In my project on GCP i setup an autmatedodeploy for a specific deploy on my kubernetes cluster, ath the end of procedure an image path like:
gcr.io/direct-variety-325450/cc-mirror:$COMMIT_SHA
was create.
If i see in my GCP "Container Registry" i se images wit tag like c15c5019183ded74814d570a9a33d2f95ecdfb32
Now my question is:
How can i in my deployment.yaml file specify the latest image name if there are no latest or other tag?
...
spec:
containers:
- name: django
image: ????
...
if i put:
gcr.io/direct-variety-325450/cc-mirror:$COMMIT_SHA
or:
gcr.io/direct-variety-325450/cc-mirror
i get an Error:
Cannot download Image, Image does not exist
What i have to put into my image: entry of deployment.yaml?
So many thanks in advance
Manuel
TL;DR: You need to specify the latest tag in your deployment.
In fact, Kubernetes automates a lot of thing for you. You tell what you want, Kubernetes compares its state with your wishes and perform actions.
If you don't specify the image tag, kubernetes will compare your wish (no tag) with the current state of the cluster (no tag) and because it's equal, it will do nothing.
Now how to automate the new tag deployment. Here no magic: you need a placeholder in your deployment.yaml file and to execute a sed in your file to replace the placeholder by the real value.
And then apply the change on this updated file.
Related
I have a private repository. I want to update my container image in Kubernetes automatically when the image is updated in my private repository. How can I achieve this?
Kubernetes natively does not have the feature of automatically redeploying pods when there is a new image. Ideally what you want is a tool which enables GitOps style deployment wherein state change in git will be synced to the Kubernetes cluster. There is Flux and ArgoCD open source tools which supports GitOps.
Recently there is an announcement to combine these two projects as ArgoFlux.
You should assign some sort of unique identifier to each build. This could be based off a source-control tag (if you explicitly tag releases), a commit ID, a build number, a time stamp, or something else; but the important detail is that each build creates a unique image with a unique name.
Once you do that, then your CI system needs to update the Deployment spec with a new image:. If you're using a tool like Kustomize or Helm, there are standard patterns to provide this; if you are using kubectl apply directly, it will need to modify the deployment spec in some way before it applies it.
This combination of things means that the Deployment's embedded pod spec will have changed in some substantial way (its image: has changed), which will cause the Kubernetes deployment controller to automatically do a rolling update for you. If this goes wrong, the ordinary Kubernetes rollback mechanisms will work fine (because the image with yesterday's tag is still in your repository). You do not need to manually set imagePullPolicy: or manually cause the deployment to restart, changing the image tag in the deployment is enough to cause a normal rollout to happen.
Have a look at the various image pull policies.
imagePullPolicy: always might come closest to what you need. I don't know if there is a way in "vanilla" K8s to achieve an automatic image pull, but I know that RedHat's OpenShift (or OKD, the free version) works with image streams, which do exactly what you ask for.
The imagePullPolicy and the tag of the image affect when the kubelet attempts to pull the specified image.
imagePullPolicy: IfNotPresent: the image is pulled only if it is not already present locally.
imagePullPolicy: Always: the image is pulled every time the pod is started.
imagePullPolicy is omitted and either the image tag is :latest or it is omitted: Always is applied.
imagePullPolicy is omitted and the image tag is present but not :latest: IfNotPresent is applied.
imagePullPolicy: Never: the image is assumed to exist locally. No attempt is made to pull the image.
So to achieve this you have to set imagePullPolicy: Always and restart you pod and it should pull a fresh latest copy of image. I don't think there is any other way in K8s
Container Images
I just wrote a bash script to achieve this.My imagePullPolicy option is always and i am running this script with crontab.(You can check everytime with infinite loops).It is checking repository and if any change occured , it is deleting the pod (automatically because of imagePullPolicy set Always) and pulling updated image.
#!/bin/bash
registry="repository_name"
username="user_name"
password="password"
##BY this you can append all images from repository to the array
#images=($( echo $(curl -s https://"$username":"$password"#"$registry"/v2/_catalog | jq .repositories | jq .[])))
##Or you can set manuaaly your image array
images=( image_name_0 image_name_1 )
for i in "${images[#]}"
do
old_image=$(cat /imagerecords/"$i".txt)
new_image=$(echo $(curl -s https://"$username":"$password"#"$registry"/v2/"$i"/manifests/latest | jq ."fsLayers" | jq .[]))
if [ "$old_image" == "$new_image" ];then
echo "image: "$i" is already up-to-date"
else
echo "image: " $i" is updating"
kubectl delete pod pod_name
echo $new_image > /imagerecords/"$i".txt
fi
done
This functionality is provided by open-source project argocd-image-updater:
https://github.com/argoproj-labs/argocd-image-updater
This question already has answers here:
Kubernetes how to make Deployment to update image
(8 answers)
Closed 1 year ago.
