cloudlena / healthcheck

A minimal health checked Docker base image

Healthcheck

A base image for minimal Docker images. It is an extension of scratch that contains a built in HTTP health check and encourages non-privileged execution. This image only adds about 2.8M to scratch and is intended for running HTTP services written in languages that compile to a binary format (e.g. Go or Rust).

Advantages

• Your binary will be executed using the non privileged app user
• A HTTP health check is run every 30 seconds

Usage

Rust

FROM rust:1 AS builder
WORKDIR /usr/src/myapp
COPY . .
RUN cargo build --release

FROM cloudlena/healthcheck:latest
WORKDIR /usr/myapp
COPY --from=builder /usr/src/app/target/release/myapp .
EXPOSE 8080
ENTRYPOINT ["./myapp"]

You can add the following lines to your Cargo.toml file to further minimize the size of the final image:

[profile.release]
opt-level = "z"
lto = true

Go

FROM golang:1 AS builder
WORKDIR /usr/src/myapp
COPY . .
RUN CGO_ENABLED=0 go build -ldflags="-s -w" -a -installsuffix cgo -o bin/myapp ./cmd/myapp

FROM healthcheck:latest
WORKDIR /usr/myapp
COPY --from=builder /usr/src/myapp/myapp .
EXPOSE 8080
ENTRYPOINT ["./myapp"]

Customize

You can set the following environment variables in your container to customize the health check:

• PORT: The port your app is listening on. Defaults to 8080.
• HEALTHCHECK_PATH: The health check path of your app. Defaults to /.