feat: add prometheus http metrics

.env.sample

@@ -1,8 +1,10 @@
-CASSETTE_APP_URL=https://cassette-app.de/
+CASSETTE_APP_URL=https://cassette-for-spotify.app/
 CASSETTE_MONGODB_URI=<CONNECTION_STRING>
 CASSETTE_NETWORK_INTERFACE=0.0.0.0
+CASSETTE_INTERNAL_NETWORK_INTERFACE=localhost
 CASSETTE_PORT=8082
+CASSETTE_INTERNAL_PORT=8083
 CASSETTE_SPOTIFY_CLIENT_ID=<ID>
 CASSETTE_SPOTIFY_CLIENT_KEY=<SECRET>
 CASSETTE_ENV=DEV
-CASSETTE_SECRET=<SOME KEY MATERIAL, THIS CAN BE SOME WEIRD BYTES OR A WEIRD SENTENCE LIKE THIS>
+CASSETTE_SECRET=<SOME KEY MATERIAL, THIS CAN BE SOME WEIRD BYTES OR A WEIRD SENTENCE LIKE THIS>

.gitignore

@@ -7,4 +7,4 @@ coverage.out
 node_modules/
 .idea/
 .vscode/
-static/
+static/

Dockerfile

@@ -23,7 +23,7 @@ RUN yarn install
 COPY .git/ .git/
 RUN GIT_VERSION=$(git describe --always) GIT_AUTHOR_DATE=$(git log -1 --format=%aI) BUILD_DATE=$(date +%Y-%m-%dT%H:%M:%S%z) yarn build
 
-FROM alpine
+FROM alpine:3.19
 RUN apk --no-cache add ca-certificates
 WORKDIR /app
 COPY ./CHECKS .