I have this workflow where I write some code and a docker image is deployed under latest. Currently, it deploys to my container registry and then I run this kubectl apply file.yaml after the container deploys, but K8s doesn't seem to recognize that it needs to re-pull and rollout a new deployment with the newly pulled image.
How can I basically feed in the YAML spec of my deployments and just rollout restart the deployments?
Alternatively, is there a better approach? I unconditionally am rolling out deployment restarts on all my deployments this way.
#daniel-mann is correct to discourage the use of :latest.
Don't read the word 'latest' when you see the tag latest. It's a default tag and it breaks the ability to determine whether the image's content has changed.
A better mechanism is to tag your images by some invariant value... your code's hash, for example. This is what Docker does with its image hashes and that's the definitive best (but not easiest) way to identify images: [[image]]#sha256:.....
You can use some SemVer value. Another common mechanism is to use the code's git commit for its tag: git rev-parse HEAD or similar.
So, assuming you're now uniquely identify images by tags, how to update the Deployment? The docs provide various approaches:
https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment
But these aren't good for robust deployments (lowercase-D). What you should also do is create unique Deployment manifests each time you change the image. Then, if you make a mistake and inadvertently deploy something untoward, you have a copy of what you did and you can correct it (making another manifest) and apply that. This is a principle behind immutable infrastructure.
So...
TAG=$(git rev-parse HEAD)
docker build \
--tag=${REPO}/${IMAGE}:${TAG} \
...
docker push ${REPO}/${IMAGE}:${TAG}
Then change the manifest (and commit the change to source control):
sed --in-place "s|image: IMAGE|image: ${REPO}/${IMAGE}:${TAG}|g" path/to/manifest.yaml
git add /path/to/manifest.yaml
git commit --message=...
Then apply the revised (but unique!) manifest to the cluster:
kubectl apply \
--filename=/path/to/manifest.yaml \
--namespace=${NAMESPACE}
I have a docker image that receives a set of environment variables to customize its execution.
A simple example would be a web-server, that has stuff like client secret for OAuth2, a secret to sign cookies, etc.
The whole app is containerized on a docker image, that receives (runtime) environment variables.
I distribute that docker image on a private registry, and I would like to document that image, so that users can understand how they can customize the image.
Is it possible to ship, as part of the docker image, annotations that e.g. using docker describe my_image output markdown to the stdout?
I could of course use a static page on the web for documentation, but the user would still need to know where that documentation could be found, and the whole distribution would be more complext this way (e.g. documentation changes with image tag).
Any ideas?
There is no silver bullet here as far as I know, All solutions below work, but require the user to be informed of how to retrieve the documentation.
There is no standard way of doing it.
The open container initiative have created an image spec annotation suggesting that
A link to more information about the image should be provided in a label called org.opencontainers.image.documentation.
A description of the software packaged inside the container should be provided in a label called org.opencontainers.image.description
According to OCI, one of the variations of option 1 below is correct.
Option 1: Providing a link in a label (Prefered by OCI)
Assuming the Dockerfile and related assets are version controlled in a git repository that is publicly accessible (for example on github), that git repository could also contain a README.md file. If you have a pipeline hooked up to the repo that builds and publishes the Docker image to a registry automatically, you could setup the docker build command to add a label with a link to the documentation as follows
# Get the current commit id
commit=$(git rev-parse HEAD)
# Build docker image and attach a link to the Readme as a label
docker build -t myimagename:myversion \
--label "org.opencontainers.image.documentation=https://github.com/<user>/<repo>/blob/$commit/README.md"
This solution links to specific commit documentation for that particular commit versioned alongside your Dockerfile. It does however require the user to have access to internet to be able to read the documentation
Option 1b: Providing full documentation in a label (Prefered by OCI)
A variation of option 1 where the full documentation is serialized and put into the label (there is no length restrictions on labels). This way the documentation is bundled with the image itself
As Jorge Leitao pointed out in the comments, the image annotaion spec from OCI specifies the name of such a label as org.opencontainers.image.description
Option 2: Bundling documentation inside image
If you prefer to actually bundle the Readme.md file inside the image to make it independent on any external web page consider the following
Upon build, make sure to copy the Readme.md file to the docker image
Also create a simple shell script describe that cats the Readme.md
describe
#!/usr/bin/env sh
cat /docs/Readme.md
Dockerfile additions
...
COPY Readme.md /docs/Readme.md
COPY describe /opt/bin/describe
RUN chmod +x /opt/bin/describe
ENV PATH="/opt/bin:${PATH}"
...
