GELF

GELF receivers accept UDP JSON, gzip/zlib, and chunked GELF, or uncompressed NUL-delimited JSON over TLS TCP.

Prerequisites

Create a GELF receiver, configure the sender’s public IPv4 or CIDR, wait for active, and copy its exact hostname and assigned port. GELF does not use an access token.

Docker GELF driver

The Docker GELF driver uses UDP because it cannot use TLS for TCP output.

export FLUXTAIL_GELF_HOST='YOUR_POOL_HOSTNAME'
export FLUXTAIL_GELF_PORT='YOUR_ASSIGNED_PORT'

docker run --rm \
  --log-driver=gelf \
  --log-opt "gelf-address=udp://${FLUXTAIL_GELF_HOST}:${FLUXTAIL_GELF_PORT}" \
  --log-opt gelf-compression-type=gzip \
  alpine sh -c 'echo "hello from Docker GELF"'

TLS TCP test

printf '{"version":"1.1","host":"app-1","short_message":"TLS TCP GELF test"}\0' |
  openssl s_client \
    -quiet \
    -verify_return_error \
    -verify_hostname "$FLUXTAIL_GELF_HOST" \
    -servername "$FLUXTAIL_GELF_HOST" \
    -connect "$FLUXTAIL_GELF_HOST:$FLUXTAIL_GELF_PORT"

Compressed TCP is not supported. Use UDP for the Docker driver and small messages. Use TLS TCP when the sender supports GELF framing and delivery matters more than UDP simplicity.

Verify and troubleshoot

Search Live Tail for the test message. If it does not arrive, confirm the endpoint state, public source IPv4 rule, destination port, and TLS hostname. Sender host is log data, not authentication.