10 files changed, 592 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1eae0cf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+dist/
+node_modules/
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..fa980b2
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,18 @@
+FROM node:alpine AS builder
+
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+
+COPY rollup.config.js ./
+COPY src ./src
+RUN npm run build
+
+FROM nginx:alpine AS server
+
+WORKDIR /usr/share/nginx/html
+RUN apk add --no-cache bash
+COPY nginx-entrypoint.sh /
+COPY --from=builder /app/dist ./
+
+ENTRYPOINT [ "bash", "/nginx-entrypoint.sh" ]
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..30b4d22
--- /dev/null
+++ b/README.md
@@ -0,0 +1,12 @@
+# Frontend application with injected environment variables
+
+## How to use
+
+    docker build -t demo .
+    docker run -e FRONTEND_EXAMPLE_ENV=foobar -p 8080:80 demo
+
+Visit http://localhost:8080 to see the result.
+
+## Author
+
+Jan Tuomi, <jans.tuomi@gmail.com>. 2019.
diff --git a/nginx-entrypoint.sh b/nginx-entrypoint.sh
new file mode 100755
index 0000000..e6ed329
--- /dev/null
+++ b/nginx-entrypoint.sh
@@ -0,0 +1,22 @@
+#!/usr/bin/bash
+
+WWW_DIR=/usr/share/nginx/html
+ENV_PREFIX=FRONTEND_
+INJECT_FILE_PATH="${WWW_DIR}/inject.js"
+
+cat >> "${INJECT_FILE_PATH}" << EOF
+window.injectedEnv = {
+  NODE_ENV: "production",
+EOF
+
+for envrow in $(printenv); do
+  IFS='=' read -r key value <<< "${envrow}"
+
+  if [[ $key == "${ENV_PREFIX}"* ]]; then
+    echo "  ${key}: \"${value}\"," >> "${INJECT_FILE_PATH}"
+  fi
+done
+
+echo "};" >> "${INJECT_FILE_PATH}"
+
+[ -z "$@" ] && nginx -g 'daemon off;' || "$@"
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..f69098b
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,477 @@
+{
+  "name": "medium-frontend-env-demo",
+  "version": "1.0.0",
+  "lockfileVersion": 1,
+  "requires": true,
+  "dependencies": {
+    "@nodelib/fs.scandir": {
+      "version": "2.1.3",
+      "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.3.tgz",
+      "integrity": "sha512-eGmwYQn3gxo4r7jdQnkrrN6bY478C3P+a/y72IJukF8LjB6ZHeB3c+Ehacj3sYeSmUXGlnA67/PmbM9CVwL7Dw==",
+      "dev": true,
+      "requires": {
+        "@nodelib/fs.stat": "2.0.3",
+        "run-parallel": "^1.1.9"
+      }
+    },
+    "@nodelib/fs.stat": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/@nodelib/fs.stat/-/fs.stat-2.0.3.tgz",
+      "integrity": "sha512-bQBFruR2TAwoevBEd/NWMoAAtNGzTRgdrqnYCc7dhzfoNvqPzLyqlEQnzZ3kVnNrSp25iyxE00/3h2fqGAGArA==",
+      "dev": true
+    },
+    "@nodelib/fs.walk": {
+      "version": "1.2.4",
+      "resolved": "https://registry.npmjs.org/@nodelib/fs.walk/-/fs.walk-1.2.4.tgz",
+      "integrity": "sha512-1V9XOY4rDW0rehzbrcqAmHnz8e7SKvX27gh8Gt2WgB0+pdzdiLV83p72kZPU+jvMbS1qU5mauP2iOvO8rhmurQ==",
+      "dev": true,
+      "requires": {
+        "@nodelib/fs.scandir": "2.1.3",
+        "fastq": "^1.6.0"
+      }
+    },
+    "@types/estree": {
+      "version": "0.0.40",
+      "resolved": "https://registry.npmjs.org/@types/estree/-/estree-0.0.40.tgz",
+      "integrity": "sha512-p3KZgMto/JyxosKGmnLDJ/dG5wf+qTRMUjHJcspC2oQKa4jP7mz+tv0ND56lLBu3ojHlhzY33Ol+khLyNmilkA==",
+      "dev": true
+    },
+    "@types/events": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/@types/events/-/events-3.0.0.tgz",
+      "integrity": "sha512-EaObqwIvayI5a8dCzhFrjKzVwKLxjoG9T6Ppd5CEo07LRKfQ8Yokw54r5+Wq7FaBQ+yXRvQAYPrHwya1/UFt9g==",
