Add ability to auto-generate alembic migrations

We move to a slightly more general model where we can support specific
Alembic operations passed as arguments.

This was very useful to easily run the auto-generated migrations.

jenkins/Pipeline.gy

@@ -28,7 +28,7 @@ pipeline {
         stage('Server Alembic Migrations Check') {
             steps {
                 echo 'Verify alembic migrations cover latest database schema'
-                sh 'jenkins/run-alembic-migrations-check'
+                sh 'jenkins/run-alembic-migrations check'
             }
         }
         stage('Linting, Unit Tests, RPM builds') {

jenkins/run-alembic-migrations-check → jenkins/run-alembic-migrations

@@ -34,4 +34,4 @@ timeout 60s bash -c 'until nc -z localhost 5432; do
 done'
 
 echo "Starting tox" >&2
-EXTRA_PODMAN_SWITCHES="${EXTRA_PODMAN_SWITCHES} --network host" jenkins/run tox -e alembic-check
+EXTRA_PODMAN_SWITCHES="${EXTRA_PODMAN_SWITCHES} --network host" jenkins/run tox -e alembic-migration -- ${1:-check}

lib/pbench/server/database/alembic.migration

@@ -0,0 +1,19 @@
+#!/bin/bash -e
+
+cd lib/pbench/server/database
+
+# First we run all our migrations to bring the blank database up to speed.
+alembic upgrade head
+
+if [[ "${1}" == "check" ]]; then
+	# We have been asked to check to see if there are any model changes not
+    # captured in existing migrations.
+	alembic check
+elif [[ "${1}" == "create" ]]; then
+    # We have been asked to auto-generate a migration based on the existing
+    # model compared against the most recent migration "head".
+    alembic revision --autogenerate
+else
+    printf "Unsupported operation requested, '%s'\n" "${1}" >&2
+    exit 1
+fi

tox.ini

@@ -41,9 +41,9 @@ deps =
     -r{toxinidir}/agent/requirements.txt
     -r{toxinidir}/agent/test-requirements.txt
 
-[testenv:alembic-check]
+[testenv:alembic-migration]
 description = Verify alembic migrations cover latest database schema
 deps =
     -r{toxinidir}/server/requirements.txt
 commands =
-    bash -c "{toxinidir}/lib/pbench/server/database/alembic.check"
+    bash -c "{toxinidir}/lib/pbench/server/database/alembic.migration {posargs}"