Chapter 17. Building Dependency Trees

OpenShift uses image change triggers in a build configuration to detect when an image stream tag has been updated. You can use the oadm build-chain command to build a dependency tree that identifies which images would be affected by updating an image in a specified image stream.

The build-chain tool can determine which builds to trigger; it analyzes the output of those builds to determine if they will in turn update another image stream tag. If they do, the tool continues to follow the dependency tree. Lastly, it outputs a graph specifying the image stream tags that would be impacted by an update to the top-level tag. The default output syntax for this tool is set to a human-readable format; the DOT format is also supported.

The following table describes common build-chain usage and general syntax:

oadm build-chain <image-stream>

$ oadm build-chain <image-stream>

oadm build-chain <image-stream>:v2 \
    -o dot \
    | dot -T svg -o deps.svg

$ oadm build-chain <image-stream>:v2 \
    -o dot \
    | dot -T svg -o deps.svg

oadm build-chain <image-stream>:v1 \
    -n test --all

$ oadm build-chain <image-stream>:v1 \
    -n test --all