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: ***@***.***>

[blsmth]

Pushed an update that addresses your review: --external-database and both interactive prompts (enable? / which engine?) are gone. SetInternalFields now infers ExternalDatabaseEngine from the app's DATABASE_URL config variable (read from SSM), comparing only the URL scheme -- postgres/postgresql/pgsql/psql -> postgres, mysql/mysql2/mariadb -> mysql. This runs for both create app and modify app, so the resulting workflow is:

apppack create app ...
apppack config set DATABASE_URL=...
apppack modify app <name>   # picks up the engine automatically

A managed AppPack database (--addon-database/--addon-database-name) always wins and forces the field back to "", and pipelines/review apps are excluded, since the CloudFormation condition requires IsApp -- so detection is idempotent no matter how many times modify app runs.

On the "no CloudFormation changes" half of your comment: that part isn't achievable. Every db-utils resource (task definitions, execution/task roles, log group, S3 bucket) is gated behind DatabaseEnabled, and app.StartTask only ever does DescribeTaskDefinition -> RunTask -- there's no task-definition family to run against for an external DB without the formations change. That half of the PR is unchanged.

One tradeoff worth flagging: since there's no flag anymore, there's also no escape hatch for a DATABASE_URL with a scheme we don't recognize -- we print one warning and leave db shell/db dump disabled rather than failing the deploy. Happy to add --external-database back as a hidden override for that case if you'd rather have one. Let me know.

[ipmb]

Could we special-case `apppack config set DATABASE_URL=...` (and `apppack config import`) to provide additional instructions on how they can modify the app to allow db shell/dump/load commands to work?

…

On Wed, Aug 19, 2026 at 2:34 PM Brendan Smith ***@***.***> wrote: *blsmth* left a comment (apppackio/apppack#173) <#173 (comment)> Pushed an update that addresses your review: --external-database and both interactive prompts (enable? / which engine?) are gone. SetInternalFields now infers ExternalDatabaseEngine from the app's DATABASE_URL config variable (read from SSM), comparing only the URL scheme -- postgres/ postgresql/pgsql/psql -> postgres, mysql/mysql2/mariadb -> mysql. This runs for both create app and modify app, so the resulting workflow is: apppack create app ... apppack config set DATABASE_URL=... apppack modify app <name> # picks up the engine automatically A managed AppPack database (--addon-database/--addon-database-name) always wins and forces the field back to "", and pipelines/review apps are excluded, since the CloudFormation condition requires IsApp -- so detection is idempotent no matter how many times modify app runs. On the "no CloudFormation changes" half of your comment: that part isn't achievable. Every db-utils resource (task definitions, execution/task roles, log group, S3 bucket) is gated behind DatabaseEnabled, and app.StartTask only ever does DescribeTaskDefinition -> RunTask -- there's no task-definition family to run against for an external DB without the formations change. That half of the PR is unchanged. One tradeoff worth flagging: since there's no flag anymore, there's also no escape hatch for a DATABASE_URL with a scheme we don't recognize -- we print one warning and leave db shell/db dump disabled rather than failing the deploy. Happy to add --external-database back as a hidden override for that case if you'd rather have one. Let me know. — Reply to this email directly, view it on GitHub <#173?email_source=notifications&email_token=AACN5NDVIBT5OXKBBPU7JS35KYFOFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZUG43DOOBZGM22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5347678935>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACN5NHBUQZUKGJ5S6JCD335KYFOFAVCNFSNUABFKJSXA33TNF2G64TZHMZTCOJXGM2TENBVHNEXG43VMU5TKMJSGQZTQNZWHE4KC5QC> . 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/AACN5NEFQRYALLIQ5OCVZ2T5KYFOFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZUG43DOOBZGM22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/AACN5NDBWJ7Z7VVR766M2ML5KYFOFA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZUG43DOOBZGM22M4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>