+      "dev": true
+    },
+    "@types/fs-extra": {
+      "version": "8.0.1",
+      "resolved": "https://registry.npmjs.org/@types/fs-extra/-/fs-extra-8.0.1.tgz",
+      "integrity": "sha512-J00cVDALmi/hJOYsunyT52Hva5TnJeKP5yd1r+mH/ZU0mbYZflR0Z5kw5kITtKTRYMhm1JMClOFYdHnQszEvqw==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "@types/glob": {
+      "version": "7.1.1",
+      "resolved": "https://registry.npmjs.org/@types/glob/-/glob-7.1.1.tgz",
+      "integrity": "sha512-1Bh06cbWJUHMC97acuD6UMG29nMt0Aqz1vF3guLfG+kHHJhy3AyohZFFxYk2f7Q1SQIrNwvncxAE0N/9s70F2w==",
+      "dev": true,
+      "requires": {
+        "@types/events": "*",
+        "@types/minimatch": "*",
+        "@types/node": "*"
+      }
+    },
+    "@types/minimatch": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/@types/minimatch/-/minimatch-3.0.3.tgz",
+      "integrity": "sha512-tHq6qdbT9U1IRSGf14CL0pUlULksvY9OZ+5eEgl1N7t+OA3tGvNpxJCzuKQlsNgCVwbAs670L1vcVQi8j9HjnA==",
+      "dev": true
+    },
+    "@types/node": {
+      "version": "12.12.21",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-12.12.21.tgz",
+      "integrity": "sha512-8sRGhbpU+ck1n0PGAUgVrWrWdjSW2aqNeyC15W88GRsMpSwzv6RJGlLhE7s2RhVSOdyDmxbqlWSeThq4/7xqlA==",
+      "dev": true
+    },
+    "@types/resolve": {
+      "version": "0.0.8",
+      "resolved": "https://registry.npmjs.org/@types/resolve/-/resolve-0.0.8.tgz",
+      "integrity": "sha512-auApPaJf3NPfe18hSoJkp8EbZzer2ISk7o8mCC3M9he/a04+gbMF97NkpD2S8riMGvm4BMRI59/SZQSaLTKpsQ==",
+      "dev": true,
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "array-union": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/array-union/-/array-union-2.1.0.tgz",
+      "integrity": "sha512-HGyxoOTYUyCM6stUe6EJgnd4EoewAI7zMdfqO+kGjnlZmBDz/cR5pf8r/cR4Wq60sL/p0IkcjUEEPwS3GFrIyw==",
+      "dev": true
+    },
+    "balanced-match": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
+      "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
+      "dev": true
+    },
+    "brace-expansion": {
+      "version": "1.1.11",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
+      "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
+      "dev": true,
+      "requires": {
+        "balanced-match": "^1.0.0",
+        "concat-map": "0.0.1"
+      }
+    },
+    "braces": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/braces/-/braces-3.0.2.tgz",
+      "integrity": "sha512-b8um+L1RzM3WDSzvhm6gIz1yfTbBt6YTlcEKAvsmqCZZFw46z626lVj9j1yEPW33H5H+lBQpZMP1k8l+78Ha0A==",
+      "dev": true,
+      "requires": {
+        "fill-range": "^7.0.1"
+      }
+    },
+    "builtin-modules": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/builtin-modules/-/builtin-modules-3.1.0.tgz",
+      "integrity": "sha512-k0KL0aWZuBt2lrxrcASWDfwOLMnodeQjodT/1SxEQAXsHANgo6ZC/VEaSEHCXt7aSTZ4/4H5LKa+tBXmW7Vtvw==",
+      "dev": true
+    },
+    "colorette": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/colorette/-/colorette-1.1.0.tgz",
+      "integrity": "sha512-6S062WDQUXi6hOfkO/sBPVwE5ASXY4G2+b4atvhJfSsuUUhIaUKlkjLe9692Ipyt5/a+IPF5aVTu3V5gvXq5cg==",
+      "dev": true
+    },
+    "concat-map": {
+      "version": "0.0.1",
+      "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
+      "integrity": "sha1-2Klr13/Wjfd5OnMDajug1UBdR3s=",
+      "dev": true
+    },
+    "dir-glob": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/dir-glob/-/dir-glob-3.0.1.tgz",
