected\nerror| AC(Requeue)
- A1 --> |Unexpected\nerror| AC(Requeue)
+ Start(Start) --> A[Ensure service.]
+ A --> AA{Are there any\nendpoints?}
+ AA --> |Yes| AAA[Connect to the cluster\nand fetch all statuses.]
+ AAA --> |Got some response| AAAA{All reachable\nmembers have the\nsame cluster ID?}
+ AAAA --> |Yes| AAAAA{Is cluster\nin quorum?}
+ AAAAA --> |Yes| AAAAAA{Are all members \nmanaged by the operator?}
+ AAAAAA --> |Yes| AAAAAAA["`
+ Promote any learners.
+ Ensure configmap with initial cluster matching existing members and cluster state=existing.
+ Ensure StatefulSet with replicas = max member ordinal + 1
+ `"]
+ AAAAAAA --> |OK| AAAAAAAA{Are all\nmembers healthy?}
+ AAAAAAAA --> |Yes| AAAAAAAAA{Are all STS pods present\nin the member list?}
+ AAAAAAAAA --> |Yes| AAAAAAAAAA{Is the\nEtcdCluster\nsize equal to the\nStatefulSet\nsize?}
+ AAAAAAAAAA -->|Yes| AAAAAAAAAAA[Set cluster\nstatus to ready.]
+ AAAAAAAAAAA --> HappyStop([Stop])
+
+ AAAAAAAAAA --> |No, desired\nsize larger| AAAAAAAAAAB[Ensure ConfigMap with\ninitial cluster state existing\nand initial cluster URLs\nequal to current cluster\nplus one member, do\n'member add' API call and\nincrement StatefulSet size.]
+ AAAAAAAAAAB --> ScaleUpStop([Stop])
+
+ AAAAAAAAAA --> |No, desired\nsize smaller| AAAAAAAAAAC[Member remove API\ncall, then decrement\nStatefulSet size\nthen delete PVC.]
+ AAAAAAAAAAC --> ScaleDownStop([Stop])
+
+ AAAAAAAAAA --> |Etcd replicas=0\nSTS replicas=1| AAAAAAAAAAD[Decrement\nSTS to zero]
+ AAAAAAAAAAD --> ScaleToZeroStop([Stop])
+
+ AAAAAAAA --> |No| AAAAAAAAB1[On timeout evict member.]
+ AAAAAAAAB1 --> AAAAAAAAB2[Delete PVC, ensure ConfigMap with\nmembers + this one and delete pod.]
+
+ AAAAAAAAA --> |No| AAAAAAAAB2
+
+ AAAAAAA -->|Error| AAAAAAAB([Requeue])
+
+ AAAAAA --> |No| AAAAAAB([Not implemented,\nstop.])
+
+ AAAAA --> |No| AAAAAB([Either the cluster will\nsoon recover when\nall pods are back online\nor something caused\ndata loss and majority\n failure simultaneously.])
+
+ AAAA --> |No| AAAAB[Cluster is in\nsplit-brain. Set\nerror status.]
+ AAAAB --> AAAABStop([Stop])
+
+ AAA --> |No members\nreached| AAAB{Is the STS\npresent?}
+ AAAB --> |Yes| AAABA{"`Does it have the correct pod spec?`"}
+ AAABA --> |Yes| AAABAA(["`The statefulset cannot be ready, as the ready and liveness probes must be failing. Hope it becomes ready or wait for user intervention.`"])
+ AAABA --> |No| AAABAB["`Patch the podspec`"]
+
+ AAAB --> |No| AAABB(["`Looks like it was deleted with cascade=orphan. Create it again and see what happens`"])
+
+ AA --> |No| AAB{Is the STS\npresent?}
+ AAB --> |Yes| AABA{Does it have the\ncorrect pod spec?}
+ AABA --> |Yes| AABAA{Is it\nready?}
+ AABAA --> |Yes| AABAAA{Then it must have\nspec.replicas==0\n Is EtcdCluster\n.spec.replicas==0?}
+ AABAAA --> |Yes| AABAAAA([Cluster successfully\nscaled to zero, stop.])
+ AABAAA --> |No| AABAAAB["`
+ Ensure ConfigMap with initial cluster = new,
+ initial cluster peers with single member name-0,
+ increment STS size.
+ `"]
+
+ AABAA --> |No| AABAAB([Stop and wait, either\nit will turn ready soon\nand the next reconcile\nwill move things along,\nor user intervention is\nneeded])
+
+ AABA --> |No| AABAB[Patch the podspec]
+
+ AAB --> |No| AABB[Create configmap, initial state new\ninitial cluster according to spec.\nreplicas, create statefulset.]
 ```