# hex_core
[![Build Status](https://github.com/hexpm/hex_core/workflows/CI/badge.svg)](https://github.com/hexpm/hex_core/actions)
Reference implementation of Hex specifications: <https://github.com/hexpm/specifications>.
## Usage
Let's use default config for now. See "Configuration" section below for customization.
```erlang
Config = hex_core:default_config().
```
**WARNING** The built-in httpc-based HTTP client adapter has insecure default settings
and thus it is not recommended for usage, in particular for API write operations.
Use HTTP clients with secure defaults like [hackney](https://hex.pm/packages/hackney) and [Mint](https://hex.pm/packages/mint).
See "Configuration" and "Wrapper Module" sections for more information on customising your usage of `hex_core`.
### Repository
Get all package names:
```erlang
> hex_repo:get_names(Config).
{ok,{200, ...,
#{packages => [
#{name => <<"package1">>},
#{name => <<"package2">>},
...]}}}
```
Get all package versions from repository:
```erlang
> hex_repo:get_versions(Config).
{ok,{200, ...,
#{packages => [[
#{name => <<"package1">>, retired => [], versions => [<<"1.0.0">>]},
#{name => <<"package2">>, retired => [], versions => [<<"0.5.0">>]},
...]}}}
```
Get package releases from repository:
```erlang
> hex_repo:get_package(Config, <<"package1">>).
{ok,{200, ...,
#{releases => [
#{checksum => ..., version => <<"0.5.0">>, dependencies => []}],
#{checksum => ..., version => <<"1.0.0">>, dependencies => []}],
...]}}}
```
### API
For a full list of all parameters and returned objects for the API, check out the API docs: <https://github.com/hexpm/specifications/blob/master/http_api.md>.
Get package from HTTP API:
```erlang
> hex_api_package:get(Config, <<"package1">>).
{ok, {200, ...,
#{
<<"name">> => <<"package1">>,
<<"meta">> => #{
<<"description">> => ...,
<<"licenses">> => ...,
<<"links">> => ...,
<<"maintainers">> => ...,
},
...,
<<"releases">> => [
#{<<"url">> => ..., <<"version">> => <<"0.5.0">>}],
#{<<"url">> => ..., <<"version">> => <<"1.0.0">>}],
...
]
}}}
```
Get package tarball:
```erlang
{ok, {200, _, Tarball}} = hex_repo:get_tarball(Config, <<"package1">>, <<"1.0.0">>).
```
Publish package tarball:
```erlang
{ok, {200, _Headers, _Body} = hex_api_package:publish(Config, Tarball).
```
### Package tarballs
Unpack package tarball:
```erlang
{ok, #{outer_checksum := Checksum, contents := Contents, metadata := Metadata}} = hex_tarball:unpack(Tarball, memory).
```
Remember to verify the outer tarball checksum against the registry checksum
returned from `hex_repo:get_package(Config, Package)`.
Create package tarball:
```erlang
{ok, #{tarball := Tarball,
inner_checksum := InnerChecksum,
outer_checksum := OuterChecksum}} = hex_tarball:create(Metadata, Contents).
```
## Configuration
The default configuration, provided by `hex_core:default_config/0`, uses built-in httpc-based adapter and Hex.pm APIs:
<https://hex.pm/api> and <https://repo.hex.pm>.
HTTP client configuration can be overridden as follows:
```erlang
Config = maps:merge(hex_core:default_config(), #{
http_adapter => {my_hackney_adapter, my_hackney_adapter_config},
http_user_agent_fragment => <<"(my_app/0.1.0) (hackney/1.12.1) ">>
}),
hex_repo:get_names(Config).
%% my_hackney_adapter.erl
-module(my_hackney_adapter).
-behaviour(hex_http).
-exports([request/5]).
request(Method, URI, ReqHeaders, Body, AdapterConfig) ->
%% ...
```
See the [`hex_core` module](src/hex_core.erl) for more information about the configuration.
## Wrapper Module
It's recommended to write a wrapper module because a lot of decisions are left to the user, e.g.:
where to get configuration from, how to handle caching, failures etc.
For a sample, see: [`examples/myapp_hex.erl`](examples/myapp_hex.erl). Here's an excerpt:
```erlang
-module(myapp_hex).
-export([
get_api_package/1,
get_repo_tarball/2,
get_repo_versions/0
]).
%%====================================================================
%% API functions
%%====================================================================
get_api_package(Name) ->
case hex_api_package:get(config(), Name) of
{ok, {200, _Headers, Payload}} ->
{ok, Payload};
Other ->
Other
end.
get_repo_versions() ->
case hex_repo:get_versions(config()) of
{ok, {200, _Headers, Payload}} ->
{ok, maps:get(packages, Payload)};
Other ->
Other
end.
%%====================================================================
%% Internal functions
%%====================================================================
config() ->
Config1 = hex_core:default_config(),
Config2 = put_http_config(Config1),
Config3 = maybe_put_api_key(Config2),
Config3.
put_http_config(Config) ->
maps:put(http_user_agent_fragment, <<"(myapp/1.0.0) (httpc)">>, Config).
maybe_put_api_key(Config) ->
case os:getenv("HEX_API_KEY") of
false -> Config;
Key -> maps:put(api_key, Key, Config)
end.
```
## Installation
### Rebar3
Add to `rebar.config`:
```erlang
{deps, [
{hex_core, "0.10.1"}
]}
```
### Mix
Add to `mix.exs`:
```elixir
defp deps do
[
{:hex_core, "~> 0.10.1"}
]
end
```
## Development
* Run `rebar3 as dev compile` to re-generate protobuf files
* Run `rebar3 as test proper` for property-based tests
* Run `rebar3 ex_doc` to generate documentation