I am having an issue with passing a pipe character | in readiness probe command.
I want to have a probe command:
curl --silent http://localhost:8080/actuator/health | grep --quiet -e '^{\"status\"\:\"UP\".*}#x27;
Here is how I have defined the probe:
# kubectl get pod my_pod -o yaml
readinessProbe:
exec:
command:
- curl
- --silent
- http://localhost:8080/actuator/health
- '|'
- grep
- --quiet
- -e
- '''^{\"status\"\:\"UP\".*}#x27;''Readiness probe fails with a message:
Readiness probe failed: curl: option --quiet: is unknown curl: try 'curl --help' or 'curl --manual' for more information
The error can be reproduce when command is executed without pipe character |:
curl --silent http://localhost:8080/actuator/health grep --quiet -e '^{\"status\"\:\"UP\".*}#x27;
For some reason pipe is not interpreted by Kubernetes.
Can you please help me with passing pipe in deployment?
Kubernetes doesn't run a shell to process commands on its own; it just runs them directly. The closest equivalent in a shell would be
curl '--silent' 'http://...' '|' 'grep' ...That is, | here doesn't split two separate commands, because that's shell syntax; without a shell it becomes another parameter to curl, as do all of the words after it.
You need to provide the shell wrapper yourself:
readinessProbe:
exec:
command:
- sh
- -c
- curl --silent http://localhost:8080/actuator/health | grep --quiet -e '^{\"status\"\:\"UP\".*}#x27;You can use alternate YAML syntax to make this a little more readable. (> means to fold following lines into a single string; - means to strip leading and trailing whitespace.
readinessProbe:
exec:
command:
- sh
- -c
- >-
curl --silent http://localhost:8080/actuator/health |
grep --quiet -e '^{\"status\"\:\"UP\".*}#x27;