After pushing RoR project to server, receive Node.js version error [Buildpack issue]

Question

git push dokku master                                          
Enumerating objects: 30, done.
Counting objects: 100% (30/30), done.
Delta compression using up to 8 threads
Compressing objects: 100% (21/21), done.
Writing objects: 100% (21/21), 35.39 KiB | 4.42 MiB/s, done.
Total 21 (delta 12), reused 0 (delta 0)
-----> Cleaning up...
-----> Building taaalk from herokuish...
-----> Adding BUILD_ENV to build environment...
-----> Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
       Detected buildpacks: ruby nodejs
-----> Ruby app detected
-----> Installing bundler 2.0.2
-----> Removing BUNDLED WITH version in the Gemfile.lock
-----> Compiling Ruby/Rails
-----> Using Ruby version: ruby-2.6.3
-----> Installing dependencies using bundler 2.0.2
       Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
       The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java`.
       Using rake 13.0.1
       Using concurrent-ruby 1.1.6
       Using i18n 1.8.3
       Using minitest 5.14.1
       Using thread_safe 0.3.6
       Using tzinfo 1.2.7
       Using zeitwerk 2.3.0
       Using activesupport 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using builder 3.2.4
       Using erubi 1.9.0
       Using mini_portile2 2.4.0
       Using nokogiri 1.10.9
       Using rails-dom-testing 2.0.3
       Using crass 1.0.6
       Using loofah 2.6.0
       Using rails-html-sanitizer 1.3.0
       Using actionview 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using rack 2.2.3
       Using rack-test 1.1.0
       Using actionpack 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using nio4r 2.5.2
       Using websocket-extensions 0.1.5
       Using websocket-driver 0.7.2
       Using actioncable 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using globalid 0.4.2
       Using activejob 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using activemodel 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using activerecord 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using mimemagic 0.3.5
       Using marcel 0.3.3
       Using activestorage 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using mini_mime 1.0.2
       Using mail 2.7.1
       Using actionmailbox 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using actionmailer 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using actiontext 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using execjs 2.7.0
       Using autoprefixer-rails 9.8.4
       Using aws-eventstream 1.1.0
       Using aws-partitions 1.334.0
       Using aws-sigv4 1.2.1
       Using jmespath 1.4.0
       Using aws-sdk-core 3.102.0
       Using aws-sdk-kms 1.35.0
       Using aws-sdk-s3 1.70.0
       Using bcrypt 3.1.13
       Using msgpack 1.3.3
       Using bootsnap 1.4.6
       Using popper_js 1.16.0
       Using method_source 1.0.0
       Using thor 1.0.1
       Using railties 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using ffi 1.13.1
       Using sassc 2.4.0
       Using sprockets 4.0.2
       Using sprockets-rails 3.2.1
       Using tilt 2.0.10
       Using sassc-rails 2.1.2
       Using bootstrap 4.4.1
       Using bundler 2.0.2
       Using orm_adapter 0.5.0
       Using responders 3.0.1
       Using warden 1.2.8
       Using devise 4.7.2
       Using font-awesome-sass 5.12.0
       Using friendly_id 5.2.5
       Using mini_magick 4.10.1
       Using ruby-vips 2.0.17
       Using image_processing 1.11.0
       Using jbuilder 2.10.0
       Using jquery-rails 4.4.0
       Using pg 1.2.3
       Using puma 4.3.5
       Using rack-proxy 0.6.5
       Using rails 6.0.3.2 from https://github.com/rails/rails.git (at 6-0-stable@75f6539)
       Using ruby_http_client 3.5.0
       Using sass-rails 6.0.0
       Using semantic_range 2.3.0
       Using sendgrid-ruby 6.3.1
       Using simple_form 5.0.2
       Using turbolinks-source 5.2.0
       Using turbolinks 5.2.1
       Using webpacker 5.1.1 from https://github.com/rails/webpacker.git (at master@d099e06)
       Using will_paginate 3.1.8
       Bundle complete! 30 Gemfile dependencies, 84 gems now installed.
       Gems in the groups development and test were not installed.
       Bundled gems are installed into `./vendor/bundle`
       Bundle completed (0.45s)
       Cleaning up the bundler cache.
-----> Installing node-v10.15.3-linux-x64
-----> Installing yarn-v1.16.0
-----> Detecting rake tasks
-----> Preparing app for Rails asset pipeline
       Running: rake assets:precompile
       yarn install v1.16.0
       [1/4] Resolving packages...
       [2/4] Fetching packages...
       info [email protected]: The platform "linux" is incompatible with this module.
       info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
       info [email protected]: The platform "linux" is incompatible with this module.
       info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
       [3/4] Linking dependencies...
       warning " > [email protected]" has unmet peer dependency "webpack@^4.0.0 || ^5.0.0".
       warning "webpack-dev-server > [email protected]" has unmet peer dependency "webpack@^4.0.0".
       [4/4] Building fresh packages...
       Done in 10.76s.
       I, [2020-06-25T13:40:05.742797 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-7cf61689b348595522e00a5634d9b35e7eb7a25d7ba7e9cce5f02484e1684377.eot
       I, [2020-06-25T13:40:05.743019 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-7cf61689b348595522e00a5634d9b35e7eb7a25d7ba7e9cce5f02484e1684377.eot.gz
       I, [2020-06-25T13:40:05.743128 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-5e54feb2d8cde6b938fa70c95c8e928eff34859e8aaa965b47320872a87ce547.eot
       I, [2020-06-25T13:40:05.743447 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-5e54feb2d8cde6b938fa70c95c8e928eff34859e8aaa965b47320872a87ce547.eot.gz
       I, [2020-06-25T13:40:05.743775 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-e938fcdde52485595e32c17bcf19a8ff23390e2081b52352d8a345f5170dce7f.svg
       I, [2020-06-25T13:40:05.746658 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-e938fcdde52485595e32c17bcf19a8ff23390e2081b52352d8a345f5170dce7f.svg.gz
       I, [2020-06-25T13:40:05.746843 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-934a94434bf9d70c1240a78d5fe78757ff91d1264ae00a1741450e0eef8e9493.eot
       I, [2020-06-25T13:40:05.748405 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-934a94434bf9d70c1240a78d5fe78757ff91d1264ae00a1741450e0eef8e9493.eot.gz
       I, [2020-06-25T13:40:05.748519 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-d20f2c71ef1e9a5b46e2aacfad2f759e8abdb20fce27fd6bc7d401af8fa7c93a.svg
       I, [2020-06-25T13:40:05.748680 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-d20f2c71ef1e9a5b46e2aacfad2f759e8abdb20fce27fd6bc7d401af8fa7c93a.svg.gz
       I, [2020-06-25T13:40:05.748788 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-46cf582bfe3502172a3a4d54cfd380444289c03c9480a107f00c190db3722950.svg
       I, [2020-06-25T13:40:05.749272 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-46cf582bfe3502172a3a4d54cfd380444289c03c9480a107f00c190db3722950.svg.gz
       I, [2020-06-25T13:40:05.749361 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-2bbd3e05518ff1f338c9c223dbb70f09733bc58ea9370a6488bc07e911ac433f.ttf
       I, [2020-06-25T13:40:05.749498 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-2bbd3e05518ff1f338c9c223dbb70f09733bc58ea9370a6488bc07e911ac433f.ttf.gz
       I, [2020-06-25T13:40:05.749580 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-370a10b3877b873b2a1ef13ec5829cca64b323dd05199dbfa7fa80e7a2b8fb65.ttf
       I, [2020-06-25T13:40:05.749656 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-370a10b3877b873b2a1ef13ec5829cca64b323dd05199dbfa7fa80e7a2b8fb65.ttf.gz
       I, [2020-06-25T13:40:05.749736 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-7d974fa4f60281b1e72f8016c13a6bad8f04958bcd04a69e4000ca573c88e8db.ttf
       I, [2020-06-25T13:40:05.749889 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-7d974fa4f60281b1e72f8016c13a6bad8f04958bcd04a69e4000ca573c88e8db.ttf.gz
       I, [2020-06-25T13:40:05.749969 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-e9fa99e59489b4d9270af15949c0df98b805649278b41063f4221819b3d8772e.woff
       I, [2020-06-25T13:40:05.750104 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-ecc54652d705cda26767bc7dd7516893e0d2838b79be2427cb9188f9e4a64eff.woff
       I, [2020-06-25T13:40:05.750221 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-fda129aceafe7c9c766010fbc4461fa2eb86563d80bbc15f0442dc7c674d9e39.woff
       I, [2020-06-25T13:40:05.750377 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-30f8635d0db9d15cac246e0402c02fdfa75eec896dc568f83a9012ed5ec47002.woff2
       I, [2020-06-25T13:40:05.750504 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-23fed01aa8356304efa21c764adac85d840c3feafe988ce828e322f0001aabe6.woff2
       I, [2020-06-25T13:40:05.750617 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-8359fc529007778d3a4d7019896d9c149233a62cc34255c2c5bd2a3bb77f97da.woff2
       I, [2020-06-25T13:40:05.750749 #385]  INFO -- : Writing /tmp/build/public/assets/manifest-b4bf6e57a53c2bdb55b8998cc94cd00883793c1c37c5e5aea3ef6749b4f6d92b.js
       I, [2020-06-25T13:40:05.750808 #385]  INFO -- : Writing /tmp/build/public/assets/manifest-b4bf6e57a53c2bdb55b8998cc94cd00883793c1c37c5e5aea3ef6749b4f6d92b.js.gz
       I, [2020-06-25T13:40:05.750882 #385]  INFO -- : Writing /tmp/build/public/assets/favicon-d3e220a5d00985ec7043ba5c160cac8a73df50fba21d2fbb684af206efe8eca3.ico
       I, [2020-06-25T13:40:05.750952 #385]  INFO -- : Writing /tmp/build/public/assets/favicon-d3e220a5d00985ec7043ba5c160cac8a73df50fba21d2fbb684af206efe8eca3.ico.gz
       I, [2020-06-25T13:40:05.751036 #385]  INFO -- : Writing /tmp/build/public/assets/intro_images/b5-24f610966758d9561e1a2189f285c71bcad9488e4ed27080551cc5aeeaba0109.jpg
       I, [2020-06-25T13:40:05.751147 #385]  INFO -- : Writing /tmp/build/public/assets/intro_images/e5-8bfbdc9416d890df0e3d69fd1587b7c5a4c98fd2629895e365327a89b41392cd.jpg
       I, [2020-06-25T13:40:05.751261 #385]  INFO -- : Writing /tmp/build/public/assets/user-fb72496d9b86b96d0eaa9cb88d48193837d6d2693e24a554c078f5a78c7a86d9.svg
       I, [2020-06-25T13:40:05.751327 #385]  INFO -- : Writing /tmp/build/public/assets/user-fb72496d9b86b96d0eaa9cb88d48193837d6d2693e24a554c078f5a78c7a86d9.svg.gz
       I, [2020-06-25T13:40:05.751403 #385]  INFO -- : Writing /tmp/build/public/assets/actiontext-78d6bd0b133feb077026c9c40bc115ede8d2ce4370d027a5178d1ceb51163cf4.css
       I, [2020-06-25T13:40:05.751456 #385]  INFO -- : Writing /tmp/build/public/assets/actiontext-78d6bd0b133feb077026c9c40bc115ede8d2ce4370d027a5178d1ceb51163cf4.css.gz
       I, [2020-06-25T13:40:05.751529 #385]  INFO -- : Writing /tmp/build/public/assets/application-367c80df5c492b1077317aca85a249037bfa4aac4ea5ae11e36d20f81d6c3900.css
       I, [2020-06-25T13:40:05.751583 #385]  INFO -- : Writing /tmp/build/public/assets/application-367c80df5c492b1077317aca85a249037bfa4aac4ea5ae11e36d20f81d6c3900.css.gz
       I, [2020-06-25T13:40:05.751762 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-934a94434bf9d70c1240a78d5fe78757ff91d1264ae00a1741450e0eef8e9493.eot.gz
       I, [2020-06-25T13:40:05.751856 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-8359fc529007778d3a4d7019896d9c149233a62cc34255c2c5bd2a3bb77f97da.woff2
       I, [2020-06-25T13:40:05.751993 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-fda129aceafe7c9c766010fbc4461fa2eb86563d80bbc15f0442dc7c674d9e39.woff
       I, [2020-06-25T13:40:05.752136 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-7d974fa4f60281b1e72f8016c13a6bad8f04958bcd04a69e4000ca573c88e8db.ttf
       I, [2020-06-25T13:40:05.752268 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-7d974fa4f60281b1e72f8016c13a6bad8f04958bcd04a69e4000ca573c88e8db.ttf.gz
       I, [2020-06-25T13:40:05.752340 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-46cf582bfe3502172a3a4d54cfd380444289c03c9480a107f00c190db3722950.svg
       I, [2020-06-25T13:40:05.764778 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-solid-900-46cf582bfe3502172a3a4d54cfd380444289c03c9480a107f00c190db3722950.svg.gz
       I, [2020-06-25T13:40:05.765368 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-370a10b3877b873b2a1ef13ec5829cca64b323dd05199dbfa7fa80e7a2b8fb65.ttf.gz
       I, [2020-06-25T13:40:05.765753 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-regular-400-d20f2c71ef1e9a5b46e2aacfad2f759e8abdb20fce27fd6bc7d401af8fa7c93a.svg.gz
       I, [2020-06-25T13:40:05.766487 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-2bbd3e05518ff1f338c9c223dbb70f09733bc58ea9370a6488bc07e911ac433f.ttf.gz
       I, [2020-06-25T13:40:05.777707 #385]  INFO -- : Writing /tmp/build/public/assets/font-awesome/fa-brands-400-e938fcdde52485595e32c17bcf19a8ff23390e2081b52352d8a345f5170dce7f.svg.gz
       I, [2020-06-25T13:40:05.777811 #385]  INFO -- : Writing /tmp/build/public/assets/cookies-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.777869 #385]  INFO -- : Writing /tmp/build/public/assets/cookies-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       I, [2020-06-25T13:40:05.777948 #385]  INFO -- : Writing /tmp/build/public/assets/msgs-d9c0994d8c78cb26d157f2232cbb3601c4e7995618454b5f84292409753775b8.css
       I, [2020-06-25T13:40:05.778002 #385]  INFO -- : Writing /tmp/build/public/assets/msgs-d9c0994d8c78cb26d157f2232cbb3601c4e7995618454b5f84292409753775b8.css.gz
       I, [2020-06-25T13:40:05.778076 #385]  INFO -- : Writing /tmp/build/public/assets/pages-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.778129 #385]  INFO -- : Writing /tmp/build/public/assets/pages-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       I, [2020-06-25T13:40:05.778233 #385]  INFO -- : Writing /tmp/build/public/assets/shared-27cf9068f3fe422fff2f375ccbfb1c14ca229b160097c8e83849cb015dc8cf11.css
       I, [2020-06-25T13:40:05.778293 #385]  INFO -- : Writing /tmp/build/public/assets/shared-27cf9068f3fe422fff2f375ccbfb1c14ca229b160097c8e83849cb015dc8cf11.css.gz
       I, [2020-06-25T13:40:05.778368 #385]  INFO -- : Writing /tmp/build/public/assets/spkrs-bf4f16e2f5243d0344fcb58bab406005db0d288cf8efcd66a13f84167677d13b.css
       I, [2020-06-25T13:40:05.778424 #385]  INFO -- : Writing /tmp/build/public/assets/spkrs-bf4f16e2f5243d0344fcb58bab406005db0d288cf8efcd66a13f84167677d13b.css.gz
       I, [2020-06-25T13:40:05.778499 #385]  INFO -- : Writing /tmp/build/public/assets/tlk_follows-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.778551 #385]  INFO -- : Writing /tmp/build/public/assets/tlk_follows-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       I, [2020-06-25T13:40:05.778627 #385]  INFO -- : Writing /tmp/build/public/assets/tlk_requests-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.778678 #385]  INFO -- : Writing /tmp/build/public/assets/tlk_requests-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       I, [2020-06-25T13:40:05.778751 #385]  INFO -- : Writing /tmp/build/public/assets/tlks-ea1b2260434f065490ed712daa84c589d7f37cd74dc9b0fda0834709d1c8ee5d.css
       I, [2020-06-25T13:40:05.778804 #385]  INFO -- : Writing /tmp/build/public/assets/tlks-ea1b2260434f065490ed712daa84c589d7f37cd74dc9b0fda0834709d1c8ee5d.css.gz
       I, [2020-06-25T13:40:05.778878 #385]  INFO -- : Writing /tmp/build/public/assets/user_follows-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.778940 #385]  INFO -- : Writing /tmp/build/public/assets/user_follows-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       I, [2020-06-25T13:40:05.779013 #385]  INFO -- : Writing /tmp/build/public/assets/users-0a17b15413a7816f33245dd5fd74397224aa4e8ebf1938b3f5d723d733a104c0.css
       I, [2020-06-25T13:40:05.779064 #385]  INFO -- : Writing /tmp/build/public/assets/users-0a17b15413a7816f33245dd5fd74397224aa4e8ebf1938b3f5d723d733a104c0.css.gz
       I, [2020-06-25T13:40:05.779137 #385]  INFO -- : Writing /tmp/build/public/assets/variables-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css
       I, [2020-06-25T13:40:05.779190 #385]  INFO -- : Writing /tmp/build/public/assets/variables-04024382391bb910584145d8113cf35ef376b55d125bb4516cebeb14ce788597.css.gz
       Webpacker requires Node.js ">=10.17.0" and you are using v10.15.3
       Please upgrade Node.js https://nodejs.org/en/download/
       Exiting!
       
       !
       !     Precompiling assets failed.
       !

Hi I'm afraid that this is an area that I am very unfamiliar with so I might not be good at asking the right question.

I have a Ruby on Rails project deployed on an ubuntu server + S3 for storage. I just performed yarn upgrade and bundle update to deal with some security dependencies. When I went to deploy my app to the server (git push dokku master) I got the error above.

I don't have Node.js on my application... as far as I can tell (as in if I search globally for "node.js" or "nodejs", I don't find it).

I don't think I have it on my server? But I'm not sure...

I have found one other person online talking about this issue (https://www.guj.com.br/t/heroku-com-node-incompativel/405283) from the 14th of June 2020, so maybe it is something new.

My application is Rails 6, running on the edge branch.

I am not sure how to proceed.

UPDATE: as @engineersmnky pointed out, this is a buildpack error...

Right now I have no specified buildpacks on my server (just the ones that are default? in my rails application? unsure about this).

I am using Dokku, which uses Heroku buildpacks. The default rails one runs node 10.15.3 (https://devcenter.heroku.com/changelog-items/1657), the same version that is causing me trouble...

Heroku suggests adding multiple buildpacks (https://devcenter.heroku.com/articles/ruby-support#installed-binaries), one which first installs nodejs, and one that does ruby.

$ heroku buildpacks:add heroku/nodejs
$ heroku buildpacks:add heroku/ruby

Question 1

If I am doing this with dokku, would I write:

$ dokku buildpacks:add node-js-app https://github.com/heroku/heroku-buildpack-nodejs.git
$ dokku buildpacks:add node-js-app https://github.com/heroku/heroku-buildpack-ruby.git

(see: http://dokku.viewdocs.io/dokku/deployment/methods/buildpacks/#adding-custom-buildpacks)

?

Question 2

It then says I need to update my package.json file, and add something like:

"Once you have done this you’ll need a package.json file in the root of your app. For example to install version 8.9.4 your package.json could look like this:

{ "engines" : { "node": "8.9.4" } }

If I have a package.json file already, can I simply update that to update my buildpack? Or do I need to do step 1 above? (the answer to question 1)?

My current package.json is:

{
  "name": "taaalk_edge",
  "private": true,
  "dependencies": {
    "@rails/actioncable": "^6.0.0",
    "@rails/actiontext": "^6.0.2-1",
    "@rails/activestorage": "^6.0.0",
    "@rails/ujs": "^6.0.0",
    "@rails/webpacker": "4.2.2",
    "trix": "^1.0.0",
    "turbolinks": "^5.2.0",
    "websocket-extensions": "0.1.4"
  },
  "version": "0.1.0",
  "devDependencies": {
    "webpack-dev-server": "^3.10.1"
  }
}

Question 3

I read about having a .nvmrc file... https://github.com/nvm-sh/nvm#nvmrc

Which can specify the node version... but only if I have nvm installed? But I don't know if I can install that on the server.

Answer 1

It seems that right now (March 2021) the heroku buildpack only contains node v10.15.3, while the current webpacker 5 (that comes with rails 6.1.1) requires Node.js ">=10.17.0".

For our projects I could solve this by reverting to webpacker 4.2.2.

Webpacker is the bridge between node and ruby, you need both a gem and a package and need to set the version twice:

• Gemfile sets the version for ruby gem 'webpacker', '~> 4.2.2'
• package.json sets the version for node "@rails/webpacker": "4.2.2"

p.s. not a solution yet: heroku offered a buildpack with the right node version for a while, but rolled it back: https://devcenter.heroku.com/changelog-items/1818