+      "integrity": "sha512-WkrWp9GR4KXfKGYzOLmTuGVi1UWFfws377n9cc55/tb6DuqyF6pcQ5AbiHEshaDpY9v6oaSr2XCDidGmMwdzIA==",
+      "dev": true,
+      "requires": {
+        "path-type": "^4.0.0"
+      }
+    },
+    "estree-walker": {
+      "version": "0.6.1",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-0.6.1.tgz",
+      "integrity": "sha512-SqmZANLWS0mnatqbSfRP5g8OXZC12Fgg1IwNtLsyHDzJizORW4khDfjPqJZsemPWBB2uqykUah5YpQ6epsqC/w==",
+      "dev": true
+    },
+    "fast-glob": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/fast-glob/-/fast-glob-3.1.1.tgz",
+      "integrity": "sha512-nTCREpBY8w8r+boyFYAx21iL6faSsQynliPHM4Uf56SbkyohCNxpVPEH9xrF5TXKy+IsjkPUHDKiUkzBVRXn9g==",
+      "dev": true,
+      "requires": {
+        "@nodelib/fs.stat": "^2.0.2",
+        "@nodelib/fs.walk": "^1.2.3",
+        "glob-parent": "^5.1.0",
+        "merge2": "^1.3.0",
+        "micromatch": "^4.0.2"
+      }
+    },
+    "fastq": {
+      "version": "1.6.0",
+      "resolved": "https://registry.npmjs.org/fastq/-/fastq-1.6.0.tgz",
+      "integrity": "sha512-jmxqQ3Z/nXoeyDmWAzF9kH1aGZSis6e/SbfPmJpUnyZ0ogr6iscHQaml4wsEepEWSdtmpy+eVXmCRIMpxaXqOA==",
+      "dev": true,
+      "requires": {
+        "reusify": "^1.0.0"
+      }
+    },
+    "fill-range": {
+      "version": "7.0.1",
+      "resolved": "https://registry.npmjs.org/fill-range/-/fill-range-7.0.1.tgz",
+      "integrity": "sha512-qOo9F+dMUmC2Lcb4BbVvnKJxTPjCm+RRpe4gDuGrzkL7mEVl/djYSu2OdQ2Pa302N4oqkSg9ir6jaLWJ2USVpQ==",
+      "dev": true,
+      "requires": {
+        "to-regex-range": "^5.0.1"
+      }
+    },
+    "fs-extra": {
+      "version": "8.1.0",
+      "resolved": "https://registry.npmjs.org/fs-extra/-/fs-extra-8.1.0.tgz",
+      "integrity": "sha512-yhlQgA6mnOJUKOsRUFsgJdQCvkKhcz8tlZG5HBQfReYZy46OwLcY+Zia0mtdHsOo9y/hP+CxMN0TU9QxoOtG4g==",
+      "dev": true,
+      "requires": {
+        "graceful-fs": "^4.2.0",
+        "jsonfile": "^4.0.0",
+        "universalify": "^0.1.0"
+      }
+    },
+    "fs.realpath": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
+      "integrity": "sha1-FQStJSMVjKpA20onh8sBQRmU6k8=",
+      "dev": true
+    },
+    "glob": {
+      "version": "7.1.6",
+      "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.6.tgz",
+      "integrity": "sha512-LwaxwyZ72Lk7vZINtNNrywX0ZuLyStrdDtabefZKAY5ZGJhVtgdznluResxNmPitE0SAO+O26sWTHeKSI2wMBA==",
+      "dev": true,
+      "requires": {
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^3.0.4",
+        "once": "^1.3.0",
+        "path-is-absolute": "^1.0.0"
+      }
+    },
+    "glob-parent": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-5.1.0.tgz",
+      "integrity": "sha512-qjtRgnIVmOfnKUE3NJAQEdk+lKrxfw8t5ke7SXtfMTHcjsBfOfWXCQfdb30zfDoZQ2IRSIiidmjtbHZPZ++Ihw==",
+      "dev": true,
+      "requires": {
+        "is-glob": "^4.0.1"
+      }
+    },
+    "globby": {
+      "version": "10.0.1",
+      "resolved": "https://registry.npmjs.org/globby/-/globby-10.0.1.tgz",
+      "integrity": "sha512-sSs4inE1FB2YQiymcmTv6NWENryABjUNPeWhOvmn4SjtKybglsyPZxFB3U1/+L1bYi0rNZDqCLlHyLYDl1Pq5A==",
+      "dev": true,
+      "requires": {
+        "@types/glob": "^7.1.1",
+        "array-union": "^2.1.0",
+        "dir-glob": "^3.0.1",
+        "fast-glob": "^3.0.3",
+        "glob": "^7.1.3",
+        "ignore": "^5.1.1",
+        "merge2": "^1.2.3",
+        "slash": "^3.0.0"
+      }
+    },
+    "graceful-fs": {
+      "version": "4.2.3",
+      "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.2.3.tgz",
