Struggling to wrap my brain around this one...
So I need to execute a Postgres COPY command in a PHP program like the following:
COPY _data_20200404_193855 FROM '/mnt/files/imports/CopyFlatFile.csv.tab' DELIMITER E'\t' CSV HEADER
The /mnt/files/xls-imports/CopyFlatFile.csv.tab is the PVC location, but Postgres Pod is thinking it is a location in the Pod, so it says it can't find the file.
I can manually move the file out of the PVC and into the Postgres Pod with a combination of scp and kubectl cp and the command executes perfectly after copying it into pgAdmin and running it.
Not an ideal method and not very efficient as I'd like the program to handle it.
Any suggestions for how to handle this?
Worst case scenario, I rewrite it to construct a massive INSERT INTO statement, but not sure if it can handle that much data being held in memory. If not, I'll just break it into smaller chunks. Oof...
It looks like I didn't even have my file storage PVC hooked up to the Postgres Deployment... did that and it is now working. Oversight on my part.
Was...
...
volumeMounts:
- name: postgres-storage
mountPath: /var/postgresql
volumes:
- name: postgres-storage
persistentVolumeClaim:
claimName: postgres-storage
...
So I changed it to:
...
- mountPath: /var/postgresql
name: postgres-storage
- mountPath: /mnt/files/xls-imports
name: file-storage
subPath: xls-imports
volumes:
- name: postgres-storage
persistentVolumeClaim:
claimName: postgres-storage
- name: file-storage
persistentVolumeClaim:
claimName: file-storage
...
One possible option is to mount same external filesystem ( such as NFS, CephFS or corresponding SaaS versions like AWS EFS ) to all php and PostgreSQL pods in ReadWriteMany access mode and use it as a shared temporary directory between all pods.
Related
I'm deploying a basic "solr:8.9.0" image to local Kubernetes env.
If I'm trying to mount pod's "/var/solr" directory, it works well.
I can see the files inside /var/solr in the mounted directory.
spec:
containers:
- image: solr:8.6.0
imagePullPolicy: IfNotPresent
name: solr
ports:
- name: solrport
containerPort: 8983
volumeMounts:
- mountPath: /var/solr/
name: solr-volume
volumes:
- name: solr-volume
persistentVolumeClaim:
claimName: solr-pvc
But somehow I can't mount "/etc/default/" directory. That doesn't work.
I knew there are files inside that directory but they are disappearing.
Any idea why?
Thanks!
this is because of how volumeMounts work.
A standard volumeMount mounts the volume in the suplied directory overwriting everything that is inside that directory.
You want to specify a subpath for the data you actually want to mount. By doing this the original contents of the directory won't get overridden.
see here for more information regarding the usage of subpaths.
After reading a lot of manuals, I still don't understand if it is possible to save a file to the host after performing a job or a cronjob.
My Job got PVC and PV like that:
volumes:
- name: name1
persistentVolumeClaim:
claimName: name2
and:
volumeMounts:
- name: save-file
mountPath: /mnt/dir
Let's say I'm running a script that saves the output to a file:
command: ["dosomething.py"]
args: [" --save-to-file output.txt"]
Is there some way to save it to the host or send it somewhere?
Mount the volume for container and give a mount path-
volumeMounts:
- name: "name1"
mountPath: "/var/www/html"
The container can save file to it.
Read more details here - https://kubernetes.io/docs/tasks/configure-pod-container/configure-persistent-volume-storage/#create-a-persistentvolume
I need to share a directory between two containers: myapp and monitoring and to achieve this I created an emptyDir: {} and then volumeMount on both the containers.
spec:
volumes:
- name: shared-data
emptyDir: {}
containers:
- name: myapp
volumeMounts:
- name: shared-data
mountPath: /etc/myapp/
- name: monitoring
volumeMounts:
- name: shared-data
mountPath: /var/read
This works fine as the data I write to the shared-data directory is visible in both containers. However, the config file that is created when creating the container under /etc/myapp/myapp.config is hidden as the shared-data volume is mounted over /etc/myapp path (overlap).
How can I force the container to first mount the volume to /etc/myapp path and then cause the docker image to place the myapp.config file under the default path /etc/myapp except that it is the mounted volume thus allowing the config file to be accessible by the monitoring container under /var/read?
Summary: let the monitoring container read the /etc/myapp/myapp.config file sitting on myapp container.
