private DeploymentPlan CreateDeploymentPlan()
{
int lastCompletedMigrationNumber = 0;
List <Migration> offlineMigrationsToRun = new List <Migration>();
List <Migration> onlineMigrationsToRun = new List <Migration>();
List <StoredCodeDefinition> storedCodeToRun = new List <StoredCodeDefinition>();
DeploymentPlan Error(string message)
{
return(new DeploymentPlan(
message,
message,
offlineMigrationsToRun,
storedCodeToRun,
onlineMigrationsToRun,
lastCompletedMigrationNumber));
}
// the _journal might throw an exception here if it was never created for the target data store
LoadDeployedMigrations();
var availableMigrations = GetAvailableMigrations();
if (availableMigrations.GroupBy(am => am.Name, StringComparer.OrdinalIgnoreCase).Any(g => g.Count() > 1))
{
// we have duplicate migration names so we can't do anything
return(Error("Cannot deploy due to migration names that are not unique."));
}
if (availableMigrations.GroupBy(am => am.MigrationNumber).Any(g => g.Count() > 1))
{
// we have duplicate migration numbers so we can't do anything
return(Error("Cannot deploy due to migration numbers that are not unique."));
}
var migrationNumbers = availableMigrations.Select(am => am.MigrationNumber).ToArray();
if (!migrationNumbers.SequenceEqual(migrationNumbers.OrderBy(v => v)))
{
// we have migration numbers out-of order so we can't do anything
return(Error("Cannot deploy due to migration numbers that are not in order."));
}
bool mustRestartLastMigration = false;
for (int i = 0; i < _deployedMigrations.Count; i++)
{
var deployedMigration = _deployedMigrations[i];
if (i == availableMigrations.Count)
{
// then we've just encountered the first deployed migration that is not known as an available one, so this is an attempt to migrate to an incompatible branch
return(Error(
"Cannot deploy due to incompatible branch. " +
$"Deployed migration ({deployedMigration.MigrationNumber}) {deployedMigration.Name} is not known."
));
}
var availableMigration = availableMigrations[i];
// if they don't match and this is a complete migration, or is the last migration and is an incomplete offline migration, this is an attempt to migrate to an incompatible branch
if (deployedMigration.MigrationNumber == availableMigration.MigrationNumber &&
deployedMigration.Name.Equals(availableMigration.Name, StringComparison.OrdinalIgnoreCase))
{
// now if the migration is complete, the fingerprints must match
if (deployedMigration.Complete)
{
lastCompletedMigrationNumber = deployedMigration.MigrationNumber;
if (deployedMigration.Fingerprint != availableMigration.Fingerprint)
{
// then a completed migration has been modified, so this is an attempt to migrate to an incompatible branch
return(Error(
"Cannot deploy due to incompatible branch. " +
$"Deployed migration ({deployedMigration.MigrationNumber}) {deployedMigration.Name} has been modified."
));
}
// otherwise, these migrations match so we'll continue in our loop.
}
else
{
// the deployed migration is incomplete. It must be the last one in the list of deployed migrations.
if (availableMigration.IsOnlineMigration == false)
{
return(Error(
"Cannot deploy due to incomplete prior offline migration. " +
$"Deployed migration ({deployedMigration.MigrationNumber}) {deployedMigration.Name} did not complete. " +
"Restore the database from a backup or manually fix the database and mark the migration complete in the journal, or delete it from the journal to have it run the next time."
));
}
// otherwise it must be an online migration so we are allowed to restart it even if its fingerprint is different
mustRestartLastMigration = true;
}
}
else
{
// then we just encountered a mismatch between the deployed and available migrations, so this is an attempt to migrate to an incompatible branch
return(Error(
"Cannot deploy due to incompatible branch. " +
$"Available migration ({availableMigration.MigrationNumber}) {availableMigration.Name} was found where deployed migration ({deployedMigration.MigrationNumber}) {deployedMigration.Name} was expected."
));
}
}
// we'll either take all the migrations after the deployed ones, or we'll take the last migration to restart it plus all the rest.
int indexOfFirstMigrationToRun = _deployedMigrations.Count;
if (mustRestartLastMigration)
{
indexOfFirstMigrationToRun -= 1;
}
// at this point, we can take the remainder of the available migrations and verify them.
if (_includeOnlineMigrationsDuringOffline)
{
offlineMigrationsToRun = availableMigrations.Skip(indexOfFirstMigrationToRun).ToList();
}
else
{
var foundOnlineMigration = false;
for (int i = indexOfFirstMigrationToRun; i < availableMigrations.Count; i++)
{
var availableMigration = availableMigrations[i];
if (availableMigration.IsOnlineMigration)
{
foundOnlineMigration = true;
onlineMigrationsToRun.Add(availableMigration);
}
else if (foundOnlineMigration)
{
// then we found that there is an offline migration that follows at least one online migration therefore this version is undeployable.
return(Error(
"Cannot deploy due to incompatible branch. " +
$"Found offline migration ({availableMigration.MigrationNumber}) {availableMigration.Name} that follows an online migration."));
}
else
{
offlineMigrationsToRun.Add(availableMigration);
}
}
}
// determine which repeatable scripts need to run
var deployedStoredCodeDefinitions =
_journal.GetDeployedStoredCodeDefinitions().ToDictionary(r => r.Name, StringComparer.OrdinalIgnoreCase);
var availableStoredCodeDefinitions = _migrationsProvider.GatherStoredCodeDefinitions();
// find the differences
storedCodeToRun = availableStoredCodeDefinitions
.Where(availableScript =>
{
if (deployedStoredCodeDefinitions.TryGetValue(availableScript.Name, out var found) &&
found.Fingerprint == availableScript.Fingerprint)
{
return(false);
}
return(true);
}
)
.ToList();
// determine whether online migration is possible
var onlineErrorMessage = offlineMigrationsToRun.Count > 1
? $"Cannot deploy online due to offline migrations that need to run first: ({offlineMigrationsToRun[0].MigrationNumber}) {offlineMigrationsToRun[0].Name}."
: null;
return(new DeploymentPlan(null, onlineErrorMessage, offlineMigrationsToRun, storedCodeToRun, onlineMigrationsToRun, lastCompletedMigrationNumber));
}
