IPv6 Socket Binding Issue

Problem Definition

Issue: Address family not supported by protocol

When starting the Monitor container, you see errors in the logs related to IPv6 socket binding:

Error binding socket
error: error creating server listener: Address family not supported by protocol (os error 97)

Or:

Failed to bind to [::]:5044
Address family not supported by protocol

The Monitor container fails to start because the host operating system has IPv6 disabled or restricted, but the container defaults to using IPv6 (::) for socket binding.

Any service that binds to a network socket may be affected, including multiple services in Vector that listen for incoming data (e.g., syslog, API). The root cause is that the default socket address is set to :: (IPv6), which is not supported on hosts with IPv6 disabled.

Solution

Step 1 — Edit the environment file

Open your .env or .env.prod file and set the following variables to force IPv4 binding:

VECTOR_SOCKET_ADDR=0.0.0.0
VECTOR_API_ADDRESS=0.0.0.0:8686

These can be added to your existing env file:

# .env or .env.prod
VECTOR_SOCKET_ADDR=0.0.0.0
VECTOR_API_ADDRESS=0.0.0.0:8686
# ... other variables

Step 2 — Restart the container

Podman:

podman restart mon

Docker:

docker restart mon

Step 3 — Verify

Check that services are now listening on IPv4:

podman exec mon netstat -tlnp

Expected output:

tcp        0      0 0.0.0.0:5044          0.0.0.0:*               LISTEN      <pid>/vector
tcp        0      0 0.0.0.0:5045          0.0.0.0:*               LISTEN      <pid>/vector
tcp        0      0 0.0.0.0:8686          0.0.0.0:*               LISTEN      <pid>/vector

Or check the logs:

podman logs mon --tail 50

You should see services starting successfully without IPv6 binding errors.

Environment Variables

VECTOR_SOCKET_ADDR

The VECTOR_SOCKET_ADDR environment variable controls which network interface Vector binds to:

Value	Description
:: (default)	Bind to all IPv6 interfaces
0.0.0.0	Bind to all IPv4 interfaces
<specific-IP>	Bind to a specific IP address

Note: If your host OS has IPv6 disabled, you must set this to 0.0.0.0.

VECTOR_API_ADDRESS

The VECTOR_API_ADDRESS environment variable controls the Vector API address used for health checks:

Value	Description
[::]:8686 (default)	IPv6 API address
0.0.0.0:8686	IPv4 API address
<specific-IP>:8686	Specific IP address

Note: Should be in IP:PORT format. Must match the socket address family (IPv4 with 0.0.0.0, IPv6 with ::).

Reference

See the Installation Environment Variables documentation for the complete list of available environment variables.