srt-redundancy-gateway

Dockerized MPEG-TS over SRT redundancy gateways built with TSDuck.

Architecture

Input failover (compose/input-failover.yml)

• tsswitch listens on PRIMARY_LISTEN_PORT and BACKUP_LISTEN_PORT.
• Input 0 is preferred (--primary-input 0); failover happens on receive timeout.
• Selected output is exposed on INPUT_FAILOVER_OUTPUT_LISTEN_PORT.
• --event-udp events can be consumed by input-event-observer (observability profile).

Output failover (compose/output-failover.yml)

• tsswitch listens on NODE_A_PORT and NODE_B_PORT; selected output is exposed on OUTPUT_FAILOVER_OUTPUT_LISTEN_PORT.
• watchdog/watchdog.py polls NODE_A_HEALTH_URL and NODE_B_HEALTH_URL (optional regex matchers).
• Watchdog controls tsswitch over UDP remote commands and reads --event-udp events.
• Policy: prefer A; switch to B only when A is stably unhealthy and B is stably healthy; fail back when A is stably healthy.

Both gateways wrap SRT legs with -I fork "tsp -I srt ... -O file -" so dropped sessions can restart without retiring a leg.

Setup

cp .env.example .env

Optional (only if tsp is not installed locally and you run examples/*.sh):

make build-tsduck-tools-local

Input failover demo

make up-input-demo

Generate traffic:

bash examples/generate-primary.sh
bash examples/generate-backup.sh

Verify failover by stopping generate-primary.sh; output remains available on INPUT_FAILOVER_OUTPUT_LISTEN_PORT.

Output failover demo

make up-output-demo-health

Generate traffic and consume output:

bash examples/generate-node-a.sh
bash examples/generate-node-b.sh
bash examples/consume-output-output.sh

Trigger node A health changes:

bash examples/set-health.sh 18081 unhealthy
bash examples/set-health.sh 18081 healthy

Bridge connectors (output mode)

Enable:

docker compose -f compose/output-failover.yml --profile bridge-connectors up --build

Relevant envs:

• BRIDGE_A_SOURCE_HOST / BRIDGE_A_SOURCE_PORT
• BRIDGE_B_SOURCE_HOST / BRIDGE_B_SOURCE_PORT
• BRIDGE_A_TARGET_HOST / BRIDGE_A_TARGET_PORT
• BRIDGE_B_TARGET_HOST / BRIDGE_B_TARGET_PORT

SRT flag overrides

Input:

• INPUT_SRT_SOURCE_COMMON_FLAGS
• INPUT_SRT_PRIMARY_EXTRA_FLAGS
• INPUT_SRT_BACKUP_EXTRA_FLAGS
• INPUT_SRT_OUTPUT_EXTRA_FLAGS

Output:

• OUTPUT_SRT_SOURCE_COMMON_FLAGS
• OUTPUT_SRT_NODE_A_EXTRA_FLAGS
• OUTPUT_SRT_NODE_B_EXTRA_FLAGS
• OUTPUT_SRT_OUTPUT_EXTRA_FLAGS

Example:

INPUT_SRT_SOURCE_COMMON_FLAGS="--multiple --transtype live --messageapi --passphrase input-secret --pbkeylen 16"
OUTPUT_SRT_NODE_A_EXTRA_FLAGS="--passphrase node-a-secret --pbkeylen 16"
OUTPUT_SRT_NODE_B_EXTRA_FLAGS="--passphrase node-b-secret --pbkeylen 16"

Observability

Start both gateways with shared observability stack:

make up-all

Endpoints:

• Input observer metrics: http://127.0.0.1:9107/metrics (when input observability profile is enabled)
• Output watchdog metrics: http://127.0.0.1:9108/metrics
• Prometheus: http://127.0.0.1:9090
• Grafana: http://127.0.0.1:3000 (admin / admin)
• Tempo: http://127.0.0.1:3200
• OTEL Collector: 127.0.0.1:4318 (HTTP), 127.0.0.1:4317 (gRPC)

Key metrics:

• gateway_active_input
• gateway_waiting_for_input
• watchdog_switch_commands_total
• watchdog_switch_events_total
• watchdog_node_health
• watchdog_health_checks_total
• gateway_bytes_total

Publishing

See scripts/README.md.