Something I have been playing around with recently are user-defined-policies (UDPs) in APIC. As a quick recap, APIs can have custom assemblies attached to them, so that custom processing will be run on the message in the gateway. Assemblies are made up of policies, and a user-defined-policy is not unlike a callable unit/function/subroutine.

I started off from these two KC articles: https://www.ibm.com/support/knowledgecenter/SSMNED_5.0.0/com.ibm.apic.policy.doc/tapim_import_custpolicies.html https://www.ibm.com/support/knowledgecenter/SSMNED_5.0.0/com.ibm.apic.policy.doc/tapim_creating_policy.html

I built myself a single DataPower action (with INPUT and OUTPUT of NULL), which was being consumed by a single DataPower processing rule. I packaged it up, and naively loaded into APIC. The API Designer returned the following error to me.

Validation failed for policy type CountToTen. The implementation zip file does not contain an export.xml file

I figured that I had copied the DP export incorrectly. The first KC link outlines the correct directory structure:

policy.yaml
implementation/
              mypolicy_dp.zip

I rebuilt my zip and tried again.

Validation failed for policy type CountToTen. The implementation zip file has the following files that are not valid: local:///foo/bar.js

And some further rebuilding…

Validation failed for policy type CountToTen. The implementation zip file has the following files that are not valid: local:///policy/bar.js

And finally, some googling. I eventually came upon another page full of gotchas on KC, that really should be the first page! https://www.ibm.com/support/knowledgecenter/en/SSMNED_5.0.0/com.ibm.apic.policy.doc/tapim_pol_implement.html Seriously, this is a good link to read start-to-end, with loads of good details. The gotchs which I was falling for was that the name of the policy has to be repeated in many places. E.g. For a UDP called my-cool-policy:

  • the policy.yaml should be my-cool-policy.yaml.
  • Inside the yaml, the value of- 
      info:
      name:

    -must be set to my-cool-policy.

  • The DP processing rule in your export should be named my-cool-policy-main.
  • The actions in your processing rule should have names starting with the prefix my-cool-policy .
  • Any files (.xsl’s and .js’s) that your processing actions need to reference should be stored in the local:///policy/my-cool-policy/ directory.