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Merge pull request #12 from arichiardi/improve-dotenv-watch
Correct dotenv watch semantics and refactor
2 parents 1803f71 + fcd420c commit 95527da

4 files changed

Lines changed: 132 additions & 92 deletions

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‎CHANGELOG.md‎

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## Fixed
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- Add an `:nrepl.middleware/descriptor` to silence the warning
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- Correct dotenv watch semantics. No matter the initial state we fix the behavior to achieve:
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| .env | .env.local | Values From |
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| ----- |----------- | ------------ |
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| ✅ | ✅ | `.env.local` |
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| ✅ | ❌ | `.env` |
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| ❌ | ✅ | `.env.local` |
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| ❌ | ❌ | latest state |
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The last line means we currently do not keep track and therefore cannot remove already set environment variables.
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# 0.36.159-alpha (2025-02-09 / eafa135)
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‎src/lambdaisland/launchpad.clj‎

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(ns lambdaisland.launchpad
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(:require
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[babashka.process :refer [process]]
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[babashka.wait :as wait]
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[clojure.edn :as edn]
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[clojure.java.io :as io]
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[clojure.java.shell :as shell]
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[clojure.pprint :as pprint]
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[clojure.string :as str]
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[lambdaisland.dotenv :as dotenv]
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[lambdaisland.launchpad.env :as env]
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[lambdaisland.launchpad.log :refer :all]
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[lambdaisland.cli :as cli])
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(:import
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;; FIXME: this means we don't "see" deps.local.edn if it
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;; gets created after launchpad started, we can do
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;; better than that.
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['(lambdaisland.classpath.watch-deps/canonical-path "deps.local.edn")]
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[])
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['(lambdaisland.classpath.watch-deps/canonical-path "deps.local.edn")])
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:launchpad/extra-deps `'~(:extra-deps <>)}))))
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(defn watch-dotenv [ctx]
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(-> ctx
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(assoc-extra-dep 'com.github.jnr/jnr-posix)
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(assoc-extra-dep 'com.lambdaisland/classpath)
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(update :java-args conj
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"--add-opens=java.base/java.lang=ALL-UNNAMED"
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"--add-opens=java.base/java.util=ALL-UNNAMED")
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(update :env #(apply merge % (map (fn [p]
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(when (.exists (io/file p))
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(dotenv/parse-dotenv (slurp p))))
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[".env" ".env.local"])))
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(update :requires conj 'lambdaisland.launchpad.env)
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(register-watch-handlers '(lambdaisland.launchpad.env/watch-handlers))))
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(update :env #(->> env/watch-paths
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(map env/->path)
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(filter env/exists?)
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(map env/parse-dotenv)
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(apply merge %)))
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(update :requires concat ['lambdaisland.launchpad.env 'lambdaisland.launchpad.env.hacks])
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(register-watch-handlers
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`(lambdaisland.launchpad.env.hacks/watch-handlers
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{:watch-paths ~(mapv #(list '.resolve 'lambdaisland.classpath.watch-deps/process-root-path %)
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env/watch-paths)
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:parse-fn 'lambdaisland.launchpad.env/parse-dotenv}))))
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(defn start-shadow-build [{:keys [deps-edn aliases] :as ctx}]
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(let [build-ids (->> aliases

‎src/lambdaisland/launchpad/env.clj‎

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(ns lambdaisland.launchpad.env
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"Make environment variables modifiable from within Java, and use that to watch a
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.env file for changes, and hot reload them.
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This is *very* dirty, it uses reflection to get at various private bits of
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Java, it relies on implementation details of OpenJDK, and it requires breaking
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module isolation (the process has to start with
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`--add-opens=java.base/java.lang=ALL-UNNAMED`
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`--add-opens=java.base/java.util=ALL-UNNAMED`). We also rely on jnr-posix to
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get to the underlying setenv system call, for good measure.
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But hey it works!"
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(:require [lambdaisland.dotenv :as dotenv]
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[lambdaisland.classpath.watch-deps :as watch-deps])
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(:import (java.nio.file Path Files LinkOption)))
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(set! *warn-on-reflection* true)
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(defn accessible-field ^java.lang.reflect.Field [^Class klz field]
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(doto (.getDeclaredField klz field)
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(.setAccessible true)))
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(defn get-static [field]
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(let [klz (Class/forName (namespace field))]
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(.get (accessible-field klz
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(name field)) klz)))
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(defn get-field [^Object instance field]
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(.get (accessible-field (.getClass instance) (str field)) instance))
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(defn set-field! [klz field obj val]
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(.set (accessible-field klz field) obj val))
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(defn set-static! [klz field val]
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(set-field! klz field klz val))
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(def ^java.util.Map theEnvironment
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(get-static 'java.lang.ProcessEnvironment/theEnvironment))
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(def ^java.lang.ProcessEnvironment$StringEnvironment theUnmodifiableEnvironment
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(get-field (get-static 'java.lang.ProcessEnvironment/theUnmodifiableEnvironment) 'm))
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(def ^jnr.posix.POSIX posix (jnr.posix.POSIXFactory/getPOSIX))
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(defn new-value [^String str]
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(assert (= -1 (.indexOf str "\u0000")))
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(let [^java.lang.reflect.Constructor init
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(first (.getDeclaredConstructors java.lang.ProcessEnvironment$Value))]
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(.setAccessible init true)
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(.newInstance init (into-array Object ["XXX" (.getBytes "XXX")]))))
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(defn new-variable [^String str]
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(assert (and (= -1 (.indexOf str "="))
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(= -1 (.indexOf str "\u0000"))))
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(let [^java.lang.reflect.Constructor init
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(first (.getDeclaredConstructors java.lang.ProcessEnvironment$Variable))]
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(.setAccessible init true)
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(.newInstance init (into-array Object ["XXX" (.getBytes "XXX")]))))
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(defn setenv
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([env]
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(run! (fn [[k v]] (setenv k v)) env))
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([^String var ^String val]
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;; This one is used by ProcessBuilder
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(.put theEnvironment (new-variable var) (new-value val))
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;; This one is used by System/getenv
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(.put theUnmodifiableEnvironment var val)
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;; Also change the actual OS environment for the process
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(.setenv posix var val 1)))
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(:require [lambdaisland.dotenv :as dotenv])
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(:import (java.nio.file Files LinkOption Path)))
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(defn exists?
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"Does the given path exist."
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[path]
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(Files/exists (watch-deps/path path) (into-array LinkOption [])))
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(Files/exists path (into-array LinkOption [])))
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(defn ->path
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[^String path]
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(Path/of path (into-array String [])))
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(defn canonical-path
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[^Path path]
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(.toRealPath path (into-array LinkOption [])))
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(def ^{:doc "The list of dotenv paths to watch.
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(defn dotenv-watch-handler [paths]
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(let [paths (map #(Path/of % (into-array String [])) paths)]
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(fn [_]
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(setenv
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(apply merge
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(map #(when (exists? %)
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(dotenv/parse-dotenv (Files/readString %)))
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paths))))))
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Order counts as we use merge semantics when reading them in."}
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watch-paths [".env" ".env.local"])
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85-
(defn watch-handlers []
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(let [h (dotenv-watch-handler [".env" ".env.local"])]
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{".env" h
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".env.local" h}))
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(defn parse-dotenv
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[^Path path]
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(when (.exists (.toFile path))
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(-> (Files/readString path)
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(dotenv/parse-dotenv))))

