KubeMQ
ConnectorsGoogle Cloud Pub/SubReference

Configuration reference

The thirteen CONNECTORS_GCP_* environment variables for the KubeMQ Pub/Sub connector, with defaults and TOML/env/Docker examples.

All values below are verified against [Connectors.Gcp] (GcpConfig) in the KubeMQ server. For the framing behind these settings — enabling the connector and its security posture — see Configuration concepts.

Configuration fields

Compound camelCase fields are snake-split in their env form — e.g. MaxMessageBytes → CONNECTORS_GCP_MAX_MESSAGE_BYTES, DefaultAckDeadlineSeconds → CONNECTORS_GCP_DEFAULT_ACK_DEADLINE_SECONDS.

Env varDefaultMeaning / validation
CONNECTORS_GCP_ENABLEfalseOpt-in. true enables the connector and binds port 8085.
CONNECTORS_GCP_PORT"8085"The gRPC listen port (the emulator convention). Must be valid and distinct from any enabled gRPC/REST/HTTP or AWS-connector port.
CONNECTORS_GCP_ADVERTISED_ENDPOINT""Cosmetic host:port shown in the dashboard's PUBSUB_EMULATOR_HOST hint. Does not affect listening.
CONNECTORS_GCP_MAX_MESSAGE_BYTES10485760Max total message size (10 MiB). Also sizes the gRPC receive frame.
CONNECTORS_GCP_DEFAULT_ACK_DEADLINE_SECONDS10Default ack deadline for new subscriptions. Must be 10..600.
CONNECTORS_GCP_MAX_OUTSTANDING_MESSAGES1000Per-StreamingPull-stream flow-control ceiling when the client requests unlimited.
CONNECTORS_GCP_MAX_INFLIGHT_PER_SUBSCRIPTION20000Hard cap on leased (un-acked) messages per subscription.
CONNECTORS_GCP_MAX_CONCURRENT_POLLS1024Poller-slot budget (a DoS guard).
CONNECTORS_GCP_DELIVERY_SHARDS16Size of the striped delivery-worker pool (fan-out concurrency). Must be 1..256.
CONNECTORS_GCP_MAX_ACK_EXTENSION_SECONDS600Ack-deadline keep-alive budget for the ordered head. 0 disables the keep-alive (expiry → redeliver); otherwise 10..3600.
CONNECTORS_GCP_STREAM_CLOSE_SECONDS1800Periodic StreamingPull close interval (forces a transparent SDK reconnect; bounds per-stream resource lifetime).
CONNECTORS_GCP_MAX_SEEK_REPLAY1000000Max messages replayed by a single Seek (hits the cap → WARN, never silent loss).
CONNECTORS_GCP_ENABLE_REFLECTIONfalseRegister gRPC server reflection (for debugging).

Validate() is a no-op when the connector is disabled. When enabled, the port must be valid and unique, the ack deadline must be 10..600, DeliveryShards must be 1..256, MaxAckExtensionSeconds must be 0 or 10..3600, and the six remaining numeric knobs must be positive. See Limits & rules for the full numeric table.

Examples

The same settings can be supplied through a TOML config file, environment variables, or docker run flags. Every environment variable uses the CONNECTORS_GCP_ prefix (with the underscore between CONNECTORS and GCP).

config.toml
[Connectors.Gcp]
  Enable = true
  Port = "8085"
  AdvertisedEndpoint = ""
  MaxMessageBytes = 10485760
  DefaultAckDeadlineSeconds = 10
  MaxOutstandingMessages = 1000
  MaxInflightPerSubscription = 20000
  MaxConcurrentPolls = 1024
  DeliveryShards = 16
  MaxAckExtensionSeconds = 600
  StreamCloseSeconds = 1800
  MaxSeekReplay = 1000000
  EnableReflection = false
gcp.env
CONNECTORS_GCP_ENABLE=true
CONNECTORS_GCP_PORT=8085
CONNECTORS_GCP_ADVERTISED_ENDPOINT=
CONNECTORS_GCP_MAX_MESSAGE_BYTES=10485760
CONNECTORS_GCP_DEFAULT_ACK_DEADLINE_SECONDS=10
CONNECTORS_GCP_MAX_OUTSTANDING_MESSAGES=1000
CONNECTORS_GCP_MAX_INFLIGHT_PER_SUBSCRIPTION=20000
CONNECTORS_GCP_MAX_CONCURRENT_POLLS=1024
CONNECTORS_GCP_DELIVERY_SHARDS=16
CONNECTORS_GCP_MAX_ACK_EXTENSION_SECONDS=600
CONNECTORS_GCP_STREAM_CLOSE_SECONDS=1800
CONNECTORS_GCP_MAX_SEEK_REPLAY=1000000
CONNECTORS_GCP_ENABLE_REFLECTION=false
docker run -d \  --name kubemq \  -p 8085:8085 \  -p 50000:50000 \  -e KUBEMQ_TOKEN=YOUR_LICENSE_KEY \  -e CONNECTORS_GCP_ENABLE=true \  -e CONNECTORS_GCP_ADVERTISED_ENDPOINT=kubemq.example.com:8085 \  -e CONNECTORS_GCP_MAX_INFLIGHT_PER_SUBSCRIPTION=50000 \  europe-docker.pkg.dev/kubemq/images/kubemq:next

The Docker example includes CONNECTORS_GCP_ENABLE=true — without it the connector stays disabled and port 8085 is not bound. CONNECTORS_GCP_ADVERTISED_ENDPOINT is a cosmetic dashboard hint (the PUBSUB_EMULATOR_HOST value to copy); it never changes the listening port.

Getting Started

Point your Pub/Sub SDK at port 8085 and run a publish-and-pull round-trip end-to-end in minutes.

Architecture

The gRPC emulator listener, the 38-RPC surface, and the publish-once-then-fan-out model.

Connectivity & emulator mode

The PUBSUB_EMULATOR_HOST drop-in, per-language emulator opt-in, and the insecure-gRPC posture.

Limits & rules

Ack deadline, max delivery attempts, filter and schema sizes, batch caps, and the config ceilings.

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Channel Mapping

How Pub/Sub topics and subscriptions map to KubeMQ — the gcp.{topic} Events Store log, the gcp.sub.{subscription} Queue grammar, reserved tags, and project.

Connections & Observability

The Pub/Sub connector's observability surface — the read-only management view, Prometheus metrics, the dashboard page, and the audit events it emits.

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Configuration fieldsExamplesRelated