dummy-cargo-toml-creater for docker cache
It's nice to have Docker build, but I just want to cache dependent packages.
But to do that, first write COPY Cargo.toml Cargo.lock. / To Dockerfile,
It's nice to build, but every time the version of the package itself goes up, for example, the hash of Cargo.toml or Cargo.lock changes.
Even a minor bug fix, the dependency package has to be rebuilt.
So we introduce a technique called dummy-cargo-toml-creater.
Just look at the source . / Src / main.rs, but it's only 70 lines of code.
We have implemented only the minimum implementation so as not to do anything extra or suspicious.
In other words, with the approach of not changing the versions of Cargo.toml and Cargo.lock,
The only fix is to fix the package version with 0.1.0 only when installing dependencies.
The final image is built with the original Cargo.toml and Cargo.lock, so There is no problem with the version of the cargo package in the binary, and if you add a dependency package, docker's cache will also work and not work.
Docker buildするのはいいんだが、依存パッケージだけキャッシュさせたい。
しかしそれをするためにDockerfileに最初に COPY Cargo.toml Cargo.lock ./ とか書いて、
ビルドするのはいいんだが、例えばそのpackage自体のversionが上がるたびに Cargo.toml または Cargo.lock のハッシュが変更され、
ほんの些細なバグfixでも依存パッケのビルドし直し・・・なんて面倒なんだ。
そこで dummy-cargo-toml-creater という手法を紹介する。
これはソース ./src/main.rs をみてくれればいいが、たった70行のコードだ。
余計なことや怪しいことはしてないよう、最低限の実装しかしていない。
つまり、Cargo.tomlとCargo.lockのversionを変えなければいいというアプローチで、
依存関係のインストール時のみパッケージバージョンを 0.1.0 で常に固定して解決しようと事だ。
最終的なイメージでは元のCargo.tomlとCargo.lockでビルドするので、 バイナリ内のcargoパッケージのバージョンには問題無く、仮に依存パッケージを追加した時はまたdockerのキャッシュは使用されずに上手くいく。
bash
$ cargo install dummy-cargo-toml-creater
1-a. maybe write gitignore DummyVersion.toml/lock
bash
$ echo DummyVersion.toml >> ./.gitignore
$ echo DummyVersion.lock >> ./.gitignore
bash
$ ~/.cargo/bin/dummy-cargo-toml-creater
$ ls ./DummyVersion.toml
./DummyVersion.toml
$ ls ./DummyVersion.lock
./DummyVersion.lock
old ```Dockerfile FROM ekidd/rust-musl-builder:nightly-2019-04-25 as builder
RUN mkdir /tmp/app WORKDIR /tmp/app COPY . . RUN sudo chown -R rust:rust . RUN cargo build --release ```
new ```Dockerfile FROM ekidd/rust-musl-builder:nightly-2019-04-25 as builder
RUN mkdir /tmp/app WORKDIR /tmp/app
COPY DummyVersion.toml ./Cargo.toml COPY DummyVersion.lock ./Cargo.lock RUN mkdir -p src/ && \ touch src/lib.rs RUN sudo chown -R rust:rust . RUN cargo build --release
COPY ./src/ ./src/ COPY Cargo.toml ./Cargo.toml COPY Cargo.lock ./Cargo.lock RUN sudo chown -R rust:rust . RUN cargo build --release ```
Run docker build
bash
$ $ docker build -t nnao45/dummy .
[+] Building 119.7s (18/18) FINISHED
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 584B 0.0s
=> [internal] load metadata for docker.io/ekidd/rust-musl-builder:nightly-2019-04-25 2.5s
=> [1/12] FROM docker.io/ekidd/rust-musl-builder:nightly-2019-04-25@sha256:e12231fc754848ccf3865d1e4e80204125c6d77baaa9 0.0s
=> CACHED [2/12] RUN mkdir /tmp/app 0.0s
=> CACHED [internal] helper image for file operations 0.0s
=> [internal] load build context 0.1s
=> => transferring context: 24.98kB 0.0s
=> [3/12] COPY DummyVersion.toml ./Cargo.toml 0.7s
=> [4/12] COPY DummyVersion.lock ./Cargo.lock 0.9s
=> [5/12] RUN mkdir -p src/ && touch src/lib.rs 1.6s
=> [6/12] RUN sudo chown -R rust:rust . 0.7s
=> [7/12] RUN cargo build --release 99.0s
=> [8/12] COPY ./src/ ./src/ 0.8s
=> [9/12] COPY Cargo.toml ./Cargo.toml 1.2s
=> [10/12] COPY Cargo.lock ./Cargo.lock 0.8s
=> [11/12] RUN sudo chown -R rust:rust . 4.0s
=> [12/12] RUN cargo build --release 2.7s
=> exporting to image 4.2s
=> => exporting layers 4.1s
=> => writing image sha256:e95b11c44810ef4abc3e5a18998b4ba20df9871d5dbcfdbf7a656d992e802857 0.0s
=> => naming to docker.io/nnao45/dummy 0.0s
Fix Cargo.toml ```bash $ vi Cargo.toml
version = "0.0.2" ```
Reun docker build
bash
$ docker build -t nnao45/dummy .
[+] Building 14.2s (18/18) FINISHED
=> [internal] load build definition from Dockerfile 0.1s
=> => transferring dockerfile: 44B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/ekidd/rust-musl-builder:nightly-2019-04-25 2.5s
=> [1/12] FROM docker.io/ekidd/rust-musl-builder:nightly-2019-04-25@sha256:e12231fc754848ccf3865d1e4e80204125c6d77baaa9 0.0s
=> CACHED [internal] helper image for file operations 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 11.46kB 0.0s
=> CACHED [2/12] RUN mkdir /tmp/app 0.0s
=> CACHED [3/12] COPY DummyVersion.toml ./Cargo.toml 0.0s
=> CACHED [4/12] COPY DummyVersion.lock ./Cargo.lock 0.0s
=> CACHED [5/12] RUN mkdir -p src/ && touch src/lib.rs 0.0s
=> CACHED [6/12] RUN sudo chown -R rust:rust . 0.0s
=> CACHED [7/12] RUN cargo build --release 0.0s
=> CACHED [8/12] COPY ./src/ ./src/ 0.0s
=> [9/12] COPY Cargo.toml ./Cargo.toml 0.5s
=> [10/12] COPY Cargo.lock ./Cargo.lock 0.9s
=> [11/12] RUN sudo chown -R rust:rust . 1.7s
=> [12/12] RUN cargo build --release 6.0s
=> exporting to image 1.6s
=> => exporting layers 1.5s
=> => writing image sha256:7904fe7a43ea67e850591d7b6c0b827a97be625b0be447fa028d0e011a2a3cb8 0.0s
=> => naming to docker.io/nnao45/dummy 0.0
chache it!!