A user that have your Docker image an now run the following command to have the markdown sent to stdout
docker run myimage:version describe
This solution bundles the documentation for this particular version of the image inside the image and it can be retrieved without any external dependencies
Docker image tags are mutable, in that image:latest and image:1.0 can both point to image#sha256:....., but when version 1.1 is released, image:latest stored within a registry can be pointed to an image with a different sha digest. Pulling an image with a particular tag now does not mean that an identical image will be pulled next time.
If a Kubernetes YAMl resource definition refers to an image by tag (not by digest), is there a means of determining what sha digest each image will actually resolve to, before the resource definition is deployed? Is this functionality supported using kustomize or kubectl?
Use case is wanting to determine what has actually been deployed in one environment before deploying to another (I'd like to take a hash of the resolved resource definition and could then use this to understand whether image:1.0 to be deployed to PROD refers to the same image:1.0 that was deployed to UAT).
Are there any tools that can be used to support this functionality?
For example, given the following YAML, is there a way of replacing all images with their resolved digests?
apiVersion: v1
kind: Pod
metadata:
name: example
spec:
containers:
- name: image1
image: image1:1.1
command:
- /bin/sh -c some command
- name: image2
image: image2:2.2
command:
- /bin/sh -c some other command
To get something like this:
apiVersion: v1
kind: Pod
metadata:
name: example
spec:
containers:
- name: image1
image: image1#sha:....
command:
- /bin/sh -c some command
- name: image2
image: image2#sha:....
command:
- /bin/sh -c some other command
I'd like to be able to do something like pipe yaml (that might come from cat, kustomize or kubectl ... --dry-run) through a tool and then pass to kubectl apply -f:
cat mydeployment.yaml | some-tool | kubectl apply -f -
EDIT:
The background to this is the need to be able to prove to auditors/regulators that what is about to be deployed to one env (PROD) is exactly what has been successfully deployed to another env (UAT). I'd like to use normal tags in the deployment template and at the time of deploying to UAT, take a snapshot of the template with the tags replaced with the digests of the resolved images. That snapshot will be what is deployed (via kubectl or similar). When deploying to PROD, that same snapshot will be used.
This tool is supporting exactly what you need...
kbld: https://get-kbld.io/
Resolves name-tag pair reference (nginx:1.17) into digest reference
(index.docker.io/library/nginx#sha256:2539d4344...)
Looks integrates quite well with templating tools like Kustomize or even Helm
You can all the containers used info with this command. This will list all namespaces, with pod names, with container image name and sha256 of the image.
kubectl get pods --all-namespaces -o=jsonpath='{range .items[*]}{"\n"}{.metadata.namespace}{","}{.metadata.name}{","}{range .status.containerStatuses[*]}{.image}{", "}{.imageID}{", "}{end}{end}' | sort
is there a means of determining what sha digest each image will actually resolve to, before the resource definition is deployed?
No, and in the case you describe, it can vary by node. The Deployment will create some number of Pods, each Pod will get scheduled on some Node, and the Kubelet there will only pull the image if it doesn’t have something with that tag already. If you have two replicas, and you’ve changed the image a tag points to, then on node A it could use the older image that was already there, but on node B where there isn’t an image, it will pull and get the newer version.
The best practice here is to avoid changing the image a tag points to. Give each build coming out of your CI system a unique tag (a datestamp or source control commit ID for example) and use that in your Kubernetes object specifications. That avoids this problem entirely.
A workaround is to set
imagePullPolicy: Always
in your pod specs, which will force the node to pull a newer version, but this is unnecessary overhead in most cases.
Here's another on - k8s-digester from google folks. It's a bit different in a sense than the main focus is on cluster-side changes(via Adm Controller) even though client-side KRM functions seems to also be possible.
Overall, kbld seems to be more about development experience and adoption with your cli/CICD/orchestration, while k8s-digester is more about administration on the cluster side.
I am trying to push a built docker container to a private registry and am having difficulty understanding how to pass the key safely and securely. I am able to successfully connect and push my container if I "build with parameters" in the Jenkins UI and just paste in my key.
This is my yaml file, and my templates to take care of most other things:
- project:
name: 'merge-monitor'
github_project: 'merge-monitor'
value_stream: 'enterprise'
hipchat_rooms:
- ''
defaults: clojure-project-var-defaults
docker_registry: 'private'
jobs:
- '{value_stream}_{name}_docker-build': # build docker images
wrappers:
- credentials-binding:
- text:
credential-id: our-credential-id
variable: DOCKER_REGISTRY_PASSWORD
I have read through the docs, and maybe I am missing something about credentials-binding, but I thought I simply had to call what key I had saved in Jenkins by name, and pass key as a variable into my password
Thank you in advance for the help
The issue here was completely different than what I was searching. Here, we simply needed to give our worker permissions within our own container registry as a user before it would have push access