I am working on the docker environment, and executed docker exec -it mycassandra cqlsh. Then, I am inserting the data, and it is occurring the following error:
WriteTimeout - Error from server: code=1100
By this, it tells me that I need to find out the cassandra.yaml document and amend the write-time, but I can not find that on my MAC.
Could you tell me how can I find it and how to amend the document?
Thanks.
for those who have installed it as brew install cassandra, yaml file will located in usr/local/etc/cassandra
If you are running the official cassandra image then cassandra.yaml may be found at /etc/cassandra/cassandra.yaml in the container. If you want to create a custom cassandra.yaml file then you may try to overwrite it in your Dockerfile or docker-compose.yml file. For example, in my docker-compose.yml file I have something like:
services:
cassandra:
image: cassandra:3.11.4
volumes:
- ./cassandra.yaml:/etc/cassandra/cassandra.yaml
which causes the cassandra.yaml file in the container to be overwritten by my local cassandra.yaml.
I hope this helps.
From the provided example, it seems that the database is executed from inside a container. So the cassandra.yaml that you're looking for will be created on the fly when the container is started up, based on the configuration that you provided.
We have set Cassandra Containers with Kubernetes, and execute them in docker, based on the instructions found here, and been able to modify the settings of the cassandra.yaml file in the configuration of the statefulset, updating the variables in env for the spec of the container.
For example, to modify the seeds list, the cluster name, and the rack of the C* cluster named c-test-qa:
apiVersion: apps/v1
kind: StatefulSet
...
spec:
serviceName: c-test-qa
replicas: 1
selector:
matchLabels:
app: c-test-qa
template:
metadata:
labels:
app: c-test-qa
spec:
containers:
- name: c-test-qa
image: cassandra:3.11
imagePullPolicy: IfNotPresent
...
env:
- name: CASSANDRA_SEEDS
value: c-test-qa-0.c-test-qa.qa.svc.cluster.local
- name: CASSANDRA_CLUSTER_NAME
value: "testqa"
- name: CASSANDRA_RACK
value: "DC1"
- name: CASSANDRA_RACK
value: "CustomRack1"
...
On MacOS :
It will be found in either of the below locations:
Cassandra package installations: /etc/cassandra
Cassandra tarball installations: install_location/conf
DataStax Enterprise package installations: /etc/dse/cassandra
DataStax Enterprise tarball installations: install_location/resources/cassandra/conf
Related
I have a simple NFS server (followed instructions here) connected to a Kubernetes (v1.24.2) cluster as a storage class. When a new PVC is created, it creates a PV as expected with a new directory on the NFS server.
The NFS provider was deployed as instructed here.
My issue is that containers don't seem to be able to perform all the functions they expect to when interacting with the NFS server. For example:
A PVC and PV are created with the following yml:
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: mssql-data
spec:
storageClassName: nfs-client
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Gi
This creates a directory on the NFS server as expected.
Then this deployment is created to use the PVC:
apiVersion: apps/v1
kind: Deployment
metadata:
name: mssql-deployment
spec:
replicas: 1
selector:
matchLabels:
app: mssql
template:
metadata:
labels:
app: mssql
spec:
terminationGracePeriodSeconds: 30
hostname: mssqlinst
securityContext:
fsGroup: 10001
containers:
- name: mssql
image: mcr.microsoft.com/mssql/server:2019-latest
ports:
- containerPort: 1433
env:
- name: MSSQL_PID
value: "Developer"
- name: ACCEPT_EULA
value: "Y"
- name: SA_PASSWORD
value: "Password123"
volumeMounts:
- name: mssqldb
mountPath: /var/opt/mssql
volumes:
- name: mssqldb
persistentVolumeClaim:
claimName: mssql-data
The server comes up and responds to requests but does so with the error:
[S0002][823] com.microsoft.sqlserver.jdbc.SQLServerException: The operating system returned error 1117(The request could not be performed because of an I/O device error.) to SQL Server during a read at offset 0x0000000009a000 in file '/var/opt/mssql/data/master.mdf'. Additional messages in the SQL Server error log and operating system error log may provide more detail. This is a severe system-level error condition that threatens database integrity and must be corrected immediately. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.