‎src/lambdaisland/launchpad/env/hacks.clj‎

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Original file line numberDiff line numberDiff line change
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(ns lambdaisland.launchpad.env.hacks
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"Make environment variables modifiable from within Java.
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This is *very* dirty, it uses reflection to get at various private bits of
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Java, it relies on implementation details of OpenJDK, and it requires breaking
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module isolation (the process has to start with
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`--add-opens=java.base/java.lang=ALL-UNNAMED`
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`--add-opens=java.base/java.util=ALL-UNNAMED`). We also rely on jnr-posix to
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get to the underlying setenv system call, for good measure.
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11+
But hey it works!"
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(:require [lambdaisland.classpath.watch-deps :as watch-deps])
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(:import (java.nio.file Path)))
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(set! *warn-on-reflection* true)
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(defn accessible-field ^java.lang.reflect.Field [^Class klz field]
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(doto (.getDeclaredField klz field)
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(.setAccessible true)))
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(defn get-static [field]
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(let [klz (Class/forName (namespace field))]
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(.get (accessible-field klz
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(name field)) klz)))
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(defn get-field [^Object instance field]
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(.get (accessible-field (.getClass instance) (str field)) instance))
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(defn set-field! [klz field obj val]
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(.set (accessible-field klz field) obj val))
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(defn set-static! [klz field val]
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(set-field! klz field klz val))
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(def ^java.util.Map theEnvironment
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(get-static 'java.lang.ProcessEnvironment/theEnvironment))
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(def ^java.lang.ProcessEnvironment$StringEnvironment theUnmodifiableEnvironment
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(get-field (get-static 'java.lang.ProcessEnvironment/theUnmodifiableEnvironment) 'm))
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(def ^jnr.posix.POSIX posix (jnr.posix.POSIXFactory/getPOSIX))
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(defn new-value [^String str]
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(assert (= -1 (.indexOf str "\u0000")))
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(let [^java.lang.reflect.Constructor init
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(first (.getDeclaredConstructors java.lang.ProcessEnvironment$Value))]
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(.setAccessible init true)
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(.newInstance init (into-array Object ["XXX" (.getBytes "XXX")]))))
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(defn new-variable [^String str]
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(assert (and (= -1 (.indexOf str "="))
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(= -1 (.indexOf str "\u0000"))))
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(let [^java.lang.reflect.Constructor init
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(first (.getDeclaredConstructors java.lang.ProcessEnvironment$Variable))]
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(.setAccessible init true)
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(.newInstance init (into-array Object ["XXX" (.getBytes "XXX")]))))
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(defn setenv
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([env]
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(run! (fn [[k v]] (setenv k v)) env))
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([^String var ^String val]
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;; This one is used by ProcessBuilder
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(.put theEnvironment (new-variable var) (new-value val))
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;; This one is used by System/getenv
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(.put theUnmodifiableEnvironment var val)
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;; Also change the actual OS environment for the process
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(.setenv posix var val 1)))
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(defn dotenv-watch-handler
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[{:keys [watch-paths parse-fn]}]
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(let [parse-fn (requiring-resolve parse-fn)]
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(fn [e]
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(let [{:keys [type _]} e]
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(when (contains? #{:modify :create :delete} type)
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(doseq [path watch-paths]
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(println "[watch-dotenv] ✨ Reloading"
77+
(str (.relativize ^Path (watch-deps/canonical-path ".") path))
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"✨"))
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;; We always reload everything so that we can preserve merge semantics.
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(setenv (apply merge (map parse-fn watch-paths))))))))
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(defn watch-handlers [opts]
83+
(let [{:keys [watch-paths]} opts
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handler (dotenv-watch-handler opts)]
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(into {}
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(map (fn [p]
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[(str p) handler]))
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watch-paths)))

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