Add --external-database flag for externally-managed databases

[blsmth]

Closes #146.

Adds --external-database <postgres|mysql> to apppack create app, which sets a new ExternalDatabaseEngine CloudFormation parameter so db shell/db dump/db load can target an externally-managed database (Neon, Crunchy, etc.) reachable via the app's DATABASE_URL config variable. Also adds a matching interactive prompt in AskForDatabase (for apppack modify app), client-side validation (mutually exclusive with --addon-database/--addon-database-name, engine must be postgres or mysql), and replaces the unhelpful "unknown database engine " error with a targeted message pointing users at either apppack modify app/--external-database or apppack create database.

Depends on the formations change (apppack-backend) landing and being released first — until formations emits dbutils.engine for externally-configured apps, setting this flag has no effect.

Caveat carried over from the spec: apppack db load's load-from-s3.sh script likely does a DROP/CREATE of the target database, which some managed providers (e.g. Neon) may not permit for the app's role. db shell and db dump are the confident wins here; db load may not reach full parity even after this lands.

Happy path (DBShellTaskInfo/DBDumpLocation/DBDumpLoadFamily, isPostgres in cmd/db.go) is unchanged.

Want a Test Plan section added, or is this concise enough as-is?

[ipmb]

I think we can do this without any confirmation changes by inspecting `DATABASE_URL` if a database isn’t connected.

…

On Tuesday, August 11, 2026, Brendan Smith ***@***.***> wrote: Closes #146 <#146>. Adds --external-database <postgres|mysql> to apppack create app, which sets a new ExternalDatabaseEngine CloudFormation parameter so db shell/db dump/db load can target an externally-managed database (Neon, Crunchy, etc.) reachable via the app's DATABASE_URL config variable. Also adds a matching interactive prompt in AskForDatabase (for apppack modify app), client-side validation (mutually exclusive with --addon-database/--addon- database-name, engine must be postgres or mysql), and replaces the unhelpful "unknown database engine " error with a targeted message pointing users at either apppack modify app/--external-database or apppack create database. *Depends on the formations change (apppack-backend) landing and being released first* — until formations emits dbutils.engine for externally-configured apps, setting this flag has no effect. *Caveat carried over from the spec:* apppack db load's load-from-s3.sh script likely does a DROP/CREATE of the target database, which some managed providers (e.g. Neon) may not permit for the app's role. db shell and db dump are the confident wins here; db load may not reach full parity even after this lands. Happy path (DBShellTaskInfo/DBDumpLocation/DBDumpLoadFamily, isPostgres in cmd/db.go) is unchanged. Want a Test Plan section added, or is this concise enough as-is? ------------------------------ You can view, comment on, or merge this pull request online at: #173 Commit Summary - 85333e4 <85333e4> Add --external-database flag for externally-managed databases File Changes (5 files <https://github.com/apppackio/apppack/pull/173/files>) - *M* app/app.go <https://github.com/apppackio/apppack/pull/173/files#diff-0f1d2976054440336a576d47a44a37b80cdf6701dd9113012bce0e3c425819b7> (53) - *A* app/db_test.go <https://github.com/apppackio/apppack/pull/173/files#diff-0b83ab9ace3cef740a068338080411c0dbf6939f6312fa859e21eecdba4ba7cf> (55) - *M* cmd/create.go <https://github.com/apppackio/apppack/pull/173/files#diff-e52f1f4fa0c533e3287cbe2ef0436582b5ca471a3fddcdf1f49fecd1ec0c7d13> (1) - *M* stacks/app_pipeline.go <https://github.com/apppackio/apppack/pull/173/files#diff-4d723cfd1f5868b91d58c87c8889fe5876308ca123e662b4dfd1d92b886539a6> (162) - *M* stacks/app_pipeline_test.go <https://github.com/apppackio/apppack/pull/173/files#diff-8896a004e806c4fd2a86ad540f059d01b03bbfc77d6d4b8e78488a5751db8f8e> (124) Patch Links: - https://github.com/apppackio/apppack/pull/173.patch - https://github.com/apppackio/apppack/pull/173.diff — Reply to this email directly, view it on GitHub <#173?email_source=notifications&email_token=AACN5NAMWYT6CG26WRO62UD5JN737A5CNFSNUABEM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UF42DENJWG43TANJTGGTHEZLBONXW5KTTOVRHGY3SNFRGKZFFMV3GK3TUVRTG633UMVZF6Y3MNFRWW>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACN5NFYIIMRRSSFGCMONXD5JN737AVCNFSNUABFKJSXA33TNF2G64TZHMZTCOJXGM2TENBVHNEXG43VMU5TKMJSGQZTQNZWHE4KC5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AACN5NF5N7GLMFI26QSEAPL5JN737A5CNFSNUABEM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UF42DENJWG43TANJTGGTHEZLBONXW5KTTOVRHGY3SNFRGKZFFMV3GK3TUVJTG633UMVZF62LPOM> and Android <https://github.com/notifications/mobile/android/AACN5NBOHZEBM7PTHYPEJIL5JN737A5CNFSNUABEM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UF42DENJWG43TANJTGGTHEZLBONXW5KTTOVRHGY3SNFRGKZFFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. Download it today! You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>