feat: add legacy-api service
실험·앱 계층 설계서 3.2의 legacy-api(VM 계층). /healthz(프로세스 생존),
/v1/price/{item}(db-primary app.price 조회, DB 불가 시 503), /metrics(Prometheus).
Go 1.27.1, pgx v5.11.0, client_golang v1.24.1. 이미지는 Cloud Build로 Artifact Registry에
올린다(MIG 인스턴스가 VM SA로 pull).
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@@ -0,0 +1,15 @@
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# legacy-api (VM layer of the self-healing lab). Built with Cloud Build into Artifact Registry.
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FROM golang:1.27.1-alpine AS build
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WORKDIR /src
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ENV CGO_ENABLED=0 GOFLAGS=-mod=mod
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COPY go.mod ./
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RUN go mod download
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COPY . .
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RUN go build -trimpath -ldflags="-s -w" -o /out/legacy-api .
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FROM alpine:3.22
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RUN apk add --no-cache ca-certificates && adduser -D -u 10001 app
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USER 10001
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COPY --from=build /out/legacy-api /usr/local/bin/legacy-api
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EXPOSE 8080
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ENTRYPOINT ["/usr/local/bin/legacy-api"]
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@@ -0,0 +1,24 @@
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module github.com/selfheal-lab/selfheal-lab-apps/legacy-api
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go 1.27
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require (
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github.com/jackc/pgx/v5 v5.11.0
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github.com/prometheus/client_golang v1.24.1
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)
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require (
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github.com/beorn7/perks v1.0.1 // indirect
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github.com/cespare/xxhash/v2 v2.3.0 // indirect
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github.com/jackc/pgpassfile v1.0.0 // indirect
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
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github.com/jackc/puddle/v2 v2.2.2 // indirect
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github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
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github.com/prometheus/client_model v0.6.2 // indirect
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github.com/prometheus/common v0.70.1 // indirect
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github.com/prometheus/procfs v0.21.1 // indirect
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golang.org/x/sync v0.22.0 // indirect
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golang.org/x/sys v0.47.0 // indirect
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golang.org/x/text v0.40.0 // indirect
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google.golang.org/protobuf v1.36.11 // indirect
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)
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@@ -0,0 +1,54 @@
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github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
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github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
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github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
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github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
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github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
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github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
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github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
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github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
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github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
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github.com/jackc/pgx/v5 v5.11.0 h1:IzBBtyK9AHqf98cctWFifYSci2hgQR/cd56wB4p+ogg=
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github.com/jackc/pgx/v5 v5.11.0/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
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github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
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github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
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github.com/klauspost/compress v1.19.1 h1:VsB4HPswih7mmZ8WleSFQ75c/Ui1M4trX5oAsJnhSlk=
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github.com/klauspost/compress v1.19.1/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
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github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
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github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
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github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
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github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
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github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
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github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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github.com/prometheus/client_golang v1.24.1 h1:JnJkREXzWxUdCuPFpIWZiPispT9xVV59uiuyR2bPlnU=
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github.com/prometheus/client_golang v1.24.1/go.mod h1:F+oSRECHg4sse5ucfYpYDeIv/hu68Zo0uoHKetWnzcE=
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github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
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github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
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github.com/prometheus/common v0.70.1 h1:1HvjP4D5oL3t8RsPlwxA9onvvStjtIHYE5XuuwOi/PY=
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github.com/prometheus/common v0.70.1/go.mod h1:VdFUQDMZK3VLkurFUVhia6uys/0suUp86TJz5qbJRhc=
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github.com/prometheus/procfs v0.21.1 h1:GljZCt+zSTS+NZq88cyQ1LjZ+RCHp3uVuabBWA5+OJI=
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github.com/prometheus/procfs v0.21.1/go.mod h1:aB55Cww9pdSJVHk0hUf0inxWyyjPogFIjmHKYgMKmtY=
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github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
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github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
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github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
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github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
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github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
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go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
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go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
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go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
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go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
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golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
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golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
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golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
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golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
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golang.org/x/text v0.40.0 h1:Ub2Z6/xjgF1WrYQz2nuITOEegKFtiIy+rieRJ5lHZKs=
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golang.org/x/text v0.40.0/go.mod h1:hpnzDAfGV753zIKo+wk3u1bVKCGPbrnF7+7LBF/UHVY=
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google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
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google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
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gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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@@ -0,0 +1,112 @@
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// legacy-api: the "VM layer" service of the self-healing lab (experiment design 3.2).