+      "integrity": "sha512-a30VEBm4PEdx1dRB7MFK7BejejvCvBronbLjht+sHuGYj8PHs7M/5Z+rt5lw551vZ7yfTCj4Vuyy3mSJytDWRQ==",
+      "dev": true
+    },
+    "ignore": {
+      "version": "5.1.4",
+      "resolved": "https://registry.npmjs.org/ignore/-/ignore-5.1.4.tgz",
+      "integrity": "sha512-MzbUSahkTW1u7JpKKjY7LCARd1fU5W2rLdxlM4kdkayuCwZImjkpluF9CM1aLewYJguPDqewLam18Y6AU69A8A==",
+      "dev": true
+    },
+    "inflight": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/inflight/-/inflight-1.0.6.tgz",
+      "integrity": "sha1-Sb1jMdfQLQwJvJEKEHW6gWW1bfk=",
+      "dev": true,
+      "requires": {
+        "once": "^1.3.0",
+        "wrappy": "1"
+      }
+    },
+    "inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "dev": true
+    },
+    "is-extglob": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/is-extglob/-/is-extglob-2.1.1.tgz",
+      "integrity": "sha1-qIwCU1eR8C7TfHahueqXc8gz+MI=",
+      "dev": true
+    },
+    "is-glob": {
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/is-glob/-/is-glob-4.0.1.tgz",
+      "integrity": "sha512-5G0tKtBTFImOqDnLB2hG6Bp2qcKEFduo4tZu9MT/H6NQv/ghhy30o55ufafxJ/LdH79LLs2Kfrn85TLKyA7BUg==",
+      "dev": true,
+      "requires": {
+        "is-extglob": "^2.1.1"
+      }
+    },
+    "is-module": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/is-module/-/is-module-1.0.0.tgz",
+      "integrity": "sha1-Mlj7afeMFNW4FdZkM2tM/7ZEFZE=",
+      "dev": true
+    },
+    "is-number": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/is-number/-/is-number-7.0.0.tgz",
+      "integrity": "sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==",
+      "dev": true
+    },
+    "is-plain-object": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/is-plain-object/-/is-plain-object-3.0.0.tgz",
+      "integrity": "sha512-tZIpofR+P05k8Aocp7UI/2UTa9lTJSebCXpFFoR9aibpokDj/uXBsJ8luUu0tTVYKkMU6URDUuOfJZ7koewXvg==",
+      "dev": true,
+      "requires": {
+        "isobject": "^4.0.0"
+      }
+    },
+    "isobject": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/isobject/-/isobject-4.0.0.tgz",
+      "integrity": "sha512-S/2fF5wH8SJA/kmwr6HYhK/RI/OkhD84k8ntalo0iJjZikgq1XFvR5M8NPT1x5F7fBwCG3qHfnzeP/Vh/ZxCUA==",
+      "dev": true
+    },
+    "jsonfile": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/jsonfile/-/jsonfile-4.0.0.tgz",
+      "integrity": "sha1-h3Gq4HmbZAdrdmQPygWPnBDjPss=",
+      "dev": true,
+      "requires": {
+        "graceful-fs": "^4.1.6"
+      }
+    },
+    "merge2": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/merge2/-/merge2-1.3.0.tgz",
+      "integrity": "sha512-2j4DAdlBOkiSZIsaXk4mTE3sRS02yBHAtfy127xRV3bQUFqXkjHCHLW6Scv7DwNRbIWNHH8zpnz9zMaKXIdvYw==",
+      "dev": true
+    },
+    "micromatch": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/micromatch/-/micromatch-4.0.2.tgz",
+      "integrity": "sha512-y7FpHSbMUMoyPbYUSzO6PaZ6FyRnQOpHuKwbo1G+Knck95XVU4QAiKdGEnj5wwoS7PlOgthX/09u5iFJ+aYf5Q==",
+      "dev": true,
+      "requires": {
+        "braces": "^3.0.1",
+        "picomatch": "^2.0.5"
+      }
+    },
+    "minimatch": {
+      "version": "3.0.4",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
+      "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
+      "dev": true,
+      "requires": {
+        "brace-expansion": "^1.1.7"
+      }
+    },
+    "once": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
