Fix race condition - envsubst $file | tee $file

[hjensas]

When running envsubst $file and pipe to tee $file there is a race causing the target file to be wiped.

The following script can be used to reproduce the race condition:

  #!/bin/sh
  echo -e "foo\nbar\nbaz" > /tmp/test_file
  count=0
  while [ -s /tmp/test_file ]; do
    envsubst < /tmp/test_file | tee /tmp/test_file > /dev/null
    ((count+=1))
  done

  if [ ! -s /tmp/test_file ]; then
    echo "File was wiped after $count run's of:  envsubst < \$file | tee \$file"
  fi

$ sh test.sh
File was wiped after 16 run's of:  envsubst < $file | tee $file
$ sh test.sh
File was wiped after 42 run's of:  envsubst < $file | tee $file
$ sh test.sh
File was wiped after 37 run's of:  envsubst < $file | tee $file
$ sh test.sh
File was wiped after 73 run's of:  envsubst < $file | tee $file
$ sh test.sh
File was wiped after 4 run's of:  envsubst < $file | tee $file

Jira: OSPRH-17012
Jira: OSPCIX-870

[steveb]

oosh

/lgtm

[softwarefactory-project-zuul]

Build failed (check pipeline). Post recheck (without leading slash)
to rerun all jobs. Make sure the failure cause has been resolved before
you rerun jobs.

https://softwarefactory-project.io/zuul/t/rdoproject.org/buildset/a511ac08567347068f8fb1ff66e7b175

✔️ noop SUCCESS in 0s
✔️ openstack-k8s-operators-content-provider SUCCESS in 1h 19m 49s
❌ podified-multinode-ironic-deployment FAILURE in 59m 36s

[hjensas]

Looks ok in CI now: https://logserver.rdoproject.org/be0/rdoproject.org/be01bb61bcf94fa79f026408fc09c6dc/controller/ci-framework-data/logs/openstack-k8s-operators-openstack-must-gather/namespaces/openstack/pods/ironic-inspector-0/logs/inspector-pxe-init.log

+ export TMP_DNSMASQ_CFG=/var/tmp/dnsmasq.conf
+ TMP_DNSMASQ_CFG=/var/tmp/dnsmasq.conf
+ cp /var/lib/ironic/dnsmasq.conf /var/tmp/dnsmasq.conf
+ envsubst
+ tee /var/lib/ironic/dnsmasq.conf
# Disable listening for DNS
port=0
enable-tftp
tftp-root=/var/lib/ironic/tftpboot
...

+ export TMP_INSPECTOR_IPXE=/var/tmp/inspector.ipxe
+ TMP_INSPECTOR_IPXE=/var/tmp/inspector.ipxe
+ cp /var/lib/ironic/inspector.ipxe /var/tmp/inspector.ipxe
+ envsubst
+ tee /var/lib/ironic/inspector.ipxe
#!ipxe

:retry_boot
...

[abays]

/lgtm

[openshift-ci]

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This pull-request has been approved by: abays, hjensas

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