Add metrics and healthchecks

.editorconfig

@@ -12,3 +12,4 @@ tab_width = 2
 [*.go]
 indent_size = 4
 tab_width = 4
+indent_style = tab

Dockerfile

@@ -13,7 +13,7 @@
 # Build deployable server
 FROM gcr.io/distroless/static:debug
 
 ENV FRITZBOX_ENDPOINT_URL="http://fritz.box:49000" \
     FRITZBOX_ENDPOINT_TIMEOUT="30s" \
     DYNDNS_SERVER_BIND=":8080" \
     DYNDNS_SERVER_USERNAME="" \
@@ -22,7 +22,9 @@
     CLOUDFLARE_API_KEY_FILE="" \
     CLOUDFLARE_ZONES_IPV4="" \
     CLOUDFLARE_ZONES_IPV6="" \
-    DEVICE_LOCAL_ADDRESS_IPV6=""
+    DEVICE_LOCAL_ADDRESS_IPV6="" \
+    METRICS_BIND="" \
+    METRICS_TOKEN_FILE=""
 
 WORKDIR /app
 

README.md

@@ -99,7 +99,7 @@ In your `.env` file or your system environment variables you can be configured:
 | CLOUDFLARE_ZONES_IPV6     | comma-separated list of domains to update with new IPv6 addresses.                                                                                          |
 | CLOUDFLARE_API_EMAIL      | deprecated, your Cloudflare account email.                                                                                                                  |
 | CLOUDFLARE_API_KEY        | deprecated, your Cloudflare Global API key.                                                                                                                 |
-| CLOUDFLARE_API_KEY_FILE   | deprecated, path to a file containing your Cloudflare Global API key.                                                                                       |
+| CLOUDFLARE_API_KEY_FILE   | deprecated, path to a file containing your Cloudflare Global API key. It's recommended to use this over `CLOUDFLARE_API_KEY`.                               |
 
 This service allows to update multiple records, an advanced example would be:
 
