🦚 Peacock Unified

🏗️ App Invariants

Layer 2 — application architecture · 1,820 documents

IDDocumentSource
app_invariants__d4e89875a3f3fcf8INVARIANT: Producers must provide deterministic sequence IDs per Partition to prevent duplicate records during retries. SHADOW: In distributed writes, network failures often mask the success of an…—
app_invariants__31fd487ad05d1684INVARIANT: Topic-level configuration overrides must be synchronized across all log directory replicas to ensure consistency. SHADOW: When broker-wide or topic-specific configurations change, the…—
app_invariants__7b254e7c01d0a05bINVARIANT: Client-provided identifiers must be deterministic, non-empty, and adhere to structural decoding constraints. SHADOW: The system validates client identity via UUID-based decoding. Empty or…—
app_invariants__d3db1c66739ac4caINVARIANT: Resource lifecycle and configuration state must be isolated from concurrent modifications by deduplicating and validating incoming alter-config requests. SHADOW: The system enforces…—
app_invariants__5ea179f787c1e669INVARIANT: Resource consumption and throttling metrics must be computed against a strictly bounded window of historical activity. SHADOW: Throttle calculations rely on a quota window size and…—
app_invariants__6d9440b2d5000941INVARIANT: Log directory failures must transition affected partitions to an offline state, preventing silent data corruption or partial write success. SHADOW: If a disk write fails during log…—
app_invariants__32db47c3289d43a1INVARIANT: READ_COMMITTED fetches are strictly bounded by the Last Stable Offset (LSO). SHADOW: Ensures transactional isolation by preventing consumers from seeing data belonging to open or aborted…—
app_invariants__9a40e400c1718c1eINVARIANT: Leader Epochs provide monotonic fencing for all fetch and append operations. SHADOW: Prevents 'zombie' leaders or stale followers from corrupting state. Any request with an epoch lower…—
app_invariants__16ec29b2eba33826INVARIANT: Leadership transitions (Leader to Follower) must trigger an atomic purge of the operation Purgatory. SHADOW: Operations like 'DelayedProduce' or 'DelayedFetch' are context-specific to the…—
app_invariants__96803e600222b9e5INVARIANT: Producer sequence numbers must be contiguous and strictly increasing per Producer ID. SHADOW: Maintains deterministic log ordering. The system rejects out-of-order sequence numbers with…—
app_invariants__95ff650250f3f328INVARIANT: Tiered Storage reads are governed by asynchronous fetch quotas and throttle-time sensors. SHADOW: Prevents remote storage (S3/GCS) latency from saturating broker I/O threads. When quotas…—
app_invariants__4e767607fbde0cdbINVARIANT: Transactional appends require synchronous partition verification with the Transaction Coordinator before log insertion. SHADOW: A 'Verification Guard' prevents 'hanging transactions' by…—
app_invariants__d416343e00a078e4INVARIANT: High Watermark checkpoints must be persisted to local storage before a clean shutdown is acknowledged. SHADOW: The High Watermark (HW) defines the 'committed' line. Loss of this state…—
app_invariants__2983f9d7ec2f63abINVARIANT: Metadata replication logs must remain consistent across all controller nodes and brokers during lifecycle transitions. SHADOW: The cluster relies on a unified view of state, specifically…—
app_invariants__b20938da2ca5bccbINVARIANT: Resource utilization metrics must trigger predictable throttling behavior when quotas are breached. SHADOW: Rate limiting (token buckets) is applied to prevent noisy neighbors or runaway…—
app_invariants__d3db5fd53dd73019INVARIANT: Registration and configuration updates must be idempotent to tolerate network partitions and retries. SHADOW: During a broker or controller lifecycle transition, heartbeat and…—
app_invariants__c7e27ae8d2b635bbINVARIANT: During KRaft node initialization, the node's configured identifier and the cluster identifier must precisely match the values persisted in its metadata log directories. SHADOW: Failure to…—
app_invariants__e449a7eab23e8b20INVARIANT: Each active log directory must be exclusively locked by a single Kafka process to prevent concurrent writes and ensure data integrity. SHADOW: Without exclusive access, multiple processes…—
app_invariants__6a981c10543abd16INVARIANT: For any given topic partition, the leader epoch must strictly and monotonically increase with each new leader election, and all records appended to that partition must be stamped with the…—
app_invariants__bcf71aa7694e3e96INVARIANT: When enabled for a producer (explicitly or via transactions), the Kafka broker must guarantee that duplicate produce requests for the same batch are detected and prevented from…—
app_invariants__075a1bc9c736e8f7INVARIANT: All client requests are subjected to dynamically configured connection and request rate quotas (per client ID, user, or IP address), and any request exceeding its allocated quota must be…—
app_invariants__1d047aff54725f40INVARIANT: Every client-initiated operation must be validated against the active Access Control List (ACL) policy for the requested resource and operation, and unauthorized requests must be…—
app_invariants__14a57e4e0ac56831INVARIANT: All configured metadata log directories must be available and readable for a KRaft node to start and participate in the quorum, guaranteeing access to the foundational cluster…—
app_invariants__dc04e21988f31f90INVARIANT: For transactional producers, all operations (produce, offset commit) within a transaction across multiple partitions, topics, and consumer groups are committed or aborted as a single,…—
app_invariants__89662448ec1c89f9INVARIANT: Authentication state is a transient barrier that must allow for logical recovery upon credential synchronization without requiring process-level restarts. SHADOW: In…—
app_invariants__e9ff572b4d5b1e4dINVARIANT: Resource consumption is governed by a multi-dimensional quota hierarchy where throughput is throttled via artificial latency to maintain cluster-wide stability. SHADOW: BaseQuotaTest and…—
app_invariants__071a5c92ecc1c45bINVARIANT: Transactional visibility is binary; records produced within a transaction remain logically non-existent to committed-read consumers until the commit marker is finalized in the…—
app_invariants__7e34de9fcce4946fINVARIANT: The cluster's 'Source of Truth' is maintained through a replicated metadata log where snapshots provide a point-in-time recovery baseline for the quorum. SHADOW: RaftClusterSnapshotTest…—
app_invariants__f3711032ead485daINVARIANT: Consumer group membership is a durable state that requires explicit signals (LeaveGroup) or heartbeat timeouts to trigger partition redistribution. SHADOW: PlaintextConsumerTest shows…—
app_invariants__168b5dc96965fa45INVARIANT: Read-load distribution can be offloaded to followers only when the follower's log state is sufficiently caught up to the leader's high-water mark. SHADOW: FetchFromFollowerIntegrationTest…—
app_invariants__380c9a57099b7271INVARIANT: Authorization is a mandatory, non-bypassable gate where every operation must map a Principal to a Resource via an explicit Allow/Deny binding. SHADOW: EndToEndAuthorizationTest and…—
app_invariants__24f8526eeabad057INVARIANT: Log integrity is maintained through physical segment validation, where index files must strictly map to log offsets to prevent data corruption during retrieval. SHADOW: DumpLogSegments…—
app_invariants__eb7ac6edb8cd2e88INVARIANT: A client tool must connect to the cluster via a single, unambiguous authority; it cannot simultaneously target both the data plane (brokers) and the control plane (controllers) for…—
app_invariants__e319d350c9705254INVARIANT: A batch operation request must contain a unique set of targets; duplicate entries are rejected to enforce explicit and unambiguous intent. SHADOW: This prevents user error where the same…—
app_invariants__04eabb37c27abd47INVARIANT: Quorum management operations must rigorously validate a node's configured identity and role before execution, rejecting actions on nodes that do not explicitly identify as…—
app_invariants__051163f552904692INVARIANT: A stateful stream processing application's state cannot be reset while the application is active. SHADOW: This prevents race conditions and guarantees the atomicity of the reset…—
app_invariants__88fb9d3307ab3747INVARIANT: The canonical state of a message range is derived by merging overlapping or contiguous state-change batches, where a newer batch's state supersedes an older one's within their intersecting…—
app_invariants__e9a252db08fb8f2dINVARIANT: A state log can only be safely truncated up to the lowest offset still referenced by any active stateful entity, ensuring no essential history is prematurely deleted. SHADOW: This…—
app_invariants__20861bf28abe7914INVARIANT: Critical cluster operations like leader election must be invoked with a single, unambiguous target scope, preventing conflicting or incomplete specifications. SHADOW: This design forces…—
app_invariants__2febb3809fa9858bINVARIANT: The observable output of a command-line interface must be captured and isolated during testing to validate its behavior without interfering with the test runner's own output. SHADOW: This…—
app_invariants__bd963eec86abee82INVARIANT: The rate of operations is constrained by ensuring that no more than a configured maximum number of operations can be initiated within a fixed time window. If the limit is reached, the…—
app_invariants__06ecb6196b901351INVARIANT: A batch of source records and their corresponding source offsets are committed as a single, indivisible unit using a Kafka transaction. The transaction encapsulates both the production of…—
app_invariants__5c1bc96a510bb1e5INVARIANT: The in-memory state of a system component, such as consumer group offsets, is reconstructed by sequentially reading and applying every record from a durable, append-only log. The final…—
app_invariants__843b4a3968c77590INVARIANT: Given a stable set of consumer group members, their subscriptions, and topic metadata, a partition assignment algorithm deterministically calculates a non-overlapping distribution of…—
app_invariants__4893c149aa10ee0bINVARIANT: A data record is processed through an ordered, multi-stage pipeline of transformations. Each stage may conditionally apply its logic based on a predicate. The entire chain is governed by a…—
app_invariants__bf411279d84c67f4INVARIANT: Offset commit operations must be idempotent and strictly ordered per partition. SHADOW: Ensures that re-processing or retrying offset commits does not result in data duplication or loss,…—
app_invariants__8c68d350663cba26INVARIANT: Distributed state transitions (rebalancing) require a global view of configuration and task assignment. SHADOW: Prevents split-brain scenarios where multiple workers attempt to manage the…—
app_invariants__f31f78d83eb4cc78INVARIANT: Connector configuration updates must be applied atomically across the cluster. SHADOW: Guarantees that all workers in a cluster operate on the same version of a connector's configuration,…—
app_invariants__2337c374bff883cfINVARIANT: Task execution must respect backpressure signals from the underlying consumer/producer buffers. SHADOW: Prevents memory exhaustion and system instability by throttling task processing…—
app_invariants__285e203ca207eb63INVARIANT: Task status and offset persistence must be decoupled from the volatile memory of the worker. SHADOW: Enables fault tolerance by ensuring that task progress and health status survive…—