I have a container which use a .json file to load the configuration it needs.
I tried to find a way to load this configuration. from what I see ConfigMap has the option to load json, but in my case the container in the pod is expected it as a mounted file.
in addition, it requires apiVersion and other parameters, so im not sure its the same case.
what is the best way to move this file to the pod context and use is in the container as a mounted file?
You should create configMap object using the Json file. Load the configMap as volume in the pod. The api version and other metada that you are referring to is relevant for configMap and not for Json configuration file that you are going use in the running container
Related
I have a deployment of 3 containers in OCP. In one of them there is a configuration file which I want to mount to the container via configMap. I created a configMap and tried to mount it to the container but it didn't work.
I use 'csanchez jenkins kubernetes' plugin, so the deployment is configured in a yml file and written in xml format. I found this in the docs of the csanchez plugin, tried to add the necessary field to the container field, but it did not worked.
I want to connect it to a single container and not to the pod, because the path of the config file is the same in another one, but the config file differs.
I tried to add to the container field:
<volumeMounts>
<org.csanchez.jenkins.plugins.kubernetes.volumes.configMapVolume>
<mountPath>/opt/selenium/config.json</mountPath>
<configMapName>selenium-config-map</configMapName>
</org.csanchez.jenkins.plugins.kubernetes.volumes.configMapVolume>
</volumeMounts>
I tried to switch volumeMounts with volumes and it also didn't work.
I have used some bitnami charts in my kubernetes app. In my pod, there is a file whose path is /etc/settings/test.html. I want to override the file. When I search it, I figured out that I should mount my file by creating a configmap. But how can I use the created configmap with the existed pod . Many of the examples creates a new pod and uses the created config map. But I dont want to create a new pod, I wnat to use the existed pod.
Thanks
If not all then almost all pod specs are immutable, meaning that you can't change them without destroying the old pod and creating a new one with desired parameters. There is no way to edit pod volume list without recreating it.
The reason behind this is that pods aren't meant to be immortal. Pods meant to be temporary units that can be spawned/destroyed according to scheduler needs. In general, you need a workload object that does pod management for you (a Deployement, StatefulSet, Job, or DaemonSet, depenging on deployment strategy and application nature).
There are two ways to edit a file in an existing pod: either by using kubectl exec and console commands to edit the file in place, or kubectl cp to copy an already edited file into the pod. I advise you against both of these, because this is not permanent. Better backup the necessary data, switch deployment type to Deployment with one replica, then go with mounting a configMap as you read on the Internet.
I want to deploy Grafana using Kubernetes, but I don't know how to attach provisioned dashboards to the Pod. Storing them as key-value data in a configMap seems to me like a nightmare - example here https://github.com/do-community/doks-monitoring/blob/master/manifest/dashboards-configmap.yaml - in my case it would me much more JSON dashboards - thus the harsh opinion.
I didn't had an issue with configuring the Grafana settings, datasources and dashboard providers as configMaps since they are defined in single files, but the dashboards situation is a little bit more tricky for me.
All of my dashboards are stored in the repo under "/files/dashboards/", and I wondered how to make them available to the Pod, besides the way described earlier. Wondered about using the hostPath object for a sec, but didn't make sense for multi-node deployment on different hosts.
Maybe its easy - but I'm fairly new to Kubernetes and can't figure it out - so any help would be much appreciated. Thank you!
You can automatically generate a ConfigMap from a set fo files in a directory. Each file will be a key-value pair in the ConfigMap with the file name being the key and the file content being the value (like in your linked example but done automatically instead of manually).
Assuming that your dashboard files are stored as, for example:
files/dashboards/
├── k8s-cluster-rsrc-use.json
├── k8s-node-rsrc-use.json
└── k8s-resources-cluster.json
You can run the following command to directly create the ConfigMap in the cluster:
kubectl create configmap my-config --from-file=files/dashboards
If you prefer to only generate the YAML manifest for the ConfigMap, you can do:
kubectl create configmap my-config --from-file=files/dashboards --dry-run -o yaml >my-config.yaml
You could look into these options:
Use a persistent volume.
Store the JSON files for the dashboards in a code repo like git, file repository like nexus, or a plain web server, and use init container to get the files before the application (Grafana) container is started and put them on a volume shared between the init container and the application (Grafana) container. This example could be a good starting point.
Notice that this doesn't require a persistent volume. See in the example - it uses a volume of type emptyDir.
I have an API that describes itself through an openapi3 file. This app is contained in a pod that also has a sidecar app that is supposed to read this file at startup time.
My probleme is how my sidecar app can read the openapi file from the other container ?
I know I could do it using a volume (emptyDir) and modify the command so my api copies the file at startup time. I'd rather not go this route. I have been looking for a feature, where I define a volume which is mapped to an existing folder in my app, but without being empty. Is there such a thing ?
One of the simplest approaches is to use emptyDir: https://kubernetes.io/docs/concepts/storage/volumes/#emptydir
In your container that generates the file that needs to be shared, mount emptyDir volume with write access and copy the file there. In your sidecar that needs to read the file, mount the same volume as read only and read the file.
With this pattern, all containers in the pod can have access to the same file system with read / write as needed.
I am using Helm charts to create and deploy applications into my K8s cluster.
One of my pods requires a config file with a SDK key to start and function properly. This SDK key is considered a secret and is stored in AWS Secret Manager. I don't include the secret data in my Docker image. I want to be able to mount this config file at runtime. A ConfigMap seems to be a good option in this case, except that I have not been able to figure out how to obtain the SDK key from Secrets Manager during the chart installation. Part of my ConfigMap looks like this:
data:
app.conf: |
[sdkkey] # I want to be able to retrieve sdk from aws secrets manager
I was looking at ways to write shell commands to use AWS CLI to get secrets, but have not seen a way to execute shell commands from within a ConfigMap.
Any ideas or alternative solutions?
Cheers
K
tl;dr; You can't execute a ConfigMap, it is just a static manifest. Use an init container instead.
ConfigMaps are a static manifest that can be read from the Kubernetes API or injected into a container at runtime as a file or environment variables. There is no way to execute a ConfigMap.
Additionally, ConfigMaps should not be used for secret data, Kubernetes has a specific resource, called Secrets, to use for secret data. It can be used in similar ways to a ConfigMap, including being mounted as a volume or exposed as environment variables within the container.
Given your description it sounds like your best option would be to use an init container to retrieve the credentials and write them to a shared emptyDir Volume mounted into the container with the application that will use the credentials.