How do I best determine if a manifest already exists?

[flickerfly]

I'd like to determine if a ConfigMap already exists before I create it so I can take appropriate actions. How do I accomplish this?

Here is the code I've tried:

#!/usr/bin/env python3

import os
import sys
import yaml
from kubernetes import client, config
from openshift.dynamic import DynamicClient
import openshift.dynamic.exceptions

# Check if code is running in OpenShift
if "OPENSHIFT_BUILD_NAME" in os.environ:
    config.load_incluster_config()
    file_namespace = open(
        "/run/secrets/kubernetes.io/serviceaccount/namespace", "r"
    )
    if file_namespace.mode == "r":
        namespace = file_namespace.read()
        print("namespace: %s\n" %(namespace))
else:
    config.load_kube_config()

# Configure cluster access 
k8s_config = client.Configuration()
k8s_client = client.api_client.ApiClient(configuration=k8s_config)
dyn_client = DynamicClient(k8s_client)

v1_configmaps = dyn_client.resources.get(api_version='v1', kind='ConfigMap')

cm_name = "rh-operators-not-here"
cm_namespace = "operator-lifecycle-manager"
try:
    configmap_list = v1_configmaps.get(namespace=cm_namespace,name=cm_name)
except 'NotFoundError':
    print("WARNING: ConfigMap " + cm_name + " not found in namespace " + cm_namespace + ". We will create it.")
    pass
except 'kubernetes.client.rest.ApiException':
    print("apiexception")
    pass
except NameError:
    print("nameerror")
    pass
except:
    print("Unexpected error:", sys.exc_info()[0])
    raise

When I run that, twice I get "During handling of the above exception, another exception occurred" and then all the output ends in "TypeError: catching classes that do not inherit from BaseException is not allowed".

How do I properly catch this so I can determine if I should .create or .replace it?

[fabianvf]

except 'NotFoundError': should be except NotFoundError:, the issue is that you have catch <string> instead of catch <Exception>.

This code should work

from openshift.dynamic.exceptions import NotFoundError, DynamicApiError

<snip>

try:
    configmap_list = v1_configmaps.get(namespace=cm_namespace,name=cm_name)
except NotFoundError:
    print("WARNING: ConfigMap " + cm_name + " not found in namespace " + cm_namespace + ". We will create it.")
    pass
except DynamicApiError:
    print("apiexception")
    pass
<snip>

[flickerfly]

Thank you @fabianvf ! Your example was extremely helpful.

I had tried it as an Exception, that was just some last-ditch efforts lingering. What I hadn't figured out was the proper import!