https://github.com/metosin/palikka
Opinionated component library
https://github.com/metosin/palikka
metosin-deprecated
Last synced: about 1 month ago
JSON representation
Opinionated component library
- Host: GitHub
- URL: https://github.com/metosin/palikka
- Owner: metosin
- Created: 2015-04-02T13:46:22.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2020-02-12T12:14:09.000Z (over 5 years ago)
- Last Synced: 2025-05-11T17:38:13.594Z (5 months ago)
- Topics: metosin-deprecated
- Language: Clojure
- Homepage: http://metosin.github.io/palikka/palikka.core.html
- Size: 149 KB
- Stars: 8
- Watchers: 14
- Forks: 3
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGES.md
- Contributing: CONTRIBUTING.md
Awesome Lists containing this project
README
# Palikka [](https://travis-ci.org/metosin/palikka)
[](http://clojars.org/metosin/palikka)
[API Docs](http://metosin.github.io/palikka/palikka.core.html).
## Project statement
Unlike more general of our libraries (like
[compojure-api](https://github.com/metosin/compojure-api) and
[ring-swagger](https://github.com/metosin/ring-swagger)) this project is
primarily intended for use in Metosin's projects. Feel free to use, but
don't expect full support.
- We might remove features if we think they are not useful anymore
- We will reject PRs and issues about features we wouldn't use ourselves
## Features
- The components use [clojure.tools.logging](https://github.com/clojure/tools.logging)
- The components use Schema to validate and coerce their configuration
- Coercion allows using strings from environment variables and system
properties easily
- Includes [test utilities](./src/palikka/test_utils.clj) for `clojure.test` and Midje.
- **Context** is curated value created from interesting parts of the system.
- Passing the whole system down to implementation is inconvenient as the
interesting bits of system are somewhere inside the components.
- Follows the semantics of using
- `(providing (mongo/create (:db env)) [:db])` will publish value of `(:db mongo)` as `(:db context)`
- `(providing (mongo/create (:db env)) {:mongo :db})` will publish value of `(:db mongo)` as `(:mongo context)`
- `(providing (mongo/create (:db env)) {:mongo (fn [component] (:db component))})` will publish value of `(:db mongo)` as `(:mongo context)`
- Ring handler can be created using a function taking `system` as argument. This makes it easy to create handler accessing system or context, directly or through middleware.
- `(http-kit/create (:http env) {:fn (fn [system] (let [ctx (palikka.core/create-context system)] (fn [req] {:body ctx})))})`
- [Idempotent components](https://github.com/stuartsierra/component#idempotence)
## Differences to [System](https://github.com/danielsz/system)
- Components log messages
- **Context**
- Schema validation and coercion for options
## Example
```clj
(defn base-system [override]
(let [env (m/build-config
(m/resource "config-defaults.edn")
(m/file "./config-local.edn"))
create-handler (fn [system]
(-> (create-handler system)
(wrap-context system)))]
(component/system-map
:mongo (-> (mongo/create (:mongo env))
(providing {:db :db, :gfs :gfs}))
:http (-> (http-kit/create (:http env) {:fn create-handler})
; Though components are accessed through context,
; complete system map is needed for creating the context
(using [:mongo]))
:nrepl (nrepl/create (:nrepl env)))))
```
## Component dependencies
This library doesn't depend on libraries used by components,
depend on these on your project.
- Http-kit: [http-kit](https://github.com/http-kit/http-kit)
- Mongo: [monger](https://github.com/michaelklishin/monger)
- Database: [hikari-cp](https://github.com/tomekw/hikari-cp) & jdbc driver for used db, e.g. [postgres driver](http://mvnrepository.com/artifact/org.postgresql/postgresql)
- Migration status checker: [flyway-core](http://mvnrepository.com/artifact/com.googlecode.flyway/flyway-core)
- RabbitMQ: [Langohr](https://github.com/michaelklishin/langohr)
- Datomic: `[com.datomic/datomic-free "0.9.5327"]` or Datomic Pro
## License
Copyright © 2015-2016 [Metosin Oy](http://www.metosin.fi)
Distributed under the Eclipse Public License, the same as Clojure.