+      "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
+      "dev": true,
+      "requires": {
+        "wrappy": "1"
+      }
+    },
+    "path-is-absolute": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/path-is-absolute/-/path-is-absolute-1.0.1.tgz",
+      "integrity": "sha1-F0uSaHNVNP+8es5r9TpanhtcX18=",
+      "dev": true
+    },
+    "path-parse": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.6.tgz",
+      "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==",
+      "dev": true
+    },
+    "path-type": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/path-type/-/path-type-4.0.0.tgz",
+      "integrity": "sha512-gDKb8aZMDeD/tZWs9P6+q0J9Mwkdl6xMV8TjnGP3qJVJ06bdMgkbBlLU8IdfOsIsFz2BW1rNVT3XuNEl8zPAvw==",
+      "dev": true
+    },
+    "picomatch": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.1.1.tgz",
+      "integrity": "sha512-OYMyqkKzK7blWO/+XZYP6w8hH0LDvkBvdvKukti+7kqYFCiEAk+gI3DWnryapc0Dau05ugGTy0foQ6mqn4AHYA==",
+      "dev": true
+    },
+    "resolve": {
+      "version": "1.14.1",
+      "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.14.1.tgz",
+      "integrity": "sha512-fn5Wobh4cxbLzuHaE+nphztHy43/b++4M6SsGFC2gB8uYwf0C8LcarfCz1un7UTW8OFQg9iNjZ4xpcFVGebDPg==",
+      "dev": true,
+      "requires": {
+        "path-parse": "^1.0.6"
+      }
+    },
+    "reusify": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/reusify/-/reusify-1.0.4.tgz",
+      "integrity": "sha512-U9nH88a3fc/ekCF1l0/UP1IosiuIjyTh7hBvXVMHYgVcfGvt897Xguj2UOLDeI5BG2m7/uwyaLVT6fbtCwTyzw==",
+      "dev": true
+    },
+    "rollup": {
+      "version": "1.27.13",
+      "resolved": "https://registry.npmjs.org/rollup/-/rollup-1.27.13.tgz",
+      "integrity": "sha512-hDi7M07MpmNSDE8YVwGVFA8L7n8jTLJ4lG65nMAijAyqBe//rtu4JdxjUBE7JqXfdpqxqDTbCDys9WcqdpsQvw==",
+      "dev": true,
+      "requires": {
+        "@types/estree": "*",
+        "@types/node": "*",
+        "acorn": "^7.1.0"
+      },
+      "dependencies": {
+        "acorn": {
+          "version": "7.1.0",
+          "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.1.0.tgz",
+          "integrity": "sha512-kL5CuoXA/dgxlBbVrflsflzQ3PAas7RYZB52NOm/6839iVYJgKMJ3cQJD+t2i5+qFa8h3MDpEOJiS64E8JLnSQ==",
+          "dev": true
+        }
+      }
+    },
+    "rollup-plugin-copy": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/rollup-plugin-copy/-/rollup-plugin-copy-3.1.0.tgz",
+      "integrity": "sha512-oVw3ljRV5jv7Yw/6eCEHntVs9Mc+NFglc0iU0J8ei76gldYmtBQ0M/j6WAkZUFVRSrhgfCrEakUllnN87V2f4w==",
+      "dev": true,
+      "requires": {
+        "@types/fs-extra": "^8.0.0",
+        "colorette": "^1.1.0",
+        "fs-extra": "^8.1.0",
+        "globby": "10.0.1",
+        "is-plain-object": "^3.0.0"
+      }
+    },
+    "rollup-plugin-node-resolve": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/rollup-plugin-node-resolve/-/rollup-plugin-node-resolve-5.2.0.tgz",
+      "integrity": "sha512-jUlyaDXts7TW2CqQ4GaO5VJ4PwwaV8VUGA7+km3n6k6xtOEacf61u0VXwN80phY/evMcaS+9eIeJ9MOyDxt5Zw==",
+      "dev": true,
+      "requires": {
+        "@types/resolve": "0.0.8",
+        "builtin-modules": "^3.1.0",
+        "is-module": "^1.0.0",
+        "resolve": "^1.11.1",
+        "rollup-pluginutils": "^2.8.1"
+      }
+    },
+    "rollup-pluginutils": {
+      "version": "2.8.2",
+      "resolved": "https://registry.npmjs.org/rollup-pluginutils/-/rollup-pluginutils-2.8.2.tgz",