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// GET /healthz process liveness only (MIG autohealing + ILB health check)
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// GET /v1/price/{item} reads app.price on db-primary (503 when the DB is unreachable)
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// GET /metrics Prometheus exposition
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package main
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import (
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"context"
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"database/sql"
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"encoding/json"
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"log"
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"net/http"
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"os"
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"strconv"
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"strings"
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"time"
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_ "github.com/jackc/pgx/v5/stdlib"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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var (
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reqTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
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Name: "legacy_http_requests_total", Help: "HTTP requests by route and status",
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}, []string{"route", "status"})
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reqDur = prometheus.NewHistogramVec(prometheus.HistogramOpts{
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Name: "legacy_http_request_duration_seconds", Help: "HTTP request latency",
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Buckets: []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5},
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}, []string{"route"})
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)
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type statusWriter struct {
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http.ResponseWriter
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code int
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}
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func (w *statusWriter) WriteHeader(c int) { w.code = c; w.ResponseWriter.WriteHeader(c) }
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func instrument(route string, h http.HandlerFunc) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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sw := &statusWriter{ResponseWriter: w, code: 200}
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start := time.Now()
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h(sw, r)
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reqDur.WithLabelValues(route).Observe(time.Since(start).Seconds())
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reqTotal.WithLabelValues(route, strconv.Itoa(sw.code)).Inc()
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}
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}
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func writeJSON(w http.ResponseWriter, code int, v any) {
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w.Header().Set("Content-Type", "application/json")
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w.WriteHeader(code)
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_ = json.NewEncoder(w).Encode(v)
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}
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func main() {
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prometheus.MustRegister(reqTotal, reqDur)
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port := os.Getenv("PORT")
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if port == "" {
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port = "8080"
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}
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dsn := os.Getenv("DB_DSN")
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var db *sql.DB
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if dsn != "" {
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var err error
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if db, err = sql.Open("pgx", dsn); err != nil {
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log.Printf("db open: %v", err)
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db = nil
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} else {
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db.SetMaxOpenConns(8)
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db.SetConnMaxLifetime(5 * time.Minute)
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}
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} else {
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log.Printf("DB_DSN not set: /v1/price will answer 503")
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}
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mux := http.NewServeMux()
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mux.HandleFunc("/healthz", instrument("healthz", func(w http.ResponseWriter, r *http.Request) {
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w.Header().Set("Content-Type", "text/plain")
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_, _ = w.Write([]byte("ok\n"))
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}))
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mux.HandleFunc("/v1/price/", instrument("price", func(w http.ResponseWriter, r *http.Request) {
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item := strings.TrimPrefix(r.URL.Path, "/v1/price/")
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if item == "" || strings.Contains(item, "/") {
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writeJSON(w, 404, map[string]string{"error": "item required"})
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return
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}
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if db == nil {
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writeJSON(w, 503, map[string]string{"error": "db unavailable"})
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return
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}
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ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
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defer cancel()
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var price float64
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var updated time.Time
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err := db.QueryRowContext(ctx, "SELECT price, updated_at FROM app.price WHERE item = $1", item).Scan(&price, &updated)
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switch {
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case err == sql.ErrNoRows:
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writeJSON(w, 404, map[string]string{"error": "unknown item", "item": item})
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case err != nil:
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log.Printf("price query: %v", err)
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writeJSON(w, 503, map[string]string{"error": "db unavailable"})
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default:
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writeJSON(w, 200, map[string]any{"item": item, "price": price, "updated_at": updated.UTC().Format(time.RFC3339)})
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}
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}))
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mux.Handle("/metrics", promhttp.Handler())
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srv := &http.Server{Addr: ":" + port, Handler: mux, ReadHeaderTimeout: 5 * time.Second}
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log.Printf("legacy-api listening on :%s", port)
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log.Fatal(srv.ListenAndServe())
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}
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Block a user