Can anyone advice please?
Can you mount shared-data at /var/read in an init container and copy config file from /etc/myapp/myapp.config to /var/read?
Consider using ConfigMaps with SubPaths.
A ConfigMap is an API object used to store non-confidential data in
key-value pairs. Pods can consume ConfigMaps as environment variables,
command-line arguments, or as configuration files in a volume.
Sometimes, it is useful to share one volume for multiple uses in a
single pod. The volumeMounts.subPath property specifies a sub-path
inside the referenced volume instead of its root.
ConfigMaps can be used as volumes. The volumeMounts inside the template.spec are the same as any other volume. However, the volumes section is different. Instead of specifying a persistentVolumeClaim or other volume type you reference the configMap by name. Than you can add the subPath property which would look something like this:
volumeMounts:
- name: shared-data
mountPath: /etc/myapp/
subPath: myapp.config
Here are the resources that would show you how to set it up:
Configure a Pod to Use a ConfigMap: official docs
Using ConfigMap SubPaths to Mount Files: step by step guide
Mount a file in your Pod using a ConfigMap: supplement
I used config map with files but i am experimenting with portable services like supervisor d and other internal tools.
we have golang binary that can be run in any image. what i am trying is to run these binary using configmap.
Example :-
We have a internal tool written in Go(size is less than 7MB) can be store in config map and we want to mount that config map inside kuberneates pod and want to run it inside pod
Question :- does anyone use it ? Is it a good approach ? What is the best practice ?
I don't believe you can put 7MB of content in a ConfigMap. See here for example. What you're trying to do sounds like a very unusual practice. The standard practice to run binaries in Pods in Kubernetes is to build a container image that includes the binary and configure the image or the Pod to run that binary.
I too faced similar issue while storing elastic.jks keystore binary file in k8s pod.
AFAIK there are two options:
Make use of configmap to store binary data. Check this out.
OR
Store your binary file remotely somewhere like in s3 bucket and pull that binary before running actual pod using initContainers concept.
apiVersion: v1
kind: Pod
metadata:
name: alpine
namespace: default
spec:
containers:
- name: myapp-container
image: alpine:3.1
command: ['sh', '-c', 'if [ -f /jks/elastic.jks ]; then sleep 99999; fi']
volumeMounts:
- name: jksdata
mountPath: /jks
initContainers:
- name: init-container
image: atlassian/pipelines-awscli
command: ["/bin/sh","-c"]
args: ['aws s3 sync s3://my-artifacts/$CLUSTER /jks/']
imagePullPolicy: IfNotPresent
volumeMounts:
- name: jksdata
mountPath: /jks
env:
- name: CLUSTER
value: dev-elastic
volumes:
- name: jksdata
emptyDir: {}
restartPolicy: Always
As #amit-kumar-gupta mentioned the configmap size constraint.
I recommend the second way.
Hope this helps.
My pod has two containers - a primary container, and a sidecar container that monitors the /var/run/utmp file in the primary container and takes action when it changes. I'm trying to figure out how to make this file visible in the sidecar container.
This page describes how to use an emptyDir volume to share directories between containers in a pod. However, this only seems to work for directories, not single files. I also can't use this strategy to share the entire /var/run/ directory in the primary container, since mounting a volume there erases the contents of the directory, which the container needs to run.
I tried to work around this by creating a symlink to utmp in another directory and mounting that directory, but it doesn't look like symlinks in volumes are resolved in the way they would need to be for this to work.
Is there any way I can make one file in a container visible to other containers in the same pod? The manifest I'm experimenting with looks like this:
apiVersion: v1
kind: Pod
metadata:
name: utmp-demo
spec:
restartPolicy: Never
containers:
- name: main
image: debian
command: ["/bin/bash"]
args: ["-c", "sleep infinity"]
volumeMounts:
- name: main-run
mountPath: /var/run # or /var/run/utmp, which crashes
- name: helper
image: debian
command: ["/bin/bash"]
args: ["-c", "sleep infinity"]
volumeMounts:
- name: main-run
mountPath: /tmp/main-run
volumes:
- name: main-run
emptyDir: {}
If you can move the file to be shared in an empty subfolder this could be a simple solution.
For example, move your file to /var/run/utmp/utmp and share /var/run/utmp folder with an emptydir.