metrics: rclone rc binding metrics endpoint

[hiddenmarten]

The associated forum post URL from https://forum.rclone.org

I don't have any, just wanted to create an issue to link my future PR with.

What is the problem you are having with rclone?

rclone rc trying to bind metrics endpoint if environment variable RCLONE_METRICS_ADDR is set

What is your rclone version (output from rclone version)

v1.68.2

Which OS you are using and how many bits (e.g. Windows 7, 64 bit)

Linux

Which cloud storage system are you using? (e.g. Google Drive)

Doesn't matter in that case.

The command you were trying to run (e.g. rclone copy /tmp remote:tmp)

RCLONE_METRICS_ADDR="0.0.0.0:9000" rclone rc -vv rc/noop

A log from the command with the -vv flag (e.g. output from rclone -vv copy /tmp remote:tmp)

NOTE: └──╼ $ RCLONE_METRICS_ADDR="0.0.0.0:9000" rclone rcd was run in advance.

└──╼ $ RCLONE_METRICS_ADDR="0.0.0.0:9000" rclone rc -vv rc/noop
2024/12/15 22:21:21 DEBUG : Setting  metrics_addr="0.0.0.0:9000" from environment variable RCLONE_METRICS_ADDR
2024/12/15 22:21:21 DEBUG : Setting --metrics-addr "0.0.0.0:9000" from environment variable RCLONE_METRICS_ADDR="0.0.0.0:9000"
2024/12/15 22:21:21 DEBUG : rclone: Version "v1.68.2" starting with parameters ["rclone" "rc" "-vv" "rc/noop"]
2024/12/15 22:21:21 CRITICAL: Failed to start metrics server: failed to init server: listen tcp 0.0.0.0:9000: bind: address already in use

How to use GitHub

• Please use the 👍 reaction to show that you are affected by the same issue.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

[hiddenmarten]

Duplicate explanation of use cases from PR for the sake of context:

I encountered this issue when running rclone in Kubernetes. Let me provide a simplified Deployment manifest to explain the context:

apiVersion: apps/v1
kind: Deployment
spec:
  template:
    spec:
      containers:
        - name: rclone
          image: rclone/rclone:1.68.2
          args:
            - rcd
          env:
            - name: RCLONE_METRICS_ADDR
              value: ":9000"
          livenessProbe:
            exec:
              command:
                - rclone rc rc/noop

In this setup, the liveness probe fails because the rclone rc rc/noop command does not work correctly when the RCLONE_METRICS_ADDR environment variable is set.

As a workaround, we can modify the liveness probe command like this: RCLONE_METRICS_ADDR="" rclone rc rc/noop

However, this approach raises a concern: it's not immediately clear from the manifest why we are overriding the RCLONE_METRICS_ADDR variable. This lack of clarity could lead to confusion for others reading the configuration.

Another potential scenario to consider: If someone sets RCLONE_METRICS_ADDR globally in their ~/.bashrc or ~/.zshrc file, they may inadvertently prevent rclone from working correctly when running commands locally from the CLI.