[Bug 2155160] Update Released

[Timo Aaltonen]

The verification of the Stable Release Update for heat has completed
successfully and the package is now being released to -updates.
Subsequently, the Ubuntu Stable Release Updates Team is being
unsubscribed and will not receive messages about this bug report.  In
the event that you encounter a regression using the package from
-updates please report a new bug using ubuntu-bug and tag the bug report
regression-update so we can easily find any regressions.

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https://bugs.launchpad.net/bugs/2155160

Title:
  heat-api.conf references nonexistent WSGI script /usr/bin/heat-api

Status in Ubuntu Cloud Archive flamingo series:
  New
Status in Ubuntu Cloud Archive gazpacho series:
  New
Status in heat package in Ubuntu:
  Fix Released
Status in heat source package in Questing:
  Won't Fix
Status in heat source package in Resolute:
  Fix Released
Status in heat source package in Stonking:
  Fix Released

Bug description:
  [ Impact ]

   * In Resolute, the `heat-api` Apache vhost points at `/usr/bin/heat-api`, but
     that file is not installed. The packaged WSGI entry point is
     `/usr/bin/heat-wsgi-api`.

   * Apache consequently cannot load the Heat API. Requests return HTTP 500 and
     the Apache error log reports that `/usr/bin/heat-api` is missing.

   * The upload updates the vhost to use the installed WSGI entry point and adds
     an autopkgtest check that configured WSGI scripts exist and are executable.

  [ Test Plan ]

   * Use a disposable Resolute system with Apache. Before enabling
     `resolute-proposed`, install and enable the released package:

         sudo apt update
         sudo apt install heat-api apache2 libapache2-mod-wsgi-py3 curl
         sudo a2ensite heat-api
         sudo systemctl restart apache2

   * Confirm the enabled vhost uses the missing path and reproduce the
  failure:

         awk '$1 == "WSGIScriptAlias" { print }' /etc/apache2/sites-enabled/heat-api.conf
         test ! -e /usr/bin/heat-api
         test -x /usr/bin/heat-wsgi-api
         curl -i http://127.0.0.1:8004/ || true
         sudo tail -n 50 /var/log/apache2/heat_api_error.log

   * Enable `resolute-proposed`, install the candidate `heat-api`, `heat-common`,
     and `python3-heat` packages, and record their versions.

   * Confirm the effective vhost now references `/usr/bin/heat-wsgi-api`, validate
     Apache, restart it, and repeat the request:

         awk '$1 == "WSGIScriptAlias" { print }' /etc/apache2/sites-enabled/heat-api.conf
         sudo apache2ctl configtest
         sudo systemctl restart apache2
         curl -i http://127.0.0.1:8004/ || true
         sudo tail -n 50 /var/log/apache2/heat_api_error.log

     Apache must remain active and the log must not contain the earlier
     missing-script error. Any remaining HTTP 500 must be investigated.

   * If a locally modified vhost is retained during upgrade, confirm the enabled
     configuration itself uses `/usr/bin/heat-wsgi-api`.

  [ Where problems could occur ]

   * A wrong alias, an unexecutable WSGI script, or an import failure would still
     prevent Apache from starting or leave Heat API requests returning HTTP 500.

   * Locally modified Apache conffiles may retain the old alias during upgrade.
     Inspecting the enabled vhost is necessary, not merely the packaged file.

   * The accompanying autopkgtest covers configured script presence, but it does
     not prove a fully configured Heat deployment can serve authenticated API
     requests. The Apache request check covers that boundary.

  [ Other Info ]

   * LP: #2155160 identifies the regression from the Apache/mod_wsgi packaging
     transition. The sibling CFN vhost already uses its installed WSGI script and
     is not changed.

  Summary:

  When heat-api runs under Apache/mod_wsgi (heat ≥ 25.0.0), Apache is unable to start the heat-api vhost because the WSGI script path in debian/heat-api.conf is wrong. Every heat-api request returns a 500 error, and the Apache error log shows:
  "Target WSGI script not found or unable to stat: /usr/bin/heat-api"

  Root cause:

  The bug was introduced in heat 1:25.0.0~rc1-0ubuntu3 (questing, 2025-09-26) when the heat-api service was migrated from a systemd daemon to Apache/mod_wsgi. The new vhost file debian/heat-api.conf contains:
  "WSGIScriptAlias / /usr/bin/heat-api"

  However, no heat package installs /usr/bin/heat-api. The actual WSGI
  entry-point script, installed by python3-heat, is /usr/bin/heat-wsgi-
  api. The sibling vhost file debian/heat-api-cfn.conf is correct
  (/usr/bin/heat-wsgi-api-cfn), making this a straightforward typo in
  heat-api.conf.

  Reproduction:

  - Install heat-api on questing or resolute
  - a2ensite heat-api && systemctl restart apache2
  - curl -i http://localhost:8004/ -> HTTP 500
  - grep "heat-api" /var/log/apache2/heat_api_error.log -> Target WSGI script not found or unable to stat: /usr/bin/heat-api

  After applying the sed one-liner s|WSGIScriptAlias / /usr/bin/heat-
  api$|WSGIScriptAlias / /usr/bin/heat-wsgi-api| to the installed conf
  file and restarting apache2, the heat-api endpoint responds normally.

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