Revert "Revert "Allow env vars OS_NAME & OS_ARCH to override os props (#53)"" (#54)

This reverts commit 6cbbdd118d.

README.md

@@ -74,7 +74,17 @@ On the JVM:
 
 ### Where does the pod come from?
 
-When calling `load-pod` with a string or vector of strings, the pod is looked up on the local file system (either using the PATH, or using an absolute path). When it is called with a qualified symbol and a version - like `(load-pod 'org.babashka/aws "0.0.5")` then it will be looked up in and downloaded from the [pod-registry](https://github.com/babashka/pod-registry).
+When calling `load-pod` with a string or vector of strings (or declaring it in your `bb.edn`),
+the pod is looked up on the local file system (either using the PATH, or using an absolute path).
+When it is called with a qualified symbol and a version - like `(load-pod 'org.babashka/aws "0.0.5")`
+then it will be looked up in and downloaded from the [pod-registry](https://github.com/babashka/pod-registry).
+
+By default babashka will search for a pod binary matching your system's OS and arch. If you want to download
+pods for a different OS / arch (e.g. for deployment to servers), you can set one or both of the following
+environment variables:
+
+- `BABASHKA_PODS_OS_NAME=Linux` (or `Mac OS X` or any other value returned by Java's `os.name` property)
+- `BABASHKA_PODS_OS_ARCH=aarch64` (or `amd64` or any other value returned by Java's `os.arch` property)
 
 ### In a babashka project
 

src/babashka/pods/impl.clj

@@ -383,14 +383,19 @@
                   (read-readers describe-reply resolve-fn))]
     {:format format, :ops ops, :readers readers}))
 
-(defn load-pod-metadata [pod-spec opts]
-  (let [{:keys [:pod-spec :opts]} (resolve-pod pod-spec opts)
-        running-pod (run-pod pod-spec opts)
+(defn run-pod-for-metadata [pod-spec opts]
+  (let [running-pod    (run-pod pod-spec opts)
         describe-reply (describe-pod running-pod)
         ops (describe->ops describe-reply)]
     (destroy* (assoc running-pod :ops ops))
     describe-reply))
 
+(defn load-pod-metadata [unresolved-pod-spec {:keys [:download-only] :as opts}]
+  (let [{:keys [:pod-spec :opts]} (resolve-pod unresolved-pod-spec opts)]
+    (if download-only
+      (resolver/warn "Not running pod" unresolved-pod-spec "to pre-cache metadata because OS and/or arch are different than system")
+      (run-pod-for-metadata pod-spec opts))))
+
 (defn load-pod
   ([pod-spec] (load-pod pod-spec nil))
   ([pod-spec opts]

src/babashka/pods/impl/resolver.clj

@@ -15,35 +15,42 @@
     "x86_64"
     arch))
 
-(def os {:os/name (System/getProperty "os.name")
-         :os/arch (let [arch (System/getProperty "os.arch")]
-                    (normalize-arch arch))})
+(defn normalize-os [os]
+  (-> os str/lower-case (str/replace #"\s+" "_")))
+
+(def os
+  (delay
+    {:os/name (or (System/getenv "BABASHKA_PODS_OS_NAME")
+                  (System/getProperty "os.name"))
+     :os/arch (let [arch (or (System/getenv "BABASHKA_PODS_OS_ARCH")
+                             (System/getProperty "os.arch"))]
+                (normalize-arch arch))}))
 
 (defn warn [& strs]
   (binding [*out* *err*]
     (apply println strs)))
 
 (defn match-artifacts
-  ([package] (match-artifacts package (:os/arch os)))
+  ([package] (match-artifacts package (:os/arch @os)))
   ([package arch]
    (let [artifacts (:pod/artifacts package)
          res (filter (fn [{os-name :os/name
                            os-arch :os/arch}]
                        (let [os-arch (normalize-arch os-arch)]
-                         (and (re-matches (re-pattern os-name) (:os/name os))
+                         (and (re-matches (re-pattern os-name) (:os/name @os))
                               (re-matches (re-pattern os-arch)
                                           arch))))
                      artifacts)]
      (if (empty? res)
-       (if (and (= "Mac OS X" (:os/name os))
-                (= "aarch64" (:os/arch os)))
+       (if (and (= "Mac OS X" (:os/name @os))
+                (= "aarch64" (:os/arch @os)))
          ;; Rosetta2 fallback on Apple M1 machines
          (match-artifacts package "x86_64")
          (throw (IllegalArgumentException. (format "No executable found for pod %s (%s) and OS %s/%s"
                                                    (:pod/name package)
                                                    (:pod/version package)
-                                                   (:os/name os)
-                                                   (:os/arch os)))))
+                                                   (:os/name @os)
+                                                   (:os/arch @os)))))
        res))))
 
 (defn unzip [{:keys [^java.io.File zip-file
@@ -148,7 +155,9 @@
     (io/file base-file
              "repository"
              (str pod-name)
-             pod-version)))
+             pod-version
+             (normalize-os (:os/name @os))
+             (:os/arch @os))))
 
 (defn data-dir
   ^java.io.File
@@ -156,7 +165,9 @@
     pod-version :pod/version}]
   (io/file @pods-repo-dir
            (str pod-name)
-           pod-version))
+           pod-version
+           (normalize-os (:os/name @os))
+           (:os/arch @os)))
 
 (defn sha256 [file]
   (let [buf (byte-array 8192)

src/babashka/pods/sci.clj

@@ -43,7 +43,8 @@
 
 (defn load-pod-metadata* [bb-edn-file pod-spec {:keys [:version :cache] :as opts}]
   (let [metadata (impl/load-pod-metadata pod-spec opts)
-        cache-file (when cache (metadata-cache-file bb-edn-file pod-spec opts))]
+        cache-file (when (and metadata cache)
+                     (metadata-cache-file bb-edn-file pod-spec opts))]
     (when cache-file
       (io/make-parents cache-file)
       (when (fs/writable? (fs/parent cache-file))