View Source Migrations
Tasks
Ash comes with its own tasks, and AshPostgres exposes lower level tasks that you can use if necessary. This guide shows the process using ash.*
tasks, and the ash_postgres.*
tasks are illustrated at the bottom.
Basic Workflow
- Make resource changes
- Run
mix ash.codegen --name add_a_combobulator
to generate migrations and resource snapshots - Run
mix ash.migrate
to run those migrations
For more information on generating migrations, run mix help ash_postgres.generate_migrations
(the underlying task that is called by mix ash.migrate
)
list_tenants/0
If you have are using schema-based multitenancy, you will also need to define a list_tenants/0
function in your repo module. See AshPostgres.Repo
for more.
Regenerating Migrations
Often, you will run into a situation where you want to make a slight change to a resource after you've already generated and run migrations. If you are using git and would like to undo those changes, then regenerate the migrations, this script may prove useful:
#!/bin/bash
# Get count of untracked migrations
N_MIGRATIONS=$(git ls-files --others priv/repo/migrations | wc -l)
# Rollback untracked migrations
mix ash_postgres.rollback -n $N_MIGRATIONS
# Delete untracked migrations and snapshots
git ls-files --others priv/repo/migrations | xargs rm
git ls-files --others priv/resource_snapshots | xargs rm
# Regenerate migrations
mix ash.codegen --name $1
# Run migrations if flag
if echo $* | grep -e "-m" -q
then
mix ash.migrate
fi
After saving this file to something like regen.sh
, make it executable with chmod +x regen.sh
. Now you can run it with ./regen.sh name_of_operation
. If you would like the migrations to automatically run after regeneration, add the -m
flag: ./regen.sh name_of_operation -m
.
Running Migrations in Production
Define a module similar to the following:
defmodule MyApp.Release do
@moduledoc """
Tasks that need to be executed in the released application (because mix is not present in releases).
"""
@app :my_app
def migrate do
load_app()
for repo <- repos() do
{:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :up, all: true))
end
end
# only needed if you are using postgres multitenancy
def migrate_tenants do
load_app()
for repo <- repos() do
repo_name = repo |> Module.split() |> List.last() |> Macro.underscore()
path =
"priv/"
|> Path.join(repo_name)
|> Path.join("tenant_migrations")
# This may be different for you if you are not using the default tenant migrations
{:ok, _, _} =
Ecto.Migrator.with_repo(
repo,
fn repo ->
for tenant <- repo.all_tenants() do
Ecto.Migrator.run(repo, path, :up, all: true, prefix: tenant)
end
end
)
end
end
# only needed if you are using postgres multitenancy
def migrate_all do
load_app()
migrate()
migrate_tenants()
end
def rollback(repo, version) do
load_app()
{:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :down, to: version))
end
# only needed if you are using postgres multitenancy
def rollback_tenants(repo, version) do
load_app()
repo_name = repo |> Module.split() |> List.last() |> Macro.underscore()
path =
"priv/"
|> Path.join(repo_name)
|> Path.join("tenant_migrations")
# This may be different for you if you are not using the default tenant migrations
for tenant <- repo.all_tenants() do
{:ok, _, _} =
Ecto.Migrator.with_repo(
repo,
&Ecto.Migrator.run(&1, path, :down,
to: version,
prefix: tenant
)
)
end
end
defp repos do
domains()
|> Enum.flat_map(fn domain ->
domain
|> Ash.Domain.Info.resources()
|> Enum.map(&AshPostgres.DataLayer.Info.repo/1)
|> Enum.reject(&is_nil/1)
end)
|> Enum.uniq()
end
defp domains do
Application.fetch_env!(@app, :ash_domains)
end
defp load_app do
Application.load(@app)
end
end
AshPostgres-specific mix tasks
mix ash_postgres.generate_migrations
mix ash_postgres.create
mix ash_postgres.drop
mix ash_postgres.migrate
(usemix ash_postgres.migrate --tenants
to run tenant migrations)mix ash_postgres.rollback
(usemix ash_postgres.rollback --tenants
to rollback tenant migrations)