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Add reload logic to collector container start script. #4099

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Merged
merged 1 commit into from
Feb 24, 2025
Merged

Add reload logic to collector container start script. #4099

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42 changes: 30 additions & 12 deletions internal/collector/instance.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ package collector

import (
"context"
"fmt"

corev1 "k8s.io/api/core/v1"

Expand All @@ -16,6 +17,8 @@ import (
"github.com/crunchydata/postgres-operator/pkg/apis/postgres-operator.crunchydata.com/v1beta1"
)

const configDirectory = "/etc/otel-collector"

// AddToConfigMap populates the shared ConfigMap with fields needed to run the Collector.
func AddToConfigMap(
ctx context.Context,
Expand Down Expand Up @@ -50,7 +53,7 @@ func AddToPod(
// Create volume and volume mount for otel collector config
configVolumeMount := corev1.VolumeMount{
Name: "collector-config",
MountPath: "/etc/otel-collector",
MountPath: configDirectory,
ReadOnly: true,
}
configVolume := corev1.Volume{Name: configVolumeMount.Name}
Expand Down Expand Up @@ -144,22 +147,37 @@ func AddToPod(

// startCommand generates the command script used by the collector container
func startCommand(includeLogrotate bool) []string {
var startScript = `
/otelcol-contrib --config /etc/otel-collector/config.yaml
`

var logrotateCommand string
if includeLogrotate {
startScript = `
/otelcol-contrib --config /etc/otel-collector/config.yaml &
logrotateCommand = `logrotate -s /tmp/logrotate.status /etc/logrotate.d/logrotate.conf`
}

var startScript = fmt.Sprintf(`
OTEL_PIDFILE=/tmp/otel.pid
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Does the otelcontrib process have a name? Or did we want the PID to check if it's running (without recourse to pgrep)?

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I'm honestly not sure of the best way to do this. I used some prior art in our codebase as a starting point


start_otel_collector() {
echo "Starting OTel Collector"
/otelcol-contrib --config %s/config.yaml &
echo $! > $OTEL_PIDFILE
}
start_otel_collector

exec {fd}<> <(:||:)
while read -r -t 5 -u "${fd}" ||:; do
logrotate -s /tmp/logrotate.status /etc/logrotate.d/logrotate.conf
%s
Comment on lines -157 to +167
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🌱 Perhaps this could always be [[ -r /etc/logrotate.d/logrotate.conf ]] && logrotate ... and the choice to rotate or not would be at the mounting of the config.

if [[ "${directory}" -nt "/proc/self/fd/${fd}" ]] && kill -HUP $(head -1 ${OTEL_PIDFILE?});
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🤔 What happens if Bash is terminated? Is the entire container torn down, including the collector?

If so, we can keep the collector pid in a variable in memory.

# start
otel ... &
OTEL_PID=$!

# here
kill -HUP ${OTEL_PID}

# below
[[ ! -e /proc/${OTEL_PID} ]]

then
echo "OTel configuration changed..."
exec {fd}>&- && exec {fd}<> <(:||:)
stat --format='Loaded configuration dated %%y' "${directory}"
fi
if [[ ! -e /proc/$(head -1 ${OTEL_PIDFILE?}) ]] ; then
start_otel_collector
fi
done
`
}
`, configDirectory, logrotateCommand)

wrapper := `monitor() {` + startScript + `}; export -f monitor; exec -a "$0" bash -ceu monitor`
wrapper := `monitor() {` + startScript + `}; export directory="$1"; export -f monitor; exec -a "$0" bash -ceu monitor`

return []string{"bash", "-ceu", "--", wrapper, "collector"}
return []string{"bash", "-ceu", "--", wrapper, "collector", configDirectory}
}
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