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Downloading non-public files via REST API from S3 in Clojure
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(ns agent-smith.s3 | |
(:require [clojure.data.codec.base64 :as b64] | |
[clojure.string :as s] | |
[clojure.java.io :refer [copy file]] | |
[clj-http.client :as client] | |
[clj-time.core :as t] | |
[clj-time.format :as tf])) | |
(defn- sign [data key] | |
(let [mac (javax.crypto.Mac/getInstance "HmacSHA1") | |
key-spec (javax.crypto.spec.SecretKeySpec. (.getBytes key "UTF8") "HmacSHA1")] | |
(.init mac key-spec) | |
(->> (.getBytes data "UTF8") | |
(.doFinal mac) | |
b64/encode | |
String.))) | |
(defn- get-resource [{:keys [api-key api-secret-key]} path options] | |
(let [[_ bucket path] (re-find #"^s3://([^/]+)/(.+)$" path) | |
timestamp (tf/unparse (tf/formatters :rfc822) (t/now)) | |
request (s/join \newline ["GET" "" "" timestamp (str "/" bucket "/" path)]) | |
authorization (str "AWS " api-key ":" (sign request api-secret-key)) | |
url (str "https://" bucket ".s3.amazonaws.com/" path) | |
headers {"Date" timestamp, "Authorization" authorization}] | |
(client/get url (assoc options :headers headers)))) | |
(defn download | |
"Downloads a file from S3. Returns clj-http response. | |
The remote path should be s3://BUCKET_NAME/PATH/TO/OBJECT." | |
[aws-creds remote-path] | |
(get-resource aws-creds remote-path {:as :byte-array})) | |
(defn download-to | |
"Downloads a file from S3 to local path. | |
The remote path should be s3://BUCKET_NAME/PATH/TO/OBJECT." | |
[aws-creds remote-path local-path] | |
(let [resource (get-resource aws-creds remote-path {:as :stream})] | |
(copy (:body resource) (file local-path)))) |
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