Plumber API を本番環境にデプロイする

本番デプロイの選択肢

Plumber APIのエントリーポイント

# api.R
# library(plumber)
#
# pr <- plumb('routes.R')
# port <- as.integer(Sys.getenv('PORT', unset = '8000'))
# pr$run(host = '0.0.0.0', port = port)
#
# Listening on 0.0.0.0 is required inside Docker
# (127.0.0.1 is only reachable inside the container)

ベースDockerイメージ — rocker/r-ver

# Dockerfile
# FROM rocker/r-ver:4.3.2
#
# Alternatively use rocker/plumber which pre-installs plumber:
# FROM rstudio/plumber:latest
#
# rocker/r-ver is more minimal and gives you full control
# over which packages are installed.

DockerfileでのRパッケージのインストール

# FROM rocker/r-ver:4.3.2
#
# RUN apt-get update && apt-get install -y \
#     libssl-dev \
#     libcurl4-openssl-dev \
#  && rm -rf /var/lib/apt/lists/*
#
# RUN Rscript -e "install.packages(c('plumber', 'jsonlite', 'httr2'), repos='https://cloud.r-project.org')"

ファイルのコピーとポートの設定

# FROM rocker/r-ver:4.3.2
# ...
# WORKDIR /app
# COPY routes.R .
# COPY api.R .
#
# EXPOSE 8000
#
# CMD ["Rscript", "api.R"]

Dockerイメージのビルドと実行

# Build the image:
# docker build -t my-r-api:1.0 .
#
# Run a container:
# docker run -d \
#   -p 8000:8000 \
#   -e API_SECRET_KEY='my_secret' \
#   -e DATABASE_URL='postgres://...' \
#   --name r-api \
#   my-r-api:1.0
#
# Test:
# curl http://localhost:8000/ping

Sys.getenv()によるシークレットの読み取り

# In routes.R:
# db_url   <- Sys.getenv('DATABASE_URL', unset = '')
# api_key  <- Sys.getenv('API_SECRET_KEY', unset = '')
#
# if (nchar(db_url) == 0)  stop('DATABASE_URL is required')
# if (nchar(api_key) == 0) stop('API_SECRET_KEY is required')
#
# Fail fast at startup rather than failing silently at request time
cat('Validate all required env vars at startup with stop()
')

ヘルスチェックエンドポイント

# #* Health check
# #* @preempt auth
# #* @get /ping
# function() {
#   list(
#     status  = 'ok',
#     version = '1.0.0',
#     time    = format(Sys.time(), '%Y-%m-%dT%H:%M:%SZ')
#   )
# }
#
# Docker HEALTHCHECK:
# HEALTHCHECK CMD curl -f http://localhost:8000/ping || exit 1

Dockerfileの完全な例

# FROM rocker/r-ver:4.3.2
# RUN apt-get update && apt-get install -y libssl-dev libcurl4-openssl-dev \
#  && rm -rf /var/lib/apt/lists/*
# RUN Rscript -e "install.packages(c('plumber','jsonlite'), repos='https://cloud.r-project.org')"
# WORKDIR /app
# COPY routes.R api.R ./
# EXPOSE 8000
# HEALTHCHECK CMD curl -f http://localhost:8000/ping || exit 1
# CMD ["Rscript", "api.R"]

本番環境でのロギング

# Log format: ISO timestamp + level + message
log_info <- function(msg) {
  cat(format(Sys.time(), '%Y-%m-%dT%H:%M:%S'), '[INFO]', msg, '
')
}

log_info('API starting up')
log_info(paste('Port:', Sys.getenv('PORT', '8000')))

Nginxによるリバースプロキシ

# Nginx config snippet (nginx.conf):
# server {
#   listen 443 ssl;
#   ssl_certificate     /etc/letsencrypt/.../fullchain.pem;
#   ssl_certificate_key /etc/letsencrypt/.../privkey.pem;
#
#   location /api/ {
#     proxy_pass         http://127.0.0.1:8000/;
#     proxy_set_header   Host $host;
#     proxy_set_header   X-Real-IP $remote_addr;
#   }
# }

クイックチェック：Docker EXPOSE

Plumber APIのデプロイのまとめ