Docker lint warnings for rstudio rhel images

[jiridanek]

2025/05/04 17:47:16 SecretsUsedInArgOrEnv%!(EXTRA string=Sensitive data should not be used in the ARG or ENV commands, string=https://docs.docker.com/go/dockerfile/rule/secrets-used-in-arg-or-env/, string=Do not use ARG or ENV instructions for sensitive data (ARG "SECRET_DIR"), []parser.Range=[{{35 0} {35 0}}])
2025/05/04 17:47:16 UndefinedVar%!(EXTRA string=Variables should be defined before their use, string=https://docs.docker.com/go/dockerfile/rule/undefined-var/, string=Usage of undefined variable '$APP_ROOT', []parser.Range=[{{114 0} {114 0}} {{115 0} {115 0}} {{116 0} {116 0}} {{117 0} {117 0}} {{118 0} {118 0}} {{119 0} {119 0}} {{120 0} {120 0}} {{121 0} {121 0}} {{122 0} {122 0}}])
2025/05/04 17:47:16 UndefinedVar%!(EXTRA string=Variables should be defined before their use, string=https://docs.docker.com/go/dockerfile/rule/undefined-var/, string=Usage of undefined variable '$APP_ROOT', []parser.Range=[{{114 0} {114 0}} {{115 0} {115 0}} {{116 0} {116 0}} {{117 0} {117 0}} {{118 0} {118 0}} {{119 0} {119 0}} {{120 0} {120 0}} {{121 0} {121 0}} {{122 0} {122 0}}])
2025/05/04 17:47:16 UndefinedVar%!(EXTRA string=Variables should be defined before their use, string=https://docs.docker.com/go/dockerfile/rule/undefined-var/, string=Usage of undefined variable '$APP_ROOT', []parser.Range=[{{114 0} {114 0}} {{115 0} {115 0}} {{116 0} {116 0}} {{117 0} {117 0}} {{118 0} {118 0}} {{119 0} {119 0}} {{120 0} {120 0}} {{121 0} {121 0}} {{122 0} {122 0}}])
2025/05/04 17:47:16 UndefinedVar%!(EXTRA string=Variables should be defined before their use, string=https://docs.docker.com/go/dockerfile/rule/undefined-var/, string=Usage of undefined variable '$APP_ROOT', []parser.Range=[{{114 0} {114 0}} {{115 0} {115 0}} {{116 0} {116 0}} {{117 0} {117 0}} {{118 0} {118 0}} {{119 0} {119 0}} {{120 0} {120 0}} {{121 0} {121 0}} {{122 0} {122 0}}])

https://github.com/jiridanek/notebooks/actions/runs/14823705307/job/41614066144#step:23:99