1. Create a remote PHP composer repo in Artifactrory-A
2. Create a remote PHP composer repo in Artifactory-B, that points to the repo in Artifactory-A. (Smart Repository), with these configurations:
http://ARTIFACTORY-A:8081/artifactory/api/composer/api/composer/composer-remote OR http://ARTIFACTORY-A:8081/artifactory/composer-remote
3. Point your .composer/config.json file to Artifactory-B remote repo
4. Use the composer client to pull a package, for example:
Then, if Artifactory-A is down or inaccessible, the composer client will not be able to get the packages from Artifactory-B.