+      "integrity": "sha512-EEp9NhnUkwY8aif6bxgovPHMoMoNr2FulJziTndpt5H9RdwC47GSGuII9XxpSdzVGM0GWrNPHV6ie1LTNJPaLQ==",
+      "dev": true,
+      "requires": {
+        "estree-walker": "^0.6.1"
+      }
+    },
+    "run-parallel": {
+      "version": "1.1.9",
+      "resolved": "https://registry.npmjs.org/run-parallel/-/run-parallel-1.1.9.tgz",
+      "integrity": "sha512-DEqnSRTDw/Tc3FXf49zedI638Z9onwUotBMiUFKmrO2sdFKIbXamXGQ3Axd4qgphxKB4kw/qP1w5kTxnfU1B9Q==",
+      "dev": true
+    },
+    "slash": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/slash/-/slash-3.0.0.tgz",
+      "integrity": "sha512-g9Q1haeby36OSStwb4ntCGGGaKsaVSjQ68fBxoQcutl5fS1vuY18H3wSt3jFyFtrkx+Kz0V1G85A4MyAdDMi2Q==",
+      "dev": true
+    },
+    "to-regex-range": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/to-regex-range/-/to-regex-range-5.0.1.tgz",
+      "integrity": "sha512-65P7iz6X5yEr1cwcgvQxbbIw7Uk3gOy5dIdtZ4rDveLqhrdJP+Li/Hx6tyK0NEb+2GCyneCMJiGqrADCSNk8sQ==",
+      "dev": true,
+      "requires": {
+        "is-number": "^7.0.0"
+      }
+    },
+    "universalify": {
+      "version": "0.1.2",
+      "resolved": "https://registry.npmjs.org/universalify/-/universalify-0.1.2.tgz",
+      "integrity": "sha512-rBJeI5CXAlmy1pV+617WB9J63U6XcazHHF2f2dbJix4XzpUF0RS3Zbj0FGIOCAva5P/d/GBOYaACQ1w+0azUkg==",
+      "dev": true
+    },
+    "wrappy": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
+      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8=",
+      "dev": true
+    }
+  }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..12f8519
--- /dev/null
+++ b/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "medium-frontend-env-demo",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "build": "rollup -c rollup.config.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "rollup": "^1.27.13",
+    "rollup-plugin-copy": "^3.1.0",
+    "rollup-plugin-node-resolve": "^5.2.0"
+  }
+}
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 0000000..56fd795
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,18 @@
+// rollup.config.js
+import resolve from 'rollup-plugin-node-resolve';
+import copy from 'rollup-plugin-copy';
+
+export default {
+  input: 'src/index.js',
+  output: {
+    file: 'dist/app.js',
+    format: 'cjs',
+    name: 'demo',
+  },
+  plugins: [
+    resolve(),
+    copy({
+      targets: [ { src: 'src/index.html', dest: 'dist/' } ],
+    }),
+  ],
+};
diff --git a/src/config.js b/src/config.js
new file mode 100644
index 0000000..ef39548
--- /dev/null
+++ b/src/config.js
@@ -0,0 +1,9 @@
+const processEnv = typeof process !== 'undefined' ? process.env : {};
+const injectedEnv = window && window.injectedEnv ? window.injectedEnv : {};
+
+const env = {
+  ...processEnv,
+  ...injectedEnv,
+};
+
+export { env };
diff --git a/src/index.html b/src/index.html
new file mode 100644
index 0000000..e7db26c
--- /dev/null
+++ b/src/index.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <title>Frontend demo with Nginx + environment variables</title>
+    <script src="/inject.js"></script>
+  </head>
+  <body>
+    <h1>Frontend demo with Nginx + environment variables</h1>
+    <div id="app"></div>
+    <script src="/app.js"></script>
+  </body>
+</html>
diff --git a/src/index.js b/src/index.js
new file mode 100644
index 0000000..b26e960
--- /dev/null
+++ b/src/index.js
@@ -0,0 +1,5 @@
+import { env } from './config';
+
+Object.keys(env).forEach(key => {
+  document.getElementById('app').innerHTML += `<div>${key}: ${env[key]}</div>`;
+});