imagePullPolicy: IfNotPresent should be Always for -SNAPSHOTs

[robinroos]

Description

Upon oc:resource oc:deploy of a Spring Boot application, the resulting Deployment has imagePullPolicy: IfNotPresent. This causes OpenShift not to fetch the new version. If the built version is a SNAPSHOT then imagePullPolicy should have value Always.

Info

• Eclipse JKube version : 1.5.1
• Maven version (mvn -v) : 3.6.3
• Kubernetes / Red Hat OpenShift setup and version : OpenShift 4.7

[manusa]

https://kubernetes.io/docs/concepts/containers/images/#imagepullpolicy-defaulting

Another option would be to leave it blank and let the cluster decide. But yes, this seems like something we should fix.

[manusa]

As agreed during triage session, we should set the value to Always (not leave it blank), and provide a warning.

[manusa]

I'm running into some problems with this scenario.

Running on Minikube and imagePullPolicy is set to Always. The scenario where the image is built in the Minikube's Docker daemon eval $(minikube docker-env) fails, since the cluster will still try to fetch the image from the remote repo.

[manusa]

Another option that we might consider is using the hash to reference the image in the generated resources when the project version is a SNAPSHOT.

[robinroos]

I understand this was tricky and could not be included in 1.6.0, but thanks for trying. I will continue to manually set this property on new deploymentsof snapshot container versions.

[manusa]

The problem is that the change may break some inner-loop scenarios (such as the mentioned issue with Minikube). We need to further evaluate this so that the fix is valid for all use cases.

[robinroos]

This is the best workaround I can find, and for the reasons stated in my opinion the workaround is not good enough.

<plugin>
    <!-- jumping through hoops here to set jkube.imagePullPolicy in a generic manner -->
    <!-- taken from: https://stackoverflow.com/questions/44002807/conditionally-set-property-in-maven -->
    <!-- in order to work around: https://github.com/eclipse/jkube/issues/1138 -->
    <!-- Personally I (Robin Roos) do not like this solution.  It is too "imperative" and very hard to read. -->
    <!-- I would prefer that JKube address the core issue, or that Apache provide a Maven capability to activate a profile if the build version is snapshot. -->
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>3.0.0</version>
    <executions>
        <execution>
            <id>build-helper-regex-is-snapshot-used</id>
            <goals>
                <goal>regex-property</goal>
            </goals>
            <configuration>
                <name>jkube.imagePullPolicy</name>
                <value>${project.version} Always IfNotPresent</value>
                <regex>(?=.*SNAPSHOT).*(Always).*|.*(IfNotPresent).*</regex>
                <replacement>$1$2</replacement>
                <failIfNoMatch>true</failIfNoMatch>
            </configuration>
        </execution>
    </executions>
</plugin>

[robinroos]

I have this approach working now. It is still a "workaround" and I look forward to moving away from it to something less brittle and more understandable.

Note that build-helper-maven-plugin is bound to the validate phase. If you run maven with other phases, then surely validate will execute. But if your maven command is instead a list of goals (goals are prefixed by plugin:) then you will have to add validate explicitly.

e.g. mvn -Pmyopenshiftprofile validate resources:resources oc:resource oc:helm oc:helm-push

[manusa]

Apparently this is an actual bug since it contravenes what's stated in the docs:

The pull policy imagePullPolicy is set according to the given configuration. If no configuration is set, the default is IfNotPresent for release versions, and Always for snapshot versions.