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https://github.com/taylorwood/clojurl

An example Clojure CLI HTTP/S client using GraalVM native image
https://github.com/taylorwood/clojurl

cli clojure graalvm https native-image

Last synced: about 2 months ago
JSON representation

An example Clojure CLI HTTP/S client using GraalVM native image

Host: GitHub
URL: https://github.com/taylorwood/clojurl
Owner: taylorwood
License: epl-2.0
Created: 2018-10-04T07:26:21.000Z (almost 6 years ago)
Default Branch: master
Last Pushed: 2019-11-21T05:15:21.000Z (over 4 years ago)
Last Synced: 2024-02-10T07:09:14.454Z (5 months ago)
Topics: cli, clojure, graalvm, https, native-image
Language: Clojure
Size: 16.6 KB
Stars: 64
Watchers: 2
Forks: 3
Open Issues: 0
Metadata Files:
- Readme: README.md
- License: LICENSE

Lists

awesome-graal - An example Clojure CLI HTTP/S client using GraalVM native image

README

# Clojurl

An example HTTP/S client CLI using Clojure and GraalVM native image.

Generated with [clj.native-cli template](https://github.com/taylorwood/clj.native-cli).
Uses deps.edn and [clj.native-image](https://github.com/taylorwood/clj.native-image).

## Prerequisites

- GraalVM 1.0.0-RC9 or higher
- Clojure

GraalVM 1.0.0-RC7 added HTTPS as a supported protocol, and this is a brief walkthrough
for using it in a Clojure project with GraalVM Community Edition for macOS.

Enable HTTPS protocol support with `native-image` options `--enable-https` or `--enable-url-protocols=https`.

#### Earlier versions of GraalVM

The following steps are only necessary with GraalVM 19.2.1 and earlier:

1. Configure path to `libsunec.dylib` on macOS (or `libsunec.do` on Linux)

This shared object comes with the GraalVM distribution and can be found in
`$GRAALVM_HOME/jre/lib/`. GraalVM uses `System.loadLibrary` to load it at run-time
whenever it's first used. The file must either be in the current working directory,
or in a path specified in Java system property `java.library.path`.

I set the Java system property at run-time, before first HTTPS attempt:
```clojure
(System/setProperty "java.library.path"
(str (System/getenv "GRAALVM_HOME") "/jre/lib"))
```

See [this](https://github.com/oracle/graal/blob/master/substratevm/JCA-SECURITY-SERVICES.md#native-implementations)
and [this](https://github.com/oracle/graal/blob/master/substratevm/URL-PROTOCOLS.md#https-support)
for more information on HTTPS support in GraalVM and native images. If you're distributing
a native image, you'll need to include libsunec. If it's in the same directory as your image
you don't need to set `java.library.path`.

You'll see a [warning](https://github.com/oracle/graal/blob/e3ef4f3f741d171a83c2dd2a0390dbede6b2c62d/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/SecuritySubstitutions.java#L204)
at run-time if this hasn't been properly configured:
```
WARNING: The sunec native library could not be loaded.
```
1. Use more complete certificate store

Some versions of GraalVM may have a smaller set of CA certificates. You can workaround this
by replacing GraalVM's `cacerts`. I renamed the file and replaced it with a symbolic link
to `cacerts` from the JRE that comes with macOS Mojave:
```bash
$ mv $GRAALVM_HOME/jre/lib/security/cacerts $GRAALVM_HOME/jre/lib/security/cacerts.bak
$ ln -s $(/usr/libexec/java_home)/jre/lib/security/cacerts $GRAALVM_HOME/jre/lib/security/cacerts
```

If you don't do this, you might see errors like this when attempting HTTPS connections:
```
Exception in thread "main" javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
8<------------------------
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
8<------------------------
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
```

## Usage

Compile the program with GraalVM `native-image`:
```bash
$ clojure -A:native-image
```

Print CLI options:
```
$ ./clojurl -h
-u, --uri URI URI of request
-H, --header HEADER Request header(s)
-d, --data DATA Request data
-m, --method METHOD GET Request method e.g. GET, POST, etc.
-o, --output FORMAT edn Output format e.g. edn, hickory
-v, --verbose Print verbose info
-h, --help Print this message
```
Responses can be printed in EDN or Hickory format.

Make a request and print response to stdout:
```
$ ./clojurl -u https://postman-echo.com/get
{:headers
{"content-encoding" "gzip",
"content-type" "application/json; charset=utf-8",
"date" "Fri, 05 Oct 2018 03:56:49 GMT",
"etag" "W/\"10b-EZIoyNoyzUvEaPxY+kzMOEgaNh0\"",
"server" "nginx",
"vary" "Accept-Encoding",
"content-length" "194",
"connection" "keep-alive"},
:status 200,
:body
"{\"args\":{},\"headers\":{\"host\":\"postman-echo.com\",\"accept\":\"text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2\",\"accept-encoding\":\"gzip, deflate\",\"user-agent\":\"Java/1.8.0_172\",\"x-forwarded-port\":\"443\",\"x-forwarded-proto\":\"https\"},\"url\":\"https://postman-echo.com/get\"}"}
```
```
$ ./clojurl -H Accept=application/json -H X-Session-Id=1234 -H Content-Type=application/json \
-u https://postman-echo.com/post \
-m post -d "{'foo':true}"
{:headers
{"content-encoding" "gzip",
"content-type" "application/json; charset=utf-8",
"date" "Fri, 05 Oct 2018 03:57:06 GMT",
"etag" "W/\"16d-FiL2opG823uS6YyXMHVrz5k+/Vk\"",
"server" "nginx",
"set-cookie"
"sails.sid=s%3Af-U0lE-XKYPefMu_II_Sggg1HGVI4LlY.lbh1ZWAEX58lBuDVpo2vRZ%2FPAo1AHllJPSPsJ01RFvc; Path=/; HttpOnly",
"vary" "Accept-Encoding",
"content-length" "237",
"connection" "keep-alive"},
:status 200,
:body
"{\"args\":{},\"data\":\"{'foo':true}\",\"files\":{},\"form\":{},\"headers\":{\"host\":\"postman-echo.com\",\"content-length\":\"12\",\"accept\":\"application/json\",\"accept-encoding\":\"gzip, deflate\",\"content-type\":\"application/json\",\"user-agent\":\"Java/1.8.0_172\",\"x-session-id\":\"1234\",\"x-forwarded-port\":\"443\",\"x-forwarded-proto\":\"https\"},\"json\":null,\"url\":\"https://postman-echo.com/post\"}"}
```

As a proof-of-concept for using Clojure 1.9 + clojure.spec.alpha + Expound with GraalVM native-image,
the CLI options are validated using specs and invalid options can be explained using Expound:
```
$ ./clojurl -u https://postman-echo.com/get -o foo --verbose
Invalid option(s)
-- Spec failed --------------------

{:headers ...,
:method ...,
:output-fn nil,
^^^
:url ...,
:verbose? ...}

should satisfy

ifn?

-- Relevant specs -------

:clojurl/output-fn:
clojure.core/ifn?
:clojurl/options:
(clojure.spec.alpha/keys
:req-un
[:clojurl/url :clojurl/output-fn]
:opt-un
[:clojurl/method :clojurl/headers :clojurl/body])

-------------------------
Detected 1 error
```