Storing the tempo-query binary under /tmp in the docker image causes problems when running on a read-only fs

[kimble]

Describe the bug
https://github.com/grafana/tempo/blob/master/cmd/tempo-query/Dockerfile#L6-L9

The tempo-query docker image ships with the binary under /tmp. Some k8s envs are configured with read only file systems so in order to have a writeable /tmp that have to be mounted which in turn removes the binary. To make matters worse the base image
ships without any utils that would make it possible to move the binary using an init container.

Expected behavior
The binary to somewhere other then /tmp :-)

Environment:

• Infrastructure: Kubernetes

[joe-elliott]

Yeah, the storing the file in /tmp is a hack b/c the GRPC plugin panic'ed if no /tmp folder existed. Heads up that in the near future we intend to drop the requirement for tempo-query and hopefully this problem will go away for you.

#382

Will leave this open b/c I think it should be fixed anyway.

[kimble]

Sounds great!

For anyone with the same problem:
I managed to work around the issue by setting $TEMP=/tmp2 and mounting a new volume in that directory.

[github-actions]

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[Hronom]

Nowadays you need to use env variable TMPDIR, so proper config for tempo-distributed helm chart will be:

  queryFrontend:
    query:
      enabled: true
      # Inspired by https://github.com/grafana/tempo/issues/434#issuecomment-754033103
      extraEnv:
        - name: TMPDIR
          value: /tmp2
      extraVolumeMounts:
        - mountPath: /tmp2
          name: tmp2
    extraVolumes:
      - name: tmp2
        emptyDir: { }

This is useful if you need to enable Kiali to work with Tempo. Related issue here:
kiali/kiali#4278
kiali/kiali#5848