My /etc/exports file has the following contents:
/srv *(rw,no_subtree_check,no_root_squash)
When the SQL container starts, it doesn't undergo any container restarts but the SQL service within the container appears to get into some sort of restart loop until a connection is attempted and then it throws the error and appears to stop.
Is there something I'm missing in the /etc/exports file? I tried variations with sync, async, and insecure but can't seem to get past the SQL error.
I gather from the error that this has something to do with the container's ability to read/write from/to the disk. Am I in the right ballpark?
The config that ended up working was:
/srv *(rw,no_root_squash,insecure,sync,no_subtree_check)
This was after a reinstall of the cluster. No significant changes elsewhere but still seems like there may have been more to the issue than this one config.
I've a simle React JS application and it's using a environment variable(REACT_APP_BACKEND_SERVER_URL) defined in .env file. Now I'm trying to deploy this application to minikube using Kubernetes.
This is my deployment file:
apiVersion: apps/v1
kind: Deployment
metadata:
name: test-ui
spec:
replicas: 1
selector:
matchLabels:
app: test-ui
template:
metadata:
name: test-ui-pod
labels:
app: test-ui
spec:
containers:
- name: test-ui
image: test-ui:1.0.2
ports:
- containerPort: 80
env:
- name: "REACT_APP_BACKEND_SERVER_URL"
value: "http://127.0.0.1:59058"
When I run the application, it's working but REACT_APP_BACKEND_SERVER_URL is giving the value which I defined in .env file. Not the one I'm overriding. Can someone help me with this please? How to override the env variable using Kubernetes deployment?
After starting the app with your deployment YAML and checking for the environment variables I see the environment variables for that environment variable.
REACT_APP_BACKEND_SERVER_URL=http://127.0.0.1:59058
you can check that by doing an kubectl exec -it <pod-name> -- sh and running env command.
So you can see that REACT_APP_BACKEND_SERVER_URL is there in the environment variables. It's available for your application to use. I suspect that you may need to understand better from the React app side on how to use the .env file.
I need to know how to connect my Kubernetes cluster to an external SQL Server database running in a docker image outside of the Kubernetes cluster.
I currently have two pods in my cluster that are running, each has a different image in it created from asp.net core applications. There is a completely separate (outside of Kubernetes but running locally on my machine localhost,1433) docker image that hosts a SQL Server database. I need the applications in my Kubernetes pods to be able to reach and manipulate that database. I have tried creating a YAML file and configuring different ports but I do not know how to get this working, or how to test that it actually is working after setting it up. I need the exact steps/commands to create a service capable of routing a connection from the images in my cluster to the DB and back.
Docker SQL Server creation (elevated powershell/docker desktop):
docker pull mcr.microsoft.com/mssql/server:2017-latest
docker run -d -p 1433:1433 --name sql -v "c:/Temp/DockerShared:/host_mount" -e SA_PASSWORD="aPasswordPassword" -e ACCEPT_EULA=Y mcr.microsoft.com/mssql/server:2017-latest
definitions.yaml
#Pods in the cluster
apiVersion: v1
kind: Pod
metadata:
name: pod-1
labels:
app: podnet
type: module
spec:
containers:
- name: container1
image: username/image1
---
apiVersion: v1
kind: Pod
metadata:
name: pod-2
labels:
app: podnet
type: module
spec:
containers:
- name: container2
image: username/image2
---
#Service created in an attempt to contact external SQL Server DB
apiVersion: v1
kind: Service
metadata:
name: ext-sql-service
spec:
ports:
- port: 1433
targetPort: 1433
type: ClusterIP
---
apiVersion: v1
kind: Endpoints
metadata:
name: ext-sql-service
subsets:
- addresses:
- ip: (Docker IP for DB Instance)
ports:
- port: 1433
Ideally I would like applications in my kubernetes cluster to be able to manipulate the SQL Server I already have set up (running outside of the cluster but locally on my machine).
When running from local docker, you connection string is NOT your local machine.
It is the local docker "world", that happens to be running on your machine.
host.docker.internal:1433
The above is docker container talking to your local machine. Obviously, the port could be different based on how you exposed it.
......
If you're trying to get your running container to talk to sql-server which is ALSO running inside of the docker world, that connection string looks like:
ServerName:
my-mssql-service-deployment-name.$_CUSTOMNAMESPACENAME.svc.cluster.local
Where $_CUSTOMNAMESPACENAME is probably "default", but you may be running a different namespace.
my-mssql-service-deployment-name is the name of YOUR deployment (I have it stubbed here)
Note there is no port number here.
This is documented here:
https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#services
Problem may be in kind of service you put. ClusterIP enable you juest to connect among pods inside cluster.
To connect to external service you should just change definition of service kind as NodePort.
Try to change service definition:
#Service created in an attempt to contact external SQL Server DB
apiVersion: v1
kind: Service
metadata:
name: ext-sql-service
spec:
type: NodePort
ports:
- port: 1433
targetPort: 1433
and execute command:
$ kubectl apply -f your_service_definition_file_name.yaml
Remember to run this command in proper namespace, where your deployment is configured.
Bad practice is to overlay an environment variable onto the container. And with "docker run" pass that environment variable VALUE to the container.
Of course in context of executing docker command
$ docker run -d -p 1433:1433 --name sql -v "c:/Temp/DockerShared:/host_mount" -e SA_PASSWORD="aPasswordPassword" -e ACCEPT_EULA=Y mcr.microsoft.com/mssql/server:2017-latest
Putting the db-password visible is insecure. Use Kubernetes secrets.
More information you can find here: kubernetes-secret.
I have a few quite large UTF-8 data files that pods need to load into memory on start up - from a couple of hundred KBs to around 50 MB.
The project (including helm chart) is open source but some of these files are not - otherwise I would probably just include them in the images. My initial thinking was to create configmaps but my understanding is that 50 MB is more than configmaps were intended for, so that might end up being a problem in some circumstances. I think secrets would also be overkill - they aren't secret, they just shouldn't be put on the open internet.
For performance reasons I'd rather have a copy in memory in each pod rather than going for a shared cache but I might be wrong on that. At the very least that will likely add more complexity than it's worth.
Are configmaps the way to go?
From my point of view, the best solution would be using init container to download the files from a secured storage (as it was mentioned by Andrew Savinykh in the comments), to the pod's volume and then use it in the pod's main container.
Please see the example:
apiVersion: v1
kind: Pod
metadata:
name: init-demo
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
volumeMounts:
- name: workdir
mountPath: /usr/share/nginx/html
# These containers are run during pod initialization
initContainers:
- name: install
image: busybox
command:
- wget
- "-O"
- "/work-dir/index.html"
- http://kubernetes.io
volumeMounts:
- name: workdir
mountPath: "/work-dir"
dnsPolicy: Default
volumes:
- name: workdir
emptyDir: {}
I am trying to provision PVC for Solr deployment in k8s and mount it as /opt/solr, which is default Solr installation directory. This way I plan to target both Solr installation and data under it on PVC. However, while storage gets provisioned just fine and statefulset gets created, my deployment doesn't work because /opt/solr ends up empty. What is a proper way to do it? Here my deployment.yaml:
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
name: solr
labels:
app: solr
spec:
volumeClaimTemplates:
- metadata:
name: datadir
annotations:
volume.alpha.kubernetes.io/storage-class: slow
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 2Gi
serviceName: solr-svc
replicas: 1
template:
metadata:
labels:
app: solr
spec:
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app"
operator: In
values:
- solr-pool
topologyKey: "kubernetes.io/hostname"
terminationGracePeriodSeconds: 300
containers:
- name: solr
image: solr:6.5.1
imagePullPolicy: IfNotPresent
resources:
requests:
memory: 512M
cpu: 500m
ports:
- containerPort: 8983
name: solr-port
protocol: TCP
env:
- name: VERBOSE
value: "yes"
command:
- bash
- -c
- "exec /opt/solr/bin/solr start"
volumeMounts:
- name: solr-script
mountPath: /docker-entrypoint-initdb.d/
- name: datadir
mountPath: /opt/solr/
volumes:
- name: solr-script
configMap:
name: solr-configs
nodeSelector:
pool: solr-pool
Provisioned storage is empty by default and there might be a Deleting retain policy on provisioned storage be sure to check those configurations. You can also exec to your pod and examine mounted volume and see if it's working properly or not (permission issues, read only file system)
In may case there was a conflict with docker container configuration which used /opt/solr as a location for solr install and my attempt to mount separate PV under same location. Once this PV is mounted obviously I loose solr install. The fixes for this are:
create another docker image which uses separate location
change solr config to use different location for data
change PV volume location