@@ -209,7 +209,7 @@ services:
     env_file: ./updater.env
     restart: unless-stopped
     ports:
-      - 8080/tcp
+      - "8080/tcp"
 ```
 
 With your secret configure in the `updater.env` file next to it (as `SOME_VARIABLE=<valua>`).
@@ -224,6 +224,26 @@ docker run --rm -it -p 8888:8080 fritzbox-cloudflare-dyndns
 If you leave `CLOUDFLARE_*` unconfigured, pushing to Cloudflare will be disabled for testing purposes, so try to
 trigger it by calling `http://127.0.0.1:8888/ip?v4=127.0.0.1&v6=::1` and review the logs.
 
+## Metrics and Health Check
+
+If you want to check whether the service is running correctly, you can configure these with the following variables:
+
+| Variable name      | Description                                                                                                                                   |
+|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------|
+| METRICS_BIND       | required, network interface to bind to, i.e. `:9876`                                                                                          |
+| METRICS_TOKEN      | token that has to be passed to the endpoints to authenticate                                                                                  |
+| METRICS_TOKEN_FILE | path ot a file containing a token that has to be passed to the endpoints to authenticate.  It's recommended to use this over `METRICS_TOKEN`. |
+
+The endpoint for prometheus-compatible metrics is `/metrics`, the endpoint for the health check is `/healthz` and the
+endpoint for liveness is `/liveness` on the configured network bind.
+If you chose to use a token, you'll have to append it using the query like `/metrics?token=123456`.
+
+The difference between the liveness and the health endpoint is that the health endpoint will return `503` if any
+subsystem has an issue and `200` if not, while the liveness endpoint will always return `204` as long as the HTTP server
+is able to respond.
+
 ## History & Credit
 
-Most of the credit goes to [@adrianrudnik](https://github.com/adrianrudnik), who wrote and maintained the software for years. Meanwhile I stepped in at a later point when the repository was transferred to me to continue its basic maintenance should it be required.
+Most of the credit goes to [@adrianrudnik](https://github.com/adrianrudnik), who wrote and maintained the software for
+years. After he moved on I stepped in at a later point when the repository was transferred to me to continue its basic
+maintenance should it be required.

alpine.Dockerfile

@@ -13,7 +13,7 @@
 # Build deployable server
 FROM alpine:3
 
 ENV FRITZBOX_ENDPOINT_URL="http://fritz.box:49000" \
     FRITZBOX_ENDPOINT_TIMEOUT="30s" \
     DYNDNS_SERVER_BIND=":8080" \
     DYNDNS_SERVER_USERNAME="" \
@@ -22,7 +22,9 @@
     CLOUDFLARE_API_KEY_FILE="" \
     CLOUDFLARE_ZONES_IPV4="" \
     CLOUDFLARE_ZONES_IPV6="" \
-    DEVICE_LOCAL_ADDRESS_IPV6=""
+    DEVICE_LOCAL_ADDRESS_IPV6="" \
+    METRICS_BIND="" \
+    METRICS_TOKEN_FILE=""
 
 WORKDIR /app
 

go.mod

@@ -5,14 +5,24 @@ go 1.23
 require (
 	github.com/cloudflare/cloudflare-go v0.108.0
 	github.com/joho/godotenv v1.5.1
+	github.com/prometheus/client_golang v1.20.5
 	golang.org/x/net v0.30.0
 	gopkg.in/xmlpath.v2 v2.0.0-20150820204837-860cbeca3ebc
 )
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/goccy/go-json v0.10.3 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
-	github.com/kr/pretty v0.3.1 // indirect
+	github.com/klauspost/compress v1.17.9 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.55.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
+	golang.org/x/sys v0.26.0 // indirect
 	golang.org/x/text v0.19.0 // indirect
 	golang.org/x/time v0.7.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
 )

go.sum

@@ -1,3 +1,7 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cloudflare/cloudflare-go v0.108.0 h1:C4Skfjd8I8X3uEOGmQUT4/iGyZcWdkIU7HwvMoLkEE0=
 github.com/cloudflare/cloudflare-go v0.108.0/go.mod h1:m492eNahT/9MsN7Ppnoge8AaI7QhVFtEgVm3I9HJFeU=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
@@ -6,30 +10,47 @@ github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/goccy/go-json v0.10.3 h1:KZ5WoDbxAIgm2HNbYckL0se1fHD6rz5j4ywS6ebzDqA=
 github.com/goccy/go-json v0.10.3/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
-github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-querystring v1.1.0 h1:AnCroh3fv4ZBgVIf1Iwtovgjaw/GiKJo8M8yD/fhyJ8=
 github.com/google/go-querystring v1.1.0/go.mod h1:Kcdr2DB4koayq7X8pmAG4sNG59So17icRSOU623lUBU=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/klauspost/compress v1.17.9 h1:6KIumPrER1LHsvBVuDa0r5xaG0Es51mhhB9BQB2qeMA=
+github.com/klauspost/compress v1.17.9/go.mod h1:Di0epgTjJY877eYKx5yC51cX2A2Vl2ibi7bDH9ttBbw=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
-github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/prometheus/client_golang v1.20.5 h1:cxppBPuYhUnsO6yo/aoRol4L7q7UFfdm+bR9r+8l63Y=
+github.com/prometheus/client_golang v1.20.5/go.mod h1:PIEt8X02hGcP8JWbeHyeZ53Y/jReSnHgO035n//V5WE=
+github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p8ais2e9E=
+github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY=
+github.com/prometheus/common v0.55.0 h1:KEi6DK7lXW/m7Ig5i47x0vRzuBsHuvJdi5ee6Y3G1dc=
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+github.com/prometheus/procfs v0.15.1/go.mod h1:fB45yRUv8NstnjriLhBQLuOUt+WW4BsoGhij/e3PBqk=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
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+golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
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