NOTES_ON_DOKKU.md

@@ -1,4 +1,4 @@
-For the git revision to be available at build time in dokku's environment it is essential to configure dokku to keep the .git directory:
+For the git revision to be available at build time in dokku's environment, it is essential to configure dokku to keep the `.git` directory:
 
 ```bash
 # keep the .git directory during builds

README.md

@@ -7,7 +7,7 @@
 
 An "audio book helper utility for Spotify®".
 
-***Try it out at https://cassette-app.de.***
+***Try it out at https://cassette-for-spotify.app.***
 
 Cassette is a small web application enabling you to pause and resume audiobooks on Spotify. Spotify offers a lot of great audiobooks but as its built with music in a broader sense in mind it does not provide essential features required in order to comfortably listen to them: pausing an audiobook and listening to some music results in you needing to think about in which chapter you left off.
 
@@ -17,17 +17,27 @@ Cassette tries to overcome this problem by enabling you to store your state, put
 
 
 ## How is this done?
-Simply spoken by using the Spotify Web API. Cassette itself consists of two components, a REST service running on a server (this directory) and a web app (./web) running in your browser. The service is talking with the Spotify Web API and a MongoDB database in with the states get persisted. The web app talks with the service via a REST interface.
+In a nutshell: By using the Spotify Web API. 
 
+Cassette itself consists of two parts: 
+- a REST service running on a server (this directory) 
+- a web app (./web) running in your browser
+
+The service is talking with the Spotify Web API, and a MongoDB database in with the states get persisted. 
+The web app talks with the service via a REST interface.
 
-## Current status of the project
-After spending a lot of time rewriting all parts of this project I finally was able to release version 2. Although version 1, which had another name that could not be kept as it violated Spotify's branding guidelines, was available to the public already it was not really too robust, not really intuitive to use and overall not meant to be used by anyone but myself. It was more kind of a proof-of-concept project hacked together in a few days.
 
-Version 2 is way more mature, takes care of data privacy, includes an interactive introduction tour and and a polished UI with both mobile and desktop users in mind. Its goal is to be, hopefully, useful to many users aside myself.
+## Current status of the project
+After spending a lot of time rewriting all parts of this project, I finally was able to release version 2. 
+Although version 1, which had another name that could not be kept as it violated Spotify's branding guidelines, was available to the public already, it was not really too robust, not really intuitive to use and overall not meant to be used by anyone but myself. 
+It was more a proof-of-concept project hacked together in a few days.
 
-Version 2 is deployed at https://cassette-app.de.
+Version 2 is way more mature, takes care of data privacy, includes an interactive introduction tour and a polished UI with both mobile and desktop users in mind. 
+Its goal is to be, hopefully, useful to many users aside myself.
 
+Version 2 is deployed at https://cassette-for-spotify.app.
 
 
 ## Disclaimer
-The authors of this project are not related to Spotify in any way beside being happy users of their platform. This service is not related to Spotify except using their API and content.
+The authors of this project are not related to Spotify in any way besides being happy users of their platform. 
+This service is not related to Spotify; it is only using their API and content.

go.mod

@@ -1,6 +1,8 @@
 module github.com/florianloch/cassette
 
-go 1.22
+go 1.22.3
+
+toolchain go1.22.4
 
 require (
 	github.com/gavv/httpexpect/v2 v2.16.0 // lock to this version, test breaks when upgrading
@@ -15,32 +17,42 @@ require (
 	golang.org/x/oauth2 v0.21.0
 )
 
+require (
+	github.com/prometheus/client_golang v1.19.1
+	github.com/slok/go-http-metrics v0.12.0
+)
+
 require (
 	github.com/TylerBrock/colorjson v0.0.0-20200706003622-8a50f05110d2 // indirect
 	github.com/ajg/form v1.5.1 // indirect
-	github.com/andybalholm/brotli v1.0.4 // indirect
+	github.com/andybalholm/brotli v1.1.0 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fatih/color v1.15.0 // indirect
 	github.com/fatih/structs v1.1.0 // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
-	github.com/golang/snappy v0.0.3 // indirect
+	github.com/golang/snappy v0.0.4 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
 	github.com/gorilla/securecookie v1.1.2 // indirect
 	github.com/gorilla/websocket v1.4.2 // indirect
 	github.com/hpcloud/tail v1.0.0 // indirect
 	github.com/imkira/go-interpol v1.1.0 // indirect
-	github.com/klauspost/compress v1.15.0 // indirect
+	github.com/klauspost/compress v1.17.8 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
-	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.1 // indirect
 	github.com/montanaflynn/stats v0.0.0-20171201202039-1bf9dbcd8cbe // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.53.0 // indirect
+	github.com/prometheus/procfs v0.15.0 // indirect
 	github.com/rs/xid v1.5.0 // indirect
 	github.com/sanity-io/litter v1.5.5 // indirect
 	github.com/sergi/go-diff v1.0.0 // indirect
-	github.com/stretchr/testify v1.7.0 // indirect
+	github.com/stretchr/testify v1.9.0 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/valyala/fasthttp v1.34.0 // indirect
+	github.com/valyala/fasthttp v1.52.0 // indirect
 	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
 	github.com/xdg-go/scram v1.1.2 // indirect
 	github.com/xdg-go/stringprep v1.0.4 // indirect
@@ -51,11 +63,12 @@ require (
 	github.com/youmark/pkcs8 v0.0.0-20181117223130-1be2e3e5546d // indirect
 	github.com/yudai/gojsondiff v1.0.0 // indirect
 	github.com/yudai/golcs v0.0.0-20170316035057-ecda9a501e82 // indirect
-	golang.org/x/crypto v0.17.0 // indirect
-	golang.org/x/net v0.10.0 // indirect
-	golang.org/x/sync v0.1.0 // indirect
-	golang.org/x/sys v0.15.0 // indirect
+	golang.org/x/crypto v0.22.0 // indirect
+	golang.org/x/net v0.24.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.20.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
+	google.golang.org/protobuf v1.34.1 // indirect
 	gopkg.in/fsnotify.v1 v1.4.7 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect