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162 lines
4.9 KiB
Markdown
162 lines
4.9 KiB
Markdown
# Migrations
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## Tasks
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The available tasks are:
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- `mix ash_postgres.generate_migrations`
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- `mix ash_postgres.create`
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- `mix ash_postgres.drop`
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- `mix ash_postgres.migrate` (use `mix ash_postgres.migrate --tenants` to run tenant migrations)
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AshPostgres is built on top of ecto, so much of its behavior is pass-through/orchestration of that tooling.
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## Basic Workflow
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- Make resource changes
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- Run `mix ash_postgres.generate_migrations` to generate migrations and resource snapshots
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- Run `mix ash_postgres.migrate` to run those migrations
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- Run `mix ash_postgres.migrate --tenants` _as well_ if you have multi-tenant resources.
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For more information on generating migrations, see the module documentation here:
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`Mix.Tasks.AshPostgres.GenerateMigrations`, or run `mix help ash_postgres.generate_migrations`
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For running your migrations, there is a mix task that will find all of the repos configured in your apis and run their
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migrations. It is a thin wrapper around `mix ecto.migrate`. Ours is called `mix ash_postgres.migrate`
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If you want to run or rollback individual migrations, use the corresponding
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For tenant migrations (see the multitenancy guides for more) generated by multitenant resources, make sure you are using
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`mix ash_postgres.generate_migrations`. It is not sufficient to run `mix ash_postgres.migrate --migrations_path tenant_migrations_path`. You will also need to define a `list_tenants/0` function in your repo module. See `AshPostgres.Repo` for more.
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### Regenerating Migrations
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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:
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```bash
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#!/bin/bash
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# Get count of untracked migrations
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N_MIGRATIONS=$(git ls-files --others priv/repo/migrations | wc -l)
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# Rollback untracked migrations
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mix ecto.rollback -n $N_MIGRATIONS
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# Delete untracked migrations and snapshots
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git ls-files --others priv/repo/migrations | xargs rm
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git ls-files --others priv/resource_snapshots | xargs rm
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# Regenerate migrations
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mix ash_postgres.generate_migrations
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# Run migrations if flag
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if echo $* | grep -e "-m" -q
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then
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mix ecto.migrate
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fi
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```
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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`. If you would like the migrations to automatically run after regeneration, add the `-m` flag: `./regen.sh -m`.
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## Multiple Repos
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If you are using multiple repos, you will likely need to use `mix ecto.migrate` and manage it separately for each repo, as the options would
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be applied to both repo, which wouldn't make sense.
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## Running Migrations in Production
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Define a module similar to the following:
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```elixir
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defmodule MyApp.Release do
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@moduledoc """
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Houses tasks that need to be executed in the released application (because mix is not present in releases).
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"""
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@app :my_ap
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def migrate do
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load_app()
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for repo <- repos() do
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{:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :up, all: true))
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end
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end
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# only needed if you are using postgres multitenancy
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def migrate_tenants do
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load_app()
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for repo <- repos() do
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repo_name = repo |> Module.split() |> List.last() |> Macro.underscore()
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path =
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"priv/"
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|> Path.join(repo_name)
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|> Path.join("tenant_migrations")
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# This may be different for you if you are not using the default tenant migrations
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{:ok, _, _} =
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Ecto.Migrator.with_repo(
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repo,
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fn repo ->
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for tenant <- repo.all_tenants() do
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Ecto.Migrator.run(repo, path, :up, all: true, prefix: tenant)
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end
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end
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)
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end
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end
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# only needed if you are using postgres multitenancy
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def migrate_all do
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load_app()
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migrate()
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migrate_tenants()
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end
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def rollback(repo, version) do
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load_app()
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{:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :down, to: version))
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end
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# only needed if you are using postgres multitenancy
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def rollback_tenants(repo, version) do
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load_app()
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repo_name = repo |> Module.split() |> List.last() |> Macro.underscore()
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path =
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"priv/"
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|> Path.join(repo_name)
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|> Path.join("tenant_migrations")
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# This may be different for you if you are not using the default tenant migrations
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for tenant <- repo.all_tenants() do
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{:ok, _, _} =
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Ecto.Migrator.with_repo(
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repo,
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&Ecto.Migrator.run(&1, path, :down,
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to: version,
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prefix: tenant
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)
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)
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end
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end
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defp repos do
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apis()
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|> Enum.flat_map(fn api ->
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api
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|> Ash.Api.resources()
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|> Enum.map(&AshPostgres.repo/1)
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end)
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|> Enum.uniq()
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end
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defp apis do
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Application.fetch_env!(:my_app, :ash_apis)
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end
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defp load_app do
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Application.load(@app)
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end
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end
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```
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