OpenShift : Waiting for image stream to be created - bash

Question

I am creating an installation script that will create resources off of YAML files†. This script will do the equivalent of this command:
oc new-app registry.access.redhat.com/rhscl/nginx-114-rhel7~http://github.com/username/repo.git
Three YAML files were created as follows:
imagestream for nginx-114-rhel7 - is-nginx.yaml
apiVersion: image.openshift.io/v1
kind: ImageStream
metadata:
labels:
build: build-repo
name: nginx-114-rhel7
namespace: ns
spec:
tags:
- annotations: null
from:
kind: DockerImage
name: registry.access.redhat.com/rhscl/nginx-114-rhel7
name: latest
referencePolicy:
type: Source
imagestream for repo - is-repo.yaml
apiVersion: v1
kind: ImageStream
metadata:
labels:
application: is-rp
name: is-rp
namespace: ns
buildconfig for repo (output will be imagestream for repo) - bc-repo.yaml
apiVersion: v1
kind: BuildConfig
metadata:
labels:
build: rp
name: bc-rp
namespace: ns
spec:
output:
to:
kind: ImageStreamTag
name: 'is-rp:latest'
postCommit: {}
resources: {}
runPolicy: Serial
source:
git:
ref: dev_1.0
uri: 'http://github.com/username/repo.git'
type: Git
strategy:
sourceStrategy:
from:
kind: ImageStreamTag
name: 'nginx-114-rhel7:latest'
namespace: flo
type: Source
successfulBuildsHistoryLimit: 5
When these commands are run one after another,
oc create -f is-nginx.yaml;oc create -f is-repo.yaml;oc create -f bc-repo.yaml;oc start-build bc/bc-rep --wait
I get this error message,
The ImageStreamTag "nginx-114-rhel7:latest" is invalid: from: Error resolving ImageStreamTag nginx-114-rhel7:latest in namespace ns: unable to find latest tagged image
But, when I run the commands with a sleep before start-build, the build is triggered correctly.
oc create -f is-nginx.yaml;oc create -f is-repo.yaml;oc create -f bc-repo.yaml;sleep 5;oc start-build bc/bc-rep
How do I trigger start-build without entering a sleep command? The oc wait seems to work only for --for=condition and --for=delete. I do not know what value is to be used for --for=condition.
† - I do not see a clear guideline on creating installation scripts - with YAML or equivalent oc commands only - for deploying applications on to OpenShift.

Answer 1

Instead of running oc start-build, you should look into Image Change Triggers and Configuration Change Triggers
In your build config, you can point to an ImageStreamTag to start a build
type: "imageChange"
imageChange: {}
type: "imageChange"
imageChange:
from:
kind: "ImageStreamTag"
name: "custom-image:latest"

Answer 2

oc wait --for=condition=available only works when status object includes conditions, which is not the case for imagestreams.
status:
dockerImageRepository: image-registry.openshift-image-registry.svc:5000/test/s2i-openresty-centos7
tags:
- items:
- created: "2019-11-05T11:23:45Z"
dockerImageReference: quay.io/openresty/openresty-centos7#sha256:db224d642ad4001ab971b934a6444da16bb87ddfcc9c048bbf68febafcac52db
generation: 2
image: sha256:db224d642ad4001ab971b934a6444da16bb87ddfcc9c048bbf68febafcac52db
tag: builder
- items:
- created: "2019-11-05T11:23:45Z"
dockerImageReference: qquay.io/openresty/openresty-centos7#sha256:082ee75ed83f161375d0d281f235b7271176b1d129f5ed9972c7d31923e08660
generation: 2
image: sha256:082ee75ed83f161375d0d281f235b7271176b1d129f5ed9972c7d31923e08660
tag: runtime
Until openshift CLI implements builtin waiting command for imagestreams, what I used to do is: request imagestream object, parse status object for the expected tag and sleep few seconds if not ready. Something like this:
until oc get is nginx-114-rhel7 -o json || echo '{}' | jq '[.status.tags[] | select(.tag == "latest")] | length == 1' --exit-status; do
sleep 1
done