Initial commit

.editorconfig

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+root = true
+
+[*.cr]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true

.github/dependabot.yml

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+# https://docs.github.com/en/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    open-pull-requests-limit: 5
+    target-branch: main

.github/workflows/automerge.yml

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+name: Auto-merge minor/patch
+on:
+  schedule:
+    - cron: "0 * * * *"
+jobs:
+  test:
+    name: Auto-merge minor and patch updates
+    runs-on: ubuntu-latest
+    steps:
+      - uses: koj-co/dependabot-pr-action@master
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          merge-minor: true
+          merge-patch: true

.github/workflows/ci.yml

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+name: Continuous Integration
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  CheckFormat:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/[email protected]
+
+      - uses: oprypin/install-crystal@v1
+        with:
+          crystal: latest
+
+      - name: Format
+        run: crystal tool format --check
+
+      - name: Set up Crystal cache
+        uses: actions/[email protected]
+        id: crystal-cache
+        with:
+          path: |
+            ~/.cache/crystal
+            bin/ameba
+            lib
+          key: ${{ runner.os }}-crystal-${{ hashFiles('**/shard.yml') }}
+          restore-keys: |
+            ${{ runner.os }}-crystal-
+
+      - name: Install shards
+        if: steps.crystal-cache.outputs.cache-hit != 'true'
+        run: shards check || shards install --ignore-crystal-version
+
+      - name: Run ameba linter
+        run: ./bin/ameba
+
+  RunSpecs:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: true
+      matrix:
+        crystal_version:
+          - 1.2.0
+          - latest
+        experimental:
+          - false
+        include:
+          - crystal_version: nightly
+            experimental: true
+
+    steps:
+      - uses: actions/[email protected]
+
+      - uses: oprypin/install-crystal@v1
+        with:
+          crystal: ${{ matrix.crystal_version }}
+
+      - name: Set up Crystal cache
+        uses: actions/[email protected]
+        id: crystal-cache
+        with:
+          path: |
+            ~/.cache/crystal
+            bin/ameba
+            lib
+          key: ${{ runner.os }}-crystal-${{ matrix.crystal_version }}-${{ hashFiles('**/shard.yml') }}
+          restore-keys: |
+            ${{ runner.os }}-crystal-
+
+      - name: Install shards
+        if: steps.crystal-cache.outputs.cache-hit != 'true'
+        run: shards check || shards install --ignore-crystal-version
+
+      - name: Run tests
+        run: crystal spec

.gitignore

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+/docs/
+/lib/
+/bin/
+/.shards/
+*.dwarf
+
+# Libraries don't need dependency lock
+# Dependencies will be locked in applications that use them
+/shard.lock

LICENSE

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+MIT License
+
+Copyright (c) 2022 Alex Piechowski <[email protected]>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# fly.cr
+
+[Fly.io multi-region postgres support](https://fly.io/docs/getting-started/multi-region-databases)
+for crystal.
+
+## Installation
+
+1. Add the dependency to your `shard.yml`:
+
+   ```yaml
+   dependencies:
+     fly:
+       github: grepsedawk/fly.cr
+       version: ~> 0.1
+   ```
+
+2. Run `shards install`
+
+## Usage
+
+### Postgres via Avram
+
+1. Add [Multi-region postgres](https://fly.io/docs/getting-started/multi-region-databases/#add-read-replicas)
+   regional database readers and multi-region web application deployments via fly.io
+1. Configure primary (writer) region by setting ENV `$PRIMARY_REGION`
+1. Require `fly/pg/error_handler` and `fly/avram` _after_ avram
+
+   ```crystal
+   # ...
+   require "avram"
+   # ...
+   require "fly/pg/error_handler"
+   require "fly/avram"
+   # ...
+   ```
+
+   This will add patching into avram in order to automatically change the port
+   to read only port (5433) when the `ENV["FLY_REGION"]`, set automatically
+   by fly.io, based on your `Fly` configuration.
+
+1. Add middleware to your HTTP stack. This supports any core Crystal HTTP server.
+   The middleware must appear after any Error Handler middleware, such as the
+   `Lucky::ErrorHandler`.
+
+   For Lucky, this looks like this:
+
+   ```crystal
+     def middleware : Array(HTTP::Handler)
+       [
+         # ...
+         Lucky::ErrorHandler.new(action: Errors::Show),
+         Raven::Lucky::ErrorHandler.new,
+         Fly::PG::ErrorHandler.new,
+         # ..,.
+       ] of HTTP::Handler
+     end
+   ```
+
+## Configuration (Optional)
+
+To override the use of `ENV['PRIMARY_REGION']`, you can set the Fly primary region
+by writing a fly config:
+
+```crystal
+# config/fly.cr
+Fly.configure do |settings|
+   settings.primary_region = ENV["WRITER_REGION"] # Can be any string
+end
+```
+
+## Development
+
+For now, make a Fly.io deploy using [lucky_jumpstart](https://github.com/stephendolan/lucky_jumpstart)
+and use that to test.
+
+It's a bit of a pain because deploys take 3-5min, but it's the best development
+option as it provides integration testing.
+
+## Contributing
+
+1. Fork it (<https://github.com/grepsedawk/fly-crystal/fork>)
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create a new Pull Request
+
+## Contributors
+
+- [Alex Piechowski](https://github.com/grepsedawk) - creator and maintainer

shard.yml

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+name: fly
+version: 0.1.0
+
+authors:
+  - Alex Piechowski <[email protected]>
+
+crystal: ">=1"
+
+license: MIT
+
+dependencies:
+  habitat:
+    github: luckyframework/habitat
+
+development_dependencies:
+  ameba:
+    github: crystal-ameba/ameba

spec/fly_spec.cr

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+require "./spec_helper"
+
+describe Fly do
+  it "has a version" do
+    Fly::VERSION.should_not be_nil
+  end
+end

spec/spec_helper.cr

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+require "spec"
+require "../src/fly"
+require "../src/fly/pg/error_handler"
+require "../src/fly/avram"

src/fly.cr

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+# TODO: Write documentation for `Fly::Crystal`
+
+require "habitat"
+require "http/server"
+
+module Fly
+  VERSION = "0.1.0"
+  Log     = ::Log.for(self)
+
+  Habitat.create do
+    setting primary_region : String = ENV["PRIMARY_REGION"]
+  end
+end

src/fly/avram.cr

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+require "../fly"
+
+class Avram::Credentials
+  private def set_url_port(io)
+    if Fly.settings.primary_region == ENV["FLY_REGION"]
+      previous_def(io)
+    else
+      io << ":5433"
+    end
+  end
+end

src/fly/pg/error_handler.cr

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+require "../../fly"
+
+class Fly::PG::ErrorHandler
+  include HTTP::Handler
+
+  delegate primary_region, to: Fly.settings
+
+  def call(context : HTTP::Server::Context)
+    call_next(context)
+  rescue error : PQ::PQError
+    raise error unless read_only_sql_transaction?(error)
+
+    Log.info { "Replaying request in region #{primary_region}" }
+    context.response.status_code = 409
+    context.response.headers["fly-replay"] = "region=#{primary_region}"
+  end
+
+  def read_only_sql_transaction?(error : PQ::PQError)
+    error.fields.find do |field|
+      field.message == "25006" && field.name == :code
+    end
+  end
+end