Synapse doesn't start if the signing key file contains a newline

[thibaultamartin]

Description

When deploying a synapse instance I copied a /data/mydomain.signing.key file which contained the line Synapse had generated on first start and a new line.

Synapse didn't start and complained with

Starting synapse with args -m synapse.app.homeserver --config-path /data/homeserver.yaml

Error in configuration:
  Error reading signing_key: not enough values to unpack (expected 3, got 0)

Steps to reproduce

• Generate a new configuration file for Synapse.
• Add a newline in /data/yourdomain.signing.key
• Start the container.

Homeserver

Container based deployment

Synapse Version

1.66.0

Installation Method

Docker (matrixdotorg/synapse)

Platform

Rocky Linux 8.5 & Podman

Relevant log output

Starting synapse with args -m synapse.app.homeserver --config-path /data/homeserver.yaml

Error in configuration:
  Error reading signing_key: not enough values to unpack (expected 3, got 0)

Anything else that would be useful to know?

No response