Don't expect paths can be any longer than 255 characters

We can reasonably assume that file paths can not be any longer
than 255 characters since that's the ceiling in most established
filesystems [1].

This fixes an issue with the MySQL implementation so we don't go
over the indexed field limit of 767 bytes.

[1]: https://en.wikipedia.org/wiki/Comparison_of_file_systems#Limits

Change-Id: I57d71c26aa1db7b31c6ef36989464c460aab70e1

ara/db/versions/001_initial_revision.py

@@ -23,7 +23,7 @@ def upgrade():
     )
     op.create_table('playbooks',
     sa.Column('id', sa.String(length=36), nullable=False),
-    sa.Column('path', sa.Text(), nullable=True),
+    sa.Column('path', sa.String(255), nullable=True),
     sa.Column('time_start', sa.DateTime(), nullable=True),
     sa.Column('time_end', sa.DateTime(), nullable=True),
     sa.Column('complete', sa.Boolean(), nullable=True),
@@ -32,7 +32,7 @@ def upgrade():
     op.create_table('files',
     sa.Column('id', sa.String(length=36), nullable=False),
     sa.Column('playbook_id', sa.String(length=36), nullable=True),
-    sa.Column('path', sa.String(length=3000), nullable=True),
+    sa.Column('path', sa.String(length=255), nullable=True),
     sa.Column('content_id', sa.String(length=40), nullable=True),
     sa.Column('is_playbook', sa.Boolean(), nullable=True),
     sa.ForeignKeyConstraint(['content_id'], ['file_contents.id'], ),

ara/models.py

@@ -137,7 +137,7 @@ class Playbook(db.Model, TimedEntity):
     __tablename__ = 'playbooks'
 
     id = std_pkey()
-    path = db.Column(db.Text)
+    path = db.Column(db.String(255))
     data = one_to_many('Data', backref='playbook')
     files = one_to_many('File', backref='playbook')
     plays = one_to_many('Play', backref='playbook')
@@ -172,7 +172,7 @@ class File(db.Model):
     # limited to a maximum key length of 3072 bytes.  This
     # restrictions stems from the fact that we are using this column in
     # a UNIQUE constraint.
-    path = db.Column(db.String(3000))
+    path = db.Column(db.String(255))
     content = many_to_one('FileContent', backref='files')
     content_id = db.Column(db.String(40),
                            db.ForeignKey